Dr. Maxime Colin Postdoctoral Researcher

Leibniz Centre for Tropical Marine Research, Germany

Dr. Maxime Colin

Abstract
To improve climate projections and weather forecasts, it is useful to know the inertia of the climate system, as it adds predictability. Here, we focus on four aspects of the Earth system's "short-term" memory.

First, we highlight the concept of convective memory, which causes persistence in clouds and precipitation. Convective memory has long been omitted from general circulation models, and attempts to incorporate it have been relatively ad hoc. Through several sets of experiments using high-resolution simulations, we show that convection memory exists, that it is strongly related to convective organisation in space, and that it relies on small-scale thermodynamic structures in the boundary layer, such as cold pools.

Second, we investigate the role of atmospheric memory in monsoon hysteresis, which can be detected by the rapid and delayed monsoon onset, as well as
other nonlinearities. We propose original simulations that can serve as an idealized test to study the effects of several boundary conditions and simulation parameters on monsoons. It turns out that atmospheric memory cannot be neglected to understand monsoon hysteresis.

Third, we examine upper-ocean memory, which explains the recharge/discharge process that occurs during El Niño cycles. In particular, while the best index characterizing recharge has been debated for 30 years, we propose an objective method to determine the optimal recharge index, which takes into account
ocean heat content stored in the equatorial and southwest Pacific.

Fourth, we will present the main ideas behind our field study in Senegal, for which we install a network of weather stations in local schools. A main objective is to study the role of soil moisture memory, which seems to have an important effect on the spatio-temporal organisation of convection.

Contact: Yi-Hsuan Chen