全球垂直基准研究中的几点思考

目前全球垂直基准问题的研究已受到各有关国家的关注。介绍了建立全球垂直基准的意义、作用和方法,指出了研究中存在的一些问题,并提出了解决这些问题的初步意见。     

月尺度降水可预报性的实验研究

利用信噪方差比探讨了山东省月尺度降水可预报性,发现２～３月、９～１０月不可预报,其它月份可预报性强。一般大气环流系统冬夏转换季节可预报性差。与１３个代表站预报评分进行了比较,发现可预报性指数越高,则实际预报评分也相对较高,两者有较好的对应关系。     

PECULIARITIES OF LONG TERM VARIATION OF SEA SURFACE TEMPERATURE IN TROPICAL WESTERN PACIFIC OCEAN

It is necessary to study the tropical western Pacific SST in association with variations of other parts of the globe. Two basic compositions are revealed of long-term variation in SST over three major tropical oceans since the 1950's (linear warming and El Nino-La Nina oscillations) and typical patterns with which they are displayed over the oceans are compared. On the basis of it, difference in long-term variation of SST over western, central and eastern tropical Pacific is analyzed in details. It is pointed out that the El Nino-La Nina oscillations are relatively weak in the long-term variation of SST in the tropical western Pacific and linear warming trend there is replaced by interdecadal oscillations. Further understanding of the peculiarity over the region helps improve short-term climatic predictions in China.     

鄂尔多斯盆地燕山运动及其与油气关系

鄂尔多斯盆地是中国中西部重要的含油气盆地之一。燕山期是盆地油气运移和聚集的主要时期。通过晚中生代及其周缘地区沉积格局、构造变形、晚侏罗世—早白垩世的岩浆及热事件的分析 ,认为晚侏罗世以前盆地主要受特提斯构造域的控制 ,古太平洋板块对盆地格局的影响在晚侏罗世晚期以后才有所表现。深部地幔蠕散是盆地古地温场变化的主要原因。它不但导致了盆地地温梯度的急剧升高 ,而且还对后期盆地周缘的地壳浅层次构造变形有一定的影响 ,也是造成晚中生代山西地区与鄂尔多斯盆地差异的重要因素 ,还对油气的运移和聚集起着控制作用。综合燕山期盆地古应力场、古地温场及构造变形特点 ,可以认为燕山期构造运动对鄂尔多斯盆地的油气分布至关重要     

THE INTERDECADAL VARIABILITY OF ADVANCE AND RETREAT OF EAST ASIAN SUMMER MONSOON AND THEIR EFFECT ON THE REGIONAL RAINFALL OVER CHINA

The daily precipitation data of 740 stations in China(1958–2001)and the daily upper air data of European Centre for Medium-Range Weather Forecasts reanalysis dataset(1958–2001)are used to define an East Asian summer monsoon(EASM)index based on dynamic and thermal factors.The index is used to represent the front(or leading edge)of EASM to describe and characterize the advance and retreat of EASM objectively.During 1958–2001,the EASM movement underwent three interdecadal abrupt shifts in 1965,1980 and 1994,respectively.During 1958–1964,the front primarily concentrated in South China and North China,while it stayed at the mid-and lower-Yangtze River for a short period.During 1965–1979,the front was located in South China and the lower reach of Yellow River for a long time.During 1980–1993,the time in which the front of EASM stayed at the mid-and lower-Yangtze River was much longer,but it settled in North China for just a short time.During 1994–2001,the front generally concentrated in the south of the mid-and lower-Yangtze River.The three interdecadal shifts of EASM directly resulted in rainfall anomalies,as well as frequent disasters of flood and drought in East China.     

DYNAMIC ANALYSIS OF INHERENT CAUSES FOR DEVIATION OF TROPICAL CYCLONE TRACKS

To have a clearer picture of mechanisms responsible for the deviation of tropical cyclone (to be simplified as TC hereafter) tracks, the current work assumes the TC as a circular vortex with a radius of R. A general motion equation of TC is then determined by averaging its horizontal motion equation over the sentire region of TC. In the meantime, with the moving track of TC assumed as a characteristic arc, the curvature equation is derived for the track of movement and patterns of its deviation due to TC structure and variation are discussed. The result shows that the scale, size, maximum wind speed and radius are factors causing the deviation of TC tracks. In addition, asymmetric structure of TC is also important for the deviation of tracks. The results, achieved with hypothesis, agree with facts in some cases but disagree with them in others, which are to be verified with more observations or numerical simulations.     

应用近景摄影法研究沙纹的移动

近景摄影能够在无干扰的条件下,精确地测定正在发育阶段的风成沙纹,以波动方式整体移动的平均移动速度V_R(cm·min^-1),和相应的沙纹波长L(cm)波高Δh(mm)及其平均值。同时,求得沙纹移动速度V_R与局地风速V_L之间的实验关系式为V_R=158×(V_L-5.5)^0.67,沙纹移动是缓慢的,其数量级变化于10^-1~10¹cm·min^-1之间。沙纹波长与波高与直接测定值相当吻合。     

沙粒跃移云及Magnus力对床面有效粗糙度的影响

建立了考虑Magnus效应的、吹过平坦沙面的稳定风场中风与跃移沙粒相互耦合的风沙跃移云模型,并通过数值模拟研究了风沙跃移运动对床面粗糙度的影响。结果表明,跃移沙粒对风速的影响类似于床面粗糙度的影响,有效粗糙度随摩阻速度的变化关系可用二次函数表征;Magnus力对有效粗糙度有明显的影响,但这种影响并不改变有效粗糙度与摩阻风速之间的二次函数关系。     

东昆仑东段新生代高原隆升重大事件的沉积响应

根据新生代沉积盆地的地层序列、环境演变及地貌和水系变迁分析将研究区新生代高原隆升过程划分为5个重大事件.首次在研究区内海拔5400m的主夷平面上发现古土壤、岩溶角砾岩及钟乳石等, 认为沱沱河组上段细碎屑沉积及五道梁组石膏沉积(中新世) 是主夷平面形成期的沉积响应, 提出了主夷平面的高程具有东西向排列的盆岭地貌特点, 这种高程差异反映了后期构造隆升的不均衡, 应该是上新世以来差异断块抬升的结果; 早更新世中期(1525.5ka后) 一套河流砂砾卵石沉积是青藏运动C幕的沉积响应, 体现在布尔汗布达山的强烈上升和成山; 早更新世晚期(1113.9~836.3ka) 先湖滨砾石沉积, 后转为河流砂砾卵石沉积, 是昆黄运动在研究区的沉积响应, 并体现在马尔争-布青山的强烈上升和成山, 中更新世早期冰碛物的发育说明昆黄运动后研究区已隆升达到"水汽冻结高度"; 研究区T5阶地沉积前的强烈下蚀, 柴达木盆地内陆水系溯源侵蚀切过布尔汗布达山主分水岭, 袭夺了昆南断裂带原由西向东流向共和古湖的东西向水系并到达阿拉克湖一带, 晚更新世洪冲积角度不整合于中更新世洪冲积之上等是共和运动的具体表现.      

黄河河口二维泥沙有限元数学模型及应用(Ⅱ)--潮流和泥沙输运沉积过程模拟分析

利用多沙黄河河口潮波平面二维泥沙数学模型,通过典型时刻近海海区潮汐、河口口门河道、河海流场、含沙量、河床变形和海底等值线等图形对入海河口海域潮汐和潮流海洋动力特性、入海泥沙运动扩散输移规律、河口拦门沙形状、形成过程、泥沙冲淤和海底地形变化进行了分析,这些都与实测资料和遥感图像的分析基本一致。