|Algorithm development PI: Dr. Yoshiaki Takeuchi (Japan Meteorological Agency)|
This document briefly describes some caveats for the AMSR-E Level 2 standard products of integrated water vapor.
This product retrieves integrated water vapor over global oceans (except over sea ice). Land areas are masked out by using land-ocean flag information based on the GTOPO30 database. Sea-ice areas are excluded by referring to the AMSR-E Level 3 sea-ice concentration product. In addition, water vapor is not retrieved in regions where the sea-surface wind speed exceeds 20 m/s or the input brightness temperatures are poor quality. Integrated water vapor may be retrieved over large lakes.
Water vapor retrieved ranges from 0 to 70 kg/m2. The retrieval error was estimated to be less than 3.5 kg/m2 using the match-up dataset of radiosonde-derived water vapor and AMSR-E estimates.
Quality flags included in the product indicate the categories of clear, cloudy, heavy rain, and low quality. The retrieval errors are within 3.5 kg/m2 only for the data with the clear category flag. Data qualities of the estimates in other categories are inferior to that of the clear category. Therefore, users must select the data depending on their purpose.