Remarkably Large Differences Among Eight Satellite, Reanalysis and Reconstructed Products of Global Sea Surface Net Radiation

Abstract

The performance of all-wave net radiation (Rn) estimates at the global sea surface is largely unknown. In this study, eight daily mean long-term sea surface Rn products were compared and evaluated using observations from 55 moored buoys. The eight products included three satellite products: Editions 4A of the Clouds and the Earth’s Energy System (CERES-4A), the Japanese Ocean Flux Datasets with Use of Remote Sensing Observations, Version 3 (J-OFURO3), and the Global Energy and Water Exchange (GEWEX) – Surface Radiation Budget; four reanalysis products: ERA-Interim, the Japanese 55-Year Reanalysis (JRA55), the Modern Era Retrospective Analysis for Research and Applications, Version 2 (MERRA2), and the National Centers for Environmental Prediction Department of Energy Reanalysis 2 (NCEP R2); and one reconstructed product: the Objectively Analyzed Air-Sea Fluxes from the International Satellite Cloud Climatology Project radiative flux D-series product (OAFlux+ISCCP). The results indicate the following: (1) large discrepancies appeared in all products, particularly in the tropics and high-latitude seas; (2) the satellite products generally outperformed  the reanalysis products, among which J-OFURO3 performed the best with an R2 of 0.883, a root-mean-square difference (RMSD) of 21.883 Wm−2, and a bias of 0.275 Wm−2 , and NCEP R2 was the worst, with an R2 of 0.341, an RMSD of 60.296 Wm−2, and a bias of -13.105 Wm−2, during the common study period from 2000 to 2013, and the conclusions were almost unaffected by the spatial resolution; and (3) the long-term trends, variations, and magnitude in the annual average sea surface Rn from all products were remarkably different, especially before 2000, and thus, it is difficult to tell which product is reliable. Overall, these eight products show significant disagreements, and each product has its own advantages and drawbacks; therefore, further studies are required to improve the accuracies of the sea surface radiative fluxes.

Keywords: net radiation, sea surface, evaluation, satellite, reanalysis, reconstructed product, moored buoy