Abstract:
The Atmospheric Infrared Sounder (AIRS) is a facility instrument aboard the second Earth Observing System (EOS) polar-orbiting platform, EOS Aqua. In combination with the Advanced Microwave Sounding Unit (AMSU) and the Humidity Sounder for Brazil (HSB), AIRS constitutes an innovative atmospheric sounding group of visible, infrared, and microwave sensors. AIRS data are generated
... continuously. Global coverage will be obtained twice daily (day and night) on a 1:30pm sun synchronous orbit from a 705-km altitude.
This precipitation estimate from AIRS is using TOVS-like algorithm, and is intended for TRMM multi-satellite merged precipitation retrieval. The precipitation estimate from AIRS Level 2 Support product, which are 6-min swath granules (240 per day) are combined here into one daily "Level 2G" global grid with dimensions (24x1440x720). Thus every hour is a "layer", and the resulting grid cell size is 0.25 degree (~25 km). Thus grid size is made to fit TRMM products. Since AIRS precipitation is retrieved at AMSU footprint resolution, which is about 45 km at nadir, many grid cells in this 0.25-deg grid are "empty". The data are stored such that the first line is the South Pole. The geolocation information for every hour-layer is also provided in the file.
(The Shortname for this product is AIRG2SSD). 
