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1.
Regional Atmospheric Modeling System (RAMS) was applied to the study of the effect of the topographical altitude of the Tibetan Plateau (TP) on a severe drought event which took place in eastern China from November 2008 to January 2009. Two simulations of this drought event were conducted: a control simulation (CNTRL run) using original model settings and a sensitive simulation (TOPO run), where no change other than to reduce the TP topography by 50 %. The results show that the CNTRL simulation validates RAMS by reproducing this drought event fairly accurately. However, as part of the TOPO simulation, the total heat flux showed a decrease over most parts of the TP, latent heat flux underwent a significant increase over the southeastern TP, contrary to sensible heat, and a universal decrease over eastern China; this led to an increase in precipitation over the southeastern TP and a decrease in precipitation over eastern China. The decrease of total heat flux over the TP is collocated with an anomalous anticyclonic circulation from the TP to the coasts of southeastern China. Changes in atmospheric circulation and low-level water vapor transport pathways were consistent with changes in precipitation. In general, reducing the topographical altitude of the TP worsens drought in eastern China and moreover causes a significant decrease in precipitation over southern China. 相似文献
2.
青藏高原作为世界第三极,其热力强迫作用不仅对亚洲季风系统的发展和维持十分重要,也会对大气环流场产生深远影响。利用欧洲中期天气预报中心（ECMWF）的ERA-Interim中1979-2016年3-10月青藏高原及其周边地区的地表热通量月平均再分析资料,通过分析得出以下结论:3-5月青藏高原主体由感热占据,感热强度快速上升且呈西高东低的分布态势,潜热强度较小但随时间而增强。季风爆发后的6-8月,青藏高原感热强度减弱,潜热强度迅速增强且呈东高西低的分布特征。季风消退后的9-10月,感热与潜热强度相当,但感热呈现出西高东低的分布特征。过去38年,青藏高原地表感热总体呈现微弱下降趋势,潜热呈较弱上升趋势。青藏高原西部地区感热呈微弱下降趋势,潜热呈上升趋势。东部感热呈较为明显的下降趋势且近年来变化趋势增强,东部潜热通量则呈现较为明显的上升趋势,分析结论与近期全球变暖条件下青藏高原气候变暖变湿这一变化状况一致,通过对青藏高原地表热通量的变化分析为下一步运用第三次青藏高原大气科学试验所获资料分析青藏高原上空大气热源的变化以及地表加热场如何影响大气环流奠定基础。 相似文献
3.
The precipitation recycling (PR) ratio is an important indicator that quantifies the land-atmosphere interaction strength in the Earth system’s water cycle. To better understand how the heterogeneous land surface in the Tibetan Plateau (TP) contributes to precipitation, we used the water-vapor tracer (WVT) method coupled with the Weather Research and Forecasting (WRF) regional climate model. The goals were to quantify the PR ratio, in terms of annual mean, seasonal variability and diurnal cycle, and to address the relationships of the PR ratio with lake treatments and precipitation amount. Simulations showed that the PR ratio increases from 0.1 in winter to 0.4 in summer when averaged over the TP with the maxima centered at the headwaters of three major rivers (Yangtze, Yellow and Mekong). For the central TP, the highest PR ratio rose to over 0.8 in August, indicating that most of the precipitation was recycled via local evapotranspiration in summer. The larger daily mean and standard deviation of the PR ratio in summer suggested a stronger effect of land-atmosphere interactions on precipitation in summer than in winter. Despite the relatively small spatial extent of inland lakes, the treatment of lakes in WRF significantly impacted the calculation of the PR ratio over the TP, and correcting lake temperature substantially improved both precipitation and PR ratio simulations. There was no clear relationship between PR ratio and precipitation amount; however, a significant positive correlation between PR and convective precipitation was revealed. This study is beneficial for the understanding of land-atmosphere interaction over high mountain regions.
相似文献4.
青藏高原表面过程对夏季青藏高压的影响--数值试验 总被引：14，自引：2，他引：14
利用IAP/LASGGOALS气候模式设计了两组敏感性试验,分别考察青藏高原表面感热输送和表面摩擦拖曳对夏季青藏高压的影响.结果表明,表面感热输送显著增强了高原近地层气柱中正涡度的制造和气旋性环流,同时增强了高原上空气柱高层的负涡度制造和反气旋性环流.另一方面,高原表面摩擦拖曳虽然使得低层的辐合略有增加,但施加给整层气柱以反气旋性涡度.因而高原表面的感热输送和表面摩擦拖曳对夏季青藏高压都有增强的作用.表面摩擦拖曳对上空环流的影响随着高度升高而减弱,而表面感热输送引起的高层负涡度的增加与低层正涡度的增加在数值上相当甚至更大. 相似文献
5.
CMIP6全球气候模式对青藏高原中东部地表感热通量模拟能力评估 总被引：1，自引：0，他引：1
利用青藏高原（以下简称高原）气象台站常规观测资料、国家青藏高原科学数据中心的青藏高原地气相互作用过程高分辨率（逐小时）综合观测数据集（2005～2016）、国际耦合模式比较计划第六阶段（CMIP6）的历史模拟试验数据和卫星辐射资料,定量评估了12个全球气候模式对1979～2014年高原中东部地表感热通量的模拟能力,并对其模拟偏差进行了成因分析。结果表明,CMIP6模式可较好地重现高原地表感热通量的年循环和季节平均的空间分布型,但数值较计算感热通量偏低,主要表现为对感热通量大值区严重低估。区域平均而言,12个模式模拟的春季高原中东部感热通量的时间演变序列整体较计算感热通量偏低,其中偏差最大的模式为MIROC6,其多年均值仅为计算值的1/3左右。进一步分析发现多模式模拟的春季高原10 m高度处风速和地气温差分别偏强和偏弱,说明CMIP6模拟的春季高原感热通量偏低可主要归因于地气温差的模拟冷偏差。地气温差的模拟冷偏差在高原中东部地区普遍存在,且地表温度和空气温度均存在明显冷偏差,尤其地表温度偏差更大,这很大程度上可能与CMIP6多模式模拟的春季高原降水偏强有关。 相似文献
6.
基于1980—2015年青藏高原、长江以南地区的站点资料,利用EOF、小波分析等方法,分析了青藏高原及各分区4月的感热通量和长江以南地区夏季降水特征,以及它们之间的相关性。结果表明:喜马拉雅地区(关键区) 4月感热通量可以作为长江以南地区夏季降水的预报因子之一;青藏高原4月感热通量和长江以南地区夏季降水均存在4 a主周期和8 a副周期,在1998年、2011年前后出现转折;高原整体、E区、G区4月感热通量均与长江以南地区夏季降水呈负相关;高原关键区4月感热通量偏弱时,长江以南地区高空(850 hPa)处于深槽槽前,西部配合有切变线系统,斜压性很强,空气相对湿度很大,利于长江以南地区降水,反之亦然。 相似文献
7.
青藏高原感热与黄土高原春季降水异常关系研究 总被引：6，自引：1，他引：5
利用1961～2000年黄土高原56站的春季降水、气温资料,用SVD方法分析了其与青藏高原感热场的关系。结果表明,降水量与青藏高原感热场的前两模态代表了两场间的主要耦合特征;上年冬季和秋季青藏高原感热场的异常通过影响大气环流,能够导致次年黄土高原春季降水异常;青藏高原感热对黄土高原西部和南部、北部的部分地区影响较显著,而对陕西北部、山西中部影响不明显。前期高原感热场SVD第一、二模态的变化,可以作为黄土高原春季降水异常的预测信号。 相似文献
8.
通过对四川盆地西部一次持续性暴雨过程的半理想数值模拟,研究了青藏高原热力作用对四川盆地持续性暴雨过程的影响。研究表明,高原的热力作用对于下游地区有着显著的影响,主要表现为:（1）关闭高原地面感热和潜热后,高原地区和四川盆地西部的降水明显减弱,而盆地中东部降水却有所加强,且四川盆地降水的日变化特征稍有减弱;（2）500 hPa青藏高原上的短波槽减弱,位于四川盆地中西部的背风槽强度、范围有所减弱,但低层盆地东部的气旋性涡旋加强;（3）涡度收支的定量分析发现,关闭高原热力作用后,盆地东部对流层低层垂直风切变的增强使得夜间倾斜项的正贡献增强,从而使该区域涡旋发展加强,盆地东部降水增强。 相似文献
9.
青藏高原感热通量的变化及与江淮流域降水异常的关系 总被引：1，自引：0，他引：1
利用1979—2010年NCEP-R2再分析资料和全国586站降水资料, 对青藏高原感热通量进行小波变换和EOF分析, 并研究了它与江淮流域降水的关系。结果发现:高原感热通量具有2 a和8 a的变化周期。空间分布上主要有东、西反相变化和南、北反相变化以及全区一致性变化3种形态。高原感热通量与江淮流域降水异常的同期相关中, 1998年以来, 春季高原东部的感热通量偏小, 其他地区偏大, 与此同期江淮流域降水偏少;夏季西藏西部的感热通量偏小, 其他地区偏大, 与此同期江淮流域降水偏多。两者超前相关中, 江淮流域降水对春季的感热通量变化最敏感。1998年以来, 当春季高原东南部的感热通量偏小, 其他地区偏大时, 江淮流域的夏季降水偏多, 秋季降水偏少;当春季高原感热通量东部偏小, 西部偏大时, 江淮流域的冬季降水以长江为界南多北少, 次年春季降水偏少。 相似文献
10.
Weather and Climate Effects of the Tibetan Plateau 总被引：5，自引：1，他引：4
Progress in observation experiments and studies concerning the effects of the Tibetan Plateau (TP) on weather and climate during the last 5 years are reviewed. The mesoscale topography over the TP plays an important role in generating and enhancing mesoscale disturbances. These disturbances increase the surface sensible heat (SH) flux over the TP and propagate eastward to enhance convection and precipitation in the valley of Yangtze River. Some new evidence from both observations and numerical simulations shows that the southwesterly flow, which lies on the southeastern flank of the TP, is highly correlated with the SH of the southeastern TP in seasonal and interannual variability. The mechanical and thermal forcing of the TP is an important climatic cause of the spring persistent rains over southeastern China. Moreover, the thermodynamic processes over the TP can influence the atmospheric circulation and climate over North America and Europe by stimulating the large-scale teleconnections such as the Asian-Pacific oscillation and can affect the atmospheric circulation over the southern Indian Ocean. Estimating the trend in the atmospheric heat source over the TP shows that, in contrast to the strong surface and troposphere warming, the SH over the TP has undergone a significant decreasing trend since the mid-1980s. Despite the fact that in situ latent heating presents a weak increasing trend, the springtime atmospheric heat source over the TP is losing its strength. This gives rise to reduced precipitation along the southern and eastern slopes of the TP and to increased rainfall over northeastern India and the Bay of Bengal. 相似文献
11.
地面加热与高原低涡和对流系统相互作用的一次个例研究 总被引：4，自引：8，他引：4
本文利用NCEP-FNL再分析资料、FY-2E卫星TBB数据、CMORPH降水资料,通过热力学和动力学诊断分析并结合中尺度天气模式WRF的数值模拟试验,研究了2012年6月下旬青藏高原一次东移对流系统的生成发展机制以及与地面加热相互作用的物理过程。结果表明,高原中西部地面感热加热是高原低涡生成、发展和东移的主导因子。而东移的高原低涡通过加强偏北、偏南气流形成的辐合带,进而触发高原东部对流系统的生成。同时,高原对流系统降水产生的凝结潜热释放也加强了东移高原低涡的强度,这表明地面加热与高原低涡和对流系统之间存在一种正反馈机制。数值试验结果进一步表明,除了适当的背景环流外,高原地面潜热通量能够增强中低层大气的不稳定性,为对流系统的发生发展积累能量,造成有利于对流降水的热力环境。 相似文献
12.
本文总结了中国国家自然科学基金委重点项目“青藏高原调控区域能量过程及其影响机理”的研究进展。着重阐明了春夏季伊朗高原和青藏高原(TIP)地表热通量特征及变化原因、TIP上空独特的水汽、云宏观和微观垂直结构,以及降水和云辐射效应;在夏季两个高原地区的感热加热存在相互影响和反馈,形成观测到的加热与大气垂直环流之间的准平衡耦合系统,由此提出了TIP系统(TIPS)的概念;项目还从天文和水文的角度佐证了TIPS对亚洲夏季风的影响,揭示TIPS导致上对流层暖、下平流层冷的南亚高压的形成机理及TIPS影响北半球环流和印度洋海气相互作用的物理过程;揭示TIPS系统对南亚高压年际变化的影响,提出高原位涡强迫激发中国东部激烈天气过程的一种新机制。此外还揭示了CMIP5模式对高原表面温度模拟存在冷偏差的原因和其中的物理过程,这是大气环流与冰雪反照率的动力耦合的结果。 相似文献
13.
Snow cover on the Tibetan Plateau (TP) has been shown to be essential for the East Asian summer monsoon. In this paper, we demonstrate that tropical cyclone (TC) 04B (1999) in the northern Indian Ocean, which made landfall during the autumn of 1999, may have contributed to climate anomalies over East Asia during the following spring and summer by increasing snow cover on the TP. Observations indicate that snow cover on the TP increased markedly after TC 04B (1999) made landfall in October of 1999. Sensitivity experiments, in which the TC was removed from a numerical model simulation of the initial field, verified that TC 04B (1999) affected the distribution as well as increased the amount of snow on the TP. In addition, the short-term numerical modeling of the climate over the region showed that the positive snow cover anomaly induced negative surface temperature, negative sensible heat flux, positive latent heat flux, and positive soil temperature anomalies over the central and southern TP during the following spring and summer. These climate anomalies over the TP were associated with positive (negative) summer precipitation anomalies over the Yangtze River valley (along the southeastern coast of China). 相似文献
14.
Yanbin Lei Kun Yang Bin Wang Yongwei Sheng Broxton W. Bird Guoqing Zhang Lide Tian 《Climatic change》2014,125(2):281-290
The water balance of inland lakes on the Tibetan Plateau (TP) involves complex hydrological processes; their dynamics over recent decades is a good indicator of changes in water cycle under rapid global warming. Based on satellite images and extensive field investigations, we demonstrate that a coherent lake growth on the TP interior (TPI) has occurred since the late 1990s in response to a significant global climate change. Closed lakes on the TPI varied heterogeneously during 1976–1999, but expanded coherently and significantly in both lake area and water depth during 1999–2010. Although the decreased potential evaporation and glacier mass loss may contribute to the lake growth since the late 1990s, the significant water surplus is mainly attributed to increased regional precipitation, which, in turn, may be related to changes in large-scale atmospheric circulation, including the intensified Northern Hemisphere summer monsoon (NHSM) circulation and the poleward shift of the Eastern Asian westerlies jet stream. 相似文献
15.
青藏和伊朗高原热力异常与北疆夏季降水的关系 总被引：5，自引：1，他引：4
青藏高原和伊朗高原热力异常对其周边地区天气气候有重要影响,已有研究多关注东部季风区,而对干旱区关注较少.针对这一不足,利用美国国家环境预测中心/美国国家大气研究中心(NCEP/NCAR)再分析月平均资料和北疆43站降水资料,分析了1961-2007年5月青藏高原和伊朗高原地表感热异常与北疆夏季降水的关系.奇异值分解(SVD)分析发现,5月青藏高原地表感热与北疆夏季降水呈负相关,伊朗高原为正相关.青藏高原和伊朗高原感热异常的大尺度对比,要比仅考虑单一高原的感热异常与北疆夏季降水有更密切的联系.定义了一个热力差异指数来表征这种地表感热异常的对比程度,相关分析发现,当5月伊朗高原地表感热偏强,青藏高原地表感热偏弱时,500hPa中亚上空和贝加尔湖上空分别为异常气旋和反气旋环流,在二者共同作用下,新疆上空盛行异常的偏南气流,有利于低纬度的暖湿气流北上,形成有利于降水的环流形势,同时越赤道索马里急流偏强,低纬度水汽被接力输送至中亚和新疆地区,为降水的发生提供了有利的水汽条件.进一步分析发现,青藏高原热力异常主要影响中高层大气环流,伊朗高原则主要影响水汽通量输送. 相似文献
16.
6种地表热通量资料在伊朗—青藏高原地区的对比分析 总被引：1，自引：1，他引：1
基于JRA25、ERA40、ERA-Interim、NCEP1、NCEP2和20CR,对比了不同资料中气候平均(1979—2008年)伊朗—青藏高原感热通量和波文比的季节演变,以及夏季高原感热的年际变率和线性趋势。6套资料均表明,由春到夏亚洲大地形区域地表热状况的季节演变存在明显差异,青藏高原东南部低空气旋生成,一方面增多了局地降水,减弱了地表西风,造成潜热加强,感热减弱,波文比减小;另一方面加强了伊朗高原的东北风,抑制了当地降水,令感热加强,波文比增加,构成了青藏—伊朗高原感热通量季节演变的纬向非对称分布。虽然近30 a来伊朗高原(青藏高原)夏季感热线性增加(减小)的趋势一致,但不同资料所反映的伊朗—青藏高原夏季感热通量的年际变化差别明显。 相似文献
17.
Simulation and Projection of Changes in Rainy Season Precipitation over China Using the WRF Model 总被引：2，自引：0，他引：2
The Weather Research and Forecasting (WRF) model is used in a regional climate model configuration to simulate past precipitation climate of China during the rainy season (May-September) of 1981-2000, and to investigate potential future (2041-2060 and 2081-2100) changes in precipitation over China relative to the reference period 1981-2000. WRF is run with initial conditions from a coupled general circulation model, i.e., the high-resolution version of MIROC (Model for Interdisciplinary Research on Climate). WRF reproduces the observed distribution of rainy season precipitation in 1981-2000 and its interannual variations better than MIROC. MIROC projects increases in rainy season precipitation over most parts of China and decreases of more than 25 mm over parts of Taiwan and central Tibet by the mid-21st century. WRF projects decreases in rainfall over southern Tibetan Plateau, Southwest China, and northwestern part of Northeast China, and increases in rainfall by more than 100 mm along the southeastern margin of the Tibetan Plateau and over the lower reaches of the Yangtze River during 2041-2060. MIROC projects further increases in rainfall over most of China by the end of the 21st century, although simulated rainfall decreases by more than 25 mm over parts of Taiwan, Guangxi, Guizhou, and central Tibet. WRF projects increased rainfall of more than 100 mm along the southeastern margin of the Tibetan Plateau and over the lower reaches of the Yangtze River and decreased rainfall over Southwest China, and southern Tibetan Plateau by the end of the 21st century. 相似文献
18.
使用区域气候模式RegCM4.4.5.7,通过改变春季欧亚大陆中高纬地区的陆面感热通量,对欧亚中高纬感热异常影响中国夏季气候进行模拟分析,并探讨其影响机制。试验结果表明:当春季欧亚中高纬陆面感热通量加强时,我国长江流域和东北东部夏季气温降低,降水偏多;华北地区气温升高,降水偏少。春季陆面感热增强引起近地面和对流层低层大气热力状况异常,进而导致高度场和环流场的异常,长江流域和东北地区有气旋环流,对流运动旺盛,结合充足的水汽条件,对应降水偏多,而华北地区则相反,有反气旋环流和微弱的气流辐合,对应降水偏少。研究表明欧亚中高纬陆面感热异常是影响我国夏季气候的一个不可忽视的因子。 相似文献
19.
利用耦合的全球海气模式（NCAR CCSM3）, 对青藏高原春季土壤湿度异常影响我国夏季7月降水的机制进行了数值模拟。结果表明, 高原6~62 cm深度的中层土壤湿度异常与表层土壤湿度异常有很好的一致性, 相对而言, 中层土壤湿度异常的持续性较好。若5月高原中层土壤偏湿, 则春末至夏初高原地面蒸发、 潜热通量增加, 而感热通量、 地面温度降低, 高原表面的加热作用减弱, 使得印度高压西撤偏晚, 环流系统的季节性转换偏晚, 东亚地区形成有利于我国夏季出现第I类雨型的环流分布形势, 使我国东部雨带偏北, 华北地区多雨, 江淮地区降水偏少, 华南地区降水偏多; 反之亦然。 相似文献
20.
The thermal forcing of the Tibetan Plateau(TP) during boreal spring,which involves surface sensible heating,latent heating released by convection and radiation flux heat,is critical for the seasonal and subseasonal variation of the East Asian summer monsoon.Distinct from the situation in March and April when the TP thermal forcing is modulated by the sea surface temperature anomaly(SSTA) in the North Atlantic,the present study shows that it is altered mainly by the SSTA in the Indian Ocean Basin Mode(IOBM) in May,according to in-situ observations over the TP and MERRA reanalysis data.In the positive phase of the IOBM,a local Hadley circulation is enhanced,with its ascending branch over the southwestern Indian Ocean and a descending one over the southeastern TP,leading to suppressed precipitation and weaker latent heat over the eastern TP.Meanwhile,stronger westerly flow and surface sensible heating emerges over much of the TP,along with slight variations in local net radiation flux due to cancellation between its components.The opposite trends occur in the negative phase of the IOBM.Moreover,the main associated physical processes can be validated by a series of sensitivity experiments based on an atmospheric general circulation model,FAMIL.Therefore,rather than influenced by the remote SSTAs of the northern Atlantic in the early spring,the thermal forcing of the TP is altered by the Indian Ocean SSTA in the late spring on an interannual timescale. 相似文献