El Nino Impact on the Earth's Radiation Budget: A Satellite Analysis

Over the last several years, the Clouds and the Earth's Radiant Energy System (CERES) team has contributed a section on the variability of radiation budget at the Top-of-Atmosphere in the annual “State of the Climate Report” published in BAMS. The analysis features the Fast Longwave And SHortwave Flux (FLASHFlux) and Energy Balanced And Filled (EBAF) data products to estimate the annual average radiative budget components from the most recent year in contrast to the CERES EBAF climatology. Previous analyses show the global annual radiative flux anomalies to be well within 2-sigma interannual variability; however, for the year 2015 the reflected shortwave (RSW) flux is above the 2-sigma value. This corresponds to the most recent El Nino event that reached peak intensification in 2015.

Previous studies have demonstrated that clouds play an important role in regulating Earth's radiation budget such that the Net radiation is relatively close to zero by reflecting shortwave radiation and reducing outgoing longwave radiation. However, a study of the 1998 El Nino showed it caused a net radiative cooling over the tropical western Pacific's warm pool due to changes of the cloud vertical structure in regions over the Pacific oceans [Cess et. al., 2001]. In this paper, we assess the nature of the 2015 RSW anomaly that coincides with the development of El Nino and investigate the physical mechanisms, such as clouds properties, causing it. The analysis uses FLASHFlux and EBAF data products together with observed surface and cloud property changes. Since the 2015-2016 El Nino's strength is comparable to that of the 1998 El Nino, we will compare the radiative flux anomalies from the 1998 El Nino using ERBE and NASA/GEWEX SRB data products in terms of magnitude and location to the most recent 2015-2016 El Nino.