Atmospheric forcing in the Arabian Sea during 1994–1995: observations and comparisons with climatology and models
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Accurate, year-long time series of winds, incoming shortwave and longwave radiation, air and sea temperatures, relative humidity, barometric pressure, and precipitation were collected from a surface mooring deployed off the coast of Oman along the climatological axis of the Findlater Jet from October 1994 to October 1995. Wind stress, heat flux, and freshwater flux were computed using bulk formulae. The Northeast Monsoon was characterized by steady but moderate winds, clear skies, relatively dry air, and two months, December and January, in which the ocean, on average, lost 45 Wm(-2) to the atmosphere. The Southwest Monsoon had strong winds, cloudy skies, and moist air. Because of reduced latent and longwave heat loss, it was accompanied by sustained oceanic heat gain, with the strongest monthly mean warming, 147 Wm(-2), in August. Large differences are found between the observations and older climatologies. Recent climatologies agree better with the observations. The means of the Southampton Oceanography Center climatology for 1980-1995 are close to the buoy monthly means. Monthly means from that climatology show that 1994-1995 was in general a typical year, with surface meteorology and air-sea fluxes within one standard deviation of the long term means. Concurrent data from the NCEP, ECMWF, and FNMOC show that the models provide realistic surface winds. FNMOC winds show that the timing and character of the onset of the Southwest Monsoon in 1995 differed from 1994 and 1996 when variability within one month is resolved. The models fail to replicate other observed surface meteorology and to produce realistic heat fluxes. Annual and monsoonal mean net heat fluxes from the models differed from those of the buoy by 50 to 80 Wm(-2). Because of these differences, some care is warranted in selecting and using air-sea flux fields in studies of the Arabian Sea. (C) 1998 Elsevier Science Ltd. All rights reserved.