|Algorithm development PI: Dr. Yoshiaki Takeuchi (Japan Meteorological Agency)|
This document briefly describes some caveats for the AMSR Level 2 standard products of integrated water vapor.
Values of integrated water vapor are retrieved over global oceans (except over sea ice) in this product. Land areas are masked out by using land-ocean flag information based on the GTOPO30 database. Sea ice areas are excluded by referring the AMSR Level 3 sea ice concentration product. In addition, retrieval is not performed in the regions where sea surface wind speeds exceed the value of 20 m/s or the input brightness temperatures are bad in quality. Retrieval may be performed over large lakes.
Range of the water vapor retrieval is between 0 and 70 kg/m2. Retrieval error was estimated within 2.5 kg/m2 by using match-up dataset of radiosonde-derived water vapor and AMSR estimates.
Quality flags are included in the product, indicating the categories of clear, cloudy, heavy rain, and low quality. Quality with the retrieval error within 2.5 kg/m2 is applicable for the data with clear category flag. Data qualities of the estimates in other categories are inferior to that of clear category. Therefore, users must select the data depending on their purpose.