Studies of Convection, Microphysics and Lightning in the Deep Convective Clouds and Chemistry Experiment (DC3)

点击翻译按钮获取中文摘要

With this award, the investigators will carry out comprehensive studies of the data collected during the Deep Convection, Clouds and Chemistry Experiment (DC3) conducted during May-June 2013. DC3 collected a comprehensive dataset on cloud dynamics, microphysics and chemistry in a variety of convective events, over three regions, the southeast U.S., the Southern Great Plains and over the semi-arid region of eastern Colorado. The research will address two of the overarching goals of the DC3 program; understanding the gross electrical structure of storms and why particular storms have a so-called "inverted" electrical polarity; and improving our understanding regarding the production of Nitrogen Oxides (NOx) by lightning. The work concerning the electrical structure of storms will utilize comprehensive Doppler and polarimetric radar and lightning mapping network data obtained in DC3 and will include a small sample of storms affected by the High Park wildfire in Colorado. Under the objective to improve how lightning-generated NOx is handled in cloud-chemistry models, the research team will use Lightning Mapping Array observations of total lightning flash rates to improve flash rate parameterizations, contribute to storm scale budget studies aimed at estimating the amount of NOx produced per lightning flash, and refine assumptions regarding where the lightning-generated NOx is "released" into the storm. The research team will relate detailed observations of ice particle types in anvil clouds (aggregates of frozen droplets) to the adjacent deep convection. Under this award, the research team will develop a number of collaborations to enhance this research, including collaborations with scientists that are conducting cloud-chemistry simulations of several DC3 cases using the Weather Research Forecasting-Chemistry (WRF-Chem) model.This research will contribute to the knowledge base regarding the coupling between cloud dynamics, microphysics and electrification/lightning. The research will utilize state of the art radar and lightning mapping information in order to improve our understanding of so-called "inverted" charge structures where positive electrical charge resides in the storm mid-levels, opposed to the more typical structure where negatively-charged hydrometeors resides at mid-levels. Utilizing the comprehensive measurements from DC3,the research team will also address the lightning-NOx problem, that is, quantifying the amount of NOx released in a storm produced by lightning. This work will be done from the point of view of improving required parameterizations for these processes in cloud-chemistry models. Hence this work will be interdisciplinary in nature, bringing together cloud physics and atmospheric chemistry specialists. This work will also improve our understanding as to how deep convection contributes to anvil ice water contents and ice particle types. Hence this work may lead to a better understanding regarding the radiative properties of anvils attached to strong convection. DC3 observations are expected to advance our understanding regarding storm dynamics, microphysics and electrification. Knowledge of these processes will provide a basis for improving the manner by which lightning-generated NOx (LNOx) is considered in cloud-chemistry models. The role of LNOx in contributing to upper tropospheric ozone, a greenhouse gas, can then be improved. In general DC3 results are expected to improve our understanding regarding the impact of deep convection on the chemical composition of the UTLS (upper troposphere-lower stratosphere). Experimental data from the DC3 project will provide important datasets for model comparison exercises and assessment reports.