89th American Meteorological Society Annual Meeting

Wednesday, 14 January 2009: 9:00 AM
Deep convective clouds and chemistry (DC3): Description of the field campaign and modeling of lightning NOx in the DC3 study areas
Room 126A (Phoenix Convention Center)
Mary C. Barth, NCAR, Boulder, CO; and C. Cantrell, S. A. Rutledge, W. Brune, C. Barthe, W. C. Skamarock, and M. Weisman
Convective transport is a major pathway of rapidly moving chemical

constituents from the boundary layer to the upper

troposphere (UT) and in some cases to the lower stratosphere (LS).

Yet the global-scale impact of convective transport on the UTLS

composition and chemistry has not been characterized. In addition,

only a few studies have attempted to examine the detailed dynamics

of deep convection and the concomitant redistribution, production,

or removal of reactive constituents. The proposed Deep Convective

Cloud and Chemistry (DC3) experiment will obtain measurements of

enough chemical species to characterize the effects of convection

on the transport and transformation of ozone and its precursors.

For example, HOx species, its precursors, and NOx species in both

inflow and outflow regions of deep convection will be measured along

with microphysical properties, storm kinematics, and lightning

discharges. These measurements are planned for over the Great Plains

of the United States, where we hope to contrast regions of remote

continental air to those more influenced by anthropogenic emissions.

The primary goals of DC3 are 1) to characterize the storm dynamics,

cloud physics, and lightning of the convective storms contrasting

environments from the U.S. High Plains to the Gulf Coast region;

2) to quantify the impact of continental, midlatitude convection on

the transport of chemical constituents to the upper troposphere in

the context of the dynamical, physical, and electrical characteristics

of the convection; 3) to determine the effects of convectively-perturbed

air masses on ozone and its related chemistry in the midlatitude upper

troposphere and lower stratosphere near the convective cores (in the

anvil region) and further downwind, 12-48 hours after the near convection

region is sampled, and 4) to contrast the influence of different

boundary-layer chemical inputs on the composition of convective outflow.

The strategy of reaching these goals as part of DC3 will be presented.

In preparation for DC3, the Weather Research and Forecasting model coupled

with Chemistry (WRF-Chem) is used to investigate the relative impact of

deep convection in the 3 DC3 locations: northeast Colorado, central Oklahoma,

and northern Alabama. These locations have characteristically different

types of storms, from high cloud base and strong shear storms in Colorado

to warm cloud bases in Oklahoma to low shear storms in Alabama.

The WRF-Chem simulations use a fine resolution (3 km or less), which is

nominally sufficient to represent convective systems and their transport

properties explicitly, without the need for convective parameterizations.

For this presentation, results of NOx produced from lightning will be emphasized.

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