Case Study in Summertime North America UTLS Ozone Budget

Upper-tropopsheric/lower-stratospheric (UTLS) ozone budget has an impact on the total radiative budget and tropospheric chemistry. Previous studies noted a UT ozone enhancement above southern United States, which was also observed by the satellite-borne Tropospheric Emission Spectrometer (TES). Using the Weather Research and Forecasting model coupled with chemistry (WRF-chem), a short-term budget has been constructed for the ozone profile within the same region at about 160 hPa the week prior to August 23, 2006. Major contributing sources of variance have been identified as chemistry, advection, convection, and dry vertical mixing. Among these identified source terms, advective tendencies dominate the short-term, local (180km x 180km) ozone variance. The WRF-Chem results suggest that direct convective transport of ozone from the PBL dilutes regional UT ozone though the transport of PBL precursors by convection, which may later impact the ozone concentration.