Cloud Responses to Modes of Climate Variability as Observed by MISR and MODIS

Clouds play a crucial role in Earth’s radiative energy budget, but remain a major source of uncertainty in climate predictions. Studying how clouds respond to internal climate variability can improve our understanding of how clouds change on monthly and inter-annual time scales, provide insight into how clouds and cloud feedbacks might be altered in a changing climate, and provide a validation metric for climate models. Here, cloud responses to several major modes of internal climate variability (including the El Nino Southern Oscillation, Pacific Decadal Oscillation, Southern Annular Mode, North Atlantic Oscillation, and North Pacific Index) are examined using 15 years of data from instruments aboard NASA’s EOS Terra platform. A combination of regression and clustering techniques are used to identify regions of the globe with distinct cloud responses to these sources of climate variability in the context of cloud occurrence histograms. Finally, the results are compared to a historical run of the HadGEM3 model using an instrument simulator to determine whether the model adequately captures this monthly to inter-annual variability.