全球大气／热带太平洋耦合距平模式中由ENSO增暖引起的全球大气环流异常

本文利用全球大气／热带太平洋耦合距平模式模拟了一次类似于实际的ENSO增暖过程，并对由ENSO增暖引起的海洋和全球大气环流异常的主要特征进行了分析，指出:耦合模式中的ENSO增暖在热带地区主要伴随着赤道中西太平洋Walker环流的减弱、中东太平洋气压降低以及表层辐合上升运动的增强；夏季和冬季低纬环流异常具有明显的差异性，夏季主要表现为印度夏季风环流的显著减弱和东亚季风的增强，而冬季则主要表现为赤道所有纬向环流圈均减弱；温带大气环流异常冬夏季也具有明显不同特征，夏季温带大气异常主要限于东半球，且发源于亚洲季风区，和赤道中东太平洋海温异常似无直接联系，但冬季温带大气异常则主要是发源于海温异常区的波列响应，反映了海温异常直接热力强迫的结果。另外，本文对耦合模式中的温带大气环流异常产生的可能机制也进行了讨论。     

冬夏东亚季风环流对太平洋热状况的响应

冬夏隔季韵律关系一直是我国长期天气预报和短期气候预测的一个重要依据,然而迄今为止对它们之间的物理过程及成因机理并不十分清楚。利用NCEP/NCAR全球2.5°×2.5°网格月平均再分析资料,研究1951~2000年冬夏东亚季风环流异常变化与太平洋海面温度(SST)的关系及对关键海温区响应机理。研究指出:冬夏东亚季风环流隔季韵律关系及其年际变化与赤道东太平洋海面温度异常(SSTA)变化密切相关,冬季赤道东太平洋出现La Ni~na(El Ni~no)型的SST分布,有利冬、夏东亚季风环流加强(减弱),其影响过程通过赤道Walker环流强(弱)以及东亚地区Hadley环流强(弱)过程完成。冬季赤道东太平洋海温变化是冬、夏东亚环流季节以及年际变化的一个重要外强迫因子。     

一个斜压海洋风生环流的数值模拟

为研究大尺度海气相互作用、气候以及气候的变化,一个具有规则海岸线和无海底地形的三层斜压海洋模式已经建立起来。积分区域包括了赤道地区在内,南北方向从-2750 km到+4750 km,东西方向宽10000 km,总深度是4 km。模式方程为原始方程,用了静力近似和Bou-sinesq近似。模式数值积分分两个阶段,在第一个阶段,海洋环流从静止状态开始,以只随纬度变化的年平均风应力和海表热通量作为强迫边条件数值积分十年,这时海洋上层的环流和温度都趋于平稳,我们将第十年末的积分状态作为模式气候的准平衡态。计算结果模拟了热带太平洋上气候平均的温度分布以及主要海流的大尺度特征,如赤道地区的狭长冷水带和强上翻区、南赤道洋流、北赤道逆流以及表层下面沿赤道自西向东的潜流。在第二个阶段,以在第一个阶段末尾得到的准平衡态作为初值,分别用冬季和夏季的风应力作为强迫边条件再积分一年。比较这两种计算结果,我们看到海洋环流随信风系统的季节变化也呈现出明显的季节变化,特别是北赤道逆流,其强度在夏季强,在冬季弱甚至不出现。南赤道洋流无论哪个季节都穿过赤道,在赤道以北的南赤道洋流冬季比夏季强,而在赤道以南的南赤道洋流夏季比冬季强。     

冬夏季节热带副热带OLR场的遥相关分析

本文利用NOAA13年月平均格点资料分析了冬夏热带副热带射出长波辐射(OLR)的气候特征及其遥相关结构。结果表明,OLR场的高低值带有明显的季节变动,低值带中心从冬至夏由赤道西太平洋地区向西北移至孟加拉湾,高值带从冬至夏北移约10—15个纬度,但东南太平洋高值区的位置无明显季节变动。 遥相关结构分析表明,冬夏季节OLR场分别有8个遥相关关键区,它们之间存在着较强的同时性遥相关联系。冬季遥相关型主要由位于赤道低纬度“印度洋—西太平洋—东太平洋—大西洋”的纬向2波式遥相关和在太平洋中部、东亚地区,南北半球副热带与赤道地区的经向负遥相关型组成。夏季OLR遥相关关键区主要分布在孟加拉湾至赤道西太平洋、东太平洋与低纬度大西洋和中纬度东亚沿海与北美大陆,构成低纬度和中纬度两类纬向正遥相关型。进一步分析发现,冬夏OLR遥相关型的年际变化较好地揭示了OLR场异常与ENSO、低纬度Walker、Hadley环流等海—气系统异常的整体联系。      

赤道西太平洋-印度洋海温异常对亚洲夏季风的影响

本文采用了p-σ五层原始方程模式模拟并研究了赤道西太平洋-印度洋海温距平场对亚洲夏季风的影响,计算了四种不同的海温距平试验方案。试验结果表明赤道西太平洋海温正距平使对流层下层的印度低压明显加强,副高北挺,季风槽加深,同时加强了对流层上层的反气旋环流。赤道西印度洋暖海温的模拟结果与赤道西太平洋暖海温对上述系统的影响相反,而赤道西印度洋冷海温对季风环流的影响与赤道西太平洋暧海温的影响一致。试验进一步表明赤道西太平洋-印度洋海温距平的纬向梯度方向对亚洲夏季风的影响是主要的,这一结论与实际观测结果一致。本文进一步讨论了赤道海温距平对越赤道气流、印度洋赤道东-西纬向环流和非绝热加热场的影响,结果都表明赤道西太平洋海温正距平和赤道西印度洋海温负距平的模拟特征与反El Nino年亚洲夏季环流特征类似,而赤道西印度洋海员正距平的模拟特征与El Nino年亚洲夏季坏流特征类似。     

1982—83年厄尼诺现象与西北太平洋夏季(6—8月)低纬环流特征的初步分析

1982—83年的厄尼诺和南方涛动是本世纪最强的一次ENSO(El-Nino/Southern Oscill-ation)事件。本文分析对比了El-Ni(?)o当年(1982)夏季(6—8月)和El-Nino次年(1983)夏季的西北太平洋低纬度环流特征发现有明显的差异,在1982年夏季,西北太平洋副热带高压明显偏弱;850hPa低纬度西风较强;200hPa上低纬度东风较强,在赤道海洋上已建立了沃克反环流,根据1982年和1983年夏季向外的长波辐射差异图可发现菲律宾以东洋面上ITCZ活跃。而在1983年夏季的低纬度环流几乎与1982年夏季的相反。这两年上述的差异是与赤道太平洋中部或东部的海温异常增暖有关的。      

DIURNAL VARIATION OF GLOBAL PRECIPITATION: AN ANALYSIS OF CMORPH DATA

In this study, the observed CMORPH precipitation data from 1998 to 2015 are used to analyze diurnal variation of global precipitation. The results reveal that the strong diurnal signals of precipitation occur over equatorial continental areas where the annual precipitation centers are located. The phase of diurnal variation of global precipitation reveals a distinct land-sea contrast with nocturnal peaks at sea and afternoon maxima over continents. The analysis of six selected area reveals that precipitation peak over equatorial land areas occur in afternoon and maximum diurnal signals appear in autumn or winter. Eastern equatorial Intertropical Convergence Zone (ITCZ) barely shows diurnal signals in the entire year. Precipitation over Sichuan Basin and northwestern Pacific shows nocturnal peak and the maximum diurnal amplitude in summer. Precipitation over coastal areas off eastern China shows an afternoon peak and the largest diurnal amplitude in summer.     

EFFECTS OF THE ATMOSPHERIC COLD SOURCE OVER THE TIBETAN PLATEAU ON THE QUASI 4-YEAR OSCILLATION OF OCEAN-ATMOSPHERIC-LAND INTERACTION

Using correlation analyses, composite analyses, and singular value decomposition, the relationship between the atmospheric cold source over the eastern Tibetan Plateau and atmospheric/ocean circulation is discussed. In winter, the anomaly of the strong (weak) atmospheric cold source over the eastern plateau causes low-level anomalous north (south) winds to appear in eastern China and low-level anomaly zonal west (east) winds to prevail in the equatorial Pacific from spring to autumn. This contributes to the anomalous warm (cold) sea surface temperature the following autumn and winter. In addition, the anomalous variation of sea surface temperature over the equatorial middle and eastern Pacific in winter can influence the snow depth and intensity of the cold source over the plateau in the following winter due to variation of the summer west Pacific subtropical high.     

东亚夏季大气环流和气候对冬季海温异常的邻响应和遥响应

本文通过ＩＡＰ－ＧＣＭ的数值模拟,研究了全球大气环流对黑潮海域和赤道东太平洋冬季ＳＳＴ异常的响应,并着重比较东亚大气环流和气候对黑潮区ＳＳＴＡ的响应（邻响应）和对赤道东太平洋ＳＳＴＡ的响应（遥响应）。首先,无论是黑潮区ＳＳＴＡ引起的邻响应还是赤道东太平洋ＳＳＴＡ所引起的遥响应对东亚大气环流和气候变化的影响都是明显而重要的。由于在大气中低频振荡被激发出来,其响应将持续较长时间。进一步分析表明,东亚大气环流对黑潮区或赤道东太平洋冬季正ＳＳＴＡ的响应都将造成华北地区夏季的多雨,其数值模拟结果与观测相一致。另外,赤道西太平洋地区大气的异常（尤其是对流活动）对于东亚地区大气环流和气候变化有重要作用     

东半球跨赤道气流季节变化的研究

跨赤道气流作为季风环流系统的组成部分,一直被气象工作者所重视。Findlater(1969)第一次证实了夏半年索马里急流的存在,陈于湘得出夏季季风区有105°E和150°E两支跨赤道气流,冯颖竹等人确定出索马里急流、印度尼西亚气流、青藏高原所在经度上的中低空向南气流以及印度尼西亚高空向南气流的存在,李曾中也得到了类似的结果。由以上研究可以看出,他们的许多结论是一致的,但是,这些研究大多数是局限于夏半年以及某些层次上,而对季风系统全年的季节变化以及     

Low-level high-frequency modes in the Tropical Atlantic and their relation to precipitation in the equatorial South America

Summary ?Evolving aspects of the dominant high-frequency modes of the 925-hPa v-component and precipitable water in the Tropical South American and Atlantic sector are studied for the austral summer and winter seasons. Their relations to the precipitation anomalies over the equatorial South America are also investigated. The highest percentages of the total variance contained in the high-frequency time-scale for the 925-hPa v-component have a clear seasonal dependency such that they are confined in the Tropical South Atlantic (TSA) during the austral summer and in the Tropical North Atlantic (TNA) during the austral winter. The high-frequency variability for the TSA during the austral summer stems from the combined effects of equatorward incursions of midlatitude synoptic and transient wave systems, equatorial trades and westward traveling disturbances in equatorial latitudes. All these systems together have a pronounced effect in modulating the summer precipitation over northeastern South America, though the isolated effect of the easterly waves is weak. In contrast, the high-frequency variability for the TNA during the austral winter is mainly due to wave-type westward traveling tropical disturbances. These disturbances have an important role in modulating the daily precipitation of northern part of the South America during the austral winter. Received June 28, 2002; accepted July 24, 2002 Published online: March 20, 2003     

太平洋大尺度环流数值模拟 Ⅲ：季节变化

本文在年平均环流数值模拟基础上,用季节变化的大气强迫场又积分了12年,并对由模拟得到的太平洋海面起伏、洋流、温度、海表热通量和上层热储存率等的季节变化特征作了较为详细的阐述和与已有观测结果进行了比较,事实证明,模式基本上模拟出了观测到的太平洋大尺度环流基本特征及其季节变化,证实基于理论考虑设计的IAP OGCM模式具有较好的性能和对实际环流的模拟能力,有些结果并优于国外一些具有同等分辨率的海洋模式。     

北半球东半部对流层夏季平均环流形成物理机制的流体模拟实验

在旋转流体盘中做物理实验 ,模拟研究北半球东半部对流层夏季平均大气环流的形成物理机制。用镍铬电阻丝通电加热实验盘底作为热源 ,用冷水循环的铜管对实验盘底制冷作为冷源。将热源及冷源分布在绘有北半球极赤射面投影地图的底面上。人工地制造出中高纬西风带及越赤道气流模型。用流体物理模拟实验方法研究北半球东半部对流层夏季平均大气环流物理机制。逐个地试验了海陆温差、青藏高原地形及其高空热源、中高纬西风带 ,及来自南半球的越赤道气流的作用     

Cross-season relation of the South China Sea precipitation variability between winter and summer

The present study reveals cross-season connections of rainfall variability in the South China Sea (SCS) region between winter and summer. Rainfall anomalies over northern South China Sea in boreal summer tend to be preceded by the same sign rainfall anomalies over southern South China Sea in boreal winter (denoted as in-phase relation) and succeeded by opposite sign rainfall anomalies over southern South China Sea in the following winter (denoted as out-of-phase relation). Analysis shows that the in-phase relation from winter to summer occurs more often in El Niño/La Niña decaying years and the out-of-phase relation from summer to winter appears more frequently in El Niño/La Niña developing years. In the summer during the El Niño/La Niña decaying years, cold/warm and warm/cold sea surface temperature (SST) anomalies develop in tropical central North Pacific and the North Indian Ocean, respectively, forming an east–west contrast pattern. The in-phase relation is associated with the influence of anomalous heating/cooling over the equatorial central Pacific during the mature phase of El Niño/La Niña events that suppresses/enhances precipitation over southern South China Sea and the impact of the above east–west SST anomaly pattern that reduces/increases precipitation over northern South China Sea during the following summer. The impact of the east–west contrast SST anomaly pattern is confirmed by numerical experiments with specified SST anomalies. In the El Niño/La Niña developing years, regional air-sea interactions induce cold/warm SST anomalies in the equatorial western North Pacific. The out-of-phase relation is associated with a Rossby wave type response to anomalous heating/cooling over the equatorial central Pacific during summer and the combined effect of warm/cold SST anomalies in the equatorial central Pacific and cold/warm SST anomalies in the western North Pacific during the mature phase of El Niño/La Niña events.     

A NUMERICAL STUDY OF THE VARIATIONS AND DISTRIBUTIONS OF TROPOSPHERIC OZONE AND ITS PRECURSORS OVER CHINA*

By means of a three-dimensional meteorological model (MM5) and a chemical model,the distributions of tropospheric ozone and its precursors over China have been simulated in summer and winter time,16-18 August 1994 and 7-9 January 1995.The distribution of ozone over the Tibetan Plateau in summer time is deeply discussed.The simulated results indicate that thedistributions of surface ozone and NO_x are in good agreement with observed results,and human activities and photochemical reactions are the main factors controlling the surface ozone and NO_x concentrations.In addition,higher ozone concentrations are coincided with the air convergence,and the lower concentrations are related to the air divergence.In summer,over the Tibetan Plateau the strong flow convergence results in higher ozone concentrations in the lower troposphere:and the strong flow divergence results in lower ozone concentrations in the upper troposphere.In winter time ozone concentrations show large-scale characteristics controlled by westerly flow,and in the jet area they are lower than those outside the jet.     

Intensified Eastward and Northward Propagation of Tropical Intraseasonal Oscillation over the Equatorial Indian Ocean in a Global Warming Scenario

Northward propagation in summer and eastward propagation in winter are two distinguished features of tropical intraseasonal oscillation(TISO) over the equatorial Indian Ocean.According to numerical modeling results,under a global warming scenario,both propagations were intensified.The enhanced northward propagation in summer can be attributed to the enhanced atmosphere-ocean interaction and the strengthened mean southerly wind;and the intensified eastward propagation in winter is associated with the enhanced convection-wind coupling process and the strengthened equatorial Kevin wave.Future changes of TISO propagations need to be explored in more climate models.     

冬夏季环流隔季相关的数值试验

利用海气耦合和大气气候模式研究东亚冬季风异常对夏季环流的影响, 结果表明, 东亚冬季风异常对于后期环流及海洋状态异常都起了很大的作用.一般情况下, 强的冬季风与后期弱的东亚夏季风和较强的南海季风相对应.与强(弱)冬季风异常相关的风应力的改变可以使热带太平洋海温从冬季至夏季呈现La Nina (El Nio)型异常分布.试验得到的由冬季风异常所产生的海洋及夏季环流的变化与实况是相当接近的.在异常的冬季风偏北风分量强迫下, 西太平洋上形成的偏差气旋环流在夏季已不存在, 这时东亚夏季风反而增强.而冬季赤道西风分量所产生的影响, 则在西太平洋上形成显著的偏差气旋环流, 使东亚副热带夏季风减弱, 南海夏季风加强.对于东亚大气环流而言, 与强弱冬季风对应的热带海洋海温异常强迫下, 不仅是冬季, 后期春季和夏季环流的特征都能得到很好的模拟.但是从分区看, 西太平洋暖池区的海温异常比东太平洋更为重要.单纯的热带中东太平洋的海温异常对东亚大气环流的影响主要表现在冬季, 对后期的影响并不十分清楚.整个热带海洋的异常型分布(不论是El Nio还是La Nia)型, 对冬夏季风的影响是重要的, 而单纯的某个地区的海温异常都比它的整体影响要小.从试验结果看, 海温在大尺度冬夏季环流的隔季相关中起了十分重要的作用.     

El Nio和La Nia冬季增强型和减弱型及其对中国夏季旱涝的影响

根据 El Nino和 La Nina发生以后冬季赤道东太平洋海温距平的月际差定义了 El Nino和 La Nina冬季增强型和冬季减弱型 ,讨论了 El Nino和 La Nina冬季增强型和减弱型冬、春、夏季大气环流、东亚季风及我国夏季降水和旱涝分布的特征 .我国夏季降水和旱涝有明显差异的四种不同分布型可能与冬季所处 ENSO循环的不同阶段以及大气环流和东亚季风对它的不同响应有关 .提出了从 El Nino和 La Nina冬季不同型→大气环流和东亚季风→我国夏季降水和旱涝分布型的物理统计概念模型 .     

冬,春季海温异常关键区对长江中下游夏季降水影响的敏感性试验

本文利用9层菱形截断15波的全球大气环流谱模式（L9R15）研究了前期冬季和春季海温异常的关键区对我国长江中下游地区夏季降水的影响,数值试验结果表明,冬季赤道东太平洋和黑潮区海温异常及春季印度洋和黑潮区海温异常使得长江中下游地区的夏季降水明显增多,同时500hPa副热带高压和100hPa南亚高压增强,但从范围和强度上来看,冬季赤道东太平洋和黑潮区海温异常时我国西南至长江中下游地区一带的夏季降水异常比春季印度洋和黑潮区海温异常时更明显,由此证实了观测资料的分析结果。     

南海夏季风强弱年环流形势与热带对流特点对比分析

利用NCEP/NCAR(美国国家环境预报中心/国家大气研究中心)再分析资料,对南海强夏季风年和弱夏季风年进行合成分析,结果表明,无论是在夏季风爆发前的1月份或是夏季风盛行的7月份,强弱夏季风年的平均经圈环流和平均纬圈环流都有明显差异。在强夏季风年,1月份的哈特莱环流、7月份的瓦克环流和季风经圈环流都比弱夏季风年同期的明显。强夏季风年的西太平洋副热带高压比弱夏季风年明显偏弱。利用OLR资料分析强夏季风年(1981年)和弱夏季风年(1983)4～9月份赤道东印度洋和南海对流活动的季节内振荡,发现在南海强夏季风年,季节内振荡的次数偏少而强度偏强,在弱夏季风年,季节内振荡的次数偏多而强度偏弱。相比之下,在南海强夏季风年,赤道东印度洋的季节内振荡比南海的更具典型性。