Tropopause‐penetrating convection is capable of rapidly transporting air from the lower troposphere to the upper troposphere and lower stratosphere (UTLS), where it can have important impacts on chemistry, the radiative budget, and climate. However, obtaining in situ measurements of convection and convective transport is difficult and such observations are historically rare. 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 (bulk microphysics or BMP and planetary boundary layer or PBL) and chemical parameterizations in the Weather Research and Forecasting model coupled with Chemistry (WRF‐Chem). In particular, we simulate multiple cases where in situ observations are available from the recent (2012) Deep Convective Clouds and Chemistry (DC3) experiment. 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 BMP. The physical characteristics of the storm and transport of insoluble trace gases are largely insensitive to the choice of PBL scheme and chemical mechanism, though several soluble trace gases (e.g., SO2, CH2O, and HNO3) exhibit some measurable sensitivity.

Recent observational studies have shown that stratospheric air rich in ozone (O 3 ) is capable of being transported into the upper troposphere in association with tropopause-penetrating convection (anvil wrapping). This finding challenges the current understanding of upper tropospheric sources of O 3 , which is traditionally thought to come from thunderstorm outflows where lightning-generated nitrogen oxides facilitate O 3 formation. Since tropospheric O 3 is an important greenhouse gas and the frequency and strength of tropopause-penetrating storms may change in a changing climate, it is important to understand the mechanisms driving this transport process so that it can be better represented in chemistry-climate models. Simulations of a mesoscale convective system (MCS) around which this transport process was observed are performed using the Weather Research and Forecasting model coupled with Chemistry. 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.

h i g h l i g h t sParameterization used to calculate the change in CH 4 concentration was evaluated. Our CAM5 simulations show that the parameterization technique is good within 10%. Methane feedback on its own lifetime was calculated. Our model dependent feedback factor is well within the range reported by IPCC (2001). a b s t r a c tAtmospheric chemistry-climate models are often used to calculate the effect of aviation NOx emissions on atmospheric ozone (O 3 ) and methane (CH 4 ). Due to the long (~10 yr) atmospheric lifetime of methane, model simulations must be run for long time periods, typically for more than 40 simulation years, to reach steady-state if using CH 4 emission fluxes. Because of the computational expense of such long runs, studies have traditionally used specified CH 4 mixing ratio lower boundary conditions (BCs) and then applied a simple parameterization based on the change in CH 4 lifetime between the control and NOxperturbed simulations to estimate the change in CH 4 concentration induced by NOx emissions. In this parameterization a feedback factor (typically a value of 1.4) is used to account for the feedback of CH 4 concentrations on its lifetime. Modeling studies comparing simulations using CH 4 surface fluxes and fixed mixing ratio BCs are used to examine the validity of this parameterization. The latest version of the Community Earth System Model (CESM), with the CAM5 atmospheric model, was used for this study. Aviation NOx emissions for 2006 were obtained from the AEDT (Aviation Environmental Design Tool) global commercial aircraft emissions. Results show a 31.4 ppb change in CH 4 concentration when estimated using the parameterization and a 1.4 feedback factor, and a 28.9 ppb change when the concentration was directly calculated in the CH 4 flux simulations. The model calculated value for CH 4 feedback on its own lifetime agrees well with the 1.4 feedback factor. Systematic comparisons between the separate runs indicated that the parameterization technique overestimates the CH 4 concentration by 8.6%. Therefore, it is concluded that the estimation technique is good to within~10% and decreases the computational requirements in our simulations by nearly a factor of 8.Published by Elsevier Ltd.