| As ubiquitous phenomena at the air-sea interface and significant signature of wave breaking, whitecap has stimulated a common interest in the past. Fully understanding to its forming mechanism, dissipation processes, and the accurate parameterization of the whitecap coverage are essential to the study of air-sea interaction, momentum, heat and mass transfers, oceanic remote sensing, and wave theories. Both laboratory experiment and field investigation show that the whitecap coverage has strong temporal and spatial variability under the influence of various environmental and meteorological factors.In the present dissertation, the phenomenon of the oceanic whitecap is described, the art-of-state of field observations and theoretical analyses of whitecap coverage is reviewed, and the significance of whitecap on various air-sea processes studies is discussed. Meanwhile, its controlling factors other than surface wind speed are pointed out as well. For the purpose of accurate estimation of whitecap coverage over the global ocean by taking a number of additional factors other than wind into account, a parameterization of whitecap fraction on the basis of previous studies and measurements, is given by employing the routine satellite observation data sets with several new formulas of optical remote sensing parameters such as sea surface emissivity.With the aid of daily measurements of brightness temperature TB , columnar water vapor V, columnar cloud liquid water L, surface wind speed U 10, and sea surface temperature TS for all 365 days and salinity S for all 12 months of 2001, 2002,2003,2004,2005, which derived by the satellite remote sensing, monthly variations of whitecap coverage (W) over the global ocean are estimated. This is the primary improvement of more approach to realistic oceanic and atmospheric condition in the macro view of point. The physical background and theoretical method, data processing and error analysis are given in details. Also, the estimate has been compared with results from empirical wind speed dependent only formula and with those from the formula including the wave information, respectively. Furthermore, the relationship between whitecap coverage distribution and that of sensitive heat flux and latent heat flux is discussed. Finally, the possible improvements to the estimation method are given.The characteristics of global whitecap coverage are revealed as follows: (1) The distribution of W shows considerable spatial and temporal variability. (2) In Pacific equatorial area, low whitecap coverage appears for all year and maintains stably in space, while a comparatively strong temporal variability is shown in other part of global ocean. (3) For the global ocean, the monthly averaged value of W ranges roughly from 4% to 5% in all months. (4) In winter, the mean W in Northern Hemisphere is higher than in Southern Hemisphere. The monthly change of whitecap coverage at high northern latitudes is more evident that that at high southern latitudes. In Northern Hemisphere, the whitecap coverage greater than 9% mostly appears from Nov. to Mar. at the high and mid-latitudes, while it appears primarily from May to Nov. at Antarctic Circumpolar Current (ACC) area in Southern Hemisphere. (5) A belt-like area with comparatively high whitecap coverage appears north to the equator, where is roughly in accordance with the ITCZ which moves seasonally between equator and about 12°N. (6) Atmospheric correction due to the attenuation caused by the cloud liquid water would reduce the mean value of estimates for W.Since the significance of the spatial and temporal distribution of whitecap coverage in air-sea interaction, a continuous, accurate and reliable algorithm for estimation of whitecap coverage from routine remote sensing data is needed, so that the further study is expected in the near future.
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