渤、黄、东海海流和潮汐共同作用下的悬浮物输运、沉积及其季节变化

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。 董礼先等(1989)首先模拟了在二维潮流场作用下，黄、渤海推移质和悬移质的输运状况，得出潮流作用下海底的冲淤状况。Graber等(1989)利用有限水深的风浪模型、模拟了风浪对悬浮物输运、沉积的作用。Yanagi等(1995)用拉格朗日粒子追踪方法对整个东中国海冬季悬浮物的输运、沉积过程进行了计算。江文胜等(2000，2001)考虑了风等气象要素、外海传入的潮波的作用、悬浮物的沉降及再悬浮机制，对渤海中悬浮物的浓度进行了数值模拟。 海洋环流、潮汐、潮流和波浪均对悬浮物的输运与沉积产生影响，尤其在中陆架和外陆架地区，环流对悬浮物的长期输运起决定性作用，因此以往仅针对潮流、风浪作用的模拟很不完整，其结果与实际情况的差别也会较大。其次，海水的流动处在不断变化之中，小到日变化、月变化，大到季节变化、年际变化，因此定常风场、定常温盐场的环流模拟，即诊断流场并不符合实际情形。本文将首先对渤、黄、东海月平均风场、温盐场作用下的环流场进行模拟，进而探讨环流以及潮汐、潮流共同作用下的悬浮物输运过程及其季节变化规律。     

山东夏季降水与西太平洋暖池区海洋热状态及夏季风异常

山东省东接太平洋，西连欧亚大陆，受海洋和大陆的影响，季风气候特点相当显著，常导致严重旱、涝灾害。山东全年降水主要集中在夏季，6~8月降水占全年降水的60%以上。其原因主要是受西太平洋副热带高压和夏季风活动的影响。副热带高压的增强和北伸与梅雨锋的位置和强度变化对山东夏季降水有直接作用，其夏季降水的年际变率较大，是旱、涝频发的省份。 我国旱涝变化与太平洋海洋热状况有着极为密切关系(翁学传等，1994)。El Nino现象对气候的影响更加引起了海洋气象学家对海洋变化的高度重视。他们分析了El Nino现象和太平洋海表温度(SST)与山东夏季降水的关系(如:奚秀芬，1988；卢金墀，1982；张苏平等1999)，但对比降水分布发现无论是 El Nino发生的当年还是次年，降水距平百分率的零线均从山东中部通过。我国夏季降水主要受三种类型雨带控制。由于山东处于一类雨带(华北多雨)和二类雨带(江淮多雨)的转换地带，近40年的降水资料分析表明，三种类型雨带在山东夏季降水正、负距平年出现率几乎均等。因此，山东夏季降水的变化有其特殊性，需要从多方面进行研究。 西太平洋暖池是全球海温最高的海域，也是全球海气能量交换总量最大的区域。它的存在和变化对北半球夏季气候异常有着重要作用。西太平洋副热带高压的变化与西太平洋暖池面积大小有密切关系(李万彪等，1998)，20世纪70年代末以来的西太平洋副高增强也与这一时期暖池的跃变有关(赵永平等，2002)，暖池及其上空的对流活动的异常影响着西太平洋副高的变化和我国雨带的位置(黄荣辉等，1992，1994)，由此所激发的大气遥相关波列可波及西欧和北美。最近的研究也表明，冬、春季暖池区热含量的变化对南海夏季风爆发早、晚有重要影响(Chen et al.，2001)。当西太平洋暖池区海洋热含量高时，南海夏季风爆发早，反之则爆发晚。这对我国夏季季风雨的变化研究有重要意义，而且也必将对山东夏季旱涝产生重要影响。 本文作者通过对山东夏季降水资料的分析，对山东夏季降水时空变化及其与西太平洋暖池区域海洋热状态及副热带环流和夏季风变化的关系和影响的可能过程进行了探讨。     

Numerical Study of Water and Suspended Matter Exchange Between the Yellow Sea and the East China Sea

INTRODUCTIONTheYellowSeaandtheEastChinaSea (ECS)aremarginalseasofthenorthwestPacificandhaveexpansivecontinentalshelves .TheuniqueandstrikingfeaturesoftheYellowSeaandtheECSarethattheyhavestrongtidalcurrent;aresubjecttostrongmonsooninfluence ;andreceiveinflowfromthebiggestriverinChina ,theChangjiangRiver ;andthatthefamouswesternboundarycurrent,theKuroshio ,passesthroughtheECS ,withitsbranchesintrudingupwardintothecontinentalshelfareas.Generallyspeaking ,thewaterexchangecapacityofthe…     

热带印度洋Rossby波的基本特征

Long wavelength baroclinic oceanic Rossby waves are of interest because they are the main mechanism of energy transfer among the oceanic basins as the rotating fluid adjusts under the forcing of gravity and buoyancy,They play an important role in dynamics and thermodynamics in the ocean.The signature of them is evident from the altimeter measurements.Sea surface beight derived from the multiple ocean satellite altimeter missions over 1993～2008 is analyzed to systematically investigate the characteristics of the Rossby waves in the tropical Indian Ocean,by jointly adopting 2D-FFT,2D-Radon Transform,Complex Empirical Orthogonal Function and the classic linear theory methods.Results are as follows.The energy of Rossby wave is mainly concentrated between 5°S～18°S.Annual Rossby wave can be observed all over the whole badin,whereas semi-annual Rossby wave can bw only detected in the equatorial area, and inter-annual Rossby wave in the off-equatorial region.The phase speeds of Rossby waves detected from altimeter satellites are basically in agreement with the calculation based on the classic linear theory, but the former are some slower(faster) north(south)of 15°S than the later,Furthemore,it is indicated from the CEOF analysis that the annual Rossby waves is apparent in the Bay of Bengal,Arabian Sea ,and the open south Indian Ocean,whereas inter-annual Rossby wave mainly presents in the south Indian Ocean ,and eastward Kelvin wave is dominant along equator.     

Surface circulation patterns observed by drifters in the Yellow Sea in summer of 2001, 2002 and 2003

In summer of 2001, 2002 and 2003, ten, six and seventeen satellite-tracked surface drifters with drogues centered at 15 and 4 m were deployed, respectively, in the southern Yellow Sea (YS). 23 drifters of them transmitted useful data of at least 30 days. The wind-driven component of the drift was removed from the original drift velocity of drifters. The wind data used are from NCEP (National Center for Environmental Prediction), USA.Trajectories and drift velocities of the 23 drifters depicted the upper circulation structure in the southern YS. There exists an anti-cyclonic eddy with a mean speed and radius of 0.063 m/s and 50km in the central southern YS, whose center lingered within 35.3-36.0°N / 123.5-124.0°E. Showed by 6 drifters, a basin-scale elliptic cyclonic gyre with a mean speed of 0.114 m/s, long and short radius of 250 and 200 km surrounds the anti-cyclonic eddy. In the southwestern part of the southern YS has obvious frontal eddy activities within about 100 km with a mean speed about 0.076     

一种估算陆架上升流流速的新方法

依据海水中悬浮物垂直通量的计算公式 ,提出了一种利用悬浮物含量、垂直通量和静水沉速估算海水垂向流速的新方法。当悬浮物静水沉速未知时 ,可用判别方法对海水是否存在显著垂向流动做基本判断。同时采用估算及判别方法对东海9404航次两连续站111和410的实测资料进行分析 ,得出了410站的海水不存在显著的上升流动 ,而111站的海水不仅存在上升流动 ,流速约为2.6×10 3cm/s ,而且在时均情况下 ,上升流不能达到表层的结果。此判断结果与以往的观测和结论以及本次观测结果相吻合。     

EAST ASIA SUMMER MONSOON ONSET DATE CALCULATED FROM OBSERVED, REANALYZED AND COMBINED DAILY RAINFALL

In this paper, the East Asia summer monsoon onset date lines in East China are calculated by the definition similar to the traditional one, with the ECMWF reanalyzed 850 hPa daily wind and observed, reana-lyzed and combined daily rainfall during 1980～1993. To make the onset date line as close as possible to the previous work, the earliest onset date limits have to be applied for the regions with different latitude and the daily mean datasets have to be smoothed by space before calculation, therefore their space-resolution is reduced to about 3 longitude ×1°latitude. The results show that the multiyear mean summer monsoon onset date lines are quite similar to each other. Compared with the one from the reanalysis, the 14-year average onset date line form combination is obviously improved in the southern Sichuan Basin and the correlation between observed and combined onset date is also slightly higher over the Huaihe valley and Northeast China. Since daily rainfall combination also improved the long term daily mean and standard deviation through the pentad CMAP, if no better daily dataset is available, such a kind of daily rainfall combination can be used to get reasonable result in the Indian monsoon region without sufficient observatories or over the North Pacific without any ground observation at all in future study.