Mesoscale Dynamics of the Near-Dryline Environment: Analysis of Data from COPS-91

Abstract

A technique is introduced using surface data from triangular networks of adjacent mesonet stations to estimate the terms in the horizontal equation of motion at anemometer level (10 m) on either side of the dryline in the southern plains of the United States. Data from an instrumented surface mesonetwork in the Texas panhandle and western and central Oklahoma during the Cooperative Oklahoma Profiler Studies (COPS-91) field program were employed for this purpose. East of the dryline and surface pressure trough the vertical-mixing term had a component normal and to the right of the surface wind in accord with Ekman theory; west of the dryline and surface pressure trough the vertical-mixing term had a component normal and to the left of the surface wind in disagreement with Ekman theory. It is suggested that disagreements with Ekman theory may be due to baroclinic effects in the boundary layer. It is also shown that during the day both the westward component of the pressure gradient force and the easterly component of the surface wind increased east of the dryline, in accord with the ?inland sea breeze? hypothesis, and that the maximum easterly wind component usually lagged the maximum westward component of the pressure gradient force by several hours.