Modeling Stratosphere-Troposphere Exchange within Extreme Extratropical Convection

Stratosphere-troposphere exchange via extreme extratropical convection has implications for climate change and is not well understood. In situ trace gas observations in convection from aircraft are limited due to hazards associated with turbulence near the core of a storm. Modeling allows us to examine the processes responsible for irreversible transport of gases into the stratosphere on the convective scale. Previous studies have examined if numerical models can represent the physical characteristics of tropopause-penetrating convection. Here, we test the ability of the ARW-WRF model to simulate the physical aspects of a real case of extreme extratropical convection that injected cloud particles into the stratosphere. We find that the model resolves storm structure sufficiently, but initiates convection in a different geographical location than that observed, a common limitation of convective-scale modeling. Despite the incorrect location, we proceed to examine the representation of trace gas transport in the upper troposphere and lower stratosphere within the same case of convection using ARW-WRF coupled with chemistry. Model output shows evidence of irreversible transport of tropospheric air to the stratosphere. Tropospheric pollutants, such as carbon monoxide or CO, are limited to altitudes 1 to 2 km above the tropopause, while transport of water vapor is found up to 5 km above the tropopause.