Shallow-to-Deep Convective Transition in the Amazon

Poster PDF

Description

The suite of observations from GOAmazon 2014/15 and CHUVA offers a unique opportunity to examine land-based convective processes in the tropics, including the poorly represented shallow-to-deep transition. This study makes use of these data to investigate the daily mean environmental conditions and development of the boundary layer and free troposphere in the Central Amazon for four separate convective event classes: 1) clear-sky, 2) nonprecipitating cumulus congestus, 3) afternoon deep convection and 4) mesoscale convective system (MCS). These cases are further differentiated into three environmental categories: 1) weak versus strong large-scale and/or synoptic-scale forcing, 2) wet versus dry season and 3) clean versus dirty based on the local aerosol concentration. Within this framework, we seek to understand the shallow-to-deep convective transition in the Amazon and determine how these processes differ by season and through large-scale and local circulations. The primary variables of interest to achieve this overarching goal include surface meteorological variables (air temperature, humidity and winds); surface precipitation; the vertical thermodynamic and dynamic structure of the troposphere; sub-cloud-layer turbulence; vertical moist static stability; cloud-base and cloud-top height and temperature; cloud type and organization (e.g., MCS, isolated); sub-cloud and cloud vertical motions; integrated column water vapor and liquid water; and surface energy fluxes. Here, in this initial stage of the analysis, we highlight the diurnal cycle in key variables for each convective classification through use of case studies and discuss how these classifications and the underlying diurnal processes differ between the wet and dry season and in the presence of intraseasonal Kelvin wave activity. Future work will further explore these processes and determine how well they are represented in both global and regional model simulations of differing resolution and convective parameterizations.