The Tropical Rainfall Measuring Mission (TRMM) is a joint U.S.-Japan  satellite
                        mission to monitor tropical and subtropical precipitation. 
                        
                        The Level 1B product file (1B01) contains calibrated radiances and
                        auxiliary geolocation information for each pixel in the scan. The
                        Level 1B data are stored in the Hierarchical Data Format (HDF), which
                        includes both core and product specific metadata applicable to the
                        VIRS measurements. A file contains a single orbit of data with a file
                        size of about 87 MB (uncompressed). The HDF-EOS &quot;swath&quot; structure is
                        used to accommodate the actual geophysical data arrays. As in the case
                        of the Level 1A data, there are 16 files of VIRS 1B01 data
                        produced per day.
                        
                        For channels 1 and 2, Level 1B radiances are derived from the Level 1A
                        sensor counts by computing calibration parameters (gain and offset)
                        derived from the counts registered during space and solar and/or lunar
                        views. New calibration parameters are produced every 1 to 4
                        weeks. Bands 3, 4, and 5 are calibrated using the internal blackbody
                        and the space view. These two data points, together with a quadratic
                        term determined pre-launch, are used to generate a counts vs. radiance
                        curve for each band, which is then used to convert the earth-view pixel
                        counts to spectral radiances.
                        
                        For the Level 1B data, geolocation and channel data are written out
                        for each pixel along the scan, whereas the time stamp, scan status
                        (containing scan quality information), navigation, calibration
                        coefficients, and satellite/ solar geometry are specified on a per-scan
                        basis. There are in general 18026 scans along the orbit with each scan
                        consisting of 261 pixels. The scan width is about 720 km.
                        
                        Spatial coverage is between 38 degrees North and 38 degrees South
                        owing to the 35 degree inclination of the TRMM satellite. This orbit
                        provides extensive coverage in the tropics and allows each location to
                        be covered at a different local time each day, enabling the analysis
                        of the diurnal cycle of precipitation.