January 19, 2001

TOMS3–F: Total Ozone

Measurements by Satellites, Sondes and Spectrometers

at FairbanksSteven Lloyd

The Johns Hopkins University Applied Physics Laboratory

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone Offsets

Total Ozone Intercomparison During POLARIS

220

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April May June July August September October

Month in 1997

Tota

l C

olu

mn

Ozo

ne

(D

ob

so

n U

nit

s)

Brewer Spectroradiometer EP TOMS Satellite Dobson (Direct Sun Only)Ozonesonde (CMR) Ozonesonde (SBUV) MkIV Interferometer

Fairbanks, Alaska 1997Spring/Summer Ozone Loss =

-30 Dobson Units/month

Earth Probe TOMS total ozone values are consistently higher than ozonesondes and ground–based spectrometers (Dobson,Brewer and MkIV).

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone OffsetsThe Earth Probe TOMS offset for Fairbanks is 1–5%.

Difference between Earth

Probe TOMS Satellite and…

Number of

“Coincident”Measurements

Absolute Difference

± 1 Std. Dev.

(Dobson Units)

RelativeDifference ± 2

(Percent)

Sondes (CMR Approximation) 31 16.0 ± 11.3 4.95 ± 1.29

Sondes (SBUV Approximation) 33 14.6 ± 9.6 4.47 ± 1.01

Dobson Spectrometerb 53 9.6 ± 9.3 2.78 ± 0.78

Brewer Spectroradiometerb 1888 9.3 ± 9.3 2.87 ± 0.55a

MkIV Interferometerb 117 6.0 ± 8.9 1.63 ± 0.46

In all cases the EP TOMS values are larger. The relative (percent) difference is relative to theTOMS values, as interpolated to the exact times of the other observations. The standard error(standard deviation of the mean) reported in the last column is ± 2 (95% confidence interval).

aAlthough the Brewer made 1888 observations during the POLARIS campaign, the standarderror for the TOMS–Brewer comparison has been calculated using 104 rather than 1888 “coincident”measurements, since TOMS provides only 104 independent observations of the ozone to comparewith.

bDirect Sun observations only

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone Offsets

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone OffsetsIn general, the offset increases with latitude.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Offset between Earth Probe TOMS and 13 Northern Hemisphere Brewer and Dobson ground stations as a function of latitude.

Total Ozone Offsets

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Apparent offset of Nimbus 7 and Earth Probe TOMS relative to 30 Northern Hemisphere ground stations (Dobson and Brewer spectrometers) over the period 1978-1999 (pluses), and also relative to 18 Southern Hemisphere ground stations (blue stars). Plot courtesy of Gordon Labow, Raytheon ITSS.

Total Ozone Offsets

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone OffsetsDoes the offset vary with season?

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone OffsetsNo seasonality to offset in Churchill dataset.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone OffsetsNo solar zenith angle dependence

to offset in Churchill dataset.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone OffsetsIssue of raw vs. filtered data in Churchill dataset

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Total Ozone OffsetsAlthough average North-South gradient in ozone is small, instantaneous gradient may be substantial.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Why? To investigate the source(s) of total ozone offset

Who? TOMS Science Team and colleagues

What? Dobsons, Brewers, sondes and Earth Probe TOMS

Where? Fairbanks, AK, 65ºN (high lat. instrumented site)

When? March–April (maximum ozone, high SZAs)

How? TOMS internal funding

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

To understand how well total ozone measured by Dobson and Brewer instruments agree over a broad range of total ozone and solar zenith angles, and to understand when, where, and why they disagree.

Key Science Issues: Goal 1.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Justification: Previous instrument intercomparisons have been done under more benign conditions, with total ozone close to 325 DU. Certain types of instrumental errors can be detected only by taking measurements over a broad range of total ozone amounts.

Key Science Issues: Goal 1.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Implementation: 2 Dobsons and 3 Brewers making multiple daily observations over 2 months, covering 50-90° SZA and 350-500 DU total ozone, will provide statistically meaningful samples.

Key Science Issues: Goal 1.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

To compare TOMS with ground-based total ozone observations over a broad range of total ozone amounts and observing conditions, with the aim of understanding the cause(s) of their difference.

Key Science Issues: Goal 2.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Justification: Comparison of total ozone from the global Dobson network with TOMS shows significant biases that vary with latitude, season and total ozone amounts. Their cause is not understood. This campaign is designed to look at few possible sources of difference, including instrument and algorithm errors in both ground and satellite retrievals.

Key Science Issues: Goal 2.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Specific questions:

• How well does TOMS agree with the median of Dobson/Brewer total O3 amounts?

• How much of the difference can be attributed to O3 variability near Fairbanks?

• Is there scan angle or mu–dependence of the difference?

Key Science Issues: Goal 2.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

To investigate the impact of replacing climatological temperature and O3 profiles assumed by Dobson, Brewer and TOMS algorithms with profiles measured by ground-based/satellite instruments near Fairbanks?

(for TOMS algorithm correction, need accurate ozone values near 30 km from ozonesondes, Umkehr, mm-wave radiometer, FTIR)

Key Science Issues: Goal 3.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

To determine if the relationship between zenith sky radiances and total ozone agrees with radiative transfer theory.

How well does the slope of the Dobson C-pair zenith-sky N-value for total O3 agree with radiative transfer calculations at SZA<75˚?

Key Science Issues: Goal 4.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningZenith Sky N-value vs. Total Ozone

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Justification: Slope of Dobson C-pair N-values against total ozone computed from the Arosa station data shows 14% difference from theory (see attached figures). Other stations (Tateno and Boulder) show 10% difference. Resolution of this difference may also shed light on satellite and ground biases since (satellite-measured) nadir and (ground-measured) zenith-sky UV radiances are intimately related through the radiative transfer theory.

Key Science Issues: Goal 4.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

• calculation requires aerosol optical depth and temperature profile, but absolute calibration of ZS N-value not required.

ZS C-pair N-values should be proportional to total O3 amount at SZA<75˚, with virtually no O3 profile sensitivity.

noise in the Arosa data are largely due to tropospheric aerosols, which have a significant effect on C-pair N-values.

Key Science Issues: Goal 4.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Instrument CalibrationDobson World Standard Instrument 83Brewer Pre–/post–calibration with Brewer TriadSondes CMDL Calibration by Sam Oltmans/Bryan JohnsonEP TOMS Validation by TOMS Science Team

Verification of calibration:

The “Dream Teams”

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Why Fairbanks? Facilities and InstrumentationFairbanks:

• Dobson 63– in continuous operation 1965–73 and 1984–present, moved from Poker Flats to the Geophysical Institute (GI) at the University of Alaska at Fairbanks (UAF) in 1992

• Sondes– staff at the GI have the experience and equipment to launch sondes, have worked with NOAA/CMDL (Oltmans and Johnson) to launch sondes for ADEOS validation and POLARIS campaign

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign Planning

Why Fairbanks? Facilities and Instrumentation

Poker Flat Research Range (PFRR):

• sondes– inflation and launch facility

• aerosol lidar– Richard Collins

• Bruker FTIR– Frank Murcray and Pierre Fogal for CRL

• mm–wave radiometer– Satoshi Ochiai

• USDA UV– and vis–MFRSR– Jim Slusser

• all–sky imaging cameras

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Satellite Instruments

Satellite Instrument Point of Contact Launch

Earth Probe TOMS Rich McPeters July 1996QuikTOMS Rich McPeters May/October 2001UARS/HALOE Jim Russell September 1991TIMED/SABER Jim Russell Summer 2001POAM III Rich Bevilacqua March 1998ERS-2/GOME Jim Gleason April 1995NOAA-11/SBUV/2 Larry Flynn September 1988NOAA-14/SBUV/2 Larry Flynn December 1994ENVISAT/GOMOS TBD June 2001ENVISAT/SCIAMACHY TBD June 2001ENVISAT/MIPAS TBD June 2001

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Satellite InstrumentsPOAM III Orbit Predictions

Overpass within 2 degrees longitude

4 Sunsets:

March 31

April 5

April 9

April 14

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Satellite InstrumentsHALOE Orbit Predictions

Only near-coincidence on April 23 at Latitude 62.86°N Longitude 145.23°W

(Fairbanks is at Latitude 64.82°N Longitude 147.87°W)

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Sondes and SpectrometersPrimary Instrumentation:

2 Dobson Spectrometers, 3 Brewer Spectroradiometers and 30 ECC Ozonesondes Launched from Fairbanks and Poker Flat Research Range (PFRR), Alaska

Primary Instrument Operator Location Period

Dobson 63 Bill Simpson and student FB, roof of Geophysical Institute building 2 months

Dobson 83 Bob Evans or Mark Clark FB, roof of Geophysical Institute building 2 weeks

Brewer 007 (single) Tom McElroy or Jim Kerr FB, roof of Internat'l. Arctic Research Center 2 months

Brewer 085 (double) Tom McElroy or Jim Kerr FB, roof of Internat'l. Arctic Research Center 2 months

Brewer 171 (double) Gordon Labow FB, roof of Internat'l. Arctic Research Center 2 months

Ozonesonde Bryan Johnson/Bill Simpson FB, parking lot behind Geophysical Institute 2 weeks

Ozonesonde Gordon Labow + TBD PF, Balloon Inflation and Launch Facility 2 weeks

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Sondes and SpectrometersSecondary Instrumentation

Secondary Instrument Operator Location

Aerosol Lidar (0-25 km) Gordon Labow PF, new LIDAR Building, guest labAerosol Lidar (20-60 km) Richard Collins PF, new LIDAR BuildingBruker FTIR (Murcray, CRL) Brian Lawson PF, Commun. Res. Lab, T. Neil Davis Building microTOPS-1 (GSFC) Steve Lloyd FB, roof of Internat'l. Arctic Research CentermicroTOPS-2 (UVIAC) Cathy Cahill PF, roof of T. Neil Davis BuildingmicroTOPS-3 (GSFC) Gary Cooper + student Delta Junction, AKmicroTOPS-4 (GSFC) TBD (teacher/student) Nenana, AKmicroTOPS-5 (UVIAC) Pam Sousanes Denali National Park, AKBrewer (EPA) Pam Sousanes Denali National Park, AKFilter Spectrometer (NSF) TBD Barrow, AKM-124 Spectrometer Boris Ivanov FB, roof of Geophysical Institute buildingCPFM Diode Array Instr. Tom McElroy (TBD) FB, roof of Internat'l. Arctic Research CenterDiode Array Spectrometer Bill Simpson FB, roof of Geophysical Institute buildingAll-sky imaging camera TBD PF, roof of T. Neil Davis BuildingAll-sky imaging camera TBD FB, roof of Geophysical Institute buildingmm-wave radiometer Satoshi Ochiai PF, Commun. Res. Lab, T. Neil Davis BuildingUSDA UV- and Vis-MFRSR Jim Slusser (UVIAC) PF, roof of T. Neil Davis Buildingin situ aerosol monitoring Melanie Wetzel (UVIAC) PF, Atmospheric Science Lab

tether sonde Cathy Cahill (UVIAC) PF, Balloon Launch Facility

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Sondes and SpectrometersSecondary Instrumentation Locations

Poker Flat

Denali

Barrow

Barrow

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningFirst Priority: Maximum Total Ozone

Plot courtesy of NOAA CMDL.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningFirst Priority: Maximum Total Ozone

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningFirst Priority: Maximum Total Ozone

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningSecondary Priority: Large Solar Zenith Angles

Plot courtesy of Bill Swartz, JHU/APL.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningSecondary Priority: Large Solar Zenith Angles

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningTime of Earth Probe TOMS Overpasses

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningMaximum Clear Sky Viewing Conditions

Plot courtesy of Bill Swartz, JHU/APL.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F Campaign PlanningTOMS 360 nm Surface Reflectivity

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Geophysical Institute (GI) and International Arctic Research Center (IARC) at the

University of Alaska at Fairbanks (UAF)

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

View of International Arctic Research Center (IARC) from Roof of Geophysical Institute (GI)

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Environment Canada

Meteorological Service of Canada

Brewer Spectroradiometer

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Campaign Headquarters with a View

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Campaign Headquarters and Sushi Bar

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Prof. Bill Simpson and the Fairbanks Dobson spectrometer on top of the Geophysical Institute Building at UAF

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Fairbanks Dobson spectrometer (instrument no. 63) inside observatory dome

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: FacilitiesFairbanks Dobson spectrometer (instrument no. 63) long–term dataset

Plot courtesy of NOAA CMDL.

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: FacilitiesFairbanks Dobson spectrometer (instrument no. 63) long–term dataset

1965–1997 Trend 1965–2001 Trend

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: FacilitiesFairbanks Dobson spectrometer

(instrument no. 63)

Seasonality of Total Ozone Offset

Total Ozone ComparisonEP TOMS Satellite - Dobson ADDSGQP

-40-30-20-10

010203040

0 100 200 300

Day of Year 1997-2000

EP

TO

MS

- D

obso

n (D

U)

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: FacilitiesFairbanks Dobson spectrometer

(instrument no. 63)

Mu-Dependence of Total Ozone Offset

Total Ozone ComparisonDobson AD / EP TOMS

0.8

0.85

0.9

0.95

1

1.05

1.1

1.15

1.2

0 1 2 3 4 5

mu

Do

bso

n A

D / T

OM

S

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: FacilitiesFairbanks Dobson spectrometer

(instrument no. 63)

Mu-Dependence of Total Ozone Offset

Total Ozone ComparisonDobson CD / EP TOMS

0.80.85

0.90.95

11.05

1.11.15

1.2

0 2 4 6

mu

Do

bso

n C

D/T

OM

S

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Site for World Standard Dobson Instrument no. 83, next to the Fairbanks Dobson dome on top of the Geophysical Institute Building

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

View from Poker Flat Research Range (PFRR), 50 km north of Fairbanks

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Balloon Inflation and Launch Facility at Poker Flat Research Range

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Environmental Test Facility at Poker Flat Research Range, to be used in the UltraViolet Impact of Aerosols and Clouds (UVIAC) Campaign

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Prof. Bill Simpson (UAF), Greg Walker (PFRR) and Gordon Labow (RITSS) in front of the Poker Flat LIDAR Building

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Gordon Labow at the Visiting Scientist facility in the Poker Flat LIDAR Building, where the Goddard aerosol LIDAR will make measurements

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Roof-mounted radiometers (UV and Visible MFRSRs) at Poker Flat Research Range, to be used in UltraViolet Impact of Aerosols and Clouds (UVIAC) Campaign

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Bruker Fourier Transform InfraRed (FTIR) Spectrometer, operated by Frank Murcray for the Japanese Communications Research Lab (CRL)

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Prof. Bill Simpson (UAF), Greg Walker (PFRR) and Gordon Labow (RITSS) in front of the Japanese Communications Research Lab (CRL) mm-wave radiometer

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

Sample spring-time ozone profile made at Poker Flat by the Japanese Communications Research Lab (CRL) mm-wave radiometer

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

TOMS3–F: Facilities

TOMS3–F: Total Ozone Measurements by Satellites, Sondes and Spectrometers at Fairbanks

Yes, children, there really is a Santa Claus in North Pole, AK