Meteorological processes affecting the transport of emissions from the Navajo generating station to Grand Canyon National Park

During the 1990 Navajo Generating Station (NGS) Winter Visibility Study, a network of surface and upper- air meteorological measurement systems was op erated in and around Grand Canyon National Park to investigate atmospheric processes in complex terrain that affected the transport of emissions from the nearby NGS. This network included 15 surface monitoring stations, eight balloon sounding stations (equipped with a mix of rawinsonde, tethersonde, and Airsonde sounding systems), three Doppler radar wind profilers, and fo ur Doppler sodars. Measurements were made from 10 January through 31 March 1990. Data from this network were used to prepare objectively analyzed wind fields, trajectoiies, and streak lines to represent transport of emissions from the NGS, and to prepare isentropic analyses of the data. The results of these meteorological analyses were merged in the form of a computer anim ation that depicted the streak line analyses along with measurements of per fluorocarbon tracer, SO2, and sulfate aerosol concentrations, as well as vi sibility measurements collected by an extensive surface monitoring network. These analyses revealed that synoptic-scale circulations associated with t he passage of low pressure systems followed by the formation of high pressu re ridges accompanied the majority of cases when NGS emittants appeared to be transported to the Grand Canyon. The authors' results also revealed terr ain influences on transport within the topography of the study area, especi ally mesoscale flows inside the Lake Powell basin and along the plain above the Marble Canyon.