A Global Study of Diurnal Warming using Infrared Satellite-derived Sea Surface Temperature

Abstract

Ten years of global infrared satellite data from NOAA's Advanced Very High Resolution Radiometer (AVHRR) have been analysed to identify the global temporal and spatial distribution of diurnal warming and assess its impacts. Daily night-time SST's are subtracted from adjacent day-time SST to give an estimate of diurnal warming (ΔTday-night). The results reveal large regions in the tropics and mid-latitudes that are frequently susceptible to diurnal warming each year, dictated by seasonal wind and insolation patterns. The analysis also reveals how the spatial distribution and magnitude of AT varies with the drift of the satellite orbit as it shifts from a local afternoon overpass time of 14h00 to 16h00. The results highlight the sensitivity of SST to its sampling time and reveal the importance of the diurnal cycle for the interpretation of SST measurements. The results also suggest important implications for air-sea interaction and upper ocean processes which are dependent on SST.