A Numerical Study of the Mesoscale Atmospheric Circulation Observed during a Coastal Upwelling Event on 23 August 1972. Part I: Sensitivity Studies

Publisher Website
Google Scholar
Abstract
A numerical model is used to study the effect of an Ocean surface temperature gradient on the mesoscale atmospheric circulation. The model is initialized with atmospheric data from 23 August 1972 over the central Oregon coastal zone. After the initial fields are balanced the model is integrated for 24 h and the results are analyzed and compared with observation. Both our analysis and the observations show the development of a coastal, low-level jet after sunset. An analysis of the mesoscale wind component shows that this jet is related to the sudden change in the top of the boundary layer and the increased thermal stratification after sunset. Turbulent mixing and terrestrial heating are found to overwhelm the inland advection of marine air so that there is no daytime thermal front over the land. After sunset the front moves inland in response to long-wave radiation cooling and stabilization of the lower atmosphere. Our analysis shows that the warm zone to the east of the thermal front and the cool zone to the west are maintained by turbulent mixing and increased stability respectively. Then results differ from the explanation of Estoque who suggested the warm zone is maintained by reduced mixing while the cool zone is maintained by strong mixing. Finally. during the day the ocean surface temperature gradient weakens the longshore component of the wind due to increased atmospheric stability and higher ocean surface temperature to the west.

This publication has 0 references indexed in Scilit: