A global study of diurnal warming using satellite-derived sea surface temperature

Ten years of global infrared satellite data from National Oceanic and Atmospheric Administration's advanced very high resolution radiometer are analyzed to investigate global variations of diurnal warming. Daily nighttime sea surface temperatures (SSTs) are subtracted from adjacent daytime SSTs to give an estimate of diurnal warming (ΔTday-night). The results reveal large regions in the tropics and midlatitudes that are frequently susceptible to diurnal warming each year. A strong seasonal pattern exists, dictated by the wind and solar insolation variability. A simple ΔT regression model confirms that the observed warming is consistent with the right meteorological conditions of low winds and high insolation. The analysis also reveals how the spatial distribution and magnitude of ΔT varies with the drift of the satellite orbit as it shifts from a local overpass time of 1400 to 1600. The results highlight the importance of the diurnal cycle for SST measurements and suggest the need for the diurnal cycle to be included in numerical models.