TJ29.2
Isolation of Summer Coastal Marine Air From California's Great Interior Valley

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Wednesday, 9 January 2013: 8:45 AM
Isolation of Summer Coastal Marine Air From California's Great Interior Valley
Room 18B (Austin Convention Center)
Clive E. Dorman, SIO/Univ. Of California, La Jolla, CA; and D. Koracin and H. Seo

It has been suggested that there is a summer, diurnal, thermally based connection between California's coastal ocean and California's great Interior Valley. An examination shows that the marine layer along California's coast is mostly isolated from California's Great Interior Valley. Coastal ridges on the north and south end are greater than five times the marine depth. Between Cape Mendocino and Point Conception, the coastal mountains exceed 91 m (300 ft). Along this area, the typical marine layer depth between is between 50-100 m and capped by a strong air temperature inversion so that Eastward movement is blocked. The only significant gap is the narrow, Caquinez Strait at sea level on the NE side of the Bay Area. Marine air entering the western side of the San Francisco Bay Area is so completely modified by local heating and downward mixing of subsiding, dry, warm air from the air temperature inversion capping the marine air that it is hard to follow except by direction. Other smaller gaps are actually passes elevated above the marine air, bathed in inversion base air. Summer heating of the SW US and the Great interior valley of California maintains a heat low over this area with a confusion of of shifting multiple minima such that the absolutely lowest value is east of California. Nevertheless, the local minimum sea level pressure over California's Great Valley is maintained day and night, often pulling air through the Caquinez Strait as well as inversion air over the coastal mountain crests, and from a northerly direction in mid-levels on along the entire length the western portion of the Great Valley in response to the general blocking of the sea level marine air. Intense Valley daytime heating mixes valley floor air above 700 m and into the inversion air. Most of the valley floor air exits up the Sierra Nevada in response to the mountain slope heating and lower pressure to the east. The hot, dry, cloudless Valley summer air is a result of isolation from the marine air and dilution of what small portion that does make it.