构造非平稳运动定量研究的MDD模式制约   总被引：4，自引：0，他引：4  

陈文寄  李齐 《地球科学》1996,21(3):277-279

利用ＭＤＤ模式得到的连续冷曲线，可以定量地描述地质体的冷却（隆升）过程；采自我国７个不同地区中３８个钾长石ＭＤＤ模式研究结果证明，快速冷却事件存在的普遍性，不同的快速冷却速度可能反映了不同的构造事件；突变因子（δｖｉ）可以定量地描述地质体非平稳运动以及突变程度，并且使得不同地质事件非平稳程度的对比成为可能。  相似文献   

祁连山地区1310年以来湿润指数及其年际变幅的变化与突变分析   总被引：23，自引：0，他引：23  

张志华  吴祥定 《第四纪研究》1996,16(4):368-378

本文通过用树木年轮资料重建的祁连山地区5～7月份1310年以来的湿润指数序列，建立了一个反映该地区湿润指数年际变幅序列，对这两个序列分别进行了等级分类和干湿、强弱的时段分析，并用最大熵谱分析法对这两个序列的不同时段分别进行了周期分析。采用HK突变检验方法对这两个序列分别进行了突变分析，发现祁连山地区的湿润指数及其年际变幅存在明显的突变年份。  相似文献   

CHARACTERISTICS OF ATMOSPHERIC HEAT SOURCE ASSOCIATED WITH THE SUMMER MONSOON ONSET OVER THE SOUTH CHINA SEA AND THE POSSIBLE MECHANISM RESPONSIBLE FOR ITS LATE OR EARLY ONSET     

蓝光东  温之平  贺海晏 《热带气象学报(英文版)》2004,10(2):190-200

The characteristics of atmospheric heat source associated with the summer monsoon onset in the South China Sea (SCS) are studied using ECMWF reanalysis data from 1979 to 1993. A criterion of the SCS summer monsoon onset is defined by the atmospheric hea…  相似文献   

茅坪滑坡稳定性的尖点突变分析     

祁生文聂洪峰  严福章刘春玲 《工程地质学报》2004,12(Z1):519-522

对茅坪滑坡体上两个监测点的位移时间序列进行尖点突变分析,发现茅坪滑坡EJ14监测点的尖点突变模型的两个控制变量均远大于0,而EJ8监测点的尖点突变模型的控制变量a＜0,这表明茅坪滑坡将来不会发生整体滑动,但其前缘(I-I'剖面)将会失稳.  相似文献   

青藏高原影响亚洲夏季气候研究的最新进展   总被引：40，自引：6，他引：40  

吴国雄  毛江玉  段安民  张琼 《气象学报》2004,62(5):528-540

文中回顾了近 10a来吴国雄等在青藏高原影响亚洲夏季气候研究方面的最新进展。通过分析东西风交界面的演变证明 ,由于青藏高原的春季加热 ,亚洲季风区对流层低层冬季盛行偏东风转变为夏季偏西南风最早发生在孟加拉湾东部 ,与其相伴随的激烈对流降水出现在其东面。因此孟加拉湾东部至中印半岛西部是亚洲季风最早爆发的地区。同时也指出盛夏伊朗高原和青藏高原加热所激发的同相环流嵌套在欧亚大陆尺度的热力环流中 ,从而加强了东亚的夏季风 ,加剧了中西亚的干旱 ;并通过其所激发的波动对夏季东亚的气候格局产生重要影响。文中还比较了夏季南亚高压的伊朗模态和青藏模态性质的异同及其对亚洲夏季降水异常分布的不同影响。  相似文献   

A Modeling Study of the Effects of Anomalous Snow Cover over the Tibetan Plateau upon the South Asian Summer Monsoon   总被引：1，自引：0，他引：1  

刘华强  孙照渤王举 闵锦忠 《大气科学进展》2004,21(6):964-975

The effect of anomalous snow cover over the Tibetan Plateau upon the South Asian summer monsoon is investigated by numerical simulations using the NCAR regional climate model (RegCM2) into which gravity wave drag has been introduced. The simulations adopt relatively realistic snow mass forcings based on Scanning Multi-channel Microwave Radiometer (SNINIR) pentad snow depth data. The physical mechanism and spatial structure of the sensitivity of the South Asian early summer monsoon to snow cover anomaly over the Tibetan Plateau are revealed. The main results are summarized as follows. The heavier than normal snow cover over the Plateau can obviously reduce the shortwave radiation absorbed by surface through the albedo effect, which is compensated by weaker upward sensible heat flux associated with colder surface temperature, whereas the effects of snow melting and evaporation are relatively smaller.The anomalies of surface heat fluxes can last until June and become unobvious in July. The decrease of the Plateau surface temperature caused by heavier snow cover reaches its maximum value from late April to early May. The atmospheric cooling in the mid-upper troposphere over the Plateau and its surrounding areas is most obvious in May and can keep a fairly strong intensity in June. In contrast, there is warming to the south of the Plateau in the mid-lower troposphere from April to June with a maximum value in May.The heavier snow cover over the Plateau can reduce the intensity of the South Asian summer monsoon and rainfall to some extent, but this influence is only obvious in early summer and almost disappears in later stages.  相似文献   

黄河流域天然径流量突变性与周期性特征   总被引：22，自引：1，他引：22  

杨志峰  李春晖 《山地学报》2004,22(2):140-146

突变性和周期性是水文时间序列的两个重要特征。黄河流域面积广阔，各区域水文水资源系统演变规律各不相同，它们的突变和周期变化及其形成的物理机制遍异，因此系统分析各区域水资源突变性和周期性特征及其影响机制具有重要意义。把黄河流域划分为15个区域，计算出各区域1951—1998年的年天然径流量系列。利用Mann-Kendall非参数检验方法检测黄河流域各区域年天然径流量的突变年份，结果表明各区域的突变年份不完全一致，主要在1953—1955年、1979—1983年、1991—1993年等发生了突变，这些突变与北半球气候突变具有一致性，且由于下垫面改变、人类活动等影响而复杂化。利用Morlet小波分析各区域年天然径流量的变化周期，发现主要存在3～4a、7～9a、11a的周期，形成这些周期的物理因子有太阳黑子、海—气相互作用和下垫面因素等。通过分析黄河流域主要产流区不同时段小波系数变化，发现20世纪80年代之后年径流量主要以短周期变化。  相似文献   

六盘水近45年日照变化的统计分析     

张润琼  万汉芸 《四川气象》2005,25(4):16-17,20

本文利用1960—2004年六盘水市各站的逐月日照时数资料，分析了近45年来六盘水的日照变化特征，发现区城平均年日照时数在减少，这种减少主要表现在春、夏两季。  相似文献   

Possible Impacts of the Arctic Oscillation on the Interdecadal Variation of Summer Monsoon Rainfall in East Asia   总被引：18，自引：5，他引：18  

JU Jianhu  Lü Junmei  CAO Jie  REN Juzhang 《大气科学进展》2005,22(1):39-48

The influences of the wintertime AO (Arctic Oscillation) on the interdecadal variation of summer monsoon rainfall in East Asia were examined. An interdecadal abrupt change was found by the end of the 1970s in the variation of the AO index and the leading principal component time series of the summer rainfall in East Asia, The rainfall anomaly changed from below normal to above normal in central China, the southern part of northeastern China and the Korean peninsula around 1978. However,the opposite interdecadal variation was found in the rainfall anomaly in North China and South China.The interdecadal variation of summer rainfall is associated with the weakening of the East Asia summer monsoon circulation. It is indicated that the interdecadal variation of the AO exerts an influence on the weakening of the monsoon circulation. The recent trend in the AO toward its high-index polarity during the past two decades plays important roles in the land-sea contrast anomalies and wintertime precipitation anomaly. The mid- and high-latitude regions of the Asian continent are warming, while the low-latitude regions are cooling in winter and spring along with the AO entering its high-index polarity after the late 1970s. In the meantime, the precipitation over the Tibetan Plateau and South China is excessive, implying an increase of soil moisture. The cooling tendency of the land in the southern part of Asia will persist until summer because of the memory of soil moisture. So the warming of the Asian continent is relatively slow in summer. Moreover, the Indian Ocean and Pacific Ocean which are located southward and eastward of the Asian land, are warming from winter to summer. This suggests that the contrast between the land and sea is decreased in summer. The interdecadal decrease of the land-sea heat contrast finally leads to the weakening of the East Asia summer monsoon circulation.  相似文献   

“龙舟水”泛滥成百年一遇的特大洪灾     

《广东气象》2005,(3):F003-F003

2005年的“龙舟水”泛滥南粤,6月18-25日持续一周的特大致洪暴雨过程,使广东省遭遇了百年一遇的洪水灾害。受高空槽、切变线和西南季风共同影响,广东省出现了较大范围连续性特大暴雨和强降水,其中,龙门县录得的过程累积雨量1300.2 mm。再加上珠江流域各大江河上游洪水的不断涌入和天文大潮的顶托,西江水位急剧上涨,6月23日中午-24日早晨,西江的封开、德庆、高要分别超警戒水位8.92 m、6.58m、2.68 m,流量达到56300m3/S,北江清远超警戒水位2.18 m。暴洪、泥石流、塌方、洪涝等自然灾害,成片出现在广东的河源、韶关、肇庆、惠州、清远、汕尾、珠海等地区的乡镇,17个市89个县(市、区)762个乡(镇)受灾,受灾人口441.6万人,直接经济损失45.2亿元人民币,特大暴雨造成京九铁路多处地段发生土方溜坍,被迫中断行车10多天。受暴雨和天文大潮夹击,广州珠江最高潮位超过基面2 m。江水漫进广州城,市内低洼地多处水浸超过1 m,南岸的铁轨一度被大水淹没,沿江路、滨江路等大马路水深盈尺,风景如画的小岛沙面顿成水泽。暴雨令著名风景区白云山出现20多处塌方,也令白云机场几度关闭。  相似文献