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Anatomy of Convective Clouds over the Amazon (ACCA)

Grant number: 20/13273-9
Support type:Scholarships in Brazil - Post-Doctorate
Effective date (Start): November 01, 2020
Effective date (End): October 31, 2021
Field of knowledge:Physical Sciences and Mathematics - Geosciences - Meteorology
Principal Investigator:Paulo Eduardo Artaxo Netto
Grantee:Micael Amore Cecchini
Home Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
Associated research grant:17/17047-0 - Aerosol and clouds life cycles in Amazonia: biogenic emissions, biomass burning and impacts on ecosystem, AP.PFPMCG.TEM

Abstract

Convective clouds play a key role in the water, carbon, and energy budgets over the Amazon. Pollution emitted by biomass burning or anthropogenic activities significantly disrupts the cloud characteristics by increasing the number of droplets while reducing their mean size. We propose a new approach to investigate whether such changes lead to cloud invigoration or inhibition, respectively increasing or decreasing their horizontal area, depth, and likelihood of transitioning from shallow to deep convection. The originality relies on integrating microphysical, dynamic, and chemical processes. The project is timely since recent studies have linked deep convective clouds to new aerosol particle formation in the upper troposphere that later nucleate clouds in the boundary layer. We will focus on processes occurring at the cloud core and at its margins. Our combined hypothesis is that smaller droplets produce both an intensification of the updrafts at the core, leading to invigoration, and an intensification of the downdrafts at the margins, promoting inhibition. We propose to objectively analyze the diurnal variability of the convective cloud anatomy over the Amazon using high-resolution (meter-scale) numerical experiments and recent remote sensing and aircraft-based measurements. The Post-Doc has actively participated in several measurement campaigns in the region, as shown in his CV. ACCA outcome will enable us to understand how cloud diurnal cycling depends on instability, wind shear and humidity to identify regimes of aerosol invigoration or inhibition of clouds and the effect on the shallow-to-deep transition. This is crucial to represent the local seasonality since aerosol concentrations span more than 2 orders of magnitude between the wet and dry seasons. This new understanding aims to reduce the uncertainty around clouds in the Amazon region.