The Impact of Precipitation Cell Morphology on Mercury Wet Deposition: Michigan

Mercury (Hg) is a toxic, bioaccumulative pollutant that is removed from the atmosphere through both dry- and wet-deposition processes. Despite nationwide reductions in the emissions of mercury, many areas of the country continue to see elevated levels of mercury within rainfall (wet-deposition) samples. In the southeastern United States, it has been suggested that tall cumulus towers associated with convective precipitation could play an important role in the scavenging of mercury from the free troposphere, providing a mechanism for regional/global source contribution to the observed wet-deposition within this region. However, within Michigan and the Great Lakes, the majority of precipitation events are non-convective and, during the winter season, are often characterized by frozen precipitation. This study investigates the correlation between precipitation cell morphology at two locations within the State of Michigan. These results will be compared with a similar companion analysis of the correlation between precipitation cell morphology at two locations within State of Florida. To meet the objectives of this study, NEXRAD radar data from Pontiac/White Lake, Michigan (KDTX), precipitation cell parameters were analyzed at two locations, Fort Street, Detroit, MI (FRT) and Dexter, MI (DXT), for the Calendar Year 2005. Precipitation cell parameters analyzed included: storm type, storm motion, maximum reflectivity, maximum echo top, CAPE, NCAPE, total wind shear and precipitable water. Although no concrete correlations were found for the year 2005, slight trends in the data raised new questions about relationships that were not originally hypothesized, but could be verified by further research. This presentation will be a showcase of the trends that resulted from the analysis of the year 2005 data.