El Niño-Induced Tropical Ocean / Land Energy Exchange in MERRA-2 and M2AMIP

Studies have shown the correlation and connection of surface temperatures across the globe, ocean and land, related to Tropical SSTs especially El Niño. This climate variability greatly influences regional weather and hydroclimate extremes (e.g. drought and flood). In this paper, we evaluate the relationship between tropical ocean SSTs and land surface temperatures over continents in MERRA-2, and also in a newly developed MERRA-2 AMIP ensemble simulation (M2AMIP). M2AMIP uses the same model and spatial resolution as MERRA-2, producing the same output diagnostics over 10 ensemble members. Composite El Niño temperature data are compared with observations to evaluate the land/sea contrast, variations and phase relationships. The temperature variations are related to surface heat fluxes and the atmospheric temperatures and transport, to identify the processes that lead to the lagged redistribution of heat in the tropics and beyond. Discernible cloud, radiation and data assimilation changes accompany the onset of El Niño affecting continental regions through the progression to and following the peak values. The impact of these processes on the Global Monsoon is identified. While the model represents these variations in general, regional strengths and weaknesses can be identified.