Global space-time scales for day-to-day variations of daily-minimum and diurnal sea surface temperatures: their distinct spatial distribution and seasonal cycles

Spatial and temporal scales of day-to-day sea surface temperature (SST) variation were estimated globally based on the microwave cloud-free SST data. By employing the diurnal correction method of SST using sea surface wind (SSW) and solar shortwave radiation data, the scales of daily-minimum SST and diurnal SST amplitude were independently investigated along with seasonal and regional dependency. The daily-minimum SST showed moderate spatial scales of O(150–400 km) and relatively long temporal scales of O(3–4 days). In eddy-rich areas, the small spatial and long temporal scales were found to be associated, which suggests that the sub-mesoscale SST structures could be reproduced by spatial–temporal interpolations. Diurnal SST amplitude, which is strongly affected by air–sea interaction and high activity in the warming seasons, showed extremely long/short scales in the zonal/meridional directions of up to 1000 km/O(100–200 km), and its temporal scales were less than 1 day.