Data availability and file formatThe L2P Data from the series of Advanced Very High Resolution Radiometer (AVHRR) sensors consist of a single orbit per file on an irregular grid with grid cell spacing about 4 km. These start in September 1991. Each file contains two sets of SSTs. The first set provides a measure of the temperature of the skin of the water at the time it was observed; the second set are estimates of the temperature at 20 cm depth and at either 1030 h or 2230 h local time. Each SST has associated with it a total uncertainty estimate, and uncertainty estimates for various contributions to that total uncertainty. The data are stored in NetCDF-4 format files. Data arrays in NetCDF files areknown as