CPP-13. The sum of its parts: Deconstructing the Relationship Between Three Atmospheric Reanalyses and Their Impact on Observed Differences in Ocean Heat Gain

Abstract
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; meaning that there is more energy to transfer from 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. Depending on patterns of seasonal sea ice retreat and weather conditions, the spring-summer heat uptake and autumn-winter heat loss can be highly variable from year to year and regionally. In previous work, we found that there are some large differences in the time series for seasonal heat gain between three atmospheric reanalyses (MERRA-2, ERA-5, CFSR). What is causing these underlying differences? Since ocean heat gain is calculated using the components of the surface energy flux, that is exactly where we needed to look. Here, we examine how the seasonality in upwelling and downwelling shortwave and longwave radiation evolves over the period 1979-2018 and the relationship between the reanalyses. A statistical relationship is calculated between each reanalysis for all four variables. We determined which reanalyses have the highest correlations and in which region for daily and seasonal values. The aim of this project is to determine which reanalyses are performing similarly and which, if any, don’t align well. If values don’t align, is there one variable that has a larger impact on the differences in ocean heat gain observed in previous work? In future work, these variables and relationships will be used to construct a statistical model for sea prediction and evaluate which variables have the strongest predictive power.