1. 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

2. Human Interaction With Weather Observations Has Been The Backbone Of The Historical Data Sets For More Than 100 Years

3. Temperature Measurements

4. 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

5. Redundant sensors, more than one thermometer in each shelter
Minimum Thermometer
Maximum Thermometer
Thermograph

6. Primary Weather Stations Were Also Equipped With Two Additional Matched Thermometers For Determining The Dew Point Temperature And Relative Humidity

7. Redundancy Of Temperature Measurement Was Lost In The 1980’s With Conversion To A Single Automated Electronic Sensor Called “The MMTS”.

8. 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)

9. Data From An “MMTS” Temperature System At A Cooperative Station

10. 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

12. Modernization Of The Equipment At The HCN Test Sites Uses The Proven Methodology Of The Past, Redundant Sensors

13. AL Greensboro HCN-M (County Jail)
32.7 N W 273’
March 16, 2007
Three Temperature Sensors in One Shield Equipped With Two Fans
Geonor All-Weather Precipitation Gage With Three Independent Sensors And Protecting “Wind Fence”
Solar Panels to Power the Station

14. Fan Ventilation Rate (R/S)
Temperature Traces of The Three Thermometers
Back-Up Fan

15. Precipitation Measurements

16. Snow Clogged Tipping Bucket Gage
The Easiest Design Is Not Always The Best

17. Tipping Bucket Mechanism Does Not Measure Snow Events, And Frequently Under-Reports Intense Rainfall

18. Snow Sticking to The Un-Heated Chute of a Weighing Precipitation Gage

19. Same Gage Type Clear of Snow When Equipped With a Heater

20. Chute Temperature Rises When Heater is Activated
Air Temperature
Wetness Sensor Readings
Traces of Three Precipitation Sensors

21. Wetness Sensor Activation Confirms Period Of Precipitation
Three Independent Sensors Of The Gage Measures Intense Precipitation Accurately