Environmental Conditions Controlling the Shallow-to-Deep Transition in Convective Clouds During GoAmazon 2014/15
Poster PDF
Authors
Michael Jensen — Brookhaven National Laboratory
Scott Giangrande — Brookhaven National Laboratory
Cari Gostic — Cornell University
Virendra Prakash Ghate — Argonne National Laboratory
David B. Mechem — University of Kansas
Tami Fairless — Pacific Northwest National Laboratory
Category
GoAmazon – Clouds and aerosols in Amazonia
Description
Nearly two years of observations from the ARM Mobile Facility (AMF) deployed at Manacapuru, Brazil during the GOAmazon 2014/15 campaign are analyzed to investigate the environmental conditions controlling the transition from shallow to deep convective clouds. W-band ARM Cloud Radar (WACR) observations are used to define: 1) Transition cases where a period of shallow convective clouds in the morning is followed by a period of deep convective clouds in the afternoon and 2) Non-transition cases where shallow convective clouds persist throughout the day without any subsequent development. For these subsets, observations of the time-varying thermodynamic properties of the atmosphere, including the surface heat and radiative fluxes, and the profiles of atmospheric state variables are composited to define averaged properties for each transition state. Initial analysis indicates that the transition state strongly depends on the pre-dawn low-level cloudiness and the free tropospheric humidity. Associated environmental thermodynamics are then used to force large-eddy simulations for the different transition states to further evaluate the sensitivity of the transition to the composite thermodynamics versus the importance of larger-scale forcing.
