S109 Effects of tropical deep convection on upper tropospheric ozone concentrations

Sunday, 6 January 2013
Exhibit Hall 3 (Austin Convention Center)
Ana P. Ortiz, NCAR, Palos Park, IL; and C. A. Davis

Ozone (O3) is harmful to breathe at the surface and acts as a greenhouse gas in the upper troposphere. It has become important to understand how O3 is distributed throughout the troposphere and how its distribution changes with time. This study focused on variations of O3 in the tropical upper troposphere over the Atlantic Ocean. It is hypothesized that tropical deep convection reduces O3 in the upper troposphere because the air processed through the storm updraft originates in a relatively pristine region at low altitudes. NSF/NCAR Gulfstream V (GV) Aircraft observations from the PRE-Depression Investigation of Cloud-systems in the Tropics (PREDICT) project along with cloud top temperatures calculated from infrared satellite images are used. To examine the relationship of O3 fluctuations with other variables, deviations from the mean vertical profile of O3 and potential temperature are calculated. Condensed water content greater than 0.0722 g m-3 and cloud top temperatures colder than the plane's temperature plus 4˚C identify periods when the GV was in cloud produced by deep convection. We find a decrease in upper tropospheric O3 concentrations 76% of the time that the GV was in cloud. O3 concentrations outside of clouds vary as much or more than the variations measured while in convection. O3 concentrations decrease 61% of the time potential temperature deviations are negative. Instances where in-cloud O3 was not reduced may indicate O3 sources from lightning or the transport of air from non-pristine boundary layers. This research contributes to a better understanding of the behavior of O3 distribution.
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