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1.
利用卫星照片和北半球雪盖图导出欧亚大陆1967～1978年春季(3～5月)雪盖区。印度夏季风推进日期是从印度半岛最南端到印度西北部的每日天气报告中得到的。将逐年印度夏季风推进日期与3～5月欧亚大陆春季雪盖区、3～5月欧亚大陆的融雪作比较。初步研究展示:春季欧亚大陆的广大雪盖区将导致印度夏季风较长的推进时段。进一步说,一种反相关(负相关)存在于印度夏季风与欧亚大陆的春季融雪之间,即欧亚大陆春季的大量融雪是和印度夏季风较短的推进时段有关。 相似文献
2.
青藏高原冬季积雪异常对东,南亚夏季风影响的初步数值模拟研究 总被引：10，自引：2，他引：10
利用一个耦合了简化的简单生物圈模式的大气环流谱模式（ＳＳｉＢ－ＧＣＭ），初步探讨了青藏高原冬季积雪异常对东、南亚夏季季风环流和降水的影响及其机理。结果表明，高原地区积雪增加将使随后地夏季东、南来季风明显减弱，主要表现为东、南亚季风区降水减少，索马里急流、印度季风的印度西南气流弱弱。另外，还提出欧亚大陆雪盖与整个高原雪盖和高原东部雪盖对东、南亚夏季风影响的敏感问题。与欧亚大陆雪盖相比，高原雪盖是影响 相似文献
3.
冬季欧亚大陆雪盖与江苏梅雨量关系的初探 总被引：2，自引：0，他引：2
本文着重讨论了冬季欧亚大陆雪盖与江苏梅雨量的年际变化关系。分析发现：冬季欧亚大陆雪盖与江苏梅雨量之间呈显著的负相关，而与沿江地区夏季降水量之间的关系不密切。异常的雪盖对江苏丰、枯梅雨有很好的指示意义。 相似文献
4.
欧亚大陆季节增（融）雪盖面积变化特征分析 总被引：3，自引：0，他引：3
利用美国冰雪资料中心(National Snow and Ice Data Center)提供的近40年逐周的卫星反演雪盖资料,定义了各季节新增(融化)雪盖而积指数(fresh snow extent),即增/融雪覆盖率P_(FSE)、增/融雪面积A_(FSE)、欧亚大陆北部增/融雪面积之和T_(FSE),针对欧亚大陆各季节平均的雪盖面积本身(snow extent,P_(SE)、A_(SE)、T_(SE)和其增(融)雪盖面积,分析比较二者的变化特征.结果表明,欧亚大陆各季节平均的雪盖面积和相应增(融)雪盖面积不论是气候态分布还是其年际、十年际变化均有明显不同,其中以冬、春季差别更为明显;夏、秋季二者虽有较好的一致性,但增(融)雪盖面积的变率明显强于雪盖而积本身;另外,冬季欧洲新增雪盖对欧业北部冬季雪盖面积以及其后的春季雪盖都有较显著的影响,而春季欧洲和中纬度亚洲地区的融雪则受到冬、春两季雪盖情况的影响.进一步分析欧亚大陆冬、春两季增(融)雪盖与ENSO关系显示,二者除在个别地区(两伯利业北部、欧洲中东部以及青藏高原)存在较明显关系外,整体上,欧亚大陆北部雪盖变化既不受控于ENSO,也不会显著影响ENSO. 相似文献
5.
华北和印度夏季风降水变化的对比分析 总被引：3，自引：0，他引：3
利用华北和印度夏季降水资料,采用趋势分析、小波变换等方法,对两地区夏季风降水进行了对比分析。结果表明：1) 华北和印度夏季风降水量都存在线性减少倾向,但华北更为显著,减少达16 mm/10 a;2) 华北和印度夏季风降水变化都以18 a周期为主,近年都有逐渐缩短的趋势,而印度的这种周期缩短得比华北更快,近年降水变化周期接近15 a;3) 华北和印度夏季风降水变化在1956、1976、1992/1993年发生了趋势转折;4) 华北和印度降水量主要集中在6-9月,夏季风降水特征非常明显,但两地变化特征表现不尽相同。 相似文献
6.
青藏高原冬季雪盖异常与冬夏季风变异
及其相互联系的物理诊断研究 总被引：23，自引：6，他引：17
利用1955～1993年各种类型青藏高原冬季异常积雪资料的综合再分析结果,首次分析、阐明并讨论了青藏高原雪盖异常与中纬度大气环流的关系及其对低纬热带大气和海洋的影响。结果表明,高原冬季雪盖异常影响东亚冬季风的异常,进而通过东亚Hadley环流引起南海南部积云对流活动的异常,结果造成赤道太平洋纬向风出现变异并引发SSTA位相和副高活动及夏季风强度的显著不同,由此对我国夏季风雨带分布产生影响。最后给出青藏高原冬季雪盖异常可能对我国夏季风影响的一个初步模型。这对于进一步认识和揭示雪盖-环流-SST-雨带的相互联系及其可能的“隔季相关”机制具有重要意义 相似文献
7.
北半球雪盖的气候特征及与印度季风降水的关系 总被引：4，自引：0，他引：4
利用卫星观测的1966年11月－2000年12月北半球雪盖资料，研究了北半球、欧亚、北美和青藏高原雪盖的气候学特征及其变化趋势。通过对雪盖与印度季风的分析，得出：（1）欧亚冬季（12月－翌年3月）雪盖面积与印度季风降水（6－9月）呈反相关，并指出印度季风降水不仅受欧亚雪盖的影响，可能与暖水年有一定的联系。（2）青藏高原10、11月雪盖面积与次年印度季风爆发及降水关系较好，并提出可能的影响机制。 相似文献
8.
9.
利用 NOAA- NESDIS提供的 1 973— 2 0 0 0年北半球雪盖面积资料 ,研究了欧亚冬季雪盖的时空特征 ,发现欧亚大陆中高纬地区积雪有明显的整体性分布特征 ,而50°N以南的冬季积雪随纬度的变率较大 ;欧亚大陆中高纬地区冬季积雪呈东西反位相分布。利用小波分析发现 ,冬季欧亚积雪具有显著的 3～ 4 a周期。最后指出 ,欧亚积雪异常引起的下垫面热力异常可能为次年 El Nino事件的爆发提供触发条件。 相似文献
10.
陕西4-10月降水量场预测研究 总被引：1，自引：0，他引：1
利用陕西省82站33a(1971-2003)逐月降水量资料,结合大气环流的重现期,用秋、冬季降水量场与4-10月降水量场的相关关系建立预测模式,预测4-10月全省降水量的分布.预测试验初步得出,秋冬季降水量场与4-10月降水量场相关系数为0.9028～0.9218,预测模式拟合相对误差为4%～7%.1964年和2003年全省性涝年回报试验结果表明,降水量距平符号一致率均在85%以上.对2007年4-10月全省降水量分布做了独立样本预测试验,降水量距平符号一致率为66 7%. 相似文献
11.
1997/1998年冬季青藏高原大部地区积雪异常偏多，出现了历史上罕见的严重雪灾。作者在回顾关于青藏高原雪盖与中国季风雨关系的基础上，分析了1998年夏季各月中国东部降水分布和主要雨带移动的特点，并与青藏高原多雪年夏季我国主要雨带活动的统计特征进行对比分析，探讨了1998年夏季长江流域洪涝的成因。结果表明，1998年夏季降水的一些重要特征:如6月强降雨出现在湖南、江西、浙江一线，7月二度梅发生在湖南北部、湖北南部、江西北部一带，8月长江上游、汉水流域和黄淮地区降水频繁，以及夏季我国主要雨带北移明显推迟，都与多雪年的情况非常相似。突出地反映了1998年夏季长江流域洪涝的发生，前期冬季青藏高原出现的积雪异常起着重要的作用。多雪年夏季西太平洋副热带高压北移也明显偏迟，致使中国主要雨带持续偏南，造成长江流域降水异常偏多。另外，分析表明，它还与1997年强厄尔尼诺的共同作用有密切关系。 相似文献
12.
Influence of the Eurasian snow cover on the Indian summer monsoon variability in observed climatologies and CMIP3 simulations 总被引：3，自引：1，他引：2
The present study is aimed at revisiting the possible influence of the winter/spring Eurasian snow cover on the subsequent Indian summer precipitation using several statistical tools including a maximum covariance analysis. The snow–monsoon relationship is explored using both satellite observations of snow cover and in situ measurements of snow depth, but also a subset of global coupled ocean–atmosphere simulations from the phase 3 of the Coupled Model Intercomparison Project (CMIP3) database. In keeping with former studies, the observations suggest a link between an east–west snow dipole over Eurasia and the Indian summer monsoon precipitation. However, our results indicate that this relationship is neither statistically significant nor stationary over the last 40 years. Moreover, the strongest signal appears over eastern Eurasia and is not consistent with the Blanford hypothesis whereby more snow should lead to a weaker monsoon. The twentieth century CMIP3 simulations provide longer timeseries to look for robust snow–monsoon relationships. The maximum covariance analysis indicates that some models do show an apparent influence of the Eurasian snow cover on the Indian summer monsoon precipitation, but the patterns are not the same as in the observations. Moreover, the apparent snow–monsoon relationship generally denotes a too strong El Niño-Southern Oscillation teleconnection with both winter snow cover and summer monsoon rainfall rather than a direct influence of the Eurasian snow cover on the Indian monsoon. 相似文献
13.
By prescribing sea surface temperature anomalies(SSTAs)over eastern equatorial Pacific inJanuary—March,the lag influence of ENSO(El Nino and La Nina)on monsoon over East Asiahas been studied.The results suggest that,due to the excitation of atmospheric low-frequencyoscillation by the SSTA,ENSO has significant lag influence on the monsoon over East Asia.During the summer after E1 Nino,the subtropical high over western Pacific is intensified andshows the northward and westward displacement,meanwhile,the rainfall over East China isbelow normal,especially in North China:during the winter after E1 Nino,both the Asian troughand the winter monsoon over East Asia are strengthened.During the summer after La Nina,theanomalous subtropical high prevails over the lower reaches of Yangtze(Changjiang)River,therainfall between Yangtze and Huaihe Rivers is below normal:during the winter after La Nina,both the Asian trough and the winter monsoon over East Asia are weaker.Compared with LaNina,the effect of El Nino is stronger,but it is not always opposite to the one of La Nina. 相似文献
14.
本文分析了1971—80年发生在南美洲西海岸的EI Nino现象及其对东亚夏季风环流的影响。结果表明,1972和1976年为强的EI Nino年,而1971和1974年为显著的反EI Nino年。还指出,1—6月份南美西海岸的海温与7月份我国东部大部分地区夏季风呈负相关.在EI Nino年,主要环流的特征为:(1)西太平洋副热带高压脊线偏北,强度偏弱.(2)澳大利亚高压位置偏南。(3)赤道缓冲脊强大.ITCZ东伸到太平洋中部。南半球的信风在105°E附近越过赤道之后,于10°N折向东去,流入西太平洋.(4)印度次大陆季风中断.孟湾西南季风直接影响我国东部地区的分量极其有限,在反EI Nino年,上述各系统特征完全相反.我们认为,EI Nino现象的发生,引起夏季风环流系统的变动,最终影响到我国夏季风的强度,这是二者之间遥相关的一种可能过程. 相似文献
15.
青藏高原积雪与亚洲季风环流年代际变化的关系 总被引：12，自引：1，他引：12
利用高原测站的月平均雪深资料和NCEP／NCAR再分析资料，分析了20世纪70年代末以来，青藏高原积雪的显著增多与亚洲季风环流转变的联系。研究表明，高原南侧冬春季西风的增强及西风扰动的活跃是造成青藏高原冬春积雪显著增多的主要原因，高原积雪的增多与亚洲夏季风的减弱均是亚洲季风环流转变的结果；20世纪70年代末以来，夏季华东降水的增多、华南降水的减少及华北的干旱化与青藏高原冬春积雪增多及东亚夏季风的减弱是基本同步的，高原冬春积雪与华东夏季降水的正相关、与华北及华南夏季降水的负相关主要是建立在年代际时间尺度上，因此，高原积雪与我国夏季降水关系的研究应以亚洲季风环流的年代际变化为背景。 相似文献
16.
Relationship between winter snow cover days in Northeast China and rainfall near the Yangtze River basin in the following summer 
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下载免费PDF全文 Based on observed snow and precipitation data and NCEP/NCAR reanalysis data,the relationship between the number of winter snow cover days in Northeast China and the following summer’s rainfall in the northern part of southern China is analyzed and the possible underlying mechanisms are discussed.The results indicate that a negative relationship is significant throughout the study period,especially more obvious after the 1980s.The pre-winter circulation patterns in years with more snow cover days and less summer rainfall in the south bank of the Yangtze River are almost the same.In years with more snow cover days,lower temperatures at the lower level over Northeast China are found in winter and spring.The winter monsoon is weaker and retreats later in these years than in those with fewer snow cover days.In spring of years with more snow cover days,anomalous cyclonic circulation is observed over Northeast China,and anomalous northerly wind is found in eastern China.In summer of these years,anomalous northeasterly wind at the lower level is found from the area south of the Yangtze River to the East China Sea and Yellow Sea;and with less southwesterly water vapor transport,the rainfall in the area south of the Yangtze River is less than normal,and the opposite patterns are true in years with fewer snow cover days.In recent years,the stable relationship between winter snow cover in Northeast China and summer rainfall in the Yangtze River basin can be used for summer rainfall prediction.The results are of great importance to short-term climate prediction for summer rainfall. 相似文献
17.
Summary ?This study presents the monthly climatology and variability of the INSAT (Indian National Satellite) derived snow cover estimates
over the western Himalayan region. The winter/spring snow estimates over the region are related to the subsequent summer monsoon
rainfall over India. The NCEP/NCAR data are used to understand the physical mechanism of the snow-monsoon links. 15 years
(1986–2000) of recent data are utilized to investigate these features in the present global warming environment.
Results reveal that the spring snow cover area has been declining and snow has been melting faster from winter to spring after
1993. Connections between snow cover estimates and Indian monsoon rainfall (IMR) show that spring snow cover area is negatively
related with maximum during May, while snow melt during the February–May period is positively related with subsequent IMR,
implying that smaller snow cover area during May and faster snow melt from winter to spring is conducive for good monsoon
activity over India. NCEP/NCAR data further shows that the heat low over northwest India and the monsoon circulation over
the Indian subcontinent, in particular the cross-equatorial flow, during May are intensified (weakened) when the snow cover
area during May is smaller (extensive) and snow melts faster (slower) during the February–May period.
The well-documented negative relationship between winter snow and summer rainfall seems to have altered recently and changed
to a positive relationship. The changes observed in snow cover extent and snow depth due to global warming may be a possible
cause for the weakening winter snow–IMR relationship.
Received January 15, 2002; revised May 5, 2002; accepted June 23, 2002 相似文献
18.
ENSO对其后东亚季风活动影响的GCM模拟研究 总被引：19，自引：1，他引：18
将１～３月赤道东太平洋海表水温距平（ＳＳＴＡ）引入大气环流模式,模拟研究了ＥＮＳＯ（厄尔尼诺和拉尼娜）对其后东亚季风活动的影响。结果表明,由于ＳＳＴＡ在大气中强迫激发出了大气低频振荡,使得ＥＮＳＯ对其后的东亚季风活动仍有明显影响。厄尔尼诺之后的夏季,西太平洋副热带高压偏强偏北且西伸明显,中国东部降水偏少,尤其是华北地区;厄尔尼诺之后的冬季,东亚大槽偏深,冬季风偏强。拉尼娜之后的夏季,中国长江下游为异常副热带高压单体控制,江淮流域雨量偏少;拉尼娜之后的冬季,东亚大槽偏弱,东亚冬季风偏弱。厄尔尼诺的影响比拉尼娜的影响略强,两者的影响并非完全反相。 相似文献
19.
Both observational and numerical studies suggest that the Eurasian winter snow cover has a strong influence on the subsequent
summer monsoon in Asia. An updated version of the ARPEGE climate model of Météo-France, including a simple but physically-based
snow parameterization, is used to test the impact of an increased snow mass prescribed at the beginning of March on the simulated
summer monsoon circulation and rainfall. The large-scale features of the Asian monsoon are reproduced in a realistic way in
the control integration, which is a necessary premise of such a sensitivity test. In the heavy snow cover experiment, the
anomalous persistence of the winter snow pack delays the springtime continental heating. This weakens the thermal low over
northern India and Persia as well as the southwesterly winds over the monsoon area. There is also a significant decrease in
the rainfall over western India and Bengal-Burma, which usually represent the centers of maximum precipitation. Radiative,
turbulence transfer and hydrological processes seem to be involved in the snow-monsoon relationship. The changes in the monsoon
precipitation are strongly related to changes in the atmospheric circulation and are not reinforced by a local evaporation/convection
feedback in our experiment.
Received: 17 May 1995 / Accepted: 27 November 1995 相似文献