NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
Within the framework of the second SPARC Stratosphere-troposphere Processes And their Role in Climate water vapour assessment WAVAS-II, profile-to-profile comparisons of stratospheric and lower mesospheric water vapour were performed by considering 33 data sets derived from satellite observations of 15 different instruments. These comparisons aimed to provide a picture of the typical biases and drifts in the observational database and to identify data-set-specific problems. The observational database typically exhibits the largest biases below 70 hPa, both in absolute and relative terms. The smallest biases are often found between 50 and 5 hPa. Typically, they range from 0.25 to 0.5 ppmv 5 to 10 in this altitude region, based on the 50 percentile over the different comparison results. Higher up, the biases increase with altitude overall but this general behaviour is accompanied by considerable variations. Characteristic values vary between 0.3 and 1 ppmv 4 to 20. Obvious data-set-specific bias issues are found for a number of data sets. In our work we performed a drift analysis for data sets overlapping for a period of at least 36 months. This assessment shows a wide range of drifts among the different data sets that are statistically significant at the 2 sigma uncertainty level.
Journal Article - Open Access
Atmospheric Measurement Techniques , 12, 5, 01 Jan 0001, 01 Jan 0001,