Comparison of microwave satellite humidity data and radiosonde profiles: A survey of European stations

[摘要] A method to compare upper tropospheric humidity (UTH) fromsatellite and radiosonde data has been applied to the Europeanradiosonde stations. The method uses microwave data as a benchmarkfor monitoring the performance of the stations. The present studyutilizes three years (2001-2003) of data from channel 18(183.31±1.00 GHz) of the Advanced Microwave Sounding Unit-B(AMSU-B) aboard the satellites NOAA-15 and NOAA-16. The comparison isdone in the radiance space, the radiosonde data were transformed tothe channel radiances using a radiative transfer model. Thecomparison results confirm that there is a dry bias in the UTHmeasured by the radiosondes. This bias is highly variable among thestations and the years. This variability is attributed mainly tothe differences in the radiosonde humidity measurements. Theanalysis also shows a difference between daytime and nighttimesoundings which is attributed to radiation error in the radiosondedata. The dry bias due to this error alone correspond toapproximately 11% relative error in the UTH measurements.

[学科分类] 大气科学