Effect of Marine and Land Convection on Vertical Distribution of Ozone Precursors Observed during SEAC4RS

The formation and development of convective clouds are the most important mechanism for vertical transport and redistribution of tropospheric pollutant gases or tracer species. The convectively-driven vertical transport of these trace gases from the planetary boundary layer to the upper troposphere can occur on timescales of less than an hour and recent studies are suggesting that microphysical scavenging is one of the dominant removal processes of soluble species precursors of tropospheric ozone (O₃) during this transport. In this work, we investigate marine and land convection motivated by recent results from the analysis and modeling of soluble O₃ precursors such as formaldehyde (CH₂O), hydrogen peroxide (H₂O₂), and methyl hydrogen peroxide (CH₃OOH) for two convective storms observed on 2 September 2013 during SEAC⁴RS. Results from this campaign revealed that scavenging efficiencies (SE) of CH₂O (43 - 53%) and H₂O₂ (~80 – 90%) were consistent between the SEAC⁴RS airmass and multicell storms and the severe convection observed during the 2012 DC3 field campaign. However, CH₃OOH SE was generally smaller in the SEAC⁴RS airmass and multicell storms (4% - 27%) compared to DC3 severe convection. The analysis showed that much larger production of precipitation between cloud base and the freezing level for severe convection compared to smaller storms is largely responsible for determining the SE for the moderately soluble (CH₂O) to highly soluble (H₂O₂) trace gases leaving only mildly soluble trace gases (CH₃OOH) to be affected by retention in ice particles during cloud drop freezing. Conversely, in airmass and multicell storms CH₂O scavenging efficiency depends on the retention of CH₂O in ice particles during cloud drop freezing. In this presentation we summarize these results from the 2 September analysis and extend the analysis to marine convection over the Gulf of Mexico and multicell convection both observed on the 18 September 2013 near and over Texas. Cloud-resolving simulations using the Weather Research and Forecasting model with Chemistry (WRF-Chem) were performed to support observations and help to understand the effect of entrainment, scavenging efficiency, and ice physics processes on these trace gases with varying solubility. Using both observation and modeling to determining the SEs and retention factors for marine convection in contrast to convection over land, we hope to learn how robust ice retention factors and liquid-only scavenging are for a variety of convection types and therefore recommend best practices in parameterizing wet scavenging of soluble trace gases.