A Preliminary Comparison of TAMDAR Aircraft and NWS Radiosonde Sounding Data

TAMDAR (Tropospheric Airborne Meteorological Data Report) is an instrument package and communications system designed by Airdat LLC as part of NASA and FAA safety initiatives. The instrument package measures atmospheric temperature, humidity, icing and pressure in addition to derived wind and turbulence data. The TAMDAR instrument was installed on 61 Mesaba Airlines Saab 240 Turboprop aircraft and evaluated in real-time as part of the TAMDAR Great Lakes Fleet Experiment (GLFE) which began in January 2005. Atmospheric sounding data was collected during ascent and descent and transmitted via satellite to an Airdat ground station. The data was relayed to NOAA's Forecast Systems Laboratory (FSL) where they were made available to National Weather Service (NWS) Forecast Offices via an interactive Java web page and the Interactive Weather Information and Processing System (AWIPS).

TAMDAR and NWS radiosonde data used in this comparison study were obtained directly from the FSL Java website. Meteorological data was gathered at 925, 850, 700 and 600mb over the course of the 12 month experiment at Minneapolis International Airport. This location was chosen because it is a busy hub with nearly one hundred aircraft soundings per day and the region experiences a variety of weather regimes throughout the year. Because the TAMDAR instrument was installed on aircraft serving smaller regional airports located across the northern and central United States, lower cruising altitudes precluded meaningful data comparisons above 600mb. Data analysis, including average error, RMS error and standard deviation will be examined based on pressure level, aircraft ascent .vs. descent, aircraft identification number, weather regime, distance from radiosonde location and departure from the radiosonde release time. Finally, the results will be contrasted to a prior WVSS-I to radiosonde comparison as the WVSS-I used similar technology to TAMDAR.