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大地形对高空行星波传播的影响 总被引:2,自引:5,他引:2
根据天气经验、沿东亚大高原南北两侧传播的高空波动中,北边的波动一般传播速度较大,而南边的较小.作者根据行星波理论说明这是在运动学边界条件下沿坡传播的波动前后气流中发生强迫的辐射辐合的结果.计算所得南北两侧波动的传播速度差异和实际情况是此较一致的. 相似文献
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青藏高原及其四周的近代气候变化 总被引:24,自引:10,他引:24
本文首先研究了近千年来高原及其四周的气候变化,表明青藏高原是百年尺度气候变化的“启动区”,并用有近百年记录的Leh和Srinagar两站间的温度垂直递减率与降水距平百分率的10年滑动平均求相关,结果表明高原上的降水与气温垂直变率密切相关,降水多的年代高原内部温度高、外部低,反之亦然,完成一个振荡的周期约40年。其次分析了近30多年高原及其四周的气候变化,发现在北半球降温的60年代随着行星西风的加强,背风下沉区降水明显减少,向风区则增多。到了70年代高原北部夏季风开始增强,沙漠区降水开始增多。最后根据以上分析结果对中国西部至本世纪末的气候变化趋势作了初步预测,认为中国西部至少到本世纪末将继续升温,高原东西两侧的降水呈现“东升西降”的态势。 相似文献
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青藏高原北侧地区干湿年夏季垂直环流差异的对比分析及青藏高原的热力影响 总被引:30,自引:2,他引:30
为了分析西北干旱的形成原因,本文首先利用高原北侧地区5站历年夏季的降水量资料等,制定了该区的干湿标准,划分了历年夏季的干湿等级。接着又利用ECMWF的格点资料等对比分析了该区干湿年夏季间垂直环流的差异,也探讨了青藏高原地面热状况与高原北侧干湿状况的联系。其主要结论是:1)文中制定的以降水标准差为判据的干湿标准适合西北干旱区;2)高原北侧干湿年夏季间在高原北侧和高原上的垂直环流存在明显差异;3)青藏高原地面热状况与上列差异有关,也即青藏高原的热力作用是西北干旱的重要成因之一。 相似文献
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A COMPARATIVE STUDY OF THE HEATING EFFECTS OF THE TIBETAN PLATEAU AND THE WESTERN PACIFIC 总被引:1,自引:0,他引:1
钱永甫 《Acta Meteorologica Sinica》1996,(3)
A zonal domain primitive equation modeling system(ZDMS)is used to study the effects of theinitial heating anomalies over the Tibetan Plateau and the western Pacific on the East Asian and theChinese summer climate,the relative importance and the mechanisms are discussed.Results showthat in spite of the different locations of the heating anomalies the influences of the two anomalyareas are much similar to each other when the scaling of the two areas is the same.The two areasof heating anomalies have their own affecting domains in which one is more important than the oth-er.In the western Pacific the heating anomaly over the western Pacific is more evident and in theTibetan Plateau area the heating anomaly over the Tibetan Plateau is more obvious.For the eastpart of China the effects of the two heating anomalies both exist and almost have the equal impor-tance.The initial anomaly of the sea surface temperature(SST)over the western Pacific can bekept during the entire time integration while in the Tibetan Plateau it can not be maintained. 相似文献
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通过数值模拟,研究了青藏高原位于不同经度位置时,亚洲夏季风的爆发和演变情况,从动力和热力学角度分析了青藏高原大地形对亚洲夏季风爆发位置的影响。结果表明,青藏高原的“热力滑轮”作用引起:高原东南面热带陆地上空的偏南气流加强,降水增加,凝结潜热加强;高原西南面热带陆地上空出现偏北气流,降水减弱,陆面的感热加热加强。青藏高原对于亚洲夏季风的爆发地点有锚定的作用,在热带海陆分布的背景下,使亚洲夏季风首先在高原东南面的海洋东岸—陆地西岸爆发,并使亚洲季风降水重新分布。 相似文献
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青藏高原云-辐射-加热效应和南亚夏季风--1985年与1987年对比分析 总被引:4,自引:0,他引:4
文中首先利用NCEP NCAR再分析的风场资料 ,分析了南亚夏季风的时空特征 ,选取了有代表性的典型强、弱夏季风年 ,继而利用ISCCP C2、ERBE S4卫星观测资料和NCEP NCAR再分析资料 ,对比分析了强、弱夏季风前期青藏高原地区的云—辐射—加热状况及其在海、陆差异中的作用。分析结果表明 ,南亚夏季风强或弱 ,其前期青藏高原地区的云—辐射—加热效应有明显的差异。在强 (弱 )南亚夏季风的前期 ,青藏高原大部分地区为相对少 (多 )云区 ,其云量变化不仅表明了此区的云—辐射—加热效应的不同 ,更重要的是与此同时出现的海、陆之间云量分布的“跷跷板”现象 ,进一步改变了海、陆之间的热力差异。而且 ,在强南亚夏季风年 ,这种热力差异不但开始得早 ,而且持续时间长、作用范围大 ,从而对南亚夏季风的形成和变化产生重要的影响 相似文献
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青海南部高原冬半年气温、降水异常的时空分布及其与雪灾的关系 总被引:4,自引:0,他引:4
利用1959—1993年冬半年(10月—次年3月)青南高原15个台站的月平均降水量和月平均气温距平资料,采用时空综合的经验正交函数分析方法,对青南高原地区冬半年降水、气温异常的时空分布特征进行了诊断研究,得到了降水与气温异常的典型配置及其反映这些典型场的年际演变规律的时间系数,并在此基础上进一步分析了降水、气温异常的时变特征与青南高原不同区域出现较严重雪灾年份之间的关系。结果表明,青南高原地区发生较严重雪灾的年份与时间系数出现极大(小)值的年份存在较好的对应关系 相似文献
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n this paper,using NCEP dataset and the Wei's method,we calculate the exchange of massacross the thermal tropopause during 1998 over the Tibetan Plateau and its surroundings.Theresults indicate that:(1)There is strong air transport from troposphere to stratosphere in summerover the Tibetan Plateau and its surroundings.The air transport reaches the summit in midsummerwith three large value centers among which the Bay of Bengal is the largest and the other two largecenters lie in the east and northwest of the Tibetan Plateau,respectively.In May and October thecross-tropopause mass exchange reaches balance.In other months the mass transport is fromstratosphere to troposphere.(2)As far as the cross-tropopause mass exchange from June toSeptember in 1998 is concerned,the net mass transport is 13.7×10~(18) kg from troposphere tostratosphere,So the area from Tibetan Plateau to the Bay of Bengal is a channel through which airmass gets into stratosphere from troposphere. 相似文献
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Using the operational model(B model)of Beijing Meteorological Center,we do some of numerical experi-ments of crossing and rounding mountains in all velocity adjustment scheme,and study dynamic effect ofQinghai-Xizang Plateau and Rocky Mountains on lee cyclones.The results show that due to air flow roundthe Qinghai-Xizang Plateau,divergence is distributed in the shape of confluence which matches cyclogenesisarea and cyclonic track in East Asia.In the downstream of the Qinghai-Xizang Plateau,convergence inthe upper troposphere restrains cyclone development in the east of China mainland.In North America,air flow primarily crosses over Rocky Mountains.Air is adiabatically cooled when it flows upward in thewest flank of Rocky Mountains,while air is warmed when it flows downward in the lee side.The fact isimportant for the lee cyclogenesis and the lee frontogenesis of Rocky Mountains.Air flow crossing over RockyMountains is also the main cause for forming dryline in the mid-west of United States. 相似文献
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青藏高原潜热感热、地形高度与我国冬、夏季温度的可能影响 总被引:4,自引:3,他引:4
利用改进后的大气环流谱模式(简称SF-AGCM)进行长时间积分,分别在青藏高原冬季感热、潜热减少,夏季感热、潜热增加和地形减半等三种情况下,求出其相应的我国温度情况,结果表明:夏季感热、潜热增加,相应次年我国冬季普遍温度程升高,冬季感热潜热减少,相应次年夏季青藏高原地区温度升高,我国中东部区温度降低,只有东部沿海的温度有少量增加,降低最多地区在黄河中游,青藏高原地形高度减半,冬季青藏高原地区温度增加,0℃线沿青藏高原穿过黄河和长江的中上游,我国的东部地区温度均降低,降低最大处是在渤海和黄海附近的地区;夏季我国普遍温度都降低,青藏高原的西部温度降低最为显著,此外,在淮河附近也有较大降温。 相似文献
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A COMPARATIVE STUDY OF THE HEATING EFFECTS OF THE TIBETAN PLATEAU AND THE WESTERN PACIFIC* 下载免费PDF全文
Qian Yongfu 《Acta Meteorologica Sinica》1996,10(3):270-283
A zonal domain primitive equation modeling system(ZDMS) is used to study the effects of the initial heating anomalies over the Tibetan Plateau and the western Pacific on the East Asian and the Chinese summer climate,the relative importance and the mechanisms are discussed.Results show that in spite of the different locations of the heating anomalies the influences of the two anomalyareas are much similar to each other when the scaling of the two areas is the same.The two areas of heating anomalies have their own affecting domains in which one is more important than the other.In the western Pacific the heating anomaly over the western Pacific is more evident and in the Tibetan Plateau area the heating anomaly over the Tibetan Plateau is more obvious.For the east part of China the effects of the two heating anomalies both exist and almost have the equal importance.The initial anomaly of the sea surface temperature(SST) over the western Pacific can be kept during the entire time integration while in the Tibetan Plateau it can not be maintained. 相似文献
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青藏高原雪盖变化对我国气候的影响 总被引:5,自引:0,他引:5
青藏高原雪盖是影响我国气候的一个重要因子,除了具有明显的季节变化之外,还有明显的年际变化和年代际变化.它通过改变高原的热力作用而影响东亚季风进程、大气环流以及我国的气温和降水.雪盖具有较为明显的持续性,且具有振幅变化大的特点,人们越来越重视雪盖的气候效应和作为季度预报因子的作用. 相似文献
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A STUDY ON THE CHARACTERISTICS AND EFFECT OF THE LOW-FREQUENCY OSCILLATION OF THE ATMOSPHERIC HEAT SOURCE OVER THE EASTERN TIBETAN PLATEAU 总被引:1,自引:1,他引:0
There has been a lot of discussion about the atmospheric heat source over the Tibetan Plateau (TP) and the low-frequency oscillation of atmospheric circulation. However, the research on low-frequency oscillation of heat source over TP and its impact on atmospheric circulation are not fully carried out. By using the vertically integrated apparent heat source which is calculated by the derivation method, main oscillation periods and propagation features of the summer apparent heat source over the eastern TP (Q1ETP) are diagnosed and analyzed from 1981 to 2000. The results are as follows: (1) Summer Q1ETP has two significant oscillation periods: one is 10-20d (BWO, Quasi-Biweekly Oscillation) and the other is 30-60d (LFO, Low-frequency Oscillation). (2) A significant correlation is found between Q1ETP and rainfall over the eastern TP in 1985 and 1992, showing that the low-frequency oscillation of heat source is likely to be stimulated by oscillation of latent heat. (3) The oscillation of heat source on the plateau mainly generates locally but sometimes originates from elsewhere. The BWO of Q1ETP mainly exhibits stationary wave, sometimes moves out (mainly eastward), and has a close relationship with the BWO from the Bay of Bengal. Showing the same characteristics as BWO, the LFO mainly shows local oscillation, occasionally propagates (mainly westward), and connects with the LFO from East China. In summary, more attention should be paid to the study on BWO of Q1ETP. 相似文献