CLICCS joint working group on the drivers of tropical circulation

Group leader:  Ann Kristin Naumann

The possibility to study the climate system with kilometer-scale models presents exciting opportunities and new science challenges. One of the challenges involves a question that interests our group: to what extent do microphysical processes influence the energy budget of the tropics, and its sensitivity to perturbations? Even at hectometer scales these processes will be crudely represented, raising the question as to whether it matters, and if it matters to what extent they can be constrained by observations.

Global storm-resolving models come along with methodological challenges: because of the large cost of the simulations, new ways to explore sensitivities using only very short runs are needed. To bring models and data together, we develop methods to compare kilometer-scale simulations and observations in the same playing field. Current topics we are working on include the questions of how water vapor and clouds covary in the trades or how rain fraction and intensity relate to the spatial distribution, size, and lifecycle of precipitating objects.

Building on the combination of storm-resolving modelling with observations and conceptual approaches, the group tries to better understand how much of the heat budget of the tropics is controlled by circulations and dynamics as compared to by microphysical processes. In an ongoing project we investigate how microphysical choices affect the albedo, radiative fluxes, and the heat budget in more general. Another project focuses on understanding the distribution of upper-tropospheric moisture and how it affects the energy budget in different global storm-resolving models.

The CLICCS joint working group on Drivers of Tropical Circulation is funded through the cluster of excellence CLICCS, and is run as a joint working group of MPI-M and the Universität Hamburg.

 

group website at the Meteorological Institute of the Universität Hamburg