Surface mesovortices in relation to the urban heat island effect over the Saint Louis metropolitan area

Abstract

Using high spatial and temporal resolution mesonet data, a comprehensive surface mesoanalysis of Saint Louis's Urban Heat Island (UHI) effect was conducted. The synoptic and mesoscale conditions were evaluated in which the surface mesovortices were observed. A long-term analysis of the surface mesovorices and four cases are presented as well as a hypothesis developed to explain the formation of the surface mesovortices.Results suggest that surface mesovortices were often observed in conjunction with UHI events and low wind speeds within the Saint Louis metropolitan area. The surface mesovortices are caused in part by the direct thermal circulation produced by the UHI enhancing existing vorticity.The surface mesovortices are also hypothesized to have impact on local air quality; surface ozone measurements at Saint Louis Science Center were noticed to spike during one surface mesovortex event. The surface mesovortices may re-circulate ozone created outside the immediate Saint Louis metropolitan area back into the immediate Saint Louis metropolitan area.