Using Saildrone Observations to Understand Diurnal Variability in Arctic Sea Surface Temperature

Changes in solar insolation throughout the day can produce diurnal patterns in surface variables such as temperature. Diurnal cycles have been extensively studied in many regions such as the tropics, but are not well understood in the Arctic, where in-situ measurements are traditionally difficult to perform. Since 2017, the NOAA Pacific Marine Environmental Laboratory (PMEL) has been deploying saildrones, unmanned surface vehicles (USVs), in the Arctic to measure sea surface variables such as temperature, wind speed, and more. Using these saildrone measurements, we investigate controls on diurnal variability in Arctic sea surface temperatures. By developing and applying an algorithm to isolate simple diurnal signals in hourly meteorological data, we found that simple sea surface temperature diurnal signals occur infrequently in the Arctic and other unusual diurnal patterns can also be observed. Comparison with other meteorological variables such as air temperature, solar radiation, wind speed, and salinity led us to identify conditions under which simple diurnal signals and other patterns in Arctic sea surface temperature may occur.