Wmi Alhap Final Report 2008

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Weather Modification Inc. October 2008


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Alberta Hail Suppression Project 2008 Final Report Page: 2



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ALBERTA HAIL SUPPRESSION PROJECT

FINAL REPORT2008

Terry W. Krauss, [email protected]

Editor

A Program forSeeding Convective Cloudswith Glaciogenic Nuclei to

Mitigate Urban Hail Damage in theProvince of Alberta, Canada

by

Weather Modification Inc.3802 - 20thStreet North

Fargo, North DakotaU.S.A. 58102

www.weathermod.com

for

Alberta Severe Weather Management SocietyCalgary, Alberta

Canada

October 2008
mailto:[email protected]:[email protected]


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EXECUTIVE SUMMARY

This report summarizes the activities during the 2008 field operations of the Alberta Hail SuppressionProject. This was the thirteenth year of operations by Weather Modification Inc. (WMI) of Fargo, NorthDakota under contract with the Alberta Severe Weather Management Society of Calgary, Alberta.2008 was the third year of the third 5-year contract cycle for this on-going program that started in1996. The program continues to be funded entirely by private insurance companies in Alberta with the

sole intent to mitigate the damage to urban property caused by hail.

The cloud-seeding project was made an on-going program in 2001 because the insurance losses dueto hail were approximately 50% less than expected during the first five-year contract period 1996-2000. Calgary and Red Deer have seen >30% increases in population in the last 10 years, and theproperty values have more than doubled during this time. Calgarys population exceeded 1 million twoyears ago. A similar hail storm that caused $400 million damage in Calgary in 1991 would almostcertainly now cause more than $1 billion damage today. Several billion dollar hail storms haveoccurred in the USA in the last 5 years. The project design has remained the same throughout theperiod, except that a fourth seeding aircraft was added to the project this summer to improve seedingcoverage on bad storm days. The program was operational from June 1st to September 15th, 2008and only storms that posed a hail threat to an urban area, as identified by the projects weather radarsituated at the Olds-Didsbury Airport, were actually seeded. The project target area covers the regionfrom High River in the south to Lacombe in the north, with priority given to the two largest cities ofCalgary and Red Deer.

2008 was an above average summer for large hail inside the project area and outside the projectarea. Hail was reported within the project area on 41 days this past summer. Larger than golf ballsize hail fell on July 9th west of Crossfield. Golf ball size hail was reported on June 17th west ofLacombe, July 4th near Caroline, July 6th west of Carstairs, July 9th near Lacombe, July 13th nearRocky Mountain House and Three Hills, July 26th west of Olds, and on August 8th in Red Deer.Walnut size hail was reported on two other days (July 18 and 27).

For the entire Province of Alberta, the Alberta Agriculture Financial Services Corporation in Lacombereported hail damage to crops on 86 days (1 day in May, 23 days in June, 27 days in July, 22 days in

August, and 13 days in September). Golf ball size hail was reported outside the project area on 4additional days (July 10, 15, 16, and Aug 21). Data from crop insurance claims indicates that crop

damage in 2008 was approximately double the historical average and one of the worst years onrecord.

In general, the weather in the project area this summer was cool and wet in June, and then warmerand humid during July, and then relatively hot and dry in August. There were an above averagenumber of days with high humidity in July which provided the atmospheric conditions for very severethunderstorms. There were thunderstorms reported within the project area on 75 days this summerand this was the highest frequency of thunderstorm days since the project started tracking thesestatistics in 1996. The number of hail days and days with large hail (greater than walnut size) wasalso above average.

A highlight of the season was WMIs participation in a research project called UNSTABLE(Understanding Severe Thunderstorms and Alberta Boundary Layers Experiment) from July 9-23, and

based at the Olds radar site. UNSTABLE was a field study designed to improve our understanding ofprocesses leading to convective initiation and severe thunderstorm development over the Albertafoothills. The field component of UNSTABLE was designed in two parts, a pilot field study in 2008(July 9-23, 2008) and a larger, full-scale experiment planned for 2011. The purpose of the 2008 pilotproject was to test critical instrumentation and measurement strategies to answer some keyUNSTABLE science questions. Hailstop-1 was outfitted with special instrumentation to measuretemperature, humidity, and wind in the boundary layer, as well as cloud physics probes to measurecloud particle characteristics. Results from the pilot project will be used to refine the science overviewand operations plan for the full-scale project in 2011. Through UNSTABLE we ultimately aim toimprove the accuracy and timeliness of summertime severe weather watches and warnings, assessthe ability of the numerical models of Environment Canada to resolve relevant processes and provide


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useful numerical guidance, and refine existing conceptual models for severe thunderstormdevelopment over Alberta and the western Canadian prairies. The project was largely funded byEnvironment Canada with participation by the Universitys of Alberta, Calgary, and Manitoba plusWeather Modification Inc.

During this season, there were 112 aircraft flights totaling 194.7 flight hrs on 48 days with operations.A total of 56 storms were seeded during 54 seeding flights (127.3 hrs) on 26 days on which seedingtook place. There were 17 patrol flights (25.2 hrs), 23 test flights (19.3 hrs), and 6 public relations

flights (1.6 hrs). There were 12 special research flights (21.3 hrs) using Hailstop 1 (N234K) for theUNSTABLE research project during July. The amount of silver-iodide nucleating agent dispensedduring the 2008 field season totaled 122.942 kg: consisting of 1648 ejectable (cloud-top) flares (32.96kg seeding agent), 548 end-burning (cloud-base) flares (82.2 kg seeding agent), and 113.5 gallons of

AgI-acetone solution (7.782 kg seeding agent).

Four specially equipped cloud seeding aircraft were dedicated to the project. One Piper Cheyenne IIand a Cessna 340A were based in Calgary, and a Beech King Air C90 and C340 were based in RedDeer. The procedures used in 2008 remained the same as for the previous years, except for the oneadditional C340 airplane in Red Deer. The Calgary office and aircraft were stationed at the formerMorgan Air hangar at the Calgary International Airport. A WMI Red Deer office was set up in the

AvTech hangar at the Red Deer Regional Airport (formerly Hillman Air).

The aircraft and crews provided a 24-hr service, seven days a week throughout the period. Eight full-time pilots and three meteorologists were assigned to the project this year. Three pilots in Red Deerwere sub-contracted from Sky Wings Aviation Academy. In addition, former WMI cloud seeding pilots(Gavin Lange, Craig Lee, Ben Hiebert, and Mark Friel), presently working in Alberta for othercompanies, were used on their days off or during special leave to fly on the project. Four other pilotswere also trained during the summer and served as captains and co-pilots for short periods. Overall,the personnel, aircraft, and radar performed exceptionally well and there were no interruptions ormissed opportunities in the service. High speed Internet was once again installed at the Calgary andRed Deer offices for the pilots so that they could closely monitor the storm evolution and storm motionusing the radar images on the web.

Numerous public relations activities occurred this year. Dr. Terry Krauss was interviewed by GlobalTV on July 7th and by City TV and CBC TV on July 8th. The Weather Network visited the radar and

flew on Hailstop 1 on July 9th. The Discovery Channel flew on Hailstop 1 on July 17th. A journalistfrom the BBC in London visited the radar and Calgary office on June 10th. Axa Pacific Insurance senttwo groups, of 11 and 14 persons respectively, to the radar site on September 2nd and 9th. All of themedia coverage was positive.

All of the projects radar data, meteorological data, and reports have been recorded onto a portablehard drive as a permanent archive for the Alberta Severe Weather Management Society. These datainclude the daily reports, radar maps, aircraft flight tracks, as well as meteorological charts for eachday. These data can be made available for outside research purposes through a special request tothe Alberta Severe Weather Management Society.

A formal statistical evaluation of the hail suppression program is still not possible without acquiringmore comprehensive, detailed, high resolution property insurance claim data. Preliminaryassessments from unofficial reports within the insurance industry indicate that the program has been afinancial success but this has not been verified. The crop-damage statistics, however, do not indicatea reduction in hail for the target area. Furthermore, there appears to be a trend towards increasinghail within the target area over the past few years, and this is expected to continue into the nearfuture, especially if La Nina conditions continue. The fact that the crop damage data does not show areduction in crop damage within the target area may be explained by the fact that hailstorms are notseeded if they do not threaten a town or city. This also means that any reduction in propertyinsurance payouts is not due to climate change since there has been an increase in storm activity.


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The 2008 field operations ran quite smoothly and, once again, there are no major recommendationsfor program improvements or upgrades. The following recommendations are presented forconsideration by the ASWMS and WMI senior management next year.

It has been 13 years since the program started. There are many new people in the insuranceindustry in Central Alberta who are not familiar with the history of the program and details ofthe current cloud seeding project. Two very successful information seminars were given atthe Olds radar site for the staff of the AXA Pacific Insurance Company this past summer. It isrecommended that similar information seminars be given as part of the Alberta InsuranceCouncil accreditation program. The intent of this training course would be to inform theinsurance industry about the background, organization, and methodology of the cloud seedingproject so that support for the program can continue based on current and accurateinformation.

Finding sufficient, qualified pilots continues to be a challenge for the program. Advertising andrecruiting of pilots should be started earlier next spring. Application for Foreign Work Permitsfor US pilots should also begin early next spring since we now have ample justification todemonstrate shortages of qualified staff in Alberta based on our experiences in the past,especially 2007 and 2008. Another possibility is to investigate sub-contracting pilots fromlocal aviation companies (e.g. Morgan Air and Sky Wings Aviation Academy) since thesecompanies offer job security and have become employers of our former pilots in the past.

There continues to be a need for more detailed property damage data in order to assess the

effectiveness of the seeding program. Several of the larger insurance companies have beencontacted to request detailed property damage data. The intent is to conduct an anonymousassessment of trends in the loss-to-risk ratios of property damage so that insight into thefinancial effectiveness of the program may be determined.

T. W. Krauss, Ph.D.October 2008


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ACKNOWLEDGMENTS

WMI wishes to acknowledge the continuing, kind support of Todd Klapak (President) and CatherineJanssen (Chief Financial Officer) and the entire Board of Directors of the Alberta Severe WeatherManagement Society (ASWMS). The understanding, support, and cooperation of the ASWMS aregreatly appreciated.

A number of organizations and people deserve recognition and thanks. The cooperation of thesepeople and agencies are very important to make the project a success and much more enjoyable.

The cooperation of NAV Canada is greatly appreciated and acknowledged. Several personsdeserve special recognition: Richard Hubbs of the Edmonton Area Control Center; and MarkMcCrea, Scott Young, and Brent Lopushinsky of the Calgary Terminal Air Operations. Theexcellent cooperation by the ATC once again played a very important role in allowing theproject pilots to treat the threatening storms in an efficient and timely manner as required,often directly over the city of Calgary.

Rob Cruickshank, Alberta Financial Services Corp. (AFSC) in Lacombe is thanked forproviding the crop insurance information.

For the thirteenth year, special thanks go to Bob Jackson for sharing his office and hangar atthe Olds-Didsbury airport, used for the radar and communications control center.

Tim Morgan and Gavin Lange of Morgan Air are sincerely thanked for their cooperation andassistance in providing very scarce office and ramp space at the Calgary airport this season,and for providing cloud seeding pilots and aircraft maintenance when required.

Dennis Cooper of Sky Wings Aviation Academy in Red Deer is acknowledged for providingco-pilots in Red Deer and for providing support for the Red Deer operations in general.

Neil Taylor (Environment Canada, Edmonton) and Craig Smith (Enivornment Canada,Saskatoon) are thanked for their co-operation, assistance and support during the UNSTABLE

research program.

WMI wishes to acknowledge the contributions of the staff who served on the project during thesummer of 2008: meteorologists (Jason Goehring and Dr. Viktor Makitov), electronics-radar technicianBarry Robinson, pilots in command (Robert Gorman, Zac Glass, Joe Wiley, Jeff Allen, Joel Zimmer,Daniel Haines, Craig Lee, Jason Schellenbaum, Ben Heibert, Mark Friel, and Michael Plouffe); the co-pilots (Steward Van Male, Conlan Besner, Aaron Cyman, Athena Chapman, and Treena King), andthe aircraft maintenance engineers (Gary Hillman and Dale Campbell). The staff performed very wellas a team. The support of the WMI corporate head office in Fargo ND is acknowledged, specifically:Patrick and James Sweeney, Randy Jenson, Hans Ahlness, Jody Fischer, Bruce Boe, Dennis Afseth,Cindy Dobbs, Mark Grove, Erin Fischer, and Mike Clancy are gratefully acknowledged.


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Figure 1: Jim Sweeney (WMI Vice President ) and Dr. Terry Krauss (WMI VP and ProjectManager).

Figure 2: Meteorologists Jason Goehring and Dr. Viktor Makitov.


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Figure 3: Gary Hillman (Airc raft Maintenance) and Barry Robinson (Electronics Maintenance).

Figure 4: Instructor Pilots Jody Fischer and Zac Glass.


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Figure 5: Pilots Jeff Allen and Joel Zimmer.

Figure 6: Pilots Robert Gorman and Joe Wiley.


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Figure 7: Pilots Steward Van Male and Aaran Cyman.

Figure 8: Pilots Conlan Besner and Jason Schellenbaum.


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Figure 9: Pilots Ben Hiebert and Michael Plouffe.

Figure 10: Pilots Athena Chapman and Treena King.


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TABLE OF CONTENTS

EXECUTIVE SUMMARY.............................................................................................................................. 4

ACKNOWLEDGMENTS............................................................................................................................... 7

TABLE OF CONTENTS............................................................................................................................. 13

LIST OF FIGURES ..................................................................................................................................... 15

LIST OF TABLES....................................................................................................................................... 16

INTRODUCTION ........................................................................................................................................ 17

THE 2008 FIELD PROGRAM .................................................................................................................... 18

PROJECT OBJECTIVES ........................................................................................................................... 19

PRIORITIES ............................................................................................................................................... 20

CONCEPTUAL HAIL MODEL ................................................................................................................... 22

HAIL SUPPRESSION HYPOTHESIS............................................................................................................... 22PRECIPITATION EFFICIENCY....................................................................................................................... 24

OPERATIONS PLAN ................................................................................................................................. 25

ONSET OF SEEDING .................................................................................................................................. 25IDENTIFICATION OF HAIL PRODUCING STORMS............................................................................................ 26CLOUD SEEDING METHODOLOGY............................................................................................................... 26NIGHT TIME SEEDING ................................................................................................................................ 27STOPPING SEEDING .................................................................................................................................. 27SEEDING RATES ....................................................................................................................................... 27SEEDING MATERIALS................................................................................................................................. 28FLARE EFFECTIVENESS TESTS .................................................................................................................. 30

Summary Of CSU Tests..................................................................................................................... 31PROGRAM ELEMENTS AND INFRASTRUCTURE................................................................................. 32

GROUND SCHOOL ................................................................................................................................... 33

PUBLIC RELATIONS................................................................................................................................. 33

UNSTABLE (UNDERSTANDING SEVERE THUNDERSTORMS AND ALBERTA BOUNDARYLAYERS EXPERIMENT)............................................................................................................................ 34

FLIGHT OPERATIONS .............................................................................................................................. 38

AIR-TRAFFIC CONTROL ............................................................................................................................. 38

CLOUD SEEDINGAIRCRAFT ....................................................................................................................... 40Piper Cheyenne II ............................................................................................................................. 40Beech King-Air C90.......................................................................................................................... 41C340A Aircraft .................................................................................................................................. 41

RADAR CONTROL AND COMMUNICATIONS CENTER........................................................................ 43

RADAR....................................................................................................................................................... 44

RADAR CALIBRATION CHECKS ................................................................................................................... 46

AIRCRAFT TRACKING GLOBAL POSITIONING SYSTEM (GPS) ......................................................... 48


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SUMMARY OF SEEDING OPERATIONS................................................................................................. 48

FLIGHTS ................................................................................................................................................... 49SEEDINGAMOUNTS................................................................................................................................... 49COMPARISON OF 2008WITH PREVIOUS YEARS .......................................................................................... 50STORM TRACKS ........................................................................................................................................ 55

WEATHER FORECASTING ...................................................................................................................... 56

CONVECTIVE DAY CATEGORY (CDC)......................................................................................................... 56COORDINATED UNIVERSAL TIME ................................................................................................................ 57DAILY BRIEFINGS ...................................................................................................................................... 57METEOROLOGICAL STATISTICS .................................................................................................................. 57FORECASTING PERFORMANCE................................................................................................................... 59THE HAILCAST MODEL .............................................................................................................................. 62JULY 27TH,2008CASE STUDY:ASEVERE STORM OVER CALGARY.............................................................. 63CLIMATE PERSPECTIVES ........................................................................................................................... 65EL NIO/SOUTHERN OSCILLATION (ENSO)DISCUSSION ............................................................................ 68

ALBERTA CROP HAIL INSURANCE RESULTS ................................................................................................ 69CONCLUSIONS AND RECOMMENDATIONS.................................................................................................... 71

REFERENCES AND RECOMMENDED READING .................................................................................. 72

APPENDICES............................................................................................................................................. 76

A. ORGANIZATIONCHART .............................................................................................................. 77B. DAILYWEATHERANDACTIVITIESSUMMARYTABLE2008 .................................................... 78

AIRCRAFT FLIGHT SUMMARY:............................................................................................................... 92

C. AIRCRAFTOPERATIONSFLIGHTSUMMARY2008 ................................................................ 112D. FLIGHTSUMMARYTABLE2008................................................................................................ 114E. FORMS........................................................................................................................................ 118F. SPECIFICATIONSFORPIPERCHEYENNEIIAIRCRAFT ........................................................ 122G. SPECIFICATIONSFORBEECHCRAFTKINGAIRC90AIRCRAFT .......................................... 123H. SPECIFICATIONSFORCESSNAC-340AIRCRAFT ................................................................. 124I. GROUNDSCHOOLAGENDA..................................................................................................... 125J. WMIAIRBORNEGENERATORSEEDINGSOLUTION.............................................................. 126K. DAILYMETEOROLOGICALFORECASTSTATISTICS2008..................................................... 127L. PROJECTPERSONNELANDTELEPHONELIST ..................................................................... 131


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LIST OF FIGURES

Figure 1: Jim Sweeney (WMI Vice President) and Dr. Terry Krauss (WMI VP and Project Manager)................8

Figure 2: Meteorologists Jason Goehring and Dr. Viktor Makitov. ......................................................................8

Figure 3: Gary Hillman (Aircraft Maintenance) and Barry Robinson (Electronics Maintenance).......................9

Figure 4: Instructor Pilots Jody Fischer and Zac Glass. .......................................................................................9

Figure 5: Pilots Jeff Allen and Joel Zimmer........................................................................................................10

Figure 6: Pilots Robert Gorman and Joe Wiley. ..................................................................................................10

Figure 7: Pilots Steward Van Male and Aaran Cyman........................................................................................11Figure 8: Pilots Conlan Besner and Jason Schellenbaum. ..................................................................................11

Figure 9: Pilots Ben Hiebert and Michael Plouffe...............................................................................................12

Figure 10: Pilots Athena Chapman and Treena King. .........................................................................................12

Figure 11: The average number of hail days per year, based on the 19511980 climate normals of Environment

Canada (1987) and taken from Etkin and Brun (1999).........................................................................................17

Figure 12: Map of southern Alberta showing the project target area (Figure courtesy J. Renick).....................20

Figure 13: The conceptual model of hailstone formation and hail mitigation processes for Alberta (adapted

from WMO, 1995). This schematic figure shows the cloud seeding methodology at feeder cloud tops and cloud-

base for a mature hailstorm...................................................................................................................................23

Figure 14: A three-dimensional schematic figure of an Alberta hailstorm, showing the cloud seeding

methodology within the new growth zone..............................................................................................................24

Figure 15: Precipitation efficiency for High Plains convective storms. Known supercell hailstorms are labeled

S. Storms that produced rain only are labeled R (Browning, 1977).....................................................................25Figure 16: A photo of a cloud seeding plane dropping ejectable flares during a cloud seeding penetration

(photo courtesy John Ulan). ..................................................................................................................................27

Figure 17: Photograph of a burning BIP flare.....................................................................................................28

Figure 18: Pilot Joel Zimmer attaching the ejectable flare racks on the belly of the King Air C90 seeding

aircraft designated as Hailstop 3...........................................................................................................................29

Figure 19: Burn-in-place (BIP) flares on the wing of HailStop-1.........................................................................29

Figure 20: Yield of ice crystals (corrected) per gram of pyrotechnic versus cloud supercooling temperature

(T


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Figure 35: WMI-NCAR CIDD display showing radar reflectivity data and topography. A vertical cross-section

and clear-air outflow boundary are also shown....................................................................................................44

Figure 36: WMI C-band radar at the Olds-Didsbury airport. .............................................................................45

Figure 37: Radar calibration of RDAS digital counts to equivalent radar reflectivity power (dBZ) for the WMI

radar at Olds-Didsbury during the 2008 field season...........................................................................................47

Figure 38: Aircraft Global Positioning System (GPS) flight tracks, and real-time information via the AIRLINK

telemetry system on July 26, 2008. ........................................................................................................................48

Figure 39: The frequency of occurrence and cumulative distributions of aircraft take-off and landing times for

all flights as a function on time during 2008. ........................................................................................................49Figure 40: Amount of seeding material dispensed per operational day in 2008. ................................................50

Figure 41: Map of all hailstorm tracks during 2008............................................................................................55

Figure 42: Maximum Reflectivity map for the storms on 27-July-2008. ...............................................................64

Figure 43: Aircraft tracks for Hailstop 1(green), 2(white), 3(blue), and 4(yellow) on 27-July-2008..................65

Figure 44: Daily and accumulated rainfall for Calgary from Oct. 21, 2007 to Oct. 21, 2008. ............................66

Figure 45: Daily and accumulated rainfall for Red Deer from Oct. 21, 2007 to Oct. 21, 2008. ..........................66

Figure 46: Departures from normal Precipitation during the summer of 2008 in Canada..................................67

Figure 47: Departures from normal Temperature during the summer of 2008 in Canada. .................................67

Figure 48: Pacific Ocean sea surface temperature (SST) anomalies for the period October 2007 to October

2008. ......................................................................................................................................................................68

Figure 49: Alberta Financial Services Corp. straight hail insurance loss-to-risk ratio and loss-ratio statistics for

the entire Province of Alberta from 1978 to 2008. ................................................................................................69

Figure 50: Alberta Financial Services Corp. straight hail insurance loss-to-risk ratio trend analysis from 1978

to 2008 for the entire Province of Alberta, separating the periods into before WMI seeding prior to 1996 and

after WMI seeding from 1996 to 2008...............................................................................................................69

Figure 51: Alberta Agriculture Financial Services Corp hail insurance loss-to-risk statistics from 1981 to 2008

for the municipalities in the Target Area, Downwind, North and South of the project area.................................70

LIST OF TABLES

Table 1: Canadian census figures (2006 versus 2001) for the largest towns and cities in the project area........21

Table 2: Yield results of ICE flares........................................................................................................................30

Table 3: Characteristic times for effective ice nuclei depletion and rate data. (LWC = 1.5 g m-3

points are

average values)......................................................................................................................................................31Table 4: A list of special research flights conducted for UNSTABLE. ..................................................................37

Table 5: Radar parameter calibration values for the ALBERTA-WMI WR100. ...................................................46

Table 6: Radar transmitted power calibration values measured during the 2008 season. ...................................46

Table 7: Operational Statistics for 1996 to 2008. .................................................................................................52

Table 8: Cloud seeding flares usage comparison by aircraft. EJ refers to 20 gm ejectable AgI flares. BIP refers

to 150 gm burn-in-place AgI flares. The AgI solution burn rate is 2.5 gal per hour. ..........................................53

Table 9: Description of Convective Day Category (CDC) Index..........................................................................56

Table 10: Summary of daily atmospheric parameters used as inputs for the daily forecast of the CDC during

2008. ......................................................................................................................................................................58

Table 11: Summary of daily forecast atmospheric parameters on 41 hail days during 2008..............................59

Table 12: Table of the Observed versus Forecast days with Hail and No-Hail for the summer of 2008.............60

Table 13: Table of Forecast versus Observed CDC daily values 2008................................................................61

Table 14: Annual Summary of Convective Day Categories (CDC)......................................................................61Table 15: Table of Forecast versus Observed CDC daily values using HAILSCAST during the summer of 2008.

...............................................................................................................................................................................62

Table 16: Probability of detection (POD). false alarm ratio (FAR) and critical success index (CSI) performance

of HAILCAST and WMI from 2002 to 2008. .........................................................................................................63


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INTRODUCTION

Hailstorms pose a serious threat to property and crops in the province of Alberta. Historically, claimsfor agricultural hail damage are received on an average of 50 days each year between 1 June and 10September (Summers and Wojtiw, 1971). The most recent climatology of hail in Canada waspublished by Etkin and Brun (1999) in the International Journal of Climatology. The average number

of hail days per year, based on the 19511980 climate normals (Environment Canada, 1987) is shownin Figure 11. The contours were hand drawn, based primarily upon about 350 weather stations. Thehighest frequency of hail in Canada occurs in Alberta between the North Saskatchewan River and theBow River, immediately downwind of the Rocky Mountain foothills. This region is often referred to ashail alley.

Figure 11: The average number of hail days per year, based on the 19511980 climate normalsof Envi ronment Canada (1987) and taken from Etkin and Brun (1999).

Etkin and Brun (1999) point out that the period 19771993 was associated with substantial increasesin hail-observing stations. As the 19511980 hail climatology was mostly based on pre-1977 data, ithad a relatively coarse resolution in comparison. An updated Alberta hail climatology for 19771993has since been completed. It has a greater resolution than the national climatology, and shows theimportance of some topographical features, such as the Rocky Mountains. The influence of localtopographical features on mesoscale hail frequency is a major control. After 1982, hail frequencies in

Alberta showed a significant increase. The City of Calgary is in a region that normally gets between 3and 4 hailstorms each year.


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By overlaying the hail frequency map with the population density map, the region of greatest financialrisk to insurance companies covers the area from Calgary to Red Deer and Rocky Mountain House.For this reason, this is the region that was selected as the target area for the hail suppressionprogram.

Insurance claims due to hailstorms in urban areas worldwide have generally escalated over the past10 years. Denver Colorado was pounded by golf-ball to tennis-ball sized hail on July 11, 1990, anddamages reached a record (for the U.S.A. at that time) $625 million. In Canada, the damagesassociated with the severe hailstorm that struck Calgary on September 7, 1991 exceeded $416 million(Insurance Bureau of Canada, 2004). Insured claims from the hailstorm that struck Sydney Australiaon April 14, 1999 were approximately $1.5 billion, making it the most damaging event in Australianinsurance history. A study by Herzog (2002) compiled and summarized the hailstorm damages in theUSA for the period 1994-2000 for the Institute for Business and Home Safety (IBHS). Verified haillosses amounted to $2.5 Billion per year, with the actual amount possibly being 50% higher. Personalbuilding losses totalled $11.5 Billion (66%), commercial building losses totalled $2.7B (15%), andvehicles accounted for $3.3B (19%). More recently, the most damaging hailstorm ever recorded in theUSA moved from eastern Kansas to southern Illinois on 10 April 2001, depositing 2.5 to 7.5 cm-diameter hailstones along a 585 km path, over portions of the St. Louis and Kansas City urban areascollectively created $1.9 billion in damage claims from a 2-day period, becoming the ninth most costlyweather catastrophe in the United States since property insurance records began in 1949 (Changnonand Burroughs, 2003).

Estimates of the average annual crop loss to hail have also continued to increase with time, from $50million annually in 1975 (Renick, 1975) to more than $150 million annually during the period 1980 -1985 (Alberta Research Council, 1986). Actual insured crop losses are typically in the $80M rangeannually.

The new Alberta Hail Suppression Project was initiated in 1996 as a result of the increased frequencyof damaging hailstorms in Alberta, compounded by an increasing population inside an area of highstorm frequency. It is the first project of its kind in the World to be entirely funded by private insurancecompanies with the sole objective of reducing the damage to property by hail. At this time, AlbertaCrop Insurance and the Provincial and Federal Governments do not contribute financially to theproject, although they stand to benefit from the seeding.

Weather Modification Inc. (WMI) has been a leader in the field of hail suppression since the early1960's. With extensive knowledge and experience in the cloud seeding industry, WMI is best knownfor its successful hail suppression operations in the northern Great Plains and other cloud modificationservices around the world e.g. Argentina, Mexico, India, Indonesia, Mali and Saudi Arabia. WMI wasawarded the first contract to conduct the Alberta Hail Suppression Project in April 1996 by the AlbertaSevere Weather Management Society. The project was made an ongoing program of the Albertainsurance industry in 2001 because of the drop in hail damage costs in Alberta, counter to the trend inthe rest of the country and the World. The contract calls for the provision of all personnel andequipment for a turnkey system of cloud seeding and related services for the purpose of reducing haildamage to property in south-central (Calgary to Red Deer) Alberta. The organization chart of theproject is shown in Appendix A.

THE 2008 FIELD PROGRAM

In 2008, WMI conducted the operational cloud-seeding program from June 1st to September 15th.The project is based upon the conceptual model, methodology, and research results of the long-termhail research project conducted by the Alberta Research Council from the late 1960s through 1985(Alberta Research Council, 1986) and by WMI in North Dakota (Smith et al, 1997). The presentprogram utilizes the latest cloud seeding technology available, incorporating several notableimprovements over previous projects in the province. These improvements include:

New fast-acting, high-yield mixtures for the silver-iodide flares and acetone solution. The flaresare manufactured by Ice Crystal Engineering (ICE) of North Dakota. The new generation ICE


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pyrotechnics produce >1011 ice nuclei per gram of AgI at -4C, and produce between 1013 and1014ice nuclei per gram of pyrotechnic between -6C and -10C. CSU isothermal cloud chambertests indicate that at a temperature of -6.3C, 63% of the nuclei are active in


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Figure 12: Map of southern Alberta showing the project target area (Figure courtesy J .Renick).

Priorities

Table 1 lists the 2006 census figures for the cities and towns within the project area. Priority is givenaccording to population, which is related to the risk of property damage. This list was posted in theradar control room as a constant reminder to the meteorologists of the priority when allocatingresources to storms on any given day. The biggest increases in population have occurred inCherstermere, Airdrie, Okotoks, Strathmore, Blackfalds, and Sylvan Lake. Project meteorologistsmade special note of the fact that the combined population of Turner Valley and Black Diamond isalmost as large as Blackfalds or Didsbury. Storms that do not threaten a town or city are not likely to


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be seeded. Also, most storms are not seeded after they cross the QEII highway, except for stormseast of Airdrie and Calgary that might threaten Strathmore.

Table 1: Canadian census figures (2006 versus 2001) for the largest towns and cities in theproject area.

Priority Geographic namePopulation,

2006Population,

2001 % Change

Canada 31612897 30007094 5%Alberta 3290350 2974807 11%

Calgary Metro Area 1079310 951494 13%

1 Calgary 988193 879003 12%

2 Red Deer 82772 67829 22%

3 Airdrie 28927 20407 42%

4 Okotoks 17145 11689 47%

5 Cochrane 13760 12041 14%

6 Lacombe 10742 9384 14%

7 High River 10716 9383 14%8 Strathmore 10225 7621 34%

9 Sylvan Lake 10208 7503 36%

10 Chestermere 9564 3856 148%

11 Innisfail 7316 6943 5%

12 Olds 7248 6607 10%

13 Rocky Mountain House 6874 6208 11%

14 Ponoka 6576 6355 3%

15 Blackfalds 4571 3116 47%

16 Didsbury 4275 3932 9%

17Turner Valley & BlackDiamond 3808 3474 10%

18 Three Hills 3089 2902 6%

19 Carstairs 2656 2254 18%

20 Crossfield 2648 2399 10%

21 Sundre 2518 2277 11%

22 Rimbey 2252 2154 5%

23 Penhold 1961 1729 13%

24 Vulcan 1940 1762 10%

25 Irricana 1243 1043 19%26 Bowden 1205 1174 3%

27 Bentley 1083 1040 4%

28 Trochu 1005 1033 -3%

29 Eckville 951 1019 -7%

30 Beiseker 804 838 -4%

31 Delburne 765 719 6%

32 Linden 660 636 4%


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33 Acme 656 648 1%

34 Caroline 515 556 -7%

35 Cremona 463 415 12%

CONCEPTUAL HAIL MODEL

The hail suppression conceptual model is based on the results of the former research program of theAlberta Research Council and the experiences of WMI in the USA, Canada, Argentina, and Greece. Itinvolves the use of silver-iodide reagents to seed the developing feeder clouds near the -10C level inthe upshear, new growth propagation region of hailstorms. The silver-iodide reagents initiate acondensation-freezing process and produce enhanced concentrations of ice crystals that compete forthe available, super-cooled liquid water in a storm and help prevent the growth of large damaging hail.The seeding also initiates the precipitation process earlier in a cloud (cell) to speed up the growth ofcloud hydrometeors via an ice-phase (graupel) to rain mechanism instead of continuing to grow todamaging hail.

Hail Suppression Hypothesis

The cloud seeding hypothesis is based on the cloud microphysical concept of "beneficial competition".Beneficial competition is based upon the documented deficiency of natural ice nuclei in theenvironment and that the injection of silver iodide (AgI) will result in the production of a significantnumber of "artificial" ice nuclei. The natural and artificial ice crystals "compete" for the available super-cooled liquid cloud water within the storm. Hence, the hailstones that are formed within the seededcloud volumes will be smaller and produce less damage if they should survive the fall to the surface.If sufficient nuclei are introduced into the new growth region of the storm, then the hailstones will besmall enough to melt completely before reaching the ground. Cloud seeding alters the microphysicsof the treated clouds, assuming that the present precipitation process is inefficient due to a deficiencyof natural ice nuclei. This deficiency of natural ice has been documented in the new growth zone of

Alberta storms (Krauss, 1981). Cloud seeding does not attempt to compete directly with the energyand dynamics of the storm. Any alteration of the storm dynamics occurs as a consequence of theincreased ice crystal concentration and initiation of riming and precipitation sized ice particles earlier in

the clouds lifetime.

The cloud seeding is based on the conceptual model of Alberta hailstorms which evolved from theexperiments and studies of Chisholm (1970), Chisholm and Renick (1972), Marwitz (1972a,b,c),Barge and Bergwall (1976), Krauss and Marwitz (1984), and English (1986). Direct observationalevidence from the instrumented aircraft penetrations of Colorado and Alberta storms in the 1970's andearly 1980s indicates that hail embryos grow within the time evolving "main" updraft of single cellstorms and within the updrafts of developing "feeder clouds" or cumulus towers that flank mature"multi-cell" and "super-cell" storms (see e.g. Foote, 1984; Krauss and Marwitz, 1984). Thecomputation of hail growth trajectories within the context of measured storm wind fields provided apowerful new tool for integrating certain parts of hail growth theories, and illustrated a strikingcomplexity in the hail growth process. Some of this complexity is reviewed in the paper of Foote(1985) that classifies a broad spectrum of storm types according to both dynamical and microphysicalprocesses thought to be critical to hail production. Hail embryo sources identified by Foote (1985)include the following: Embryos from first-ice in a time-developing updraft Embryos from first-ice in the core of a long-lived updraft Embryos from flanking cumulus congestus Embryos from a merging mature cell Embryos from a mature cell positioned upwind Embryos from the edges of the main updraft Embryos created by melting and shedding Embryos from entrainment of stratiform cloud Embryos from embedded small-scale updrafts and downdrafts


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Recirculation of embryos that have made a first pass through the updraft core

The growth to large hail is hypothesized to occur primarily along the edges of the main storm updraftwhere the merging feeder clouds interact with the main storm updraft (WMO, 1995). The maturehailstorm may consist of complicated airflow patterns and particle trajectories, therefore, the cloud-seeding cannot hope to affect all embryo sources but attempts to modify the primary hail formationprocess. In other words; the cloud seeding cannot attempt to eliminate all of the hail but canreduce the size and amount o f hail.

Studies of the internal structure of large hailstones in Alberta and elsewhere have shown thathailstones can have either a graupel hail embryo or a frozen drop hail embryo. The different hailembryos indicate different growth histories and trajectories and illustrate the complexity within a singlehailstorm. The present seeding methodology attempts to compete with the graupel embryo process.Drop hail embryos are thought to originate from secondary sources (shedding from large existing hailstones, or via a recirculation process at the edge of the main updraft). The seeding can only reducethe hail with drop embryos if the liquid water can be reduced to limit their growth, or if the dynamics ofthe storm can be affected to eliminate the recirculation processes that formed the drop embryo in thefirst place.

A schematic diagram of the conceptual storm model showing the hail origin and growth processeswithin a severe Alberta hailstorm is shown in Figure 13. A three-dimensional schematic figure of an

Alberta hailstorm is shown in Figure 14, showing the cloud seeding methodology in the new growthzone.

Figure 13: The conceptual model of hailstone formation and hail mitigation processes forAlber ta (adapted from WMO, 1995). This schematic figure shows the cloud seeding

methodology at feeder-cloud tops and c loud-base for a mature hailstorm.


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Figure 14: A three-dimensional schematic figure of an Alberta hailstorm, showing the cloudseeding methodology with in the new growth zone.

As mentioned previously, cloud seeding cannot prevent or completely eliminate the occurrence ofdamaging hail. We presently do not have the ability to predict with any certainty exactly the amountand size of hail that would occur if cloud seeding did not take place. Therefore, we do not have theability to predict with certainty the net effect of the seeding. Our purpose is to seed the new growthzone of hailstorms and observe the amount and type of precipitation at the surface, as well as theradar reflectivity characteristics of the storm before, during, and after seeding. We expect that thesuccessful application of the technology will yield a decrease of damaging hail by approximately 50%of the amount that would have occurred if seeding had not taken place. This goal is consistent withthe results reported in North Dakota (Smith et al, 1997) and in Greece (Rudolph et al, 1994). Thedecrease in hail can only be measured as an average over time (e.g. 5 years) and over an area andthen compared with the historical values for the same areas. Because of these uncertainties, theevaluation of any hail mitigation program requires a statistical analysis. Both seeded storms andunseeded storms have variability and populations of seeded and unseeded storms overlap in allmeasurements of their characteristics.

Precipitation Efficiency

A common question about cloud seeding concerns the effect on the rainfall. Krauss and Santos

(2004) analyzed two years of Alberta radar data and concluded that seeded storms produced morerain than non-seeded storms of the same height. The seeding effect was estimated to increase themean rainfall volume (averaged for categories 7.5 to 11.5 km height storms) by a factor of 2.2 with anaverage 95% confidence interval of 1.4 to 3.4. The seeded storms lived longer (+50%), had greatermean precipitation rates (+29%), and had greater mean total rain area-time integrals (+54%).

There is a general (yet false) assumption by the public and some scientists that thunderstormsoperate at near 100% efficiency in producing rainfall, therefore, any modification of the hail, or causingthe rainfall to start earlier, may limit the amount of precipitation that can fall later in a storms lifetime,down wind of the project area. There have been numerous studies of the fluxes of air and water vaporthrough convective clouds and these are summarized in Figure 15.


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Precipitation efficiencies can vary widely from as little as 2% for storms studied by Marwitz (1972) andDennis et al. (1970) to near 100%. Marwitz (1972) and Foote and Fankhauser (1973) show that in thecase of High Plains storms there is an inverse relation between the precipitation efficiency and theenvironmental wind shear in the cloud-bearing layer. The least efficient storms tend to be supercellhailstorms; the highly efficient storms tend not to produce hail. The average wind shear on hail daysin Alberta is approximately 2.5 x 10-3 sec-1. This average shear value corresponds to an averageprecipitation efficiency of approximately 50%.

It is logical that the production of large, damaging hail is a result of the natural inefficiency of the stormto produce rain. Therefore, the introduction of more precipitation embryos earlier in a clouds lifetime ishighly advantageous to the initiation of precipitation earlier, making the cloud more efficient as a rainproducer, and in the process reducing the amount and size of the hail. Increasing the rainfall from ahailstorm by 20% due to the seeding is a very achievable goal, and means that less water is lost eithervia the entrainment of dry environmental air through the sides and top of the cloud, or water lost to icecrystals that are exhausted out of the anvil at the top of the troposphere and which eventuallysublimate back to the vapor phase at high altitudes.

Figure 15: Precipitation efficiency for High Plains convective storms. Known supercellhailstorms are labeled S. Storms that produced rain only are labeled R (Browning, 1977).

OPERATIONS PLAN

The following guidelines represent the current state of the science of hail suppression operationsbeing applied by Weather Modification Inc.

Onset of Seeding

In order for cloud seeding to be successful, it is the goal of the program to seed (inject ice nucleatingagents) the developing "new growth" cloud towers of a potential hail producing storm at least 20minutes before the damaging hail falls over a town or city within the target zone. For the Albertaproject, the principle targets are the towns and cities within the project area. Since 20 min is theminimum time reasonably expected for the seeding material to nucleate, and have the seeded ice


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crystals grow to sufficient size to compete for the available super-cooled liquid water in order to yieldpositive results, a 30 min lead time is generally thought to be advisable.

Identification of Hail Producing Storms

The height of the 45 dBZ contour was a criterion tested in the Swiss hail suppression program. TheSwiss research indicated that all hailstorms had 45 dBZ contours that exceeded the 5C temperature

level (Waldvogel, Federer, and Grimm, 1979). There was a False Alarm Rate (FAR) of 50%, largelybecause some strong rainstorms also met the criterion. However, it is preferable to make an error andassume that a heavy rainstorm is going to produce hail than to mistakenly believe that a hailstorm isonly going to produce heavy rain. Studies of Alberta hailstorms also indicated that 50% of all Albertahail storms had a maximum radar reflectivity greater than 45 dBZ, higher than the -5C level(Humphries, English, and Renick, 1987). The Russian criteria for hail identification stated that theheight of the 45 dBZ contour had to exceed the height of the 0C isotherm by more than 2 km(Abshaev, 1999). Similarly, the criteria used by the National Hail Research Experiment in the USA1972-1974 for a declared hail day was defined by radar maximum reflectivity greater than 45 dBZabove the -5C level (Foote and Knight, 1979).

Our experience suggests that the Swiss/Alberta/Russian/USA criterion is reasonable (Makitov, 1999).The physical reasoning behind it is simply that high radar reflectivity implies that significant

supercooled liquid water exists at temperatures cold enough for large hail growth.

In Alberta, the TITAN cell identification program was set to track any cell having >10 km3of 40 dBZreflectivity, extending above 3 km altitude (MSL). Each cell tracked by TITAN was then considered tobe a potential hail cell, therefore, this represents our seeding criteria. A storm is a seeding candidateif the storm cell (as defined by TITAN) is moving towards, and is expected to reach, a town or citywithin the target area in less than 30 min.

Cloud Seeding Methodology

Radar meteorologists are responsible for making the "seed" decision and directing the cloud seedingmissions, incorporating the visual observations of the pilots into their decisions. Patrol flights are oftenlaunched before clouds within the target area meet the radar reflectivity seeding criteria, especially

over the cities of Calgary and Red Deer. These patrol flights provide a quicker response todeveloping cells. In general, a patrol is launched in the event of visual reports of vigorous toweringcumulus clouds or when radar cell tops exceed 25 kft height over the higher terrain along the westernborder on days when the forecast calls for thunderstorms with large hail potential.

Launches of more than one aircraft are determined by the number of storms, the lead time required fora seeder aircraft to reach the proper location and altitude, and projected overlap of coverage andon-station time for multiple aircraft missions. In general, only one aircraft can work safely at cloud topand one aircraft at cloud base for a single storm. The operation of four aircraft is used to provideuninterrupted seeding coverage at either cloud-base or cloud-top and/or to seed four stormssimultaneously if required.

Factors that determine cloud top or cloud base seeding are: storm structure, visibility, cloud base

height, or time available for aircraft to reach seeding altitude. Cloud base seeding is conducted byflying at cloud base within the main inflow of single cell storms, or the inflow associated with the newgrowth zone (shelf cloud) located on the upshear side of multi-cell storms.

Cloud top seeding can be conducted between -5C and -15C. The 20 g pencil flares fallapproximately 1.5 km (approximately 10C) during their 35-40 s burn time. Figure 16 shows a cloudseeding plane dropping flares. The seeding aircraft penetrate the up-shear edges of single convectivecells meeting the seed criteria. For multi-cell storms, or storms with feeder clouds, the seeding aircraftpenetrate the tops of the developing cumulus towers on the upshear sides of convective cells, as theygrow up through the -10C flight level.


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Figure 16: A photo of a cloud seeding plane dropping ejectable flares during a cloud seedingpenetration (photo courtesy John Ulan).

Night Time Seeding

Occasionally, with embedded cells or convective complexes at night, there are no clearly definedfeeder turrets visible to the flight crews or on radar. In these instances, a seeding aircraft willpenetrate the storm edge at an altitude between -5C and -10C, on the upshear side (region of tight

radar reflectivity gradient) and seed by igniting an end-burner flare and injecting droppable pencilflares when updrafts are encountered. If visibility is good below cloud base, nighttime seeding atbase is also performed. Lightning can often help provide illumination at the cloud base.

Stopping Seeding

Strictly speaking, if the radar reflectivity criteria are met, seeding of all cells is to be continued.However, seeding is effective only within cloud updrafts and in the presence of super-cooled cloudwater, i.e. the developing and mature stages in the evolution of the classic thunderstorm conceptualmodel. The dissipating stages of a storm should be seeded only if the maximum reflectivity isparticularly severe and there is evidence (visual cloud growth, or tight reflectivity gradients) indicatingthe possible presence of embedded updrafts. Storm cells being tracked by TITAN may not be seededif there are no other indications of updraft or super-cooled liquid water, or if the storm does notthreaten a town or city.

Seeding Rates

A seeding rate of one 20 g flare every 5 sec is typically used during cloud penetrations. A higher rateis used (e.g. 1 flare every 2 to 3 sec) if updrafts are very strong (e.g. greater than 2000 ft/min) and thestorm is particularly intense. A cloud seeding pass is repeated immediately if there are visual signs ofnew cloud growth or if radar reflectivity gradients remain tight (indicative of persistent updrafts). If not,a 5 to 10 min waiting period may be used between penetrations, to allow the seeding material to takeeffect and the storm to dissipate, or for visual signs of glaciation to appear or radar reflectivity values


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to decrease and gradients to weaken. This waiting period is meant to reduce the waste of seedingmaterial and help assure its optimum usage. Calculations show that the seeding rate of one flareevery 5 sec will produce >1300 ice crystals per litre averaged over the plume within 2.5 min. This ismore than sufficient to deplete the liquid water content produced by updrafts up to 10 m/s (2000ft/min), thereby preventing the growth of hailstones within the seeded cloud volumes (Cooper andMarwitz, 1980). For effective hail suppression, sufficient dispersion of the particles is required for the

AgI plume from consecutive flares to overlap by the time the cloud particles reach hail size. The workby Grandia et al. (1979) based on turbulence measurements within Alberta feeder clouds indicated

that the time for the diameter of the diffusing line of AgI to reach the integral length scale (200 m) inthe inertial subrange size scales of mixing, is 140 seconds. This is insufficient time for ice particles togrow to hail size, therefore, dropping flares at 5 sec (assuming a true-airspeed of 80 m/s) intervalsshould provide sufficient nuclei and allow adequate dispersion to effectively deplete the super-cooledliquid water and reduce the growth of hail particles. The use of the 20 gm flares and a frequent droprate provides better seeding coverage than using larger flares with greater time/distance spacingbetween flare drops. In fact, the above calculations are conservative when one considers that thecenter of the ice crystal plume will have a greater concentration of ice crystals.

For cloud base seeding, a seeding rate using two acetone generators or one end-burner flare istypically used, dependent on the updraft velocity at the cloud base. For an updraft >500 ft/min,generators and consecutive flares per seeding run are typically used. Cloud seeding runs arerepeated until no further inflow is found. Acetone burners are used to provide continuous silver iodide

seeding if extensive regions of weak updraft are found at cloud base and in the shelf cloud region.Base seeding is not conducted if only downdrafts are encountered at cloud base, since this wouldwaste seeding material.

Seeding Materials

WMI exclusively uses silver-iodide formulation flares manufactured by Ice Crystal Engineering (ICE) ofDavenport, ND. The ejectable flares contain 20 gm of seeding material and burn for approximately 37sec and fall approximately 4000 ft. The end-burning or burn in place (BIP) flares contain 150 gm ofseeding material, and burn for approximately 6 min. A photograph of a burning BIP flare test is shownin Figure 17.

Figure 17: Photograph of a burning BIP flare.


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Silver-iodide is dispensed using droppable/ejectable (shown in Figures 16 and 18) and/or end-burningpyrotechnics (Figures 17 and 19) and/or acetone burners (shown in Figures 31 and 32). In 2008 theWMI acetone generators performed very well and the level of required maintenance decreasedsignificantly. Crews kept a close watch on igniter rods, valves, nozzles, and seals in order that thegenerators operated reliably. Details of the silver-iodide acetone solution are given in an Appendix.

Arrangements were once again made with Solution Blend Services, a Calgary chemical company topre-mix the acetone seeding solution. All required handling, mixing, storage, and labellingrequirements were satisfied.

Figure 18: Pilot Joel Zimmer attaching the ejectable flare racks on the belly o f the King Air C90seeding aircraft designated as Hailstop 3.

Figure 19: Burn-in-place (BIP) flares on the wing of HailStop-1.


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Flare Effectiveness Tests

The Cloud Simulation and Aerosol Laboratory (cloud chamber) at Colorado State University hastested the ice nucleating ability of aerosols produced from cloud seeding flares for many years(Garvey, 1975). Note: The CSU laboratory has now stopped this service and a new testing facility toconduct these standardized tests is desperately needed for the cloud seeding industry. The latest ICEpyrotechnics were tested at CSU in 1999 and the results are reported in DeMott (1999). Aerosols

were collected and tested at nominal temperatures of -4, -6 and -10 C. At least two tests were done ateach temperature, with greater emphasis placed on warmer temperatures. Liquid water content (LWC)was 1.5 g m-3 in most tests, but was altered to 0.5 g m-3 in a few other experiments. In this way,information concerning the rate-dependence on cloud droplet concentration was obtained. Theprimary product of the laboratory characterization is the "effectiveness plot" for the ice nucleant whichgives the number of ice crystals formed per gram of nucleant as a function of cloud temperature. Yieldresults for the ICE flares at various sets of conditions are shown in Figure 20 and are tabulated inTable 2.

1.00E+10

1.00E+11

1.00E+12

1.00E+13

1.00E+14

1.00E+15

0 5 10 15

Supercooling (C)

Yield

(#

g-1p

yro)

ICE Pyro

July 1999

___________

___________

Figure 20: Yield of ice crystals (corrected) per gram of pyrotechnic versus cloud supercooling

temperature (T


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-10.5 0.5 2.38x1014 2.41x1014 2.91x1013 2.96x1013 5.92x1014

Tests were also performed using the method of DeMott et al., (1983) to determine the characteristictimes for effective ice nuclei depletion, and these are summarized in Figure 21 and Table 3.

y = 57.483x-1.9653

R2= 0.8298

y = 4.723x-1.1862

R2= 0.8552

0

1

2

3

4

5

6

7

8

9

10

0 2 4 6 8 10 12Supercooling (C)

Time(minutes)

63

9

__________________

Figure 21: Times for 63% (diamond symbols) and 90% (square symbols) ice formation versus

supercooling (T


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formulation used by ICE was modest at -6C, but most significant (factor of 3 increase inYield) at -4C.

2. The ICE pyrotechnics burned with a fine smoke and a highly consistent burn time of ~37s.

3. Rates of ice crystal formation were very fast, suggestive of a rapid condensation freezing

process. The balance of observations showed no significant difference in the rate dataobtained at varied cloud densities, supporting a conclusion that particles activate iceformation by condensation freezing.

The CSU isothermal cloud chamber tests indicate that, on a per gram basis of pyrotechnic, thesevalues are comparable to the best product available worldwide in the pyrotechnic format. High yieldand fast acting agents are important for hail suppression since the time-window of opportunity forsuccessful intervention of the hail growth process is often less than 10 minutes. More informationabout the ICE flares can be found on the internet at www.iceflares.com.

PROGRAM ELEMENTS AND INFRASTRUCTURE

A schematic diagram of the operational elements for the hail suppression project is shown in Figure22. Details of the individual elements are described in more detail in the following sections.

Figure 22: A schematic of the operational elements of the Alberta Hail Suppression Project.

The radiosonde (weather balloon) depicted in Figure 22 was part of the system on a limited basesduring 2003 and 2004, when WMI participated in the Alberta GPS Atmospheric Moisture Evaluation(A-GAME) research project with the University of Calgary, and from July 8 to 22, 2008 in support ofthe UNSTABLE research project (described in more detail in a later section). From those experimentswe learned that the ETA/NAM model from the USA does an excellent job in predicting the mainfeatures of the atmospheric profile for Calgary and Red Deer. Although subtle details of inversionlayers and moisture layers may not be resolved, the meteorologists have generally sufficientinformation about the instability of the atmosphere to construct a good forecast. One of the greatest
http://www.iceflares.com/http://www.iceflares.com/


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gaps in our knowledge and data concerns the presence, absence, or timing of trigger mechanismsfor the onset of convection. The increasing availability of near real time surface and satellite imagesvia the internet is improving this situation. All meteorological information was received via the internet.WMI no longer needed a commercial agreement with Environment Canada.

GROUND SCHOOL

A ground school was conducted prior to the commencement of the project field operations on May30th, 2008 for all available project personnel. Ground School was held in the training room at INGInsurance in downtown Calgary. Operational procedures about who does what, where, when andwhy, as well as general conduct and reporting requirements were presented and reviewed at theground school. Two representatives of NAV Canada in Calgary and Edmonton participated in theground school. A copy of the Ground School Program, as well as copies of the Flight Log and RadarLog forms, are included in the Appendices. The ground school training topics included:i. program overview and design, project area, target areas, and prioritiesii. overview of operations and proceduresiii. cloud seeding hypotheses for hail suppressioniv. cloud seeding theory and techniquesv. aviation weather problems and special procedures

vi. aircraft controlling techniques and proceduresvii. seeding aircraft equipment and characteristicsviii. weather radar equipment and basic principlesix. basic meteorological concepts and severe weather forecastingx. weather phenomena, fronts, and stormsxi. daily routines and proceduresxii. communications proceduresxiii. computers, documentation, and reporting proceduresxiv. safety, security precautions and procedures

PUBLIC RELATIONS

Numerous public relations activities occurred this year. Dr. Terry Krauss was interviewed by Global

TV on July 7thand by City TV and CBC TV on July 8th. The Weather Network visited the radar andflew on Hailstop 1 on July 9th. The Discovery Channel flew on Hailstop 1 on July 17th. A journalistfrom the BBC London visited the radar and Calgary crews on June 10th. All of the media coveragewas positive.

It has been 13 years since the program started. There are many new people in the insurance industryin Central Alberta who are not familiar with the history of the program and details of the current cloudseeding project. Axa Pacific Insurance sent two groups of 11 and 14 persons to the radar site onSeptember 2ndand 9th. These information field trips were very well received and appreciated. Aphoto of the group from Axa Pacific Insurance that visited on September 2ndis shown in Figure 23.

It is recommended that similar information seminars be given as part of the Alberta Insurance Councilaccreditation program. The intent of this training course would be to inform the insurance industry

about the background, organization, and methodology of the cloud seeding project so that support forthe program can continue based on current and accurate information.


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Figure 23: A photo o f the group from Axa Pacific Insurance that visited the radar onSeptember 2nd.

UNSTABLE (UNDERSTANDING SEVERE THUNDERSTORMS AND ALBERTABOUNDARY LAYERS EXPERIMENT)

A highlight of the season was WMIs participation in a research project called UNSTABLE(Understanding Severe Thunderstorms and Alberta Boundary Layers Experiment) from July 9thto 23rd,and based at the Olds radar site. The project was largely funded by Environment Canada withparticipation by the Universities of Alberta, Calgary, and Manitoba, plus Weather Modification, Inc.

UNSTABLE was a field study designed to improve our understanding of processes leading toconvective initiation and severe thunderstorm development over the Alberta foothills. The fieldcomponent of UNSTABLE was designed in two parts, a pilot field study in 2008 (July 9-23) and alarger, full-scale experiment planned for 2011. The purpose of the 2008 pilot project was to test critical

instrumentation and measurement strategies to answer some key UNSTABLE science questions.

The principal scinetific investigators were as follows:

Neil M. Taylor: Hydrometeorology and Arctic Lab, Environment Canada, EdmontonDavid Sills: Cloud Physics and Severe Weather Research Section, Environment Canada, TorontoJohn Hanesiak and Julian C. Brimelow: Centre for Earth Observation Science (CEOS), University ofManitobaJason A. Milbrandt: Recherche en Prvision Numrique [RPN] (Numerical Weather PredictionResearch Section), Environment Canada, MontrealCraig D. Smith: Climate Research Division, Environment Canada, Saskatoon


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Geoff Strong: Department of Earth and Atmospheric Sciences, University of Alberta (Adjunct),EdmontonSusan Skone: Department of Geomatics Engineering, University of CalgaryPatrick J. McCarthy: Prairie and Arctic Storm Prediction Centre, Environment Canada, Winnipeg

It is worth noting that Dr. Jason Milbrandt and Julian Brimelow worked as meteorologists for WMI onthe Alberta Hail Suppression Projects in the past, and have since gone on to earn advanced degrees.

Hailstop-1 was outfitted with special instrumentation to measure temperature, humidity, and wind inthe boundary layer, as well as cloud physics probes to measure cloud particle characteristics. A photoof N234K with the special cloud physics instrumentation is shown in Figure 24.

Figure 24: A photo of Hail Stop-1 (N234K) with the special cloud physics instrumentation usedfor UNSTABLE.

Special upper air soundings using instrumented radiosonde balloons were conducted at the Olds-Didsbury airport during the research field program. A photo of Erin Tompson (Environment Canada

Saskatoon) launching a radiosonde balloon on the first day of the program on July 8th

is shown inFigure 25.

A graphical comparison of the vertical profile from the surface to 5 km MSL (16 kft) of temperature anddew point measured by Hailstop-1 with the radiosonde balloon on July 8 th is shown in Figure 26. Agraphical comparison of the wind speed and direction measured by Hailstop-1 with the radiosondeballoon on July 8th is shown in Figure 27. The temperature, dew point and wind measurements ofN234K agreed well with the radiosonde and are considered to be of equal quality.


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Figure 25: A photo of Erin Tompson (Environment Canada Saskatoon) launching a radiosondeballoon on July 8

thfo r UNSTABLE.

Figure 26: Comparison of the vertical profile of temperature and dew point measured byHailstop-1 with the radiosonde balloon on July 8th.


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Figure 27: Comparison of the vertical profile of wind speed and direction measured byHailstop-1 with the radiosonde balloon on July 8th.

Results from the pilot project will be used to refine the science overview and operations plan for thefull-scale project in 2011. Through UNSTABLE the ultimate goals are to improve the accuracy and

timeliness of summertime severe weather watches and warnings, assess the ability of the numericalmodels of Environment Canada to resolve relevant processes and provide useful numerical guidance,and refine existing conceptual models for severe thunderstorm development over Alberta and thewestern Canadian prairies.

A list of special research flights conducted for UNSTABLE is given in Table 4.

Table 4:A l is t of special research f lights conducted for UNSTABLE.

ALBERTA UNSTABLE RESEARCH PROJECT 2008unstable

= 24:51 Hours

Operations Flights UTC UTC hr:mm UTC UTC hr:mm

TOTALSflights

= 12 24:51 12 21:19Date

(UTC) AircraftEngine

OnEngine

OffTotalTime Take-off Landing

AirTime

08-Jul-08 N234K 18:22 18:54 00:32 18:35 18:53 00:1808-Jul-08 N234K 22:41 23:11 00:30 22:45 23:07 00:2208-Jul-08 N234K 23:29 23:57 00:28 23:33 23:50 00:1709-Jul-08 N234K 16:22 19:16 02:54 16:40 19:11 02:3109-Jul-08 N234K 22:33 23:05 00:32 22:47 23:03 00:1609-Jul-08 N234K 23:26 00:41 01:15 23:34 00:37 01:03


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10-Jul-08 N234K 00:47 01:16 00:29 00:53 01:13 00:2012-Jul-08 N234K 17:58 22:08 04:10 18:15 22:02 03:4713-Jul-08 N234K 16:00 20:05 04:05 16:30 19:58 03:2820-Jul-08 N234K 17:26 20:51 03:25 17:40 20:48 03:0821-Jul-08 N234K 20:30 23:27 02:57 20:41 23:22 02:4122-Jul-08 N234K 16:42 20:16 03:34 17:04 20:12 03:08

FLIGHT OPERATIONS

Three specially equipped cloud seeding aircraft were dedicated to the project. The aircraft and crewsprovided 24 hr coverage, seven days a week throughout the period. Two aircraft were stationed inCalgary and one aircraft in Red Deer. This permitted close proximity to storms and fast response tolaunch decisions. Delays in launching from Calgary were minimized thanks to the co-operation ofNav-Canada air traffic control in Calgary.

When convective clouds were detected by radar, the seeding aircraft were placed on standby status.Aircraft on standby status are able to launch and reach a target cloud within 60 min after the request

to launch has been made by the controlling meteorologist. When seedable clouds are imminent, theseeding aircraft are placed on alert status. Aircraft on alert status are able to launch and reach atarget cloud within 25 min after the request to launch. Aircraft were available and prepared tocommence a seeding mission at any time and the seeding of a storm often continued after darknesswith due regard to safety.

Ai r-Traff ic Control

Prior to the start of field operations, arrangements were made with NAV Canada managers of AirTraffic Services in Calgary and Edmonton to coordinate the cloud seeding aircraft operations.Permission was granted to file pre-defined flight plans for the project aircraft, with special designationsand fixed transponder codes. The designated aircraft were as follows: Hail-Stop 1 for the Cheyenne IIairplane (N234K) based in Calgary, Hail-Stop 2 for the C340 aircraft (N457DM) based in Calgary, Hail-

Stop 3 for the King Air C90 aircraft (N911FG) stationed in Red Deer, and Hail-Stop 4 for the C340aircraft (N98560) based in Red Deer.

Direct-line telephone numbers were used to notify air traffic controllers of cloud seeding launches.Aircraft were launched to a specific location identified by VOR and DME coordinates, or town. Distinctair traffic clearance was given to project aircraft within a 10 nautical mile radius of the specified stormlocation. Cloud top aircraft were given 2,000 ft clearances above their altitude and 7,000 ft below theiraltitude. Cloud base aircraft were given a +/- 1,000 ft altitude clearance. This procedure worked verywell in general. On a few occasions, seeding aircraft were asked to climb to a higher altitude over thecity of Calgary or to suspend seeding for a few minutes (


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Figure 28: Schematic figure showing aircraft cloud seeding block altitudes required for AirTraffic Cont rol (ATC).


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Cloud Seeding Aircraft

Piper Cheyenne II

The Cheyenne II is a high performance twin-engine turboprop aircraft that has proven itself duringseeding operations. The Cheyenne II stationed in Calgary, Hail Stop 1 (N234K), is shown in Figure29. In Alberta, two pilots are used at all times for improved communications and safety. Standardequipment includes full dual VFR/IFR instrumentation, pressurized cabin, and emergency oxygen.The Cheyenne II has full de-ice equipment and is particularly well suited for flying in icing conditionsfor extended periods of time. These conditions are common at seeding altitudes within thethunderstorms of Alberta. The longer mission times of this aircraft can provide coverage of the entireproject area if required, allowing significant savings in aircraft, fuel and personnel costs. The addedperformance of the Cheyenne II means that it has sufficient power to climb safely above thedangerous icing zone (-10C to -15C) if required, or descend to lower and warmer altitudes to de-iceand quickly climb back up to feeder cloud-top seeding altitude. It can also provide accuratemeasurements of cloud conditions and cloud temperature. A third seat was provided for training orobserving purposes. The major advantages of the Cheyenne II are as follows: 4 hour duration or more for longer seeding missions and better seeding coverage; lower Jet fuel price per liter; reserve power for severe icing conditions; high speed for rapid response or ferry between target areas; and higher margin of safety;

The specifications of the Cheyenne II are given in an Appendix. All three aircraft were equipped withflare racks carrying 306 droppable flares containing 20 grams of AgI and also 28 end-burning flarescontaining 150 grams of AgI for seeding at cloud base. The Cheyenne II was also equipped with GPSnavigation system, onboard weather avoidance radar, and a VHF radio system for direct contact withoperational personnel at the communications and control center.

Figure 29: Piper Cheyenne II aircraft (N234K) designated as Hail-Stop 1 shown with CaptainBob Gorman at the Olds-Didsbury Airport.


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Beech King-Air C90

Figure 30: Beech Craft King-Air C90 aircraft (N911FG) designated as Hail-Stop 3 shown at the

Olds-Didsbury Airport.

A photo of the Beechcraft King Air C90 designated Hail Stop 3 (N911FG) is shown in Figure 30 at theOlds-Didsbury Airport. The specifications of the King Air C90 are given in an Appendix. The King Airwas similarly equipped as the Cheyenne II. The Cheyenne II and King Air C90 are both highperformance twin-engine

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Wmi Alhap Final Report 2008

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