Towards improved corrections for radiation-related biases in radiosonde observations

Upper-air temperature, humidity, pressure, and wind observations made by balloon-borne radiosonde instruments have had important applications in weather prediction, upper-air climate research, and satellite data validation. However, measurement biases undermine their value in all of these applications, and various approaches have been taken to correct them. Here we present an analysis of temperature biases in radiosonde observations (raobs), with the intention of facilitating improvements in correction techniques.

This study employs over 3 years (May 2008- August 2011) of Global Positioning System (GPS) Radio Occultation (RO) data as a reference to assess and quantify the radiation related biases for sonde types in the global operational radiosonde network. Collocated radiosonde and GPSRO data are collected with the NOAA satellite Products Validation System (NPROVS) operated at the NOAA/NESDIS Center for Satellite Application and Research (STAR). Using the Constellation Observing System for Meteorology Ionosphere & Climate (COSMIC) data as a reference, we analyze the raob-minus-COSMIC temperature differences at different solar elevation angles, seasons, and zonal belts, both for the global radiosonde network and for individual sondes, and evaluate the radiative impact of clouds. The impact of radiosonde radiation error on numerical weather prediction is discussed.