Phase II of the ARM Program’s special series of radiosonde flights, coordinated with overpasses of the National Aeronautics and Space Administration’s “Aqua” satellite, began in September 2003 at all three of ARM’s locales. Because ARM is the only program that can provide ongoing, consistent, and coordinated research-grade radiosonde data from stations located in the arctic, mid-latitudes, and the tropics, the global distribution of the ARM Climate Research Facility was a key factor for scientists involved in validating the Atmospheric Infrared Sounder (AIRS), one of the instruments onboard Aqua. Consisting of two flights per overpass—the first timed so one radiosonde is near the tropopause (10-18 km depending on the site and season) while the second radiosonde is near the surface—ARM Climate Research Facility operators successfully concluded the series of 90 sampling events in March 2004.
Because AIRS is intended to measure profiles of atmospheric temperature and humidity, using ARM’s radiosonde observations is an extremely important activity for evaluating the satellite sensor’s performance. Sampling for Phase III of the program, which again includes 90 sampling events at each ARM locale, began in April 2004.