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) 32.7 N 87.6 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

Fan Ventilation Rate (R/S) Temperature Traces of The Three Thermometers 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 Wetness Sensor Readings Traces of Three Precipitation Sensors

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