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1.
With Empirical Orthogonal Function （EOF） and trend analysis method adopted, the spatio-temporal variation of total cloud amount is analyzed for 75 stations on the Qinghai-Tibet Plateau during the period 1971-2004. Analysis indicates that the total cloud amount decreases from the southeast to the northwest of the plateau, and that the annual and seasonal variations in total cloud amount both show an apparent declining tendency over the past decades. Correlation analysis demonstrates that the total cloud amount is negative with sunshine duration and diurnal temperature range （DTR）, and is positive with precipitation and the relative humidity, respectively. The negative correlation is consistent with the radiative effect of cloud, while the positive correlation between total cloud amount and precipitation is obscured because of the influence of topographic factors. Discussion implies that the decrease of total cloud amount is possibly due to the variation of atmospheric aerosol content and ozone concentration over the plateau, although it is difficult to quantify the driving force mechanism up to now. 相似文献
2.
With Empirical Orthogonal Function (EOF) and trend analysis method adopted, the spatio-temporal variation of total cloud amount is analyzed for 75 stations on the Qinghai-Tibet Plateau during the period 1971-2004. Analysis indicates that the total cloud amount decreases from the southeast to the northwest of the plateau, and that the annual and seasonal variations in total cloud amount both show an apparent declining tendency over the past decades. Correlation analysis demonstrates that the total cloud amount is negative with sunshine duration and diurnal temperature range (DTR), and is positive with precipitation and the relative humidity, respectively. The negative correlation is consistent with the radiative effect of cloud, while the positive correlation between total cloud amount and precipitation is obscured because of the influence of topographic factors. Discussion implies that the decrease of total cloud amount is possibly due to the variation of atmospheric aerosol content and ozone concentration over the plateau, although it is difficult to quantify the driving force mechanism up to now. 相似文献
3.
1971-2004年青藏高原总云量时空变化及其影响因子 总被引：7，自引：0，他引：7
利用青藏高原及其周边地区75 个地面气象台站的云量日均值资料,采用正交经验函数(EOF) 和线性倾向估计等方法,分析了高原地区1971-2004 年总云量的时空变化特征。结果表明,高原总云量分布呈自东南向西北减少的态势,且年与四季总云量变化都存在显著下降趋势。进而,研究了高原总云量变化与其他气候因子的相关性。其中,(1) 高原总云量与日照时数、日较差之间存在较好的负相关。本文从云的辐射效应出发,解释了存在这种负相关关系的原因;(2) 青藏高原总云量与相对湿度之间有很好的正相关性,受地形因素、不同云型和云水路径等因素共同影响,高原总云量与降水之间的关系却不显著。在此基础上,重点讨论了高原总云量与气溶胶和臭氧等因子之间的复杂关系。指出：青藏高原总云量减少趋势可能与高原大气气溶胶特别是吸收性气溶胶的增加以及臭氧的损耗有关。 相似文献
4.
The summer day-by-day precipitation data of 97 meteorological stations on the Qinghai–Tibet Plateau from 1961 to 2004 were selected to analyze the temporal-spatial dis-tribution through accumulated variance, correlation analysis, regression analysis, empirical orthogonal function, power spectrum function and spatial analysis tools of GIS. The result showed that summer precipitation occupied a relatively high proportion in the area with less annual precipitation on the Plateau and the correlation between summer precipitation and annual precipitation was strong. The altitude of these stations and summer precipitation ten-dency presented stronger positive correlation below 2000 m, with correlation value up to 0.604 (α=0.01). The subtracting tendency values between 1961–1983 and 1984–2004 at five altitude ranges (2000–2500 m, 2500–3000 m, 3500–4000 m, 4000–4500 m and above 4500 m) were above zero and accounted for 71.4% of the total. Using empirical orthogonal function, summer precipitation could be roughly divided into three precipitation pattern fields: the Southeast Plateau Pattern Field, the Northeast Plateau Pattern field and the Three Rivers' Headstream Regions Pattern Field. The former two ones had a reverse value from the north to the south and opposite line was along 35°N. The potential cycles of the three pattern fields were 5.33a, 21.33a and 2.17a respectively, tested by the confidence probability of 90%. The station altitudes and summer precipitation potential cycles presented strong negative corre-lation in the stations above 4500 m, with correlation value of –0.626 (α=0.01). In Three Rivers Headstream Regions summer precipitation cycle decreased as the altitude rose in the sta-tions above 3500 m and increased as the altitude rose in those below 3500 m. The empirical orthogonal function analysis in June precipitation, July precipitation and August precipitation showed that the June precipitation pattern field was similar to the July’s, in which southern Plateau was positive and northern Plateau negative. But positive value area in July precipita-tion pattern field was obviously less than June’s. The August pattern field was totally opposite to June’s and July’s. The positive area in August pattern field jumped from the southern Pla-teau to the northern Plateau. 相似文献
5.
利用西藏高原地区1987-2016年的逐月夏季降水资料和印度洋偶极子指数资料分析了两者的关系,结果表明：高原地区盛夏降水与表征西印度洋异常海温的西极子指数表现出良好的相关关系,在西极子指数正异常年时高原降水偏多10%~30%,其中高原中部偏多最为显著,而在负异常年时与之相反。分析其机理研究发现,在正西极子异常年,南海和西太暖池区域的深对流加强、西太副高偏西偏南和印度热低压的减弱使得来自热带的水汽更容易深入高原腹地,其次,南亚高压东体异常增强,配合低空异常辐合,都使得高原降水偏多。同时,高原上空局地纬圈环流在高原中部（90 °E附近）上空（400 hPa以上）有异常辐合上升区,使得高原中部更容易发展暖湿切变线、高原低涡等中尺度涡旋低值系统,造成更多的降水。本研究从高原气候变化响应海洋年际变化的角度分析了区域降水的季节差异,可以为高原气候预测提供新的思路。 相似文献
6.
Using NCEP/NCAR reanalysis geopotential height (GHT) and wind at 850 hPa, GHT at 500 hPa, precipitation rate, sea level pressure (SLP) and precipitation observations from more than 600 stations nationwide in June–August from 1951 to 2006, and focusing on the East Asia–West Pacific region (10o–80oN, 70o–180oE), interannual variation of East Asian summer monsoon (EASM) and its correlations with general circulation and precipitation patterns are studied by using statistical diagnostic methods such as 9-point high pass filtering, empirical orthogonal function (EOF) analysis, composite analysis and other statistical diagnosis, etc. It is concluded as follows: (1) EOF analysis of SLP in the East Asia–West Pacific region shows the existence of the zonal dipole oscillation mode (APD) between the Mongolia depression and the West Pacific high, and APD index can be used as an intensity index of EASM. (2) EOF analysis of GHT anomalies at 500 hPa in the East Asia–West Pacific region shows that the first EOF mode is characterized with an obvious meridional East Asian pattern (EAP), and EAP index can also be used as an EASM intensity index. (3) The composite analysis of high/low APD index years reveals the close correlation of APD index with EAP at 500 hPa (or 850 hPa). The study shows an obvious opposite correlation exists between APD index and EAP index with a correlation coefficient of –0.23, which passes the confidence test at 0.10 level. (4) Both APD and EAP indexes are closely correlated with precipitation during flood-prone season in China and precipitation rate over the East Asia–West Pacific region. The significant correlation area at 5% confidence level is mainly located from the southern area of the Yangtze River valley to the ocean around southern Japan, and the former is a positive correlation and the latter is a negative one. 相似文献
7.
1960~2005年西北地区低云量的时空变化及成因分析 总被引：4，自引：0，他引：4
基于西北地区177个站点1960~2005年逐日的低云量观测资料,运用地统计学、交叉小波分析和多元回归分析,分析了近46 a来西北地区低云量的时空变化特征及影响因素。结果表明：近46 a来西北地区低云量呈较显著上升趋势,1997年之后上升显著。低云量空间呈自东南向西北递减的趋势。低云量与降水、相对湿度等呈显著的正相关,与昼夜温差、日照时数等呈显著的负相关。低云量存在2~4 a、准6 a、准11 a的周期变化,与宇宙射线在1982~1993年存在5~8 a的共振周期,与NOI指数存在2~4 a、准5 a、准11 a的共振周期,和太阳黑子的共振周期为9~11 a。 相似文献
8.
贵州和四川盆地云量的气候研究 总被引：1，自引：1，他引：0
贵州和四川盆地是我国云量最多的地区,素有“天无三日晴”和“蜀犬吠日”之说,盆地西缘的雅安古时还有“雅州天漏”的谚语。从全球日照百分率分布推知,川黔地区也是世界上天气最阴沉的地区之一。川黔之阴一向为国内外气象界所注意,本文根据1951—1980 相似文献
9.
通过采用Mann-Kendall趋势分析法、小波分析方法、地统计插值等方法,基于黄土高原塬面保护区及临近的21个站点的逐日降水量数据,对区域内降雨侵蚀力的时空变化,趋势及主要影响因素进行了分析。结果表明：(1) 黄土塬面保护区1960—2017年多年平均降雨量为599.2 mm;多年平均降雨侵蚀力为1 871.91 MJ·mm·hm-2·h-1·a-1,降雨侵蚀力在过去60 a来呈微弱上升趋势且变化的季节差异显著。(2) 黄土高原塬面保护区降雨侵蚀力的空间分布大体呈由南部向两侧递减的趋势,Mann-Kendall Z值除研究区北部、东部呈下降趋势,其余区域都为上升趋势。(3) 黄土高原塬面保护区降雨侵蚀力多年存在32 a的大周期,在大周期内还存在13 a、52 a的小周期。(4) 影响北半球中高纬度地区的主要的大气环流因子中仅Cold & Warm Episodes by Season因子的波动对整个区域和陕西塬区的降雨侵蚀力有一定影响,二者存在一定的负相关性,其余环流指数与降雨侵蚀力没有显著的关联性;此外太阳黑子与陕西塬区降水侵蚀力变化规律存在一定的正相关,与其他塬区并无显著关联性。 相似文献
10.
西北地区5-9月极端干期长度的概率特征分析 总被引：4，自引：0，他引：4
应用西北地区131个测站1961-2000年逐日降水资料,统计逐年5-9月极端干期长度,分析近40 a年平均极端干期长度的空间分布特征以及极端干期长度与降水量的关系,采用概率加权法(PWM)估计其分布函数的参数,探讨用Gumbel分布拟合我国西北地区极端干期长度的适用性,进而给出我国西北地区极端干期长度的概率以及≥20 d、≥50 d极端干期长度的重现期概率特征。结果表明:西北地区近40 a平均极端干期长度总体上自东南向西北递增,但极端干期最短的地方并不在降水量最大的陕南地区,而在海拔较高的青海南部以及甘肃甘南高原。极端干期长度与5-9月降水总量呈负相关。≥20 d界限的极端干期长度的概率与50 a一遇极端干期长度的空间分布基本相似,降水较少的南疆、青海西部、河西走廊西段,基本上每年多雨期都存在20 d以上的连续无雨期,而祁连山以南的青海、甘肃中南部、宁夏南部、陕西中南部≥20 d极端干期长度的概率不到0\^1。 相似文献
11.
利用吐哈盆地2011-2015年逐时FY-2E静止气象卫星红外云图资料,吐鲁番市1976-2015年5个国家气象站和2013-2015年26个区域气象站降水资料,采用卫星资料反演和统计分析方法,首次定义TK（地面气温与云顶亮温的差值）来规避地面辐射对卫星接收辐射的影响,分析吐鲁番盆地各级别TBB（-10~-20℃、-20~-30℃、-30~-40℃、-40~-50℃）云的分布状况及其与降水的关系、降水的时空分布特征和变化趋势。结果表明,吐鲁番盆地TBB各级别云覆盖度与海拔高度显著正相关,云量从盆地平原区向山区递增;TK的月变化同月降水具有较好的正相关性,TK正值时段4~8月与盆地汛期相对应,TK极大值对应月降水量最大的6月;降水与海拔高度显著正相关,降水先随海拔高度增加而增多,1 400~1 900 m区域是降水量和降水垂直变率最大的区域,之后降水随海拔高度增加而减少;降水高度集中在夏季与秋季,6月降水最多（占3~4成）;降水集中出现在白天,平原地区集中在早晨至中午,山区集中在下午至傍晚。综合分析得出吐鲁番盆地人工增水作业区域、作业月份、作业"时间窗"选择的参考依据,其中最佳作业区域在1 400~1 900 m,最佳作业月份为6月,最佳作业"时间窗"为上午的06~10时与下午的14~18时。 相似文献
12.
PATMOS-x、ISCCP云量产品及地面观测在中国区域的对比分析 总被引：2，自引：1，他引：1
利用1986~2006年PATMOS-x 、ISCCP总云量和低云量产品与中国区域地面台站观测的总云量、低云量资料进行对比分析,对比不同来源、不同观测方法造成的云量数据在时间、空间上的差异,为资料使用者提供参考。结果表明,与台站观测资料相比,无论PATMOS-x还是ISCCP其总云量数据的空间分布、与站点观测数据的格点相关性均好于低云量数据;PATMOS-x总云量、低云量多年平均的空间分布较ISCCP更接近站点观测;中国区域平均低云量的线性趋势PATMOS-x与站点观测一致,表现为显著的上升趋势,而ISCCP低云量数据则呈现微弱的下降趋势。 相似文献
13.
Comparisons on seasonal and annual variations of δ<Superscript>18</Superscript>O in precipitation 总被引：1，自引：0，他引：1
The spatial and temporal variations of stable oxygen isotope in precipitation on different time scales are analyzed according
to the data from the IAEA/WMO stations with long survey series in the Northern Hemisphere. Temperature effect is mainly distributed
in mid-high latitudes on seasonal scale except for Bamako and Addisababa stations. The δ18O/temperature slope displays the positive correlation against altitude for most of the statistical stations. Amount effect
appears primarily in the region south of 30°N and coastal areas. The δ18O/precipitation slope is indirectly proportional to precipitation amount. For some of the sampling stations at mid-high latitudes
where their seasonal distribution of precipitation is contrary to that of temperature, coupled with temperature effect, the
amount effect appears synchronistically. Either the temperature effect or the amount effect on seasonal scale, there are positive
correlations to a certain extent between the annual weighted mean δ18O and the annual mean temperature for almost all the stations. The correlation between composite δ18O and temperature on spatial scale is much more marked, compared with that of individual station. There is a good agreement
between 10-year moving average temperature curves I and II, with the values of the former all markedly smaller than corresponding
ones of the latter, calculated by the monthly mean series group I and the annual mean series group II, respectively. However,
two calculated dδ18O/dT curves display the distinct difference: the variation amplitude of slope series II is larger than that of slope series
I. Both curves had similar ascending trend from the 1960s to the 1970s, and then, their variations display the anti-phase.
Moreover, the analyses show that there is negative correlation between slope series FI and temperature series II. However,
the status is different for slope series I and temperature series I. Both series have contrary trend from the 1960s to the
1970s, whereas the same trend since the 1980s. 相似文献
14.
Based on 1961-2000 NCEP/NCAR monthly mean reanalysis datasets, vapor transfer and hydrological budget over the Tibetan Plateau are investigated. The Plateau is a vapor sink all the year round. In summer, vapor is convergent in lower levels (from surface to 500 hPa) and divergent in upper levels (from 400 to 300 hPa), with 450 hPa referred to as level of non-divergence. Two levels have different hydrologic budget signatures: the budget is negative at the upper levels from February to November, i.e., vapor transfers from the upper levels over the plateau; as to the lower, the negative (positive) budget occurs during the winter (summer) half year. Evidence also indicates that Tibetan Plateau is a "vapor transition belt", vapor from the south and the west is transferred from lower to upper levels there in summer, which will affect surrounding regions, including eastern China, especially, the middle and lower reaches of the Yangtze. Vapor transfer exerts significant influence on precipitation in summertime months. Vapor transferred from the upper layers helps humidify eastern China, with coefficient -0.3 of the upper budget to the precipitation over the middle and lower reaches of the Yangtze (MLRY); also, vapor transferred from east side (27.5o-32.5oN) of the upper level has remarkable relationship with precipitation, the coefficient being 0.41. The convergence of the lower level vapor has great effects on the local precipitation over the plateau, with coefficient reaching 0.44, and the vapor passage affects the advance and retreat of the rainbelt. In general, atmospheric hydrologic budget and vapor transfer over the plateau have noticeable effects on precipitation of the target region as well as the ambient areas. 相似文献
15.
The spatial and temporal variations of stable oxygen isotope in precipitation on different time scales are analyzed according to the data from the IAEA/WMO stations with long survey series in the Northern Hemisphere. Temperature effect is mainly distributed in mid-high latitudes on seasonal scale except for Bamako and Addisababa stations. The δ18O/temperature slope displays the positive correlation against altitude for most of the statistical stations. Amount effect appears primarily in the region south of 30oN and coastal areas. The δ18O/precipitation slope is indirectly proportional to precipitation amount. For some of the sampling stations at mid-high latitudes where their seasonal distribution of precipitation is contrary to that of temperature, coupled with temperature effect, the amount effect appears synchronistically. Either the temperature effect or the amount effect on seasonal scale, there are positive correlations to a certain extent between the annual weighted mean δ18O and the annual mean temperature for almost all the stations. The correlation between composite δ18O and temperature on spatial scale is much more marked, compared with that of individual station. There is a good agreement between 10-year moving average temperature curves I and II, with the values of the former all markedly smaller than corresponding ones of the latter, calculated by the monthly mean series group I and the annual mean series group II, respectively. However, two calculated dδ18O/dT curves display the distinct difference: the variation amplitude of slope series II is larger than that of slope series I. Both curves had similar ascending trend from the 1960s to the 1970s, and then, their variations display the anti-phase. Moreover, the analyses show that there is negative correlation between slope series II and temperature series II. However, the status is different for slope series I and temperature series I. Both series have contrary trend from the 1960s to the 1970s, whereas the same trend since the 1980s. 相似文献
16.
基于CERES的宁夏空中云水资源特征及其增雨潜力研究 总被引：1，自引：1，他引：0
利用2009-2014年NASA地球观测系统(EOS)云与地球辐射能量系统(CERES)云资料和气象站降水资料,对宁夏北部引黄灌区、中部干旱带及南部山区3个具有不同地形、地貌、气候特征的地区云水资源及增雨潜力特征进行了对比研究。结果表明:宁夏地区大气可降水量在空间分布上呈现从东南向西北方向递减,从季节变化看表现出随夏秋春冬依次递减的特征。在东亚季风和贺兰山地形的共同影响下,全年总云量和低云量在南部山区最大,北部川区最小。云光学厚度与水云粒子半径及冰云等效直径呈显著的负相关关系,其中中部干旱带相关关系最强是开展人工增雨效果最显著的地区。随着全年四季天气气候变化,宁夏人工增雨主要潜力区会逐渐由春季的贺兰山沿山、中部干旱带地区,移动到夏季的银川以南同心以北和固原西南部地区,秋季缩减到海原、西吉一带。 相似文献
17.
近42 年来青藏高原年内降水时空不均匀性特征分析 总被引：7，自引：1，他引：6
根据青藏高原1967-2008 年逐日站点降水资料,定义了高原降水集中度(PCD) 和集中期(PCP)。并运用EOF、相关分析等方法分析高原PCD和PCP的时空分布特征、PCD与高原强降水的关系以及PCP前期强影响信号。结果表明：高原大部分地区PCD处于0.4~0.8 之间,PCP则处于36~41 候之间。高原PCD以全区一致型的空间分布为主;而PCP 则以南北反向型分布为主,全区一致型分布次之。整个高原PCD均呈减弱趋势,而PCP均表现为提前特征。除高原南侧个别地区,高原PCD 无论与高原强降水日数还是强降水量均呈显著正相关。同时,高原南北部PCP对应的水汽输送存在显著差异, 高原南部PCP主要受孟加拉湾季风爆发的影响。 相似文献
18.
利用南极长城站和中山站的降水、风、湿度、气压和云量等高质量的地面气象观测资料,对两站基本气候特征和变化趋势进行了分析。结果显示,长城站年降水量为503mm,年际变化呈减少趋势,变化速率为-27mm/10a。长城站和中山站年降水日数均呈下降趋势,变化速率分别为-2.9d/10a和-12.1d/10a。长城站和中山站年平均相对湿度分别为88%和58%。长城站年平均湿度总体上呈不明显下降趋势,中山站没有趋势。长城站盛行风向为西北风,中山站为偏东风,年平均风速分别为7.3m/s和7.1m/s。两站年平均风速呈减小趋势,变化速率分别为-0.09m/s/10a和-0.23m/s/10a。长城站平均大风日数为137d,记录的极大风速为37.2m/s。中山站平均大风日159d,记录的极大风速为50.3m/s。长城站和中山站年平均气压分别为990hPa和985hPa,变化速率分别为0.65hPa/10a和-0.80hPa/10a。其变化趋势相反,并与两站风速和大风日数及降水日数的变化倾向基本相同。长城站和中山站月平均云量分别为8.8和6.2,其差异显示了两站所处气候带的特点,即长城站地区全年阴天多、云量大,中山站则与此相反。 相似文献
19.
根据常规气象观测资料以及MODIS卫星气溶胶产品,分析了西安近50 a总辐射变化特征及其相关影响因子。结果表明：西安地区1961-2005年总辐射变化经历了“持续”、“变暗”、“变亮”、“再变暗”4个阶段,西安总辐射的变化幅度较全国平均变化幅度大,其“变亮”过程开始于1985年,较全国平均时间略早;西安4个季节总辐射总体均呈现出下降趋势,其变化幅度存在一定差异。通过对云量、气溶胶、水汽压、相对湿度等影响因子的分析,水汽压和相对湿度对总辐射变化影响不明显,总云量和气溶胶的变化对西安总辐射的变化存在较显著的影响,春、夏季总辐射的变化主要受云量和气溶胶直接辐射强迫的共同影响,其中总云量的变化在一定程度上决定了总辐射变化的振幅,城市发展所导致的气溶胶增加所产生的直接辐射强迫作用可能决定了总辐射的总体下降趋势;秋、冬季节的总辐射下降趋势主要与气溶胶的直接辐射强迫有关。 相似文献
20.
利用滇西北高原1961-2009年逐月降水量资料,采用多种统计分析方法,研究滇西北高原降水量的时空变化特征。结果表明:滇西北高原冬季、夏季和年平均降水量空间分布的主要特征是一致多雨或少雨型,且均具有经向分布特征,其次为"西北部-东南部"或者"西部-东部"反位相振荡型。冬季、夏季和年平均降水量的两种主要空间分布型所对应的时间系数均以年际变化为主,周期变化主要集中在4年以下的高频振荡时域内,其次是周期为12年的年代际变化。近48年来,滇西北高原冬季和年平均降水量随时间变化总体上均以增加趋势为主,增加趋势不明显,夏季降水量变化则呈减少趋势,其中香格里拉县夏季降水量减少趋势明显。 相似文献