MESOSCALE DYNAMICS OF THE NEAR-DRYLINE ENVIRONMENT - ANALYSIS OF DATAFROM COPS-91

A technique is introduced using surface data from triangular networks of adjacent mesonet stations to estimate the terms in the horizontal e quation of motion at anemometer level (10 m) on either side of the dry line in the southern plains of the United States. Data from an instrum ented surface mesonetwork in the Texas panhandle and western and centr al 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 norm al and to the right of the surface wind in accord with Ekman theory; w est of the dryline and surface pressure trough the vertical-mixing ter m had a component normal and to the left of the surface wind in disagr eement with Ekman theory. It is suggested that disagreements with Ekma n 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 pre ssure gradient force and the easterly component of the surface wind in creased east of the dryline, in accord with the ''inland sea breeze'' hypothesis, and that the maximum easterly wind component usually lagge d the maximum westward component of the pressure gradient force by sev eral hours.