中文摘要：

衰减深度是传感器检测到的水体信息的90%的深度,衰减深度越大,传感器检测到的水体信息越多,提取水体信息的精确度越高,同时从衰减深度还可了解传感器获取的水体信息到底来自水下多深的水层。以MODIS数据为数据源,对渤海海域衰减深度进行计算,分析了某一时间渤海海域衰减深度波谱变化和某一波段渤海海域衰减深度季节变化。衰减深度波谱曲线为单峰曲线,不同区域的衰减深度波谱曲线的相似和差异情况与前人根据渤海海域悬浮泥沙含量和光谱情况进行分区的情况较一致,衰减深度最大值具有红移现象（不同区域衰减深度最大值的情况是：渤海西北海岸外区域和渤海海峡区域在波段531 nm,渤海中部区域在波段551 nm,现黄河口影响区域、老黄河口影响区域、辽东湾西侧区域、辽东湾东侧区域在波段555 nm）,衰减深度波谱佐证了渤海海域为二类水体 衰减深度在夏季最大,在秋季次之,在春季和冬季在不同区域大小顺序有所不同。不同区域衰减深度由小到大顺序是现黄河口影响区域和辽东湾东侧区域、辽东湾西侧区域、老黄河口影响区域、渤海西北海岸外区域和渤海中部区域、渤海海峡区域（除去412和645 nm）,其中现黄河口影响区域与辽东湾东侧区域和渤海中部区域与渤海西北海岸外区域的衰减深度的大小顺序在不同季节和不同波段有差异。

英文摘要：

An attenuation depth is defined for remote sensing purposes as a depth above which 90% of the arising light leaving the water surface is emanated. The deeper the attenuation depth, the more informa- tion of water is detected by remote sensing, then the more precise information of water is extracted. Mean while, the attenuation depth is help to know water layer （by its thickness） from which remote sensing will be able to extract information. A number of investigators are using the moderate resolution imaging spec- troradiometer （or MODIS） for remote sensing of ocean color. It is necessary to have a rough idea of the ef fective attenuation depth of imagery in each of the spectral bands employed by the MODIS. The attenua tion depth is directly determined from MODIS data. Though analyzing the spectral distributions of attenu ation depth on 7 August 2003 and the seasonal variations of attenuation depth （551nm） in the Bohai Sea in- dicated that the spectral distributions of the attenuation depth for the spectral range 400-700 nm are sin gle-peak curves, and their similar and difference in different regions consist with other scholars＇ results of zoning, moreover their support the Bohai Sea is Case 2 water; the maximum attenuation depths shift to- ward longer wavelengths, liking the red shift, with increase of turbidity of water, just like in these regions representing by Points C and G is at 531nm, by Point F is the maximum attenuation depth at 551nm, by Points A, B, D and E is at 555nm; the seasonal change of the attenuation depth is the largest in the sum- mer, followed by the fall, and the ranking of winter and spring in different regions is varied. The attenua- tion depth in different regions is varied： the attenuation depth of Points A and E is less than that of Point D less than that of Pint B less than that of Points C and F less than that of point G （excluding 412 and 645nm）, in which the order of attenuation depth of between Points A and E （and between Points F and C） representing regio