Date post: | 14-Jan-2016 |
Category: |
Documents |
Upload: | geraldine-nelson |
View: | 212 times |
Download: | 0 times |
Why The Need For HCN-M ?
More Accurate Data Through:Redundant Sensors
Near Real Time Diagnostics
Time Resolution of Five Minutes vs The Current Daily
Human Interaction With Weather Observations Has Been The Backbone Of The Historical Data Sets For More Than 100 Years
Temperature Measurements
Louvered Shelter For Ventilation Of Temperature Sensors And Protection From Direct Solar And Terrestrial Radiation
Used By Both Primary And Cooperative Stations For More than 100 Years
Redundant sensors, more than one thermometer in each shelter
Minimum Thermometer
Maximum Thermometer
Thermograph
Primary Weather Stations Were Also Equipped With Two Additional Matched Thermometers For Determining The Dew Point Temperature And Relative Humidity
Redundancy Of Temperature Measurement Was Lost In The 1980’s With Conversion To A Single Automated Electronic Sensor Called “The MMTS”.
Lightning, the worst nightmare for electrically operated temperature sensors. Those same electronic temperature sensors are also subject to salt air corrosion, and insect nests. (See next slide)
Data From An “MMTS” Temperature System At A Cooperative Station
Ventilation problems and slippage of the mechanically driven clutch read-out of the automated temperature sensor at the Asheville Airport compromised the readings from the site for more than 20 years. (See Next Slide)
Even Primary Airport Weather Stations Are Not Exempt From Single Sensor Failures
Modernization Of The Equipment At The HCN Test Sites Uses The Proven Methodology Of The Past,
Redundant Sensors
AL Greensboro HCN-M (County Jail)AL Greensboro HCN-M (County Jail)32.7 N 87.6 W 273’
March 16, 2007
Geonor All-Weather Precipitation Gage With Three Independent Sensors And Protecting “Wind Fence”
Three Temperature Sensors in One Shield Equipped With Two Fans
Solar Panels to Power the Station
Temperature Traces of The Three Thermometers
Fan Ventilation Rate (R/S)
Back-Up Fan
Precipitation Measurements
Snow Clogged Tipping Bucket Gage
The Easiest Design Is Not Always The Best
Tipping Bucket Mechanism Does Not Measure Snow Events, And Frequently Under-Reports Intense Rainfall
Snow Sticking to The Un-Heated Chute of a Weighing Precipitation Gage
Same Gage Type Clear of Snow When Equipped With a Heater
Chute Temperature Rises When Heater is Activated
Air Temperature
Traces of Three Precipitation Sensors
Wetness Sensor Readings