高低频系统相互作用对Rossby波破碎过程的影响     

张潮  谭言科  李崇银  平已川 《大气科学》2019,43(2):221-232

利用美国国家环境预报中心和能源部（NCEP/DOE）的逐日再分析资料（NCEP-DOE AMIP-Ⅱ）,对2010年12月20日发生在北太平洋一次典型的反气旋式波破碎（AWB）事件进行研究,分析了波破碎过程中等熵位涡场的演变特征,揭示了波破碎过程中高频扰动以及低频信号的逐日演变特征,并对2010年冬季350 K等熵面上逐日高频位涡（PV）扰动和低频变化做经验正交函数（EOF）分析,得到了其主要模态,并从等熵位涡方程出发研究了波破碎过程中位涡高、低频变化的原因。研究表明,波破碎过程中高频低PV空气从北太平洋西部日本附近沿东北方向向对流层上层侵入,而来自阿拉斯加湾附近的高频高PV空气向对流层下层侵入。高频位涡场EOF分解得到的前两个模态共同描述了北太平洋中纬度地区自西向东移动的天气尺度波列;低频位涡场EOF分解的第一模态在北太平洋呈弧形波列结构。天气尺度波在传播过程中受到低频场的平流作用逐渐偏离其传播主要模态的位置,并发生破碎,同时高频流场对高频位涡的平流可以产生低频变化,使得低频变化的空间形态向其冬季主要模态转变。  相似文献   

冬季蒙古高压与北太平洋海温异常的年际尺度关系   总被引：7，自引：1，他引：6       下载免费PDF全文

李崇银  王力群  顾薇 《大气科学》2011,35(2):193-200

蒙古高压和北太平洋海区的气压差被认为是造成东亚冬季风及其变化的重要原因,而过去有关的研究以其年代际时间尺度为多,本文的研究揭示了冬季蒙古高压和北太平洋海温异常(SSTA)在年际时间尺度上的相互关系.冬季蒙古高压的活动与太平洋年代际振荡(PDO)之间在年际时间尺度上也存在明显的负相关,冬季的强(弱)蒙古冷高压活动往往对应...  相似文献   

真实基流中非线性Rossby波演变特征(二):能量、结构演变及初始场影响   总被引：1，自引：0，他引：1       下载免费PDF全文

张立凤  张亮  李崇银 《地球物理学报》2011,54(4):886-895

针对非线性的准地转正压位涡方程,利用自行设计的差分格式和高斯函数拟合得到的真实基流分布,数值研究了线性和非线性Rossby波流场结构和总能量的演变以及初值对总能量演变的影响.发现在非线性的真实基流中,线性和非线性Rossby波的相对总能量出现振荡型增长或衰减,非线性波动的振荡周期明显小于线性波动,非线性项不仅抑制能量的...  相似文献   

An Observational Study of the 30-50 Day Atmospheric Oscillations Part I: Structure and Propagation     

李崇银 《大气科学进展》1990,(3)

Features of structure and propagation of the 30 to SO day atmospheric oscillations are investigated using the ECMWF analysis of 1980-1983. Evidence is provided to confirm the characteristics of the oscillation in the equatorial region. Those in the mid-high latitudes, however, are revealed to be very different from the tropics and pose a strong barotropic structure. Horizontal coherence shows teleconnection patterns which can be identified as EAP and PNA. The wind field of the specified time scale of the oscillation appears as long-lived vortices and vortex pairs. Mid-latitude perturbations propagate clearly westwards, especially during the winter season. In the high latitudes, they propagate westwards in the winter but eastwards in the summer. Meridional propagations are rather different from region to region.  相似文献   

基于SPEI的中国西南地区1961-2012年干旱变化特征分析   总被引：6，自引：0，他引：6  

熊光洁  张博凯  李崇银  尚可政  王式功 《气候变化研究进展》2013,(3):192-198

利用1961—2012年中国西南地区86个气象站逐月降水量和平均气温资料,引入一个新的干旱指数——标准化降水蒸散指数(SPEI)作为干旱等级划分指标,研究了1961—2012年该地区不同时间尺度干旱的变化特征。结果表明:该地区12个月尺度干旱频率在云贵交界区呈显著增加趋势,其他区域变化不显著且不一致;少雨期(11—4月)6个月尺度干旱频率在全区显著增加,而在多雨期(5—10月)大部分区域干旱频率呈缓慢减少趋势,减少最明显的区域在四川南部;3个月尺度干旱频率在春季变化不明显,在秋季和冬季显著增加,其中2000—2012年的增加趋势尤为显著,干旱化趋势严重。  相似文献   

THE CONTRASTS BETWEEN STRONG AND WEAK MJO ACTIVITY OVER THE EQUATORIAL WESTERN PACIFIC IN WINTER     

陈雄  李崇银  谭言科  郭文华 《热带气象学报(英文版)》2017,23(2):133-145

This paper investigates the contrasts between strong and weak Madden-Julian Oscillation (MJO) activity over the equatorial western Pacific during winter using the NCEP reanalysis data. It is shown that the MJO over the equatorial western Pacific in winter shows significant interannual and interdecadal variabilities. During the winters with strong MJO activity, an anomalous cyclonic circulation lies east of the Philippines, strong anomalous easterlies control the equatorial eastern Pacific, and anomalous westerlies extend from the Indian Ocean to the western Pacific in the lower troposphere, which strengthens the convergence and convection over the equatorial western Pacific. The moisture convergence in the lower troposphere is also enhanced over the western Pacific, which is favorable to the activity of MJO. Eastward propagation is a significant feature of the MJO, though there is some westward propagation. The space-time spectral power and center period of the MJO are higher during strong MJO activity winters. The anomalous activity of MJO is closely related to the sea surface temperature (SST) and East Asian winter monsoon (EAWM). During strong MJO activity winters, there are positive/negative anomalies at high/low latitudes in both sea level pressure and 500 hPa geopotential height, and the temperature is lower over the central part of the Chinese mainland, which indicates a strong EAWM. China experiences more rainfall between the Yellow and Yangtze Rivers, but less rainfall south of the Yangtze River. The SSTA is negative near the Taiwan Island due to the impact of strong EAWM and shows a La Ni?a pattern anomaly over the eastern Pacific. During the weak MJO activity winters, the situation is reversed.  相似文献   

大气MJO研究的几个前沿问题   总被引：2，自引：0，他引：2  

李崇银  凌健  袁媛  潘静 《热带气象学报》2016,(6):797-816

就MJO研究的几个前沿问题进行简要归纳分析,主要包括:MJO对流的形成机制;MJO与ENSO的相互作用;MJO对天气气候的影响;MJO的数值模拟和预报等。在论述中更多地给出了中国学者的研究工作及其主要结果。在MJO的影响方面主要论及其对西太平洋台风、亚洲季风和中国东部降水的影响,目的在于能对中国的相关研究及其预报应用有所帮助。  相似文献   

INTERDECADAL VARIATION OF THE INTENSITY OF SOUTH ASIAN HIGH     

杨光  李崇银  谭言科 《热带气象学报(英文版)》2016,22(1):19-29

The characteristics and possible physical mechanism of interdecadal variation of the intensity of the South Asian High (SAH) in summer are analyzed using the NCEP/NCAR reanalysis data and NOAA extended reconstructed sea surface temperature (SST) data. The results indicate that a remarkable interdecadal transition occurred in the late 1970s that increased the intensity of SAH, or, an abrupt climate change was around 1978. A comparative analysis between the weak and strong period of the SAH intensity shows that the related anomalous patterns of the atmospheric circulation (including wind field, air temperature field and vertical velocity field) are nearly opposite to each other. The surface latent heat flux anomalies over the plateau (especially in the northwest of the plateau) in summer exert great influence on the interdecadal variation of the SAH intensity and the surface sensible heat flux anomalies play a more important role. Consistent with the interdecadal variation of the SAH intensity, the monopole mode of the tropical Indian Ocean SST in summer also experienced a low to high transition in the late 1970s. To some extent, this can reveal the impact of the anomalous monopole mode of the tropical Indian Ocean SST in summer on interdecadal variation of the SAH.  相似文献   

北太平洋副热带环流变异及其对我国近海动力环境的影响   总被引：1，自引：0，他引：1  

吴立新  刘秦玉  胡敦欣  李崇银  左军成  俞永强  孙澈  王启 《地球科学进展》2007,22(12):1224-1230

我国东部陆架海和南海是国防安全的重要门户;位处第二岛链以西的副热带北太平洋既是各国争夺的重要海区,又是我国从近海走向大洋的重要通道.围绕"北太平洋副热带环流变异如何通过黑潮与我国近海动力环境之间相互作用"这一国际前沿科学问题,国家重点基础研究发展计划项目"北太平洋副热带环流变异及其对我国近海动力环境的影响"于2007年9月正式立项.该项目不仅有助于拓展和丰富海洋动力学理论,揭示我国近海及邻近大洋动力环境变异机制,提高预测能力,而且也将为维护我国国防安全和海洋权益,为可持续开发利用海洋资源提供海洋动力环境保障.该项目主要研究内容包括:①北太平洋副热带环流变异和调整机理;②黑潮与我国近海的能量与水体交换过程及机制;③北太平洋副热带环流变异与大气驱动力的耦合效应;④我国近海及邻近大洋动力环境变异的可预测性研究.拟解决的关键科学问题为:北太平洋副热带内区环流变异的机理及其对黑潮的影响;黑潮源头变异机理及其对吕宋海峡水交换的影响和黑潮变异机理及其对东部陆架海域动力环境的影响.  相似文献   

The Relation between Atmospheric Intraseasonal Oscillation and Summer Severe Flood and Drought in the Changjiang-Huaihe River Basin   总被引：6，自引：2，他引：6  

杨辉  李崇银 《大气科学进展》2003,20(4):540-553

The intraseasonal oscillation (ISO) is studied during the severe flood and drought years of the Changjiang-Huaihe River Basin with the NCEP/NCAR reanalysis data and the precipitation data in China. The results show that the upper-level (200 hPa) ISO pattern for severe flood (drought) is charac-terized by an anticyclonic (cyclonic) circulation over the southern Tibetan Plateau and a cyclonic (anti-cyclonic) circulation over the northern Tibetan Plateau. The lower-level (850 hPa) ISO pattern is char-acterized by an anticyclonic (cyclonic) circulation over the area south of the Changjiang River, the South China Sea, and the Western Pacific, and a cyclonic (anticyclonic) circulation from the area north of the Changjiang River to Japan. These low-level ISO circulation patterns are the first modes of the ISO wind field according to the vector EOF expansion with stronger amplitude of the EOF1 time coefficient in se-vere flood years than in severe drought years. The analyses also reveal that at 500 hPa and 200 hPa,the atmospheric ISO activity over the Changjiang-Huaihe River basin, North China, and the middle-high latitudes north of China is stronger for severe flood than for severe drought. The ISO meridional wind over the middle-high latitude regions can propagate southwards and meet with the northward propagating ISO meridional wind from lower latitude regions over the Changjiang-Huaihe River Basin during severe flood years, but not during severe drought years.  相似文献