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1.
西北地区东部秋季降水日数时空特征分析 总被引：7，自引：0，他引：7
利用西北地区东部(95°~112°E,32°~41°N)共104个测站的1960~2000年秋季(9~11月)降水日数资料,通过主成分分析和旋转主成分分析等方法,对我国西北地区东部秋季降水日数异常的时空特征进行了研究。结果表明:西北地区东部秋季0.1 mm以上的降水日数多年平均分布总体上从南向北减少,并存在两个多雨日中心,一个位于祁连山地区;另一个位于青海南部和四川北部地区。其异常分布主要表现为一致性异常和西北与东南相反的异常两种形式,降水日数气候区可主要划分为西北东部副热带季风区、青海东北及甘肃中部区、甘肃河西及河套地区、青海高原南部及川西高原区。各气候区代表站降水日数年代际变化均呈现下降趋势,1978年前后是秋季降水日数由多变少的转折点。 相似文献
2.
本文利用1961~2012年夏季西北地区东部(32~40°N,100~110°E)156个站点逐日降水资料,以及1982~2012年青藏高原70个站点的地面感热观测资料,采用EOF、相关分析等方法分析了西北地区东部夏季降水、青藏高原冬末春初(2~4月)地面感热的时空变化特征,讨论了西北地区东部夏季降水对于青藏高原冬末春初地面感热异常的响应,通过环流场分析高原感热异常对西北东部夏季降水的影响成因。结果表明:高原东部冬末春初地面感热偏强时,西北东部地区北部降水偏少,东南部和西南部降水偏多;反之,西北东部北部降水偏多,东南部和西南部降水偏少。 相似文献
3.
西北地区初夏冰雹及其环流背景气候特征 总被引：6，自引：0，他引：6
应用西北地区194个气象站1961~2001年初夏6月冰雹日数资料,研究了西北地区初夏冰雹发生日数的时空分布特征,讨论了典型多雹年和少雹年大尺度环流的气候特征。结果表明:西北地区初夏冰雹发生日数最高的地方在天山山脉西端、沿祁连山脉及其以南的青海大部(除柴达木盆地)和甘肃甘南高原等海拔较高的地方。在冰雹发生日数最高的地方年代际变化明显,而在冰雹发生日数偏少的地方年代际变化不明显。另外多雹年和少雹年的北半球极涡中心强度、高原高度场、印缅槽、欧洲环流C型天数等环流特征量以及北半球500 hPa环流形势和OLR场均存在着明显差异。 相似文献
4.
利用1983年7月～2001年9月国际卫星云气候计划ISCCP D2的月平均资料，对西北不同区域不同类型云的云量和云水路径的时空分布及其与降水的关系进行了研究。结果表明:高原气候区是各种云出现最多的地区，特别是积状云的云量明显高于其他两区，但这些云的云水路径值低；西北地区大多数云云量的高值区出现在天山山区、北疆地区、陕西东南部和青藏高原的部分地区。高云和部分中云云量空间分布特征与降水有着较好的一致性:沿着天山—昆仑山—祁连山一带以及陕南和／或陇南地区是高值区，低值区在塔里木盆地—内蒙古西部戈壁沙漠—黄土高原西北部一带；绝大多数云类春夏季节云量维持较高，秋冬季节云量较少。云水路径值较大的层状云类的云量多寡与降水多寡相一致；积状云类和层积云类云量多少与降水没有一定的关系，在降水偏少时，这类云的云量大多与降水正常时相近，有些云的云量甚至比降水偏多时还要多。 相似文献
5.
利用1951-2005年雷暴和冰雹观测资料,统计出中国743个站点的雷暴以及冰雹发生日数.统计结果表明,中国雷暴和冰雹等强对流天气发生的概率分布具有明显的地理和日变化差异,日间与夜间强对流天气分布变化很大.中国雷暴发生频繁的区域共有5个,分别是青藏高原东部、云南中南部、四川境内、华南两广地区及新疆西部,各区域雷暴日数存在不同的年际变化特征.全国雷暴日数除青藏高原地区略有上升外,总体呈下降趋势.冰雹发生频繁的区域主要在青藏高原祁连山地区,天山地区和华北北部为冰雹活动的次频繁中心.冰雹日的年际变化也因区域不同而有所区别.由中国雷暴日数的REOF分析可以看出,华南、长江流域等地区都存在独立的异常时空分布,与特定的大尺度环流密切相关. 相似文献
6.
利用甘肃５５ 个测站,１９６８ ～１９９７ 年５ 月中旬至６ 月中旬降水资料,采用 Ｅ Ｏ Ｆ、 Ｒ Ｅ Ｏ Ｆ、波谱分析,对春末夏初降水异常的空间结构及时间演变特征作了研究。结果表明,甘肃河东春末夏初降水异常在空间上主要表现为陇东、中部、陇东南、甘南４ 个主要类型。河东各主要气候区春末夏初降水的时间变化基本趋势是：８０ 年代春末夏初降水增加,而９０ 年代以来,降水均有不同程度减少,干旱加剧。甘肃河东春末夏初降水变化以短周期振荡为其主要特征。在１０ 年的年际变化中,陇东比各型均落后１ ～２ 年。从环流形势看,当春末夏初北半球５００ｈ Ｐａ 高度距平场结构呈现出明显的正 Ｐ Ｎ Ａ 型时,中国西北地区同期降水偏少 相似文献
7.
中国西北夏季气温变化及其对青藏高原地面感热异常响应的诊断与数值试验 总被引：11，自引：1，他引：10
利用陕、甘、宁、青、新五省（区）９０个测站,１９６０～１９９０年历年夏季月平均气温,采用主成分分析、旋转主成分分析和全球大气环流模式,对中国西北夏季气温变化的时空异常特征及其对青藏高原地面感热通量强弱变化的响应进行了诊断分析和数值试验。结果表明：中国西北地区气温变化在空间上具有较好的一致性,但由于地形和下垫面的影响,夏季气温异常主要表现为６种气候类型（区）,即青海高原区、河套区、北疆区、渭水流域区、南疆西部区、东疆－河西走廊区。５０年代以来气温演变的主要特点是除青海高原和北疆外的西北大部分地方夏季由暖变冷。当北半球５００ｈＰａ高度距平场呈欧亚型振荡,则有利于中国西北大范围气温偏高（低）。青藏高原地面感热通量的异常增强,可引起西北夏季西部偏暖,东部偏冷。 相似文献
8.
YU Yaxun WU Guoxiong WANG Baoling DONG Anxiang BAI Huzhi 《Acta Meteorologica Sinica》2001,15(2):191-204
The interannual and intermonthly climatic features of the water vapor content(hereafterWVC)and its mean transfer in the atmosphere over Northwest China(hereafter NWC)arecalculated and analyzed by using the NCEP/NCAR global reanalysis grid data(2.5°×2.5°Lat/Lon)for 40 years(1958—1997).The results show that the WVC in the total air column over NWC infour seasons of the year is mainly concentrated on eastern and western NWC respectively.On theaverage,the WVC over eastern NWC decreases obviously during recent forty years except forwinter.while it decreases over western NWC in the whole year.But the WVC over NWC has beenincreasing since late 1980s in summer.The water vapor comes from the southwestern warm andwet air current along the Yarlung Zangbo River Valley and the Bay of Bengal.and from mid-western Tibetan Plateau and also from the Qinling Mountains at southern Shaanxi Province.Theyearly water vapor divergence appears over the middle of NWC to northern Xinjiang andsoutheastern Shaanxi Province.The yearly water vapor convergence appears over the Tarim Basinand the Tibetan Plateau as well as western Sichuan and southern Gansu. 相似文献
9.
西北干旱区感热异常对中国夏季降水影响的模拟 总被引：12，自引：0，他引：12
利用最新版的RegCM3模式通过增加西北干旱区地面向大气的感热输送,模拟了西北干旱区春、夏季感热异常对中国夏季降水的影响。结果表明:西北地区地面向大气的感热输送增加后,西北干旱区低层空气温度升高,空气密度减小使得空气有上升运动距平,减弱了空气的下沉运动,从而在新疆地区降水增加。西北地区下沉气流减弱使得高空气压更强,形成反气旋气流距平,导致高原地区上升气流减弱,在青藏高原降水减少。高原地区上升气流减弱导致在长江中下游和东北北部分别有负的气压距平中心,使得这里有气旋式距平环流,降水增加;而在华南、西南、华北南部和东北南部降水减少。 相似文献
10.
Using the hindcasts provided by the Ensemble-Based Predictions of Climate Changes and Their Impacts(ENSEMBLES) project for the period of 1980–2005, the forecast capability of spring climate in China is assessed mainly from the aspects of precipitation, 2-m air temperature, and atmospheric circulations. The ENSEMBELS can reproduce the climatology and dominant empirical orthogonal function(EOF) modes of precipitation and 2-m air temperature, with some differences arising from different initialization months. The multi-model ensemble(MME) forecast of interannual variability is of good performance in some regions such as eastern China with February initialization.The spatial patterns of the MME interannual and inter-member spreads for precipitation and 2-m air temperature are consistent with those of the observed interannual spread, indicating that internal dynamic processes have major impacts on the interannual anomaly of spring climate in China. We have identified two coupled modes between intermember anomalies of the 850-hPa vorticity in spring and sea surface temperature(SST) both in spring and at a lead of 2 months, of which the first mode shows a significant impact on the spring climate in China, with an anomalous anticyclone located over Northwest Pacific and positive precipitation and southwesterly anomalies in eastern China.Our results also suggest that the SST at a lead of two months may be a predictor for the spring climate in eastern China. A better representation of the ocean–atmosphere interaction over the tropical Pacific, Northwest Pacific, and Indian Ocean can improve the forecast skill of the spring climate in eastern China. 相似文献
11.
西北地区冰雹时空分布特征 总被引：12，自引：3，他引：9
应用1991—2000年西北地区基本站资料,统计分析了西北地区降雹的时空分布特征。结果表明：西北地区降雹主要的高频区在青藏高原中部、祁连山和天山山脉西段,并呈带状分布,多雹中心一般位于东西走向山脉的南坡,南北走向山脉的东坡。西北地区降雹旬、侯分布不均匀,产生双一多峰特征,从多雹区各代表站的旬或候际演变看,高原北部降冰雹来的比其南部早且持续时间长,但降雹日数明显少于其南部。天山山脉、祁连山降雹盛发期处于波动状态而高原中部降雹盛发期比较集中。 相似文献
12.
1951/1952～2004/2005年中国冬季降水变化研究 总被引：12，自引：1，他引：11
运用AREM模式对2005年5月31日发生在湖南新邵的一次特大暴雨天气过程进行模拟分析.利用模式输出的1 h基本物理量计算螺旋度,结果表明:螺旋度对特大暴雨的预报有指示意义,特大暴雨产生在低层正螺旋度中心与高层负螺旋度中心相配合的区域.在暴雨强盛期,螺旋度中低层最大正值位于750 hPa,最大负值位于450 hPa.比较新邵1 h实况降雨量和AREM模式模拟的降水值与相应时刻的螺旋度,发现5月31日19～22时之间的暴雨增幅最大,为172 mm/3 h,而螺旋度值也相应出现了最大的增幅20 m2/(s2·3 h),31日21～22时新邵暴雨出现峰值,但螺旋度却开始减小,此后两者又一致地逐渐减弱. 相似文献
13.
Aifang Cheng Qi Feng Guobin Fu Jiankai Zhang Zongxing Li Meng Hu Gang Wang 《大气科学进展》2015,32(10):1391-1406
Changes in rainfall extremes pose a serious and additional threat to water resources planning and management, natural and artificial oasis stability, and sustainable development in the fragile ecosystems of arid inland river basins. In this study, the trend and temporal variation of extreme precipitation are analyzed using daily precipitation datasets at 11 stations over the arid inland Heihe River basin in Northwest China from 1960 to 2011. Eight indices of extreme precipitation are studied. The results show statistically significant and large-magnitude increasing and decreasing trends for most indices, primarily in the Qilian Mountains and eastern Hexi Corridor. More frequent and intense rainfall extremes have occurred in the southern part of the desert area than in the northern portion. In general, the temporal variation in precipitation extremes has changed throughout the basin. Wet day precipitation and heavy precipitation days show statistically significant linear increasing trends and step changes in the Qilian Mountains and Hexi Corridor. Consecutive dry days have decreased obviously in the region in most years after approximately the late 1980s, but meanwhile very long dry spells have increased, especially in the Hexi Corridor. The probability density function indicates that very long wet spells have increased in the Qilian Mountains. The East Asian summer monsoon index and western Pacific subtropical high intensity index possess strong and significant negative and positive correlations with rainfall extremes, respectively. Changes in land surface characteristics and the increase in water vapor in the wet season have also contributed to the changes in precipitation extremes over the river basin. 相似文献
14.
The relationship between the Spring Asian Atmospheric circulation and the previous winter Northern Hemisphere annular mode 总被引：2，自引：0，他引：2
Summary By using the NCEP/NCAR reanalysis data, the Northern Hemisphere annular mode index (NAMI), China dust storm frequency data
and China’s 160-station monthly precipitation data, the relationship between the previous winter (December–February) Northern
Hemisphere annular mode (NAM) and the following spring (March–May) Asian atmospheric circulation is examined statistically
in this study. Results demonstrate that the relationship between the spring Asian atmospheric circulation and the previous
winter NAM is more significant on decadal time scales than on interannual time scales. There are significant negative correlations
between the previous winter NAM and the spring temperature in what is almost a troposphere over Northwest China. There is
a significant positive correlation between the winter NAMI and following spring geopotential height field over the Mongolian
Plateau and Middle Siberia (MPMS) at the upper level. The positive correlation coefficients center moves to the south with
the level from high to low. At lower level the high correlation coefficients center is located over the North China. There
is a significant negative correlation between the winter NAMI and the surface horizontal wind intensity in the following spring
for Northwest China on decadal timescales. The results suggest that a strong NAM in winter is followed by a negative temperature
anomaly and a positive anomaly of the spring 500 hPa geopotential height over the MPMS, while at the same time the spring
anomaly of the southeast wind is experienced in the surface layer in Northwest China, implying that the intensity of the northwest
wind tends to weaken, and vice versa. This circulation pattern can affect the change of the spring dust storm frequency in Northwest China on decadal time scales. 相似文献
15.
利用1961—2010年NCEP/NCAR的月平均和逐日再分析资料、中国区域589个站月降水量和气温月平均资料,研究夏季亚洲—太平洋涛动 (APO) 异常与我国西北地区东部秋季干湿变化的关系。结果表明:夏季亚洲—太平洋涛动指数 (APOI) 的异常变化与我国西北地区东部干湿指数 (DROI) 呈显著正相关。夏季APOI正异常年对应的秋季中高纬度地区500 hPa高度场乌拉尔山以西高压脊加强、巴尔喀什湖至贝加尔湖之间的低压槽加深、鄂霍次克海东部高压脊加强;东亚西风急流轴偏北;经阿拉伯海、印度半岛—孟加拉湾的西风水汽以及北太平洋反气旋底部的偏东水汽输送均为加强趋势,并结合中纬度西风水汽输送使研究区秋季偏湿,反之亦然。进一步研究表明,夏季APO为正异常时,秋季西北地区东部上升运动加强、暖湿气流加强 (均在第54—56候最为明显)。 相似文献
16.
甘肃省河西内陆河流量长期变化特征 总被引：11，自引：2，他引：9
利用甘肃省河西地区3条主要内陆河石羊河、黑河、疏勒河40余年的流量资料以及河西走廊地区和祁连山区气象资料对河西地区内陆河流量的长期变化特征进行了分析,并对所获结果进行了讨论,得到一些有意义的结论. 相似文献
17.
This study investigates the statistical linkage between summer rainfall in China and the
preceding spring Eurasian snow water equivalent (SWE), using the datasets of summer rainfall
observations from 513 stations, satellite-observed snow water equivalent, and atmospheric circulation
variables in the NCEP/NCAR re-analysis during the period from 1979 to 2004. The first two coupled
modes are identified by using the singular value decomposition (SVD) method. The leading SVD mode of
the spring SWE variability shows a coherent negative anomaly in most of Eurasia with the opposite
anomaly in some small areas of the Tibetan Plateau and East Asia. The mode displays strong interannual
variability, superposed on an interdecadal variation that occurred in the late 1980s, with persistent
negative phases in 1979--1987 and frequent positive phases afterwards. When the leading mode is in its
positive phase, it corresponds to less SWE in spring throughout most of Eurasia. Meanwhile, excessive
SWE in some small areas of the Tibetan Plateau and East Asia, summer rainfall in South and Southeast
China tends to be increased, whereas it would be decreased in the up-reaches of the Yellow River. In
recent two decades, the decreased spring SWE in Eurasia may be one of reasons for severe droughts in
North and Northeast China and much more significant rainfall events in South and Southeast China. The
second SVD mode of the spring SWE variability shows opposite spatial variations in western and eastern
Eurasia, while most of the Tibetan Plateau and East Asia are in phase. This mode significantly correlates
with the succeeding summer rainfall in North and Northeast China, that is, less spring SWE in western
Eurasia and excessive SWE in eastern Eurasia and the Tibetan Plateau tend to be associated with decreased
summer rainfall in North and Northeast China. 相似文献
18.
邻接青藏高原地区的中国西北地区是最大的欧亚干旱区,其降水变化对全球变化的响应和对干旱环境及其青藏高原气候变化都具有特殊的指示意义。基于1961～2018年中国西北地区144个站的逐日降水、逐月气温观测资料,分析了西北地区的降水变化特征及趋势。结果表明:（1）近60年以来,西北地区92%站点的年降水量呈现增加的趋势,只有甘肃东南部不到10%的站点呈下降趋势;（2）季节尺度上,春、夏、秋季中超过75%站点的降水呈现增加的趋势,但最显著的是,几乎所有站点在冬季的降水为增加趋势,秋、冬季降水的增加相对较少,反映了冬季风对西北地区降水影响的特点;（3）进入21世纪以来,西北地区夏季和年降水量仍然维持准3 a周期特征,春、秋季的周期具有阶段性、冬季降水量具有较稳定的约3 a周期,因此,自然周期变化对降水增加的贡献并不大。西北地区降水量在过去60年来确实呈现出增加趋势,尤其21世纪以来降水量持续增加,但增加的量是有限的,不足以改变其干旱半干旱的气候特征。 相似文献
19.
LI Yaohui SONG Lianchun ZHANG Cunjie GAO Xuejie ZHAO Jianhua 《Acta Meteorologica Sinica》2006,20(5):13-22
A numerical study on CO2 doubling effects upon temperature and precipitation in NW China is conducted using an improved regional climate model, with the modeling data from a global climate model (Australian CSIRO R21L9) as the background. Results suggest that the doubling would lead to the rise of surface temperature in the project region, with the maximum occurring in southern Xinjiang Basin and eastern Qilian Mountains in contrast to a relatively smaller increase in northern Xinjiang and southern Shaanxi Provinces. On a seasonal basis the winter temperature warming is most pronounced while the autumn shows a relatively less signi cant rising trend. The study region experiences the greatest warming compared with other parts of the country. With CO2 content doubling, rainfall change varies from place to place in this region, with rainfall increase in the west, particularly in northern Xinjiang, in the vicinity of the Tianshan area, southwestern Qinghai, and Hexi area (west of the Yellow River of Gansu), as opposed to the eastern
portion of NW China, where precipitation decreases.
If CO2 concentration is doubled, most of the study region would receive more rainfall in spring, implying that spring drought would be alleviated while its eastern part would see varying-degree decreased precipitation in the other three seasons, especially in summer, suggesting that drought there would be intensified in summer and autumn, thereby exerting major influence on rain-fed agriculture there. 相似文献
20.
青藏高原冬春季积雪异常对中国春夏季降水的影响 总被引：27，自引：3，他引：27
利用1956年12月～1998年12月共42a，青藏高原及其附近地区78个积雪观测站的雪深和我国160站月降水的距平资料，分析了其气候特征，并用SVD方法分析了冬春季积雪异常与春夏季我国降水异常的关系。用区域气候模式RegCM2模拟了青藏高原积雪异常的气候效应并检验了诊断分析的结果。分析表明，雪深异常，尤其是冬季雪深异常是影响中国降水的一个因子。研究证明，高原冬季雪深异常对后期中国区域降水的影响比春季雪深异常的影响更为重要。数值模拟的结果表明，高原雪深和雪盖的正异常推迟了东亚夏季风的爆发日期，减弱了季风强度，造成华南和华北降水减少，而长江和淮河流域降水增加。冬季雪深异常比冬季雪盖异常和春季雪深异常对降水的影响更为显著。机理分析指出，高原及其邻近地区的积雪异常首先通过融雪改变土壤湿度和地表温度，从而改变了地面到大气的热量、水汽和辐射通量。由此所引起的大气环流变化又反过来影响下垫面的特征和通量输送。在湿土壤和大气之间，这样一种长时间的相互作用是造成后期气候变化的关键过程。与干土壤和大气的相互作用过程有本质差别。 相似文献