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Using Storm Kinematics and Surface Ozone Measurements to Describe the Convective Transport in Downdrafts Over the Brazilian Amazon
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A correlation between enhancements in surface ozone observations and decreased equivalent potential temperature (i.e. surface downdraft identifiers) is observed in the Brazilian Amazon during convective events. Meteorological and chemical data collected during the Green Ocean Amazon (GoAmazon 2014/5) field campaign are used to explore the link between storm kinematics and surface ozone enhancement events. Contoured frequency by altitude diagrams (CFADs) of S-band radar reflectivity values are used to gather more information about the structure and evolution of storms during ozone enhancement events in the Amazon. Using a smaller domain than previous CFAD studies, the evolution of individual storm characteristics (i.e. downdrafts) is more apparent. A branch of higher reflectivity breaking off near 7 km and descending to the surface is observed in the CFADs near the time of descending motion and maximum surface ozone. This phenomenon, which we refer to as a descending arm, is found to be a robust feature during ozone events. Case studies of varying surface ozone enhancement intensities illustrate the relationship between the shape and distinctiveness of the descending arm and the timing and magnitude of the enhancement events. Strong ozone enhancements correspond to stronger, well-defined descending arms. Vertical velocity retrievals from vertical profilers are used to confirm the presence of descending motion. A descending arm metric is created to automate the detection of descending arms and their relative strength. Future work will refine this metric and allow us to test the sensitivity of descending arms on other environmental factors and their use in identifying convective cold pools.
Upton, Hannah Marie (2016). Using Storm Kinematics and Surface Ozone Measurements to Describe the Convective Transport in Downdrafts Over the Brazilian Amazon. Master's thesis, Texas A & M University. Available electronically from