The MOD02SSH data product is a subsample of the MODIS Level-1B 1 km data. It contains a 5 km by 5 km subsampling of the data from MOD021KM, along with the associated metadata. Except for the different sizes of the arrays, it has the same structure as the parent file (including dimension names that no longer match). The HDF-EOS dimension map has been adjusted to reflect the fact that data fields and the geolocation fields are at exactly the same resolution.
Every fifth pixel is taken from the MOD021KM product and written to MOD02SSH. The subsampling starts at the third frame, and at the third line. Here, 'frame' and 'line' are naming conventions for pixels along and across the scan, respectively. Since MOD02SSH is a subsampled Level-1B product, most of the Level-1B documentation applies. That is, the MOD02SSH data product contains calibrated and geolocated at-aperture radiances for 36 bands generated from MODIS Level-1A scans of raw radiance (MOD01). The radiance units are in W/(m^2 µm sr). Additional data are provided including quality flags, error estimates and calibration data. Visible, shortwave infrared (SWIR), and Near Infrared (NIR) measurements are made during daytime only, while radiances for Thermal Infrared (TIR) are measured continuously.
MOD02SSH is in HDF-EOS format, and all metadata structures and names are preserved. However, some relevant changes are made where appropriate, for example, the dimension mappings are updated to reflect the new one-to-one correspondence between the data and geolocations. The latter is one of the most important differences: in the MOD02SSH, there is no oet between data and geolocation pixels. The spatial coverage is almost similar to that from MOD021KM (nominally it is 2330 km by 2030 km, cross-track by along-track, respectively). The MOD02SSH is produced continuously, and thus the processing provides 2-day repeat observations of the Earth with a repeat orbit pattern every 16 days.