Mechanisms responsible for stratosphere-to-troposphere transport around a mesoscale convective system anvil

The Weather Research and Forecasting model coupled with Chemistry model adequately simulates anvil wrapping of ozone-rich air. Possible mechanisms that influence the transport, including small-scale static and dynamic instabilities and MCS-induced mesoscale circulations, are evaluated. Model results suggest that anvil wrapping is a two-step transport process (1) compensating subsidence surrounding the MCS, which is driven by mass conservation as the MCS transports tropospheric air into the upper troposphere and lower stratosphere, followed by (2) differential advection beneath the core of the MCS upper-tropospheric outflow jet which wraps high O-3 air around and under the MCS cloud anvil.

Static and dynamic instabilities are not a leading contributor to this transport process. Continued fine-scale modeling of these events is needed to fully represent the stratosphere-to-troposphere transport process.