Surface, Aerosol, and Meteorological Controls on Subtropical Coastal Metropolitan Convective Clouds: Observations and Simulations from TRACER

Surface, Aerosol,

aerosols

Small particles or droplets, such as wildfire smoke, volcanic gases, or salty sea spray, that float in the air. They are emitted by both natural events and human activities.

Source: NASA Global Climate Change Source

and Meteorological Controls on Subtropical Coastal Metropolitan Convective Clouds: Observations and Simulations from TRACER

Yongjie Huang, University of Oklahoma (Principal Investigator)
Lulin Xue, National Center for Atmospheric Research (Co-Principal Investigator)
Alexander Ryzhkov, University of Oklahoma (Co-Principal Investigator)
Ming Xue, University of Oklahoma (Co-Principal Investigator)
Greg M. McFarquhar, University of Oklahoma (Co-Principal Investigator)

Abstract
Convective clouds play important roles in Earth’s climate system, while interactions between convective clouds and their surrounding environments remain insufficiently understood due to large uncertainties in key dynamical and microphysical processes, as well as in aerosol-convection interactions, whose realistic representation is a grand challenge for both numerical weather prediction and Earth system models.

earth system model (ESM)

A model that simulates how chemistry, biology, and physical forces work together. These models are similar to, but much more comprehensive than, global climate models.

Source: U.S. Department of Energy Source

The Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Tracking Aerosol Convection Interactions Experiment (TRACER) field campaign in the Houston area tracked the full life cycle of a large number of isolated convective cells under a wide range of environmental conditions. Thus, this is a unique dataset that allows hypotheses on the key processes that control the properties of individual convective cells in a warm and humid subtropical coastal metropolitan region to be tested. We will synergistically combine the unique campaign observational datasets and high-resolution model simulations to test our hypotheses in the project: 1) For given underlying surface conditions and weak synoptic-scale forcing, dynamic and thermodynamic environments control the life cycle of convective cells; 2) increases in aerosol concentration enhance convective cells through stronger condensational heating (warm-phase invigoration) in the initiating stage; and 3) increased aerosol concentrations shorten the lifetimes of convection

convection

The rising of warm air and the sinking of cool air. Convection can cause local breezes, winds, and thunderstorms.

Source: NASA earth observatory Source

through stronger evaporative cooling associated with the more numerous small cloud particles. The unique campaign observational datasets used in this project include the second-generation C-band Scanning ARM Precipitation Radar (CSAPR2) observations of individual convective cells, as well as in-situ and remote-sensing observations of aerosol and meteorological environments. We will use a dual-polarization radar retrieval method and polarimetric measurements from CSAPR2 to quantify the macro- and micro-physical properties of convective clouds during their lifetimes and examine the dependence of convective cloud properties on surface, aerosol, and thermodynamic conditions. We will conduct large eddy simulations of isolated convective cells using the DOE-supported Weather Research and Forecasting (WRF) model with a spectral-bin microphysics scheme in a piggybacking framework to test the above hypotheses on roles of underlying surface, aerosol, and thermodynamic conditions on the life cycle of convective cells. The piggybacking framework can separate the effects of thermodynamics,

thermodynamics

The study of the effects of work, heat, and energy on a system. Thermodynamics is only concerned with large scale observations.

Source: NASA Source

microphysics and dynamics from their interactions and quantify their roles in the life cycle of convective cells, which is very difficult using observations only. The project will contribute to a comprehensive process-based understanding of convective clouds and their interactions with surrounding environments and to improving representation of convective clouds in numerical weather prediction and Earth system models.