众所周知,ENSO(El Nio/Southem Oscillation)是发生在热带太平洋的年际时间尺度上最强的气候信号,与El Nio(La Nina)相应的正(负)海温距平(SSTA)主要分布于赤道中东太平洋地区(Rasmusson et al .,1982)。相对于热带太平洋的年际ENSO现象,人们注意到北太平洋海平面气压(SLP)存在更长周期的年代际变化(Trenberth etal.,1994),有人认为这与北太平洋的表层温度(SST)变化有关(Latif el al.,1994),
20世纪60年代,Namias(1969)就发现北太平洋海平面气压(SLP)存在10a以上长周期的变化,这种变化与北美冬季气温异常密切相关。70年代以后,又有人(Whiteet al.,1972;Trenberth,1990;Trenberth el al.,1994)对上述变化作了进一步的验证,并指出1976年以后北太平洋的SLP异常偏低,即阿留申低压异常偏强。以阿留申低压为主要活动中心的大气年代际振荡被称为北太平洋涛动(NPDO)。
The spatial and temporal variabilities of summer rainfall over Shandong for the period 1961～2000 were analyzed by EOF and wavelet analysis. The links between the variabilities of the rainfall and the Western Tropical Pacific Warm Pool areas thermal state and the summer monsoon were studied by SVD. The results showed that there are mainly 3 patterns of summer rainfall in Shandong,one of which is important that present in-phase variance of rainfall over all Shandong;besides it,there still exist the distributive differences between eastern and western;northern and southern. Variability of summer rainfall over Shandong is very closely links to the thermal state in the Western Tropical Pacific Warm Pool area. When the Western Tropical Pacific Warm Pool is warmer than normal,summer rainfall throughout Shandong is heavy,and vice versa. The impact of the thermal state variations in the Western Tropical Pacific Warm Pool area on the summer rainfall in Shandong seems to be through the changes in position of the western Pacific subtropical high and intension of the east Asian summer monsoon.
The Princeton Ocean model was used to simulate the circulation in the Huanghai Sea and East China Sea and its annual cycle showing that:(1) A weak countercurrent exists on the left side of the Kuroshio.The countercurrent separates from the main stream of the Kuroshio around 30°N,128°E,flows southwestward along isobaths,meets with the offshore branch of the Taiwan Warm Current around 28°N,124°E,then returns back and joins the main stream,thus forming a cyclonic circulation.(2) The Taiwan Warm Current has an inshore branch and an offshore branch.Only in summer,the inshore branch can reach to about 30°N,where separates into two branches;one flows northward Changjiang River mouth,the other flows eastward,to be one of the sources of the Tsushima Warm Current.(3) The Tsushima Warm Current has multiple-sources.(4) In summer,Huanghai Sea Warm Current does not enter the southern Huanghai Sea.It mainly origins from the middle shelf flow in seasons other than autumn,in summer,it seemingly comes from the extension of the inshore branch of the Taiwan Warm Current.(5) The Eddy in the northern East China Sea exists all year round,with a closing cyclonical circulation in winter and summer.The seasonal variation of the eddy is influenced by the components of the cyclonical circulation,such as the Huanghai Sea Warm Current and middle shelf flow.
渤、黄、东海是一个水动力状况相当复杂的半封闭宽陆架海,本海区悬浮颗粒物含量高,季节变化明显,影响范围广,是世界上悬浮物含量最高的海域之一。对于该海域悬浮物的输运沉积过程、分布规律以及底质分布等中外学者均进行过比较深入的研究(秦蕴珊,1963;Honjo et al.,1974;Milliman et al.,1985,1986;秦蕴珊等,1987,1989;杨作升等,1992;Li et al.,1997;孙效功等,2000;雷坤等,2001)。然而,以往的研究大都基于实际海洋调查资料,由于受实测资料在时间和空间覆盖范围上的限制,很难从整体上把握渤、黄、东海陆架区悬浮物输运的时间和空间变化规律。数值模拟的方法能很好地克服上述局限,已有学者从不同角度对渤、黄、东海的某些海域的悬浮物进行了模拟研究。
