Application of the Pseudo-Global Warming Approach in a Kilometer-Resolution Climate Simulation of the Tropics

Abstract

192133 -Exploiting km-resolution climate models in the tropics to constrain climate change uncertainties (trCLIM) (SNF) 820829 -LC-CLA-08-2018 | RIA | Constraining uncertainty of multi decadal climate projections (EC) This page was generated automatically upon download from the ETH Zurich Research Collection. For more information, please consult the Terms of use.Plain Language Summary Tropical clouds are an important component of the climate system as they can either amplify or dampen human-induced climate change. However, predicting how clouds will change in a warming climate is challenging due to their small-scale nature. We perform high-resolution atmospheric climate simulations over the tropical Atlantic to study what we can learn about tropical clouds from this relatively novel type of models. We validate the simulation under current climate conditions and find a good representation of tropical clouds in comparison to coarser climate models. In particular, the high-resolution simulation does not suffer from the double intertropical convergence zone (ITCZ) problem commonly present in global climate models. We then study how tropical clouds will change in a warming climate and find differences between our high-resolution simulation and coarser climate simulations. The tropical overturning (Hadley) circulation weakens in both model types, but the narrowing of the ITCZ (known as the deep-tropics squeeze) is not so pronounced in the high-resolution simulation, likely due to the absence of a double ITCZ bias.

Dynamical Downscaling of Climate Simulations in the Tropics

“…The considered fields are the same as the study of Heim et al. (2022), which includes near‐surface fields such as surface humidity, skin temperature, sea‐surface temperature, and surface pressure, as well as the three‐dimensional fields of temperature, humidity, velocity and geopotential. The bias‐corrected MPI‐ESM1‐2‐HR fields are then used to drive the COSMO model (named “bias‐corrected downscaling” in the following context).…”

“…Dynamical downscaling is applied to the result of the CMIP6 historical simulation of the MPI-ESM1-2-HR model (Max Planck Institute for Meteorology, 2020;von Storch et al, 2017), following a recent study (Heim et al, 2022). The MPI-ESM1-2-HR input for the COSMO model has a horizontal resolution of around 100 km and 95 vertical levels.…”