High Latitude Sea-Surface Skin Temperatures Derived from Saildrone Infrared Measurements

Short abstract

From 15th May to 11th October 2019, six Saildrone autonomous surface vehicles (ASVs) were deployed for 150-day cruises collecting a suite of atmospheric and oceanographic measurements from Dutch Harbor, Alaska, transiting the Bering Strait into the Chukchi Sea. Two Saildrones funded by NASA (the National Aeronautics and Space Administration), SD-1036 and SD-1037, were equipped with infrared pyrometers in a “unicorn” structure on the deck for the determination of the ocean sea-surface skin temperature (SSTskin). We present an algorithm to derive SSTskin from the downward- and upward-looking radiometers and estimate the main contributions to inaccuracy of the SSTskin. After stringent quality control of data and eliminating measurements influenced by sea ice and precipitation, and restricting the acceptable tilt angle of the ASV based on line-by-line radiative transfer model (LBLRTM) simulations, SSTskin can be derived to an accuracy of 0.12 K. The error budget of the derived SSTskin is developed and the largest component comes from the instrumental uncertainties assuming the viewing geometry is adequately determined. Thus, Saildrones equipped with these sensors could provide sufficiently accurate SSTskin retrievals for studying the physics of the thermal skin effect, in conjunction with accurate sub-surface thermometer measurements, and for validating satellite-derived SSTskin at high latitudes.