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1.
多因子协同作用对1992年和1998年黄淮地区夏季降水异常的影响 总被引：1，自引：0，他引：1
1991年5月和1997年4月赤道中东太平洋均发生了El Ni?o事件,但是1992年夏季黄淮地区降水异常偏少,而1998年夏季却异常偏多。分析结果显示,1992年夏季西北太平洋副热带高压（以下简称副高）偏东,中高纬阻塞高压偏弱,黄淮地区降水异常偏少;而1998年夏季,副高偏西,中高纬阻塞高压活动频繁,黄淮地区降水异常偏多。对海温外强迫信号的诊断和数值模式试验显示:当西太平洋对流活动偏弱时,有利于副高西伸;鄂霍茨克海及以东海温偏高时,其上空的阻塞高压增强;北大西洋中纬度地区海温偏高时,有利于后期乌拉尔山高压脊明显增强。即在赤道中东太平洋发生El Ni?o事件的背景下,西太平洋对流、鄂霍茨克海附近亲潮区域和北大西洋中纬度区域海温异常可能是导致黄淮区域1992年夏季和1998年夏季降水差异大的主要原因。该工作显示仅根据El Ni?o事件的发生时间和强度无法完全预测黄淮地区夏季降水变化,需要综合考虑西太平洋对流、鄂霍茨克海附近海域和北大西洋中纬度区域海温异常对季风环流的影响,从多因子协同作用的角度诊断和预测黄淮地区夏季降水异常趋势,提高预测能力。 相似文献
2.
华南夏季风降水开始日的异常与前冬大气环流和海温的关系 总被引：3，自引：2，他引：1
利用1951～2004年NCEP/NCAR再分析资料及ERSST海温资料,研究了华南夏季风降水开始日期的变化特征及其与前期冬季大气环流和海温的关系。小波分析表明,夏季风降水开始日期具有明显的年际和年代际变化,年际变化以准2～3年变化为主,年代际变化周期约16年。华南夏季风降水开始偏早年在大气环流上的前兆信号表现为前期冬季乌拉尔山阻塞高压偏强、东亚大槽较深,阿留申低压偏强,冷空气活动偏强。冬季,鄂霍次克海附近的海温异常为华南夏季风降水开始迟早有物理意义的、稳定正相关前兆信号。合成分析表明,冬季鄂霍次克海附近SST正异常时,5月100 hPa青藏高压偏东偏北偏弱,异常偏西风控制华南;850 hPa环流在华南表现为东北风,华南受冷空气影响为主,华南夏季风降水开始日期偏晚。相反时,若冬季鄂霍次克海附近SST负异常,5月100 hPa青藏高压偏西偏南偏强,异常偏东风控制华南;850 hPa环流在华南表现为偏南风,华南受热带系统影响为主,华南夏季风降水开始日期偏早。并提出冬季中高纬度地区冷空气活动影响华南夏季风降水开始日异常的物理机制。 相似文献
3.
利用1961-2009年NCEP/NCAR再分析资料及ERSST-v3海温资料,研究了湘中雨季结束日期的变化特征及其与前期大气环流和海温的关系.结果表明,近49 a湘中雨季结束日期具有较显著的年际和年代际变化特征,呈2.6天/10a的较显著变晚趋势.湘中雨季结束偏早(晚)年在大气环流上的前兆信号表现为前期冬春季北半球副热带高压、鄂霍茨克海高压和阿留申低压强度弱(强),东亚大槽较浅(深),冷空气活动偏弱(强).前期冬春季中东赤道及以北太平洋和印度洋海温异常是湘中雨季结束的重要短期气候预测信号,前期冬春季赤道中东太平洋、印度洋区域海温偏低(高),北太平洋区域海温偏高(低),湘中雨季结束日期偏早(晚). 相似文献
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《气象与环境学报》2016,(3)
利用常规气象观测资料和NCEP再分析资料对2013年12月1—8日常州地区一次持续性严重霾天气过程进行了综合分析。结果表明:常州地区此次持续性霾天气过程中高纬地区高层环流较平直,低层为弱西南暖湿气流,冷空气势力较弱;2013年11月30日常州地区位于地面"L"型高压顶部,偏西风对常州上游地区污染物的输送和12月1日清晨出现的逆温层,导致扩散条件较差是此次霾过程爆发的主要原因;持续的地面均压场控制和频繁出现的逆温层为霾提供了维持机制,12月9日的强冷空气造成了此次霾过程消散。持续性霾天气过程期间,温度露点差减小,相对湿度增大,风力减小,多为偏西偏南风,且近地面多为弱的上升运动,为霾的维持提供了稳定的层结和充足的水汽。常州地区此次霾天气过程的主要污染物为颗粒物(PM2.5、PM10),部分SO_2、NO_2及O_3等污染物通过协同转化作用生成颗粒物,导致霾粒子浓度剧增是此次霾过程爆发的重要内因;后向轨迹模式的模拟结果也表明常州上游地区污染物的输送对此次霾过程亦有贡献。 相似文献
5.
本文着重从气候变暖以来春防期高火险日数偏多年和偏少年北半球500hPa环流场背景分析,偏多年时距平场上正负中心形成以黑龙江省为中心自高纬向低纬呈"-,+"距平型,偏少年时距平场上正负中心形成以黑龙江省为中心自高纬向低纬呈"-,+"距平型.从前期北半球500hPa环流场异常形势演变,偏多年前期北半球500hPa距平场上极区为大范围正距平,极涡偏弱,鄂霍茨克海有阻塞高压存在,东亚大槽偏强,阿留申低压活跃,偏少年时前期极区为大范嗣负距平,极涡偏强,鄂霍茨克海没有明显的阻塞高压形势,东亚大槽偏弱,阿留申低压也不活跃.北半球500hPa环流场异常是造成春防期森林火险高火险日数多少重要原因,通过前期的环流背景对春防期高火险日数进行预测,进而做出春防期森林防火期趋势预测. 相似文献
6.
利用1961—2013年内蒙古地区102个气象台站的观测数据和NCEP再分析资料,分析了内蒙古地区2013年夏季降水特征和降水异常的成因。结果表明:内蒙古夏季降水的整体特点是雨带偏北,6、7月全区大部降水偏多,8月降水强度、范围减弱、减小。大气环流特征为东亚夏季风强度偏强,西北太平洋副热带高压偏强偏北,北太平洋涛动处于负位相,鄂霍次克海阻塞高压稳定维持。受鄂霍次克海阻塞高压阻挡,西北冷空气在内蒙古东北地区堆积,而西北太平洋的反气旋环流又将水汽源源不断的输送到此地,冷暖气流交汇造成该地区降水极端异常。 相似文献
7.
利用NCEP再分析资料、L波段雷达探空资料、常规气象资料及自动气象站资料和空气污染资料,对2005年12月25-28日重庆主城区一次重度霾天气过程进行了分析.结果表明:此次重度霾天气过程发生在一定天气背景下,500 hPa青藏高原南侧南支槽槽区宽广,槽前西南气流较为强盛,850 hPa重庆地区持续处于均压场控制,气压梯度小,水平风速弱,且影响重庆地区的冷空气活动少、强度弱,有利于重度霾的形成和维持;低层风速较小、中低层逆温层的持续存在、气温较低也是此次重度霾形成和维持的重要条件;在未达到饱和的情况下,适当增加湿度有利于霾的加强,霾天气过程中,气溶胶粒子的吸湿增长会使能见度更加恶化. 相似文献
8.
瞬变波活动与江淮地区夏季旱涝的关系 总被引：3，自引：0，他引：3
利用1951-2000年中国160站逐月降水量资料划分了江淮地区夏季旱涝年。通过对旱涝年500hPa高度距平场的合成分析发现：多雨年鄂霍茨克海阻塞高压稳定维持，少雨年鄂霍茨克海附近的高压脊减弱。为了了解江淮地区旱涝年500hPa中高纬环流形势异常的原因，计算了Eliassen-Palm通量，结果表明多雨年瞬变波对平均气流的强迫作用使经、纬向风异常分布有利于鄂霍茨克海阻塞形势的维持，冷空气向南输送增强，江淮地区降水偏多；少雨年瞬变波对平均气流的强迫作用使鄂霍茨克海高压脊减弱，冷空气向南输送减弱，江淮地区降水偏少。 相似文献
9.
2013/2014年东亚冬季风异常偏弱的可能成因 总被引：3，自引：2，他引：1
2005年之后东亚冬季风连续7年强度偏强,而2013/2014年冬季,东亚冬季风强度突然由强转弱,原因可能与前期秋季北极海冰的异常有关,受2013年秋季北极海冰异常影响,冬季西伯利亚高压偏弱,进而导致东亚冬季风偏弱以及我国气温偏高。季内,东亚冬季风强度变化显著,前冬偏弱,后冬偏强。受冬季风季节内变化影响,我国前冬暖、后冬冷;此外,前冬暖、后冬冷还受到北太平洋上空阻塞高压的异常活动影响,北太平洋地区的阻塞高压加强西移至日界线以西,导致东亚地区经向型环流加强,改变了前冬以纬向型为主的环流,前冬高纬地区堆积的冷空气向东亚地区侵袭。加之,前冬我国气温偏高,导致后冬我国多地降温显著,气温由偏高转偏低。而阻塞高压的西移可能与平流层环流的异常活动有关。 相似文献
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The rapid economic growth has increased trace gas emissions in East Asia, resulting in various environmental issues, including acid deposition, regional haze, air quality degradation, and climate change, which are critical to the human existence. In particular, air quality degradation became an object of rising concern in East Asian countries. In order to understand sources, transport, and chemical transformation of air pollutants, scientists have widely used atmospheric chemical transport models (CTMs) in East Asia. Here we review our knowledge related to the present air quality issues and their modeling, focusing on O3 and particulate matter in East Asia. We finally suggest a few recommendations for the next generation of air quality models to improve their capability and use in this region. 相似文献
12.
利用中国东北地区1981—2018年166个地面气象观测站资料, 定义了中国东北地区秋冬季霾日指数, 分析了年际尺度上该地区霾日数与同期大气环流异常的内在关系。结果表明: 中国东北地区秋冬季霾日指数存在显著的年际变化特征, 欧亚—太平洋遥相关型(Eurasia-Pacific Teleconnection Pattern, EUP)负位相、东亚大槽偏弱等大气环流异常配置导致中国东北地区秋冬季霾的发生频次增加。巴伦支海与喀拉海北部海域是影响中国东北地区秋冬季霾日年际变化的海冰关键区, 该区域海冰面积与霾日数呈显著负相关, 北极海冰通过改变大气环流间接影响中国东北地区秋冬季霾日发生频次, 当北极海冰异常偏少时, 东亚冬季风偏弱, 近地面风速偏低, 环境湿度偏高, 中国东北地区受东北亚异常反气旋西侧的异常偏南风控制, 且受“EUP”负位相模态影响, 东亚大槽减弱, 有利于大气污染物和水汽向中国东北地区输送, 该地区秋冬季霾的发生频次增加。 相似文献
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This study compares the impacts of interannual Arctic sea ice loss and ENSO events on winter haze days in mainland China through observational analyses and AGCM sensitivity experiments. The results suggest that (1) Arctic sea ice loss favors an increase in haze days in central–eastern China; (2) the impact of ENSO is overall contained within southern China, with increased (reduced) haze days during La Niña (El Niño) winters; and (3) the impacts from sea ice loss and ENSO are linearly additive. Mechanistically, Arctic sea ice loss causes quasi-barotropic positive height anomalies over the region from northern Europe to the Ural Mountains (Urals in brief) and weak and negative height anomalies over the region from central Asia to northeastern Asia. The former favors intensified frequency of the blocking over the regions from northern Europe to the Urals, whereas the latter favors an even air pressure distribution over Siberia, Mongolia, and East Asia. This large-scale circulation pattern favors more frequent occurrence of calm and steady weather in northern China and, as a consequence, increased occurrence of haze days. In comparison, La Niña (El Niño) exerts its influence along a tropical pathway by inducing a cyclonic (anticyclonic) lower-tropospheric atmospheric circulation response over the subtropical northwestern Pacific. The northeasterly (southwesterly) anomaly at the northwestern rear of the cyclone (anticyclone) causes reduced (intensified) rainfall over southeastern China, which favors increased (reduced) occurrence of haze days through the rain-washing effect. 相似文献
15.
江苏秋季霾的年代际变化特征及其影响因素分析 总被引：5，自引：0，他引：5
利用1961-2010年江苏地级市气象站资料分析了近50年江苏秋季霾的年代际变化特征,并从气候背景的影响方面探讨其形成变化的特点：少霾期,大气环流以及水汽输送特征都有利于污染物的输送和稀释;而在调整期,气象条件有所调整,但不显著;在显著上升期,气候背景场对霾的发生起到十分积极的作用。另外,1961-2010年大气净化次数显著减少。海温与霾的年代际变化存在密切关系,当霾日数不断上升时,印度洋到南海海域的海温升高,引起低层风场的辐合,并通过类似于Hadley环流形式使得东亚同经度的中纬度地区低层辐散,利于水汽通道转换,进而有利于霾天气的发生。 相似文献
16.
两类江淮大水的大气环流特征 总被引：5，自引：1，他引：5
文中研究了江淮流域特大洪涝的环流特征。江淮流域洪涝年全国降水有两类分布型:即江淮流域大水年中国降水偏多型和江淮流域大水其南北降水偏少型。研究了这两类降水分布型的环流特征,结果指出:北半球500 hPa位势高度场有着显著的差异。东亚大西洋相关链的建立(南海高压、梅雨槽和鄂霍茨克海高压)是江淮流域多雨的重要条件,而欧洲阻塞高压的建立在全国降水分布型中起着重要的作用。进而研究了东亚大西洋相关链与北太平洋海温的关系。 相似文献
17.
Based on the NCEP/NCAR reanalysis data and Chinese observational data during 1961–2013, atmospheric circulation patterns over East Asia in summer and their connection with precipitation and surface air temperature in eastern China as well as associated external forcing are investigated. Three patterns of the atmospheric circulation are identified, all with quasi-barotropic structures: (1) the East Asia/Pacific (EAP) pattern, (2) the Baikal Lake/Okhotsk Sea (BLOS) pattern, and (3) the eastern China/northern Okhotsk Sea (ECNOS) pattern. The positive EAP pattern significantly increases precipitation over the Yangtze River valley and favors cooling north of the Yangtze River and warming south of the Yangtze River in summer. The warm sea surface temperature anomalies over the tropical Indian Ocean suppress convection over the northwestern subtropical Pacific through the Ekman divergence induced by a Kelvin wave and excite the EAP pattern. The positive BLOS pattern is associated with below-average precipitation south of the Yangtze River and robust cooling over northeastern China. This pattern is triggered by anomalous spring sea ice concentration in the northern Barents Sea. The anomalous sea ice concentration contributes to a Rossby wave activity flux originating from the Greenland Sea, which propagates eastward to North Pacific. The positive ECNOS pattern leads to below-average precipitation and significant warming over northeastern China in summer. The reduced soil moisture associated with the earlier spring snowmelt enhances surface warming over Mongolia and northeastern China and the later spring snowmelt leads to surface cooling over Far East in summer, both of which are responsible for the formation of the ECNOS pattern. 相似文献
18.
Characteristics of Two General Circulation Patterns During Floods over the Changjiang-Huaihe River Valley 总被引：2，自引：0，他引：2 
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下载免费PDF全文 Characteristics of the atmospheric general circulation during the catastrophic floods over the Changjiang- Huaihe River Valley(CHRV)are investigated.There are two precipitation patterns over China in the CHRV flood years:the CHRV flood-whole country-wet(P1)pattern and the CHRV flood-south(north)side-dry (P2)pattern.The circulation analysis results show that there are obvious differences between the NH 500- hPa geopotential height fields of P1 and P2 precipitation patterns.The establishment of East Asia-Atlantic (EAA)correlation chain(the South China Sea(SCS)high-the Meiyu trough-the Okhotsk Sea high over East Asia)is a critical condition for excessive summer precipitation over the CHRV,while the European blocking high plays an important role in determining the precipitation pattern over China in the CHRV flood years.Besides,the relation between the EAA correlation chain and the sea surface temperature anomaly (SSTA)in the North Pacific is also studied. 相似文献
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Factors favorable to frequent extreme precipitation in the upper Yangtze River Valley 总被引：1，自引：0，他引：1
Extreme precipitation events in the upper Yangtze River Valley (YRV) have recently become an increasingly important focus in China because they often cause droughts and floods. Unfortunately, little is known about the climate processes responsible for these events. This paper investigates factors favorable to frequent extreme precipitation events in the upper YRV. Our results reveal that a weakened South China Sea summer monsoon trough, intensified Eurasian-Pacific blocking highs, an intensified South Asian High, a southward subtropical westerly jet and an intensified Western North Pacific Subtropical High (WNPSH) increase atmospheric instability and enhance the convergence of moisture over the upper YRV, which result in more extreme precipitation events. The snow depth over the eastern Tibetan Plateau (TP) in winter and sea surface temperature anomalies (SSTAs) over three key regions in summer are important external forcing factors in the atmospheric circulation anomalies. Deep snow on the Tibetan Plateau in winter can weaken the subsequent East Asian summer monsoon circulation above by increasing the soil moisture content in summer and weakening the land–sea thermal contrast over East Asia. The positive SSTA in the western North Pacific may affect southwestward extension of the WNPSH and the blocking high over northeastern Asia by arousing the East Asian-Pacific pattern. The positive SSTA in the North Atlantic can affect extreme precipitation event frequency in the upper YRV via a wave train pattern along the westerly jet between the North Atlantic and East Asia. A tripolar pattern from west to east over the Indian Ocean can strengthen moisture transport by enhancing Somali cross-equatorial flow. 相似文献