Cold Pools Reduce the Impacts of Deforestation on Convection Initiation

TL;DR

This study uses idealized simulations to examine how cold pools and land surface heterogeneity influence convection initiation in the Amazon, revealing that cold pools can counteract heterogeneity effects and affect convection patterns.

Contribution

It demonstrates that cold pools can disaggregate convection initiation locations and precipitation, partially offsetting the effects of land surface heterogeneity.

Findings

Cold pools have minimal impact over homogeneous vegetation.

Heterogeneous vegetation promotes aggregation of convection initiation.

Cold pools propagate into deforested areas, disaggregating convection patterns.

Abstract

The individual and synergistic impacts of cold pools and land surface heterogeneity on convection initiation are investigated. Idealized large eddy simulations of deep convection over the Amazon rainforest are conducted. Simulations test realistic and homogenized vegetation, along with realistic and suppressed low-level evaporation which eliminates cold pools. Updrafts are tracked to determine convection initiation locations. The aggregation of initiation locations is quantified with an organization index. Initiation locations are randomly distributed over homogeneous vegetation, with or without cold pools, demonstrating that cold pools have minimal impacts on initiation locations over homogeneous vegetation. With realistic vegetation, convection initiation is more frequent over forested than deforested areas due to favorable thermodynamics. Heterogeneous vegetation effectively aggregates initiation locations and precipitation compared to homogeneous vegetation, whereas cold pools disaggregate initiation locations and precipitation by propagating into deforested regions and initiating convection. Thus, cold pools partially counteract the effects of anthropogenically driven land surface heterogeneity.