Investigating Environmental Controls on Tropical Mesoscale Convective System Lifecycles

Investigating Environmental Controls on Tropical Mesoscale Convective System Lifecycles

Sayali R. Kulkarni¹, Kathleen A. Schiro¹, Gregory Elsaesser²

University of Virginia¹, NASA Goddard Institute of Space Studies/Columbia University²

Tropical mesoscale convective systems (MCS) are some of the most intense and frequent precipitating systems occurring throughout the year, contributing up to 75% or more of the annual rainfall across the tropics. However, multi-scale interactions between MCSs and their environments are not well understood, likely leading to model biases in precipitation and cloud properties. Our study invokes observational data from multiple platforms to identify the dominant thermodynamic controls on MCS lifecycle. Remotely sensed data (GPM, AIRS/Aqua), reanalyses (ERA-5), and surfaced-based (PMEL buoy) data are being used to answer science questions pertaining to MCS and cold pool dynamics. MCS lifecycle is quantified using Tracked IMERG Mesoscale Precipitation System data (TIMPS; Russell et al. 2022). Each system is spatiotemporally tracked, providing statistics on precipitation rate, area, and lifetimes. We show how estimates of buoyancy evolve with MCSs in space and time, for growth, mature, and decay stages. Our preliminary results suggest that before MCSs are detected, an increase in column moisture and environmental buoyancy can be detected up to 24 hours beforehand; however, this increase is observed over a shorter period for MCSs occurring over land. Additionally, we show storm-centric spatial composites of moisture and temperature perturbations that suggest a significant downdraft cooling near surface with enhanced buoyancy surrounding it. Rotational composites of these perturbations show evidence that MCS directions of motion may be driven by local perturbations in the thermodynamic environment. Secondly, the study delves into understanding the role of cold pools in modulating MCS lifecycles. We collocate the dataset developed in the previous task with buoy data to obtain a broader understanding of cold pool intensity and spatial extent. To quantify the potential for cold pools to modulate updraft buoyancy and MCS longevity, creation of a cold-pool expansion metric as a function of cold pool strength and extent is underway. This work aims to inform revisions to current parameterizations of moist convection across scales and support MCS parameterization efforts.