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1.
近55年来澜沧江流域降水时空变化特征分析 总被引：1，自引：0，他引：1
本文利用澜沧江流域及周边共30个气象站点1960-2014年的逐月降水数据,采用气候倾向率、Mann-Kendall趋势检验、Morlet小波分析、Co-Kriging插值以及重心模型等方法,分析了澜沧江流域降水的时空变化特征。结果表明：① 分析时段内全区、北部和中部年降水量呈现增加趋势,南部年降水量出现减少趋势。春季全区、北部、中部和南部降水均呈增加趋势;夏季均呈减少趋势;秋季全区和南部降水呈现减少趋势,北部和中部呈增加趋势;冬季全区、中部和南部呈下降趋势,只有北部呈增加趋势。② 近55年来,全区包括北部、中部和南部年降水都存在近29年、近22年和5-10年左右的周期,这3个周期在分析时段内表现很稳定,具有全域性。全区、北部和南部还存在明显的13年左右的周期,中部1975年前和1995年后也存在13年左右的周期,北部1975年前存在明显的7-10年的周期,1995年后,7-10年的周期表现也比较稳定。降水量变化的第一主周期是近29年,第二主周期是近22年。③ 澜沧江流域多年平均降水量由南部向北部减少,流域南部降水最多,多年平均降水量在1200 mm以上,中部多年平均降水量处于800~1100 mm,北部多年平均降水量多小于800 mm,大部分在400~800 mm;澜沧江流域年降水重心和月降水重心都集中在中部,其中11月的降水重心迁移距离最大,向东南方向迁移了131.82 km。从季节来看,春季、夏季和秋季降水重心向东南迁移,冬季的向西北方向迁移,雨季降水重心相对比较集中,旱季降水重心相对 比较分散。 相似文献
2.
针对长江中下游持续性降水的研究多为个例诊断,很少从合成的角度考虑,利用长江中下游地区89站的1961~2011年的逐日降水资料和NCEP/NCAR逐日再分析资料,采用数理统计和合成分析的方法,统计长江中下游地区夏季持续性降水事件,并合成分析了其环流特征。结果表明:1961~2011年,长江中下游地区夏季持续性异常降水事件发生了50次,主要集中在6月和7月,长江中下游地区持续性异常降水事件平均每2~3年发生一次。厄尔尼诺次年多有持续性异常降水发生;长江中下游地区持续性异常事件发生时,总伴有环流场的异常调整,低纬西太平洋副热带高压西伸,南北经向风在长江流域交汇,高层上,南亚高压东移,长江中下游地区出现强的辐散中心,为异常降水提供了重要条件。水汽来源主要是索马里越赤道气流途径暖湿的阿拉伯海,孟加拉湾和我国南海北部,进入长江中下游地区。 相似文献
3.
《广东海洋大学学报》2019,(5)
【目的】研究1993-2017年南海中尺度涡的空间分布、季节变化、移动速度等特征。【方法】根据AVISO提供的地转流数据,应用Nencioli等人提出的涡旋识别算法。【结果】南海中尺度涡主要分布在南海东北部和越南东部海域,冬(夏)季有利于(反)气旋涡产生,中尺度涡以2.0～9.0cm/s的速度向西传播。【结论】南海气旋涡与反气旋逐年生成个数与ENSO事件相关,在1993-2007年期间,强(温和)厄尔尼诺年气旋涡生成数大于反气旋,弱(温和)拉尼娜年反气旋生成数大于气旋涡。2008-2017年,强厄尔尼诺年气旋涡生成数大于反气旋,温和拉尼娜年反气旋生成数小于气旋涡。在涡旋的生命周期内,涡旋半径与移动速度变化趋势相反。复杂海底地形会阻碍涡旋的传播。 相似文献
4.
基于植被状态指数的云南省农业干旱状况时空分析 总被引：2，自引：0，他引：2
本文首先计算了云南省2004-2013年农业干旱指数VCI,然后使用Pearson相关系数评价降水与VCI的相关性,基于VCI识别云南省2004-2013年农业干旱事件,最后,与SPEI气象干旱识别结果进行对比分析,在VCI农业干旱识别的基础上,使用干旱频率和干旱面积占比指标分析了云南省2004-2013年农业干旱时空特征。结果表明：降水只是影响VCI指数的关键因素之一;VCI和SPEI指数均能够较好对干旱进行监测并识别典型干旱,但两者的识别结果存在差异;云南省农业干旱频率在春冬两季较高,夏季较低,秋季介于夏季和春冬季之间;春夏冬三季农业干旱频率空间分布较为均匀,秋季农业干旱频率呈南低北高的分布态势,整体上北部干旱频率高于南部;2004-2013年云南省整体干旱面积占比呈现先减小后增加再波动的趋势,春冬两季整体干旱面积占比最高,分别为46.63%和47.18%,呈现下降趋势,夏季整体干旱面积占比最低,为43.81%,呈现上升趋势,秋季整体干旱面积占比介于冬春季和夏季之间,为45.74%,呈现下降趋势。总之,云南省农业干旱春冬易发性最高,影响范围最大,夏季易发性最低,影响范围最小。 相似文献
5.
为研究亚非夏季风降水的时空变化特征及其与热带东风急流的相关性,利用1948-2008年61年NCEP／NCAR再分析资料,采用经验正交函数分解和奇异值分解等方法讨论了亚非夏季风降水的变化及其与热带东风急流的关系。结果表明：从包括撒赫勒在内的北非地区到印度西北部、青藏高原南部,直到中国华北东北地区,是亚非夏季降水的最主要的空间分布型式。亚非夏季风降水总体呈现出逐年递减的趋势。多年亚非季风区夏季降水分布与热带东风急流的强度有密切关系,在急流不同部位降水特征不同。亚非夏季风降水与热带东风急流呈显著正相关,二者的分布趋势在极大程度上吻合。 相似文献
6.
范伶俐 《广东海洋大学学报》2004,24(4):38-46
用Nino 3指数、印度洋单极指数、偶极子指数描述热带太平洋、印度洋海表温度 (SST)的年际异常 ,季节分析表明 :冬季Nino3区与热带印度洋海表温度距平 (SSTA)相互关系表现为单极 ,且 1976年以后两者的相互关系减弱 ,其可能原因 :一是冬季是ENSO(厄尔尼诺 )事件的盛期 ;二是冬季西太平洋暖水区东移 ,造成两洋的垂直纬向环流耦合减弱。夏季两者相互关系表现为偶极 ,1976年以后两者的相互关系加强 ,其可能原因 ,一是夏季是偶极子盛期 ,ENSO事件的发展期 ;二是夏季西太平洋暖水区虽然东移 ,但暖水区位置偏北 ,且东南印度洋的上升支强度增大 ,造成两洋的纬向环流耦合更强烈 相似文献
7.
范伶俐 《广东海洋大学学报》2004,24(4):38-46
用Nino3指数、印度洋单极指数、偶极子指数描述热带太平洋、印度洋海表温度(SST)的年际异常，季节分析表明：冬季Nino3区与热带印度洋海表温度距平(SSTA)相互关系表现为单极，且1976年以后两者的相互关系减弱，其可能原因：一是冬季是ENSO(厄尔尼诺)事件的盛期；二是冬季西太平洋暖水区东移，造成两洋的垂直纬向环流耦合减弱。夏季两者相互关系表现为偶极，1976年以后两者的相互关系加强，其可能原因，一是夏季是偶极子盛期，ENSO事件的发展期；二是夏季西太平洋暖水区虽然东移，但暖水区位置偏北，且东南印度洋的上升支强度增大，造成两洋的．纬向环流耦合更强烈。 相似文献
8.
利用NECP/NCAR月平均再分析资料,研究1951～2010年夏季青藏高原主体大气热源分布、对东亚地区的环流影响及其与同期中国降水的关系.针对高原加热局地特征明显的特点,采用旋转经验正交函数等方法探讨不同类型的热源分布以及对东亚地区大气环流的影响.结果表明,当加热中心位于高原东南侧时,青藏高原夏季风加强,南亚高压偏南偏东,西太平洋副热带高压西伸加强,而东亚中高纬地区两脊一槽的经向环流分布形势明显,有利于中国长江流域的降水而不利于华南华北的降水发展.当加热中心位于高原中北部与西南地区时,青藏高原夏季风减弱,南亚高压偏西,西太副高明显偏东偏弱,中高纬环流的纬向特征明显,有利于中国地区北方降水而不利于南方地区的降水. 相似文献
9.
西南地区空中云水量分布特征及变化趋势 总被引：1，自引：0，他引：1
为了能更好的合理开发空中水资源,采用NCEP 1980~2009年云水量的逐月再分析资料,通过统计和EOF分析等方法,研究了30年来西南地区(云南、贵州、重庆、四川)云水量的时空分布特征和变化趋势。结果表明:西南地区年和季节云水量分布均具有明显的地区性差异,东南多,西北少,最小值出现在四川西部高原地区;云水量在夏季最多,春季略高于秋季,冬季最少;逐月云水量呈近似的正态分布,1月到6月逐渐增加,7月到12月逐渐减少;西南地区云水量的空间变化既存在南部与北部相反的变化趋势,也存在整体一致型。 相似文献
10.
夏季黄海冷水团的多年际变化及原因浅析 总被引：3，自引：0，他引：3
基于ROMS(the Regional Ocean Model System)模式,以等温线范围变化作为黄海冷水团范围变化的示性指标,采用谱分析及相关分析的方法,分析夏季黄海冷水团范围变化。结果表明:黄海冷水团范围的变化存在明显的年变化特征,与纬向风速和经向风速相关,风速大则范围就大;黄海冷水团的范围还存在着5年的周期变化特征,其与ENSO现象相关;厄尔尼诺年时,滞后17个月的黄海冷水团的分布范围一般会较小;而拉尼娜年时,滞后17个月的黄海冷水团的分布范围会比较大。 相似文献
11.
利用GRACE时变重力场模型反演2009-07～2017-06期间亚马孙平原的水储量变化，在移除趋势和季节性周期信号后，计算得到其与ENSO指数之间具有较强的相关关系和一定的时延性，并从季节层面进行分析得到ENSO对亚马孙平原旱、雨两季的不同影响，表现为旱季受到ENSO显著影响而雨季受到的影响则较小。最后，结合水文数据分析指出，ENSO会通过影响降雨量进而影响相应区域的水储量变化，且该现象在流域内两次极端旱灾中有较为突出的表现。 相似文献
12.
为探究ENSO事件对GNSS ZTD(水汽)周期变化的影响及其相互关系,以河北省为例开展ENSO事件对GNSS ZTD及其周期变化的影响研究。首先利用快速傅里叶变换方法筛选出南方涛动指数（SOI）与GNSS水汽的共同周期,再利用小波变换提取GNSS水汽与SOI共同周期所在的高频项,并将重构的高频项与SOI进行相关性分析。结果表明,SOI与GNSS ZTD存在负相关性,由此推断ENSO事件与GNSS ZTD的周期变化存在一定关联。利用快速傅里叶变换方法分别提取ENSO事件和正常气候下GNSS ZTD的变化周期,分析ENSO事件对GNSS ZTD周期变化的影响,结果表明,ENSO暖事件（厄尔尼诺事件）对GNSS ZTD的最长显著周期存在显著影响;ENSO冷事件（拉尼娜事件）对GNSS ZTD的最长显著周期影响较弱。 相似文献
13.
By using Season-reliant Empirical Orthogonal Function (S-EOF) analysis, three dominant modes of the spatial-temporal evolution of the drought/flood patterns in the rainy season over the east of China are revealed for the period of 1960-2004. The first two leading modes occur during the turnabout phase of El Nino-Southern Oscillation (ENSO) decaying year, but the drought/flood patterns in the rainy season over the east of China are different due to the role of the Indian Ocean (IO). The first leading mode appears closely correlated with the ENSO events. In the decaying year of El Nino, the associated western North Pacific (WNP) anticyclone located over the Philippine Sea persists from the previous winter to the next early summer, transports warm and moist air toward the southern Yangtze River in China, and leads to wet conditions over this entire region. Therefore, the precipitation anomaly in summer exhibits a ’Southern Flood and Northern Drought’ pattern over East China. On the other hand, the basin-wide Indian Ocean sea surface temperature anomaly (SSTA) plays a crucial role in prolonging the impact of ENSO on the second mode during the ENSO decaying summer. The Indian Ocean basin mode (IOBM) warming persists through summer and unleashes its influence, which forces a Matsuno-Gill pattern in the upper troposphere. Over the subtropical western North Pacific, an anomalous anticyclone forms in the lower troposphere. The southerlies on the northwest flank of this anticyclone increase the moisture transport onto central China, leading to abundant rainfall over the middle and lower reaches of the Yangtze River and Huaihe River valleys. The anomalous anticyclone causes dry conditions over South China and the South China Sea (SCS). The precipitation anomaly in summer exhibits a ’Northern Flood and Southern Drought’ pattern over East China. Therefore, besides the ENSO event the IOBM is an important factor to influence the drought/flood patterns in the rainy season over the east of China. The third mode is positively correlated with the tropical SSTA in the Indian Ocean from the spring of preceding year(-1) to the winter of following year(+1), but not related to the ENSO events. The positive SSTA in the South China Sea and the Philippine Sea persists from spring to autumn, leading to weak north-south and land-sea thermal contrasts, which may weaken the intensity of the East Asia summer monsoon. The weakened rainfall over the northern Indian monsoon region may link to the third spatial mode through the ’Silk Road’ teleconnection or a part of circumglobal teleconnection (CGT). The physical mechanisms that reveal these linkages remain elusive and invite further investigation. 相似文献
14.
Multi-year SST and NCEP/NCAR reanalyzed wind data were employed to study the impacts of El Nino on the Southeast Asian summer monsoon(SEASM),It was found that the impacts of El Nino on the SEASM differed distinctly from those on the East Asian Summer monsoon (EASM) and the Indian summer monsoon(ISM).Composite analysis indicated that the “gear point“of coupling between the Indo-mosoon circulation and the Pacific-Walker circulation was located in the western margins of Southeast Asia when the developing stage of El Nino events covered the boreal summer.The anomalous circulations in the lower and upper troposphere and divergent circulation are all favorable for the strengthening of the SEASM during this period.Following the evolution of El Nino,the “gear point“ of the two cells shifted eastward to the central Pacific when the mature or decaying period of El Nino events covered the boreal summer.The anomalous circulations are favorable for the weakening of the SEASM ,The anomalous indexes of intenstity of SEASM accord well with the above resultsl.Additionally,the difference of SSTA patterns in the tropical In-do-Pacific OCean between the two stages of the El Nino may play an important role. 相似文献
15.
The characteristics of circulation corresponding to two kinds of indices of summer monsoon onset over the South China Sea
(SCS) have been discussed using the reanalysis data of the National Centers for Environmental Prediction-National Center for
Atmospheric Research. It is found that there are two patterns of deep convection that occur at different locations and influence
the summer monsoon onset over the SCS. One is over the Asia continent and the western Pacific corresponding to the southwesterly
of summer monsoon prevailing over the northern and central part of the SCS, while the other is near the Philippines that affects
the westerly summer monsoon as prevailing over the central and southern southern part of the SCS. Since these two kinds of
convection affecting the summer monsoon onset do not always occur together, thus the summer monsoon onset time is different
when determined by various indices. 相似文献
16.
钱步东 《中国地理科学(英文版)》1997,(3)
I.I~IOXENds(EINabs/SouthernOscillation)eventsaretheintensivesignalsofair-seainteractionintropicalarea.PlentyOfresultsfromdifferentresearchersshoWthattheENdssignalcanbedetectedoninterannualvallationsoflargescaleatmOSPhericcirculationandclimateregimeSovermostpartsoftheworld.SeveralkindsofrelationShipbetweenENdsandprecipitationoverChinahavebeenrevealedbydifferentreSearcherS,buttherearemanydifferencesamongthepublishedreSults.Itmayberesulted*fromthatdifferentreSearchersuseddifferentindic… 相似文献
17.
ENSO cycle and climate anomaly in China 总被引：2，自引：0，他引：2
The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly (SOTA) and the associated anomalous atmospheric circulation over the Asian North Pacific during the El Ni o-Southern Oscillation (ENSO) were investigated using National Centers for Environmental Prediction/ National Center for Atmospheric Research (NCEP/NCAR) atmospheric reanalysis data and simple ocean data simulation (SODA). The relationship between the ENSO and the climate of China was revealed. The main results indicated the following: 1) there are two ENSO modes acting on the subsurface tropical Pacific. The first mode is related to the mature phase of ENSO, which mainly appears during winter. The second mode is associated with a transition stage of the ENSO developing or decaying, which mainly occurs during summer; 2) during the mature phase of El Ni o, the meridionality of the atmosphere in the mid-high latitude increases, the Aleutian low and high pressure ridge over Lake Baikal strengthens, northerly winds prevail in northern China, and precipitation in northern China decreases significantly. The ridge of the Ural High strengthens during the decaying phase of El Ni o, as atmospheric circulation is sustained during winter, and the northerly wind anomaly appears in northern China during summer. Due to the ascending branch of the Walker circulation over the western Pacific, the western Pacific Subtropical High becomes weaker, and south-southeasterly winds prevail over southern China. As a result, less rainfall occurs over northern China and more rainfall over the Changjiang River basin and the southwestern and eastern region of Inner Mongolia. The flood disaster that occurred south of Changjiang River can be attributed to this. The La Ni a event causes an opposite, but weaker effect; 3) the ENSO cycle can influence climate anomalies within China via zonal and meridional heat transport. This is known as the "atmospheric-bridge", where the energy anomaly within the tropical Pacific transfers to the mid-high latitude in the northern Pacific through Hadley cells and Rossby waves, and to the western Pacific-eastern Indian Ocean through Walker circulation. This research also discusses the special air-sea boundary processes during the ENSO events in the tropical Pacific, and indicates that the influence of the subsurface water of the tropical Pacific on the atmospheric circulation may be realized through the sea surface temperature anomalies of the mixed water, which contact the atmosphere and transfer the anomalous heat and moisture to the atmosphere directly. Moreover, the reason for the heavy flood within the Changjiang River during the summer of 1998 is reviewed in this paper. 相似文献
18.
We investigated the intraseasonal variability of equatorial Pacific subsurface temperature and its relationship with El Nino-Southern Oscillation(ENSO) using Self-Organizing Maps(SOM) analysis.Variation in intraseasonal subsurface temperature is mainly found along the thermocline.The SOM patterns concentrate in basin-wide seesaw or sandwich structures along an east-west axis.Both the seesaw and sandwich SOM patterns oscillate with periods of 55 to 90 days,with the sequence of them showing features of equatorial intraseasonal Kelvin wave,and have marked interannual variations in their occurrence frequencies.Further examination shows that the interannual variability of the SOM patterns is closely related to ENSO;and maxima in composite interannual variability of the SOM patterns are located in the central Pacific during CP El Nino and in the eastern Pacific during EP El Nino.The se results imply that some of the ENSO forcing is manife sted through changes in the occurrence frequency of intraseasonal patterns,in which the change of the intraseasonal Kelvin wave plays an important role. 相似文献
19.
Sea surface temperature （SST） variation in the Subei coastal waters, East China, which is important for the ecological environment of the Yellow Sea where Enteromorphaprolifera blooms frequently, is affected by the East Asian winter monsoon （EAWM）, El Nifio-Southem Oscillation （ENSO）, and Pacific Decadal Oscillation （PDO）. In this study, correlations between climatic events and SST anomalies （SSTA） around the Subei （North Jiangsu Province, East China） Coast from 1981-2012 are analyzed, using empirical orthogonal function （EOF） and correlation analyses. First, a key region was determined by EOF analysis to represent the Subei coastal waters. Then, coherency analyses were performed on this key region. According to the correlation analysis, the EAWM index has a positive correlation with the spring and summer SSTA of the key region. Furthermore, the Nifio3.4 index is negatively correlated with the spring and summer SSTA of the key region 1 year ahead, and the PDO has significant negative coherency with spring SSTA and negative coherency with summer SSTA in the key region 1 year ahead. Overall, PDO exhibits the most significant impact on SSTA of the key region. In the key region, all these factors are correlated more significantly with SSTA in spring than in summer. This suggests that outbreaks ofEnteromorpha prolifera in the Yellow Sea are affected by global climatic changes, especially the PDO. 相似文献