Temporal And Spatial Variation Of The Sea Surface Roughness Over The Northwest Pacific Ocean

As a parameter to express the characteristics of surface undulation,the sea surface roughness has stimulated a common interest in the past.Fully understanding it and the accurate parameterization of its distribution 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 variation has strong temporal and spatial variability under the influence of sea state factors.In the present dissertation,the observations and theoretical analyses of variation of sea surface roughness is reviewed,and the significance of sea surface roughness 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 distribution of sea surface roughness over the northwest Pacific ocean by taking a number of additional factors other than wind into account,with the aid of daily measurements of surface wind speed U₁₀,for all 12 months from 2000 to 2008 which derived by the satellite remote sensing,monthly variations of distribution over the northwest Pacific 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,and data processing are given in details.Also,the estimate has been compared with results from empirical formula including the wave information,respectively.The characteristics of distribution of sea surface roughness that are revealed as follows.(1) The distribution of z₀ shows considerable spatial and temporal variability.(2) In Pacific equatorial area,low roughness distribution appears for all year and maintains stably in space,while a comparatively strong temporal variability is shown in other part of other area.(3) In winter,the mean z₀ in the mid-latitude northern Pacific ocean is higher than in low-latitude area.In mid-latitude northern Pacific ocean,the roughness distribution greater than 5mm mostly appears from Nov. to Mar.At the lower-latitudes,while it appears primarily from Summer to Fall which is controlled by the northeast Monsoon and the tropical cyclones.Since the significance of the spatial and temporal distribution of sea surface roughness in air-sea interaction,a continuous,accurate and reliable algorithm for estimation of variation of sea surface roughness from routine remote sensing data is needed,so that the further study is expected in the near future.