Atmospheric forcing in the Arabian Sea during 1994-1995: observations and comparisons with climatology and models

Accurate, year-long time series of winds, incoming shortwave and longwave r adiation, air and sea temperatures, relative humidity, barometric pressure, and precipitation were collected from a surface mooring deployed off the c oast of Oman along the climatological axis of the Findlater Jet from Octobe r 1994 to October 1995. Wind stress, heat flux, and freshwater flux were co mputed using bulk formulae. The Northeast Monsoon was characterized by stea dy but moderate winds, clear skies, relatively dry air, and two months, Dec ember and January, in which the ocean, on average, lost 45 Wm(-2) to the at mosphere. The Southwest Monsoon had strong winds, cloudy skies, and moist a ir. 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 climatologie s. Recent climatologies agree better with the observations. The means of th e Southampton Oceanography Center climatology for 1980-1995 are close to th e buoy monthly means. Monthly means from that climatology show that 1994-19 95 was in general a typical year, with surface meteorology and air-sea flux es within one standard deviation of the long term means. Concurrent data fr om the NCEP, ECMWF, and FNMOC show that the models provide realistic surfac e 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 wit hin one month is resolved. The models fail to replicate other observed surf ace 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 selec ting and using air-sea flux fields in studies of the Arabian Sea. (C) 1998 Elsevier Science Ltd. All rights reserved.