Recorded presentation1.5
Ocean-atmosphere coupling in the area of orographically-intensified flow in coastal upwelling modeling studies
Natalie Perlin, Oregon State Univ., Corvallis, OR; and E. Skyllingstad and R. Samelson
The current modeling research focuses on studying the summertime wind-driven upwelling along the Oregon-California coastline, examining areas of flow intensification downwind of major capes, and mesoscale air-sea interaction affecting boundary layer development in both ocean and atmosphere. The study simulates this coastal circulation using a two-way coupled ocean model and atmosphere model.
The model domain represents a semi-idealized coast about 800 km long, stretched from north to south, and features a central coastal bend. Bathymetry and coastal terrain are approximated and derived from the average data for the Oregon coast; horizontal resolution is 3 km. Data exchange between the ocean and atmosphere in the coupled model occurs every 5 minutes, and model simulations are run for five days (120 h). The atmospheric model develops a marine boundary layer over the ocean and shows a diurnal cycle of boundary layer formation over the land, with stratus formation and dissipation in the coastal zone.
The area of wind intensification is well defined downwind of the first bend. At the same time, the ocean responds to the wind forcing by developing an upwelling jet tracing the coastline. Upwelled water found along the straight coastline leads to a reduction of surface wind stress, which, in turn, creates positive wind stress curl and further supports upwelling. When surface winds intensify downwind of the coastal bend, topographic effects result in strong small-scale wind changes yielding both positive and negative curl regions; positive curl values are comparable or exceeding those due to upwelling along the straight coastline. On the scale of tens of kilometers off the coast, the nearshore wind stress field and its derivatives are not tied to sea surface temperature front variations in these areas. Strong spatially variable wind forcing of the coastal ocean around the bend, combined with well developed upwelling, could possibly force coastal ocean jet separation and eddy formation.
Session 1, Coastal atmosphere, ocean, and marine biology-I
Monday, 12 January 2009, 10:45 AM-12:00 PM, Room 126A
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