Is it all garbage?: Using atmospheric reanalyses to assess seasonal ocean heat gain from the net surface flux.

As the Arctic Ocean loses its sea ice cover, there is a larger oceanic heat gain from the net surface flux throughout the spring and summer; ultimately meaning that there is more energy to transfer out of the ocean to the atmosphere and outer space in the autumn and winter. Recent work has shown that the increased oceanic heat content at the end of summer delays autumn ice growth, with implications for marine shipping and other economic activities. Comparisons between reanalyses has shown that ocean heat gain values range widely. Due to the harsh conditions of the Arctic and the expense of instrument installation, many scientists rely on reanalysis data for their work. But how comparable are these models to actual measurements? Here, we compare downwelling shortwave radiation values collected aboard the RV Araon , a South Korean ice breaker, in the Chukchi Sea during August of 2018 to values from three reanalyses (MERRA-2, ERA-5, CFSR). Although we will only be using downwelling shortwave radiation values from RV Araon , this variable is a key component of the surface flux calculations. Additionally, comparisons are also made between the CERES radiation values and reanalyses in order to find where the discrepancies between ocean heat gain values may originate. We determine which regions have the largest differences between the ground truth data and model values. Will there be agreement within one standard deviation? If not, what creates the differences observed?