Weakening or strengthening of the Hadley Cell?

Master thesis, University of Ljubljana, Faculty of Mathematics and Physics, 2019

Graduate student Matic Pikovnik will study the yearly and monthly trends in Hadley circulation in the ERA5 reanalyses. The climate models and the majority of reanalyses are showing very distinct trends: the former show weakening, while the latter predict strengthening. The most recent argument which favors climate models’ prediction versus that of reanalyses is that the reanalyses overestimate the tropical precipitation, based on the verification with GPCP data. Precipitation is the nearest proxy for condensation heating and vertical motions. Consequently, too strong precipitation would result in enhanced Hadley cell. However, latest ERA5 data verify much better with available precipitation datasets, but still show mild enhancement of the Hadley cell over the 1980-2018 period.