The Statistical Relationship between the Synoptic-Scale Pressure Field and the Development and Morning Transition of Surface Inversions at Two Rural Sites

Abstract

The association between the synoptic-scale sea level pressure field and the behavior of the morning inversion at two 60-m tower sites in North and South Carolina is investigated. Daily gridded pressure data for 1976 through 1982 for the eastern third of the United States are objectively classified according to their similarity with one of four basic eigenvector patterns developed for the dataset. The occurrence and site-to-site correlation of predawn inversion strength at the two tower locations, as well as the transition time between sunrise and inversion breakdown are then compared and contrasted for the different synoptic types. Results show a statistically significant relationship between inversion strength and synoptic type. As expected, strong inversions are most common when anticyclones are centered over the region. However, strong inversions are also found when anticyclones are centered southwest of the sites. The synoptic association is very similar for both tower sites expect for conditions when local care of a lake near one site lead to obvious modifications there. Transition times are only occasionally related to the synoptic type and relate best when the pressure gradient is weakest (long transition) or strongest (short transition).