Convective Meteorology (Mesoscale Dynamics)

Sensitivity of simulated convection-driven stratosphere-troposphere exchange in WRF-Chem to chosen model parameterizations

Dan Phoenix

School of Meteorology

23 September 2016, 3:30 PM

National Weather Center, Room 5600
120 David L. Boren Blvd.
University of Oklahoma
Norman, OK

Tropopause-penetrating convection is capable of rapidly transporting air from the lower troposphere to the upper troposphere and lower stratosphere (UTLS). Since the vertical redistribution of gases in the atmosphere by convection can have important impacts on the chemistry of the UTLS, the radiative budget, and climate, it has become a recent focus of observational and modeling studies. Despite being otherwise limited in space and time, recent aircraft observations from field campaigns such as the Deep Convective Clouds and Chemistry (DC3) experiment have provided new high-resolution observations of convective transport. Modeling studies, on the other hand, offer the advantage of providing output related to the physical, dynamical, and chemical characteristics of storms and their environments at fine spatial and temporal scales. Since these characteristics of simulated convection depend on the chosen model design, we examine the sensitivity of simulated convective transport to the choice of physical and chemical parameterizations in the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) for several DC3 cases in this study. In particular, we conduct sensitivity tests for the choice of 1) bulk microphysics parameterization, 2) planetary boundary layer parameterization, and 3) chemical mechanism. Model output is evaluated using ground-based radar observations of each storm and in situ trace gas observations from two aircraft operated during the DC3 experiment. Model results show measurable sensitivity of the physical characteristics of a storm and the transport of water vapor and additional trace gases into the UTLS to the choice of microphysics parameterization. The physical characteristics of the storm and transport of insoluble trace gases are largely insensitive to choice of PBL scheme and chemical mechanism, though several soluble trace gases (e.g., SO2, CH2O, NH3) exhibit some measurable sensitivity.

Convective Meteorology (Mesoscale Dynamics) Seminar Series website