共查询到20条相似文献，搜索用时 15 毫秒
1.
Multi-scale Cyclone Activity in the Changjiang River–Huaihe River Valleys during Spring and Its Relationship with Rainfall Anomalies 总被引：4，自引：0，他引：4
Based on the recognition framework of the outermost closed contours of cyclones, an automated identification algorithm capable of identifying the multi-scale cyclones that occur during spring in the Changjiang River–Huaihe River valleys(CHV)were developed. We studied the characteristics of the multi-scale cyclone activity that affects CHV and its relationship with rainfall during spring since 1979. The results indicated that the automated identification algorithm for cyclones proposed in this paper could intuitively identify multi-scale cyclones that affect CHV. The algorithm allows for effectively describing the shape and coverage area of the closed contours around the periphery of cyclones. We found that, compared to the meso- and sub-synoptic scale cyclone activities, the synoptic-scale cyclone activity showed more intimate correlation with the overall activity intensity of multi-scale CHV cyclones during spring. However, the frequency of occurrence of sub-synoptic scale cyclones was the highest, and their effect on changes in CHV cyclone activity could not be ignored. Based on the area of impact and the depth of the cyclones, the sub-synoptic scale, synoptic scale and comprehensive cyclone intensity indices were further defined, which showed a positive correlation with rainfall in CHV during spring. Additionally, the comprehensive cyclone intensity index was a good indicator of strong rainfall events. 相似文献
2.
Based on an analysis of the relationship between the tropical cyclone genesis frequency and large-scale circulation anomaly in NCEP reanalysis, large-scale atmosphere circulation information forecast by the JAMSTEC SINTEX-F coupled model is used to build a statistical model to predict the cyclogenesis frequency over the South China Sea and the western North Pacific. The SINTEX-F coupled model has relatively good prediction skill for some circulation features associated with the cyclogenesis frequency including sea level pressure, wind vertical shear, Intertropical Convergence Zone and cross-equatorial air flows. Predictors derived from these large-scale circulations have good relationships with the cyclogenesis frequency over the South China Sea and the western North Pacific. A multivariate linear regression （MLR） model is further designed using these predictors. This model shows good prediction skill with the anomaly correlation coefficient reaching, based on the cross validation, 0.71 between the observed and predicted cyclogenesis frequency. However, it also shows relatively large prediction errors in extreme tropical cyclone years （1994 and 1998, for example）. 相似文献
3.
The paper shows the statistical analysis of cyclone tracks that have influence on the western Antarcticregion.Based on the conditions of cyclone movement and its impact upon the weather,cyclone tracks areclassified into three categories,i.e.,the track moving towards the northern tip of the Antarctic Peninsula,southern track,and northern track.Moreover,in this paper,the frequency distributions of cyclone tracks,the major tracks with higherfrequencies,the original region of Antarctic cyclones and the seasonal features of Antarctic cyclones have beenanalyzed.The results show that there are higher cyclogeneses in summer,whereas relatively fewer cycloge-neses in winter,and cyclone numbers in transitional seasons are close to the climatological average.Theanalysis also shows that the moving velocity of Antarctic cyclone is about the same in winter and summer.It obviously speed up during the transitional season. 相似文献
4.
ERA40再分析资料揭示的北半球和东亚地区温带气旋生成频率变化 总被引：6，自引：0，他引：6
本文利用欧洲中心再分析数据ERA40的6小时间隔海平面气压场和一种改进的客观判定和追踪方法研究19582001年北半球和东亚地区温带气旋生成频率的气候态、年代际变化及可能原因。结果表明:(1)北半球温带气旋的源地主要位于北美东部(落基山下游地区)、西北大西洋地区、格陵兰至欧洲北部地区、蒙古地区和日本至西北太平洋地区。大洋的西岸和陡峭地形的背风坡有利于大气斜压性的增强和正涡度的发展,从而有利于地面气旋的形成。(2)年、冬季和春季30°～60°N气旋生成数目呈现减少的变化趋势,60°～90°N地区的气旋生成数呈增加的变化趋势。这在一定程度上支持了北半球风暴路径北移的观点。60°N以南和以北的温带气旋数目同北极涛动指数(AO)分别呈现负相关和正相关,这种相关性在年、春季和秋季最为显著。(3)1 958—2001年东亚地区的年气旋数目呈现明显的年代际变化。20世纪60年代至80年代中期40°～60°N、80°～140°E地区气旋数目呈增加趋势,而80年代中期之后温带气旋数目则锐减,主要原因是80年代以后该地区大气斜压性减弱,更高纬度地区的大气斜压性增强,从而导致了气旋源地的北移。在较低纬带的20°～40°N、110°～160°E地区气旋数目线性增加,这主要是由于位于40°～55°N的北太平洋风暴轴有向低纬度偏移的变化趋势造成的。 相似文献
5.
Judit Bartholy Rita Pongrácz Margit Pattantyús-Ábrahám 《Theoretical and Applied Climatology》2009,96(1-2):133-144
Midlatitude cyclones are analyzed on a selected region covering most of southern Europe and the western part of the Mediterranean Sea (35–50°N, 10°W–25°E). On the basis of mean sea level pressure fields of the ECMWF (European Centre for Medium-range Weather Forecast) Reanalysis Dataset (ERA-40), detailed evaluation of Mediterranean cyclones is accomplished for the period between 1957 and 2002 on a 1° horizontal resolution grid. Cyclone centers are identified and their paths are tracked with a 6-h time step (using 00 UTC, 06 UTC, 12 UTC, and 18 UTC). Decadal, annual, and seasonal statistical analysis of cyclone tracks includes the study of the genesis, frequency, and activity of the Mediterranean cyclones as well as the variability of cyclone tracks. The results suggest that the cyclone frequency in the western Mediterranean region increased in summer and autumn, and decreased in winter and spring. A special belt-shaped area is identified, which plays a special role in cyclogenesis, and also, the cyclone tracks often remain within this belt. An overall decreasing trend is detected in winter and spring in the entire Mediterranean belt, while cyclone frequency increased in autumn. The largest positive and negative trend coefficients are identified in summer. 相似文献
6.
陆面热力异常与东亚夏季中纬度气旋年代际变化的联系 总被引：1，自引：0，他引：1
基于欧洲中期预报中心的再分析数据ERA-interim,利用统计学方法分析了1979—2013年期间东亚中纬度地区气旋生成频率和陆面热力异常的年代际变化及两者的可能联系。结果表明,东亚中纬度地区存在气旋活动频繁的气旋源地,该地区的温带气旋生成频率具有明显的年代际变化,1990年之前气旋生成频率偏多,1990s至今偏少,而且东亚中纬度地区陆面热力异常的变化有明显的年代际增暖信号;进一步的分析发现,东亚夏季中纬度气旋活动的年代际变化与陆面异常异常之间存在密切的联系,东亚中纬度地区陆面年代际增暖,是引起温度气旋活动年代际减弱的一个重要原因。由于陆面增暖的非均匀性,在50°N以北存在一个影响中纬度气旋生成频率的关键区,关键区陆面的年代际异常增暖,导致气旋源地温度经向梯度减弱,大气斜压性随之减弱,从而使得气旋生成频率年代际减少。 相似文献
7.
Summary Based on the six-hourly re-analysis sea-level pressure data of the European Centre for Medium-Range Weather Forecast (ECMWF)
a cyclone statistics for the Arctic region north of 60° is elaborated for the period 1 November 1986 to 31 October 1991. For
each low pressure center on a weather map its location, central pressure and horizontal pressure gradients in E, W, N, and
S direction are determined. Furthermore, cyclone centers are followed with time to calculate trajectories, pressure tendencies,
and lifetimes.
A horizontal grid of 300 km × 300 km is used as unit area for the statistical computations. A unit area experiences about
20 cyclone passages per year (range 5–40). On the average, six cyclones occur simultaneously in the Arctic region. Lifetimes
vary from 6 h to 15 days.
The annual cyclone activity over the 5-year period is nearly the same. Cyclones are more frequent in summer (about 94 per
month) than in winter (77 per month). In general summer cyclones are weaker than winter cyclones. On the average, the minimum
central pressure during the lifetime of a cyclone is about 1000 hPa (typical range 980–1020) in summer and about 988 hPa (typical
range 940–1030) in winter.
In winter, a zone of high cyclone frequency extends from the region near Iceland over the Greenland Sea, Barents Sea, and
Kara Sea to the Laptev Sea while the interior of the Arctic shows little cyclone frequency. In summer, the region near Iceland
and the interior of the Arctic are separate centers of high cyclone frequency. Both in winter and summer very high cyclone
frequencies are observed over the northern Baffin Bay. The regional distribution of mean central pressures and maximum pressure
gradients roughly follows the distribution of cyclone frequencies except for the Baffin Bay cyclones which are generally weak.
Cyclolysis dominates cyclogenesis over largest parts of the Arctic. Regions of high cyclone frequency are also regions of
frequent cyclogenesis and frequent cyclolysis. One third of all cyclones is generated in a region with an already existing
cyclonic circulation.
Cyclones in the Fram Strait are studied in more detail because of their special impact on the ice export from the Arctic Ocean
to the Atlantic Ocean. On the average, there are 5 cyclones per month. the cyclone frequency in the Fram Strait is higher
during the winter period than during the summer period. This is in contrast to the overall Arctic frequency which is higher
in summer than in winter. Cyclogenesis predominates in winter and cyclolysis in summer in the Fram Strait. The most frequent
direction of motion is from SW to NE.
Received November, 1999 Revised June 22, 2000 相似文献
8.
用1958到1989年共32年资料对东亚及西太平洋地区的锋面气旋做了统计研究,气旋生成有两个主要的集中区,蒙古生成区次数最多,沿海生成区次之并还可以分为两个分区。各生成区中心位置和中心数值随季节有不同的变化。 气旋中心气压24小时变化值呈负偏态分布,海洋地区气旋的负偏度更大,爆发性气旋主要出现在海洋上,沿海地区也时有发生。有明显年际、月际变化,主要发生在冬季,次为春季.文中还对爆发性气旋各种特征参数做了详细统计。 用计算气旋活动的相对变率方法,定出了四季气旋主要活动路径。 相似文献
9.
东半球500hPa闭合低压系统的统计分析 总被引：1，自引：0，他引：1
通过分析５００ｈＰａ东半球闭合低压系统，研究其气候规律。低压活动次数有年际、月际、季际变化。低压活动于中高纬度带，主要集中于两大地区，第一区是西太平洋及大陆东岸，第二区是东欧地区。第一区中心夏季向西移到大陆上，强度增大，对中国气候有重要作用。低压中心高度值的频数分布是双峰型。低压生命期比阻塞高压还长些。强低压主要出现在大陆高纬地带和西太平洋。强发展的低压多数出现在西太平洋。亚洲低压移动路径有两条，一条从西西伯利亚北部到库页岛，一条从咸海东移到库页岛 相似文献
10.
Based on NCEP/CFSR 0.5° reanalysis data and the best track data from the Japan Tokyo Typhoon Center,composite and comparative analyses demonstrate the asymmetrical structures of the temperature and humidity in tropical cyclones over the Western North Pacific and the South China Sea from 1979 to 2010.The results are shown as follows.(1) With intensifying tropical cyclones,the flow field tends to become gradually more axisymmetric;however,the asymmetry of the specific humidity in the outer regions is more obvious.(2) In general,tropical cyclones have a non-uniform,vertical, "double warm-core" structure.The "warm-cores" in the lower level of weak tropical cyclones and in the higher level of strong tropical cyclones are the stronger of the two.(3) The distribution area of a "warm-core" is enhanced with cyclone intensification and tends to become more axisymmetric.At 200 hPa,the "warm-core" of a weak cyclone has a weak anticyclone in the center,whereas that of a strong cyclone has a weak cyclone in the center.(4)The "wet-core" of a tropical cyclone is primarily located in the lower level(700-850 hPa).With the cyclone's intensification,the intensity of the "wet-core" increases and the scope of the 0.8 g kg~(-1) specific humidity anomaly tends to expand to higher levels.(5) With the cyclone's deepening,the pseudo-equivalent potential temperature at different levels in different regions increases.In addition,the largest warming rates at each intensity level in the different regions occur in the core area,followed in turn by the envelope and outer areas. 相似文献
11.
利用江苏近10 a（2005-2014年）暖季（5-9月）69站逐时降水资料,详细分析了短时强降水的空间分布、年际变化、季节内演变以及日变化特征。分析结果表明：短时强降水空间分布不均,整体上北部比南部活跃,最活跃区均位于沿淮西部,高强度短时强降水多发生在淮北东部,且空间分布集中。近10 a来江苏短时强降水整体呈减少趋势,主要表现为北部地区减少最为显著。短时强降水季节内分布不均匀,以7月最为活跃,高强度短时强降水在8月最为频繁;其逐候分布显示,梅期短时强降水骤增,于7月第2候达到峰值,盛夏期间高强度短时强降水增多,8月第3候达到峰值。江苏短时强降水的日变化整体呈双峰结构,主峰和次峰分别出现在傍晚17时（北京时间,下同）和清晨07时,高强度短时强降水多发于午后;短时强降水日变化存在季节内演变的阶段性特征和地域性差异,其中梅期和盛夏两个高发阶段均呈单峰结构,但梅期峰值出现在清晨,盛夏阶段峰值则出现在傍晚;由南向北,日变化特征由单峰向双峰、多峰演变,在淮河以南地区日峰值大多出现在午后至傍晚,而淮河以北地区多出现在夜间至清晨。 相似文献
12.
浙江省热带气旋倒槽暴雨气候特征研究 总被引：2，自引：1，他引：2
基于近40年热带气旋（Tropical Cyclone,简称TC）日降水和最佳路径等观测资料,采用数理统计、天气学分析等方法对浙江省TC倒槽暴雨分布特征及其与TC的相互关系进行研究。（1）浙江省年均会发生1.8次TC倒槽暴雨,占TC暴雨总数约4成,是浙江省台风暴雨中的一种重要形式。每年8—9月是TC倒槽暴雨高发期,暴雨主要发生在宁波南部至温州一带沿海地区,暴雨中心多位于台州和温州沿海。（2）引发浙江省TC倒槽暴雨的热带气旋多在粤东至浙南登陆之后北上转向或西北行,登陆当天最易发生暴雨且雨强最强。暴雨发生时,福建中部沿海经海峡至台湾东北部一带是TC高频活动区。（3）距TC中心2.5~5.0纬距之间和TC东北偏北象限是倒槽暴雨中心的高频落区;较强暴雨发生在TC强度为热带低压时,且强中心易位于TC东北偏东象限,极端强降水发生主要与热带低压和副高等相互作用形成的偏东暖湿急流、TC倒槽强辐合和TC东北偏东象限中尺度深对流系统频繁活动有关。 相似文献
13.
利用1953-2007年NCEP／NCAR再分析逐日海平面气压场资料,统计分析东亚地区北方气旋和南方气旋的时间和地域分布特征。结果表明：南、北气旋活动频数存在明显的年际和年代际变化,伴随着一次全球性的年代际气候跃变,20世纪80年代初期北方气旋活动频数出现了显著的突变。从月际分布可知,5月北方气旋频数最多,8月南方气旋频数最多;春季北方气旋活动频繁,存在着明显的两个高值中心,分另Ij位于蒙古国中部和中国东北地区北部;夏季南方气旋活动频繁,主要集中在中国东部沿海及日本南部海面。南北气旋活动频数的季节变化与大气环流的变化密切相关。相关统计结果可增加对东亚温带气旋活动规律的认识和了解,并为预测和预报提供参考。 相似文献
14.
利用中国气象局提供的1951—2018年台风最佳路径数据集,筛选经过江苏的热带气旋个例,发现历史上所有经过江苏的热带气旋都发生在夏秋季节。基于春季130种气候信号指数,利用C4.5决策树算法建立“台风是否经过江苏”的预测模型。结果表明:基于C4.5算法的决策树能够较为直观且准确地对每年“台风是否经过江苏”进行预测。利用1951—2000年(51 a)的数据样本进行训练,学习准确率达到82%,利用2001—2018年(18 a)的数据样本对模型进行泛化能力测试,测试准确率达到83.3%,最后利用2019年第9号热带气旋“利奇马”经过江苏的事实进行个例检验,符合决策树规则C。可以证明C4.5算法对“台风是否经过江苏”的预测具有较高的准确率和通用性。 相似文献
15.
M. C. Serreze J. E. Box R. G. Barry J. E. Walsh 《Meteorology and Atmospheric Physics》1993,51(3-4):147-164
Summary Synoptic activity for the Arctic is examined for the period 1952–1989 using the National Meteorological Center sea level pressure data set. Winter cyclone activity is most common near Iceland, between Svalbard and Scandinavia, the Norwegian and Kara seas, Baffin Bay and the eastern Canadian Arctic Archipelago; the strongest systems are found in the Iceland and Norwegian seas. Mean cyclone tracks, prepared for 1975–1989, confirm that winter cyclones most frequently enter the Arctic from the Norwegian and Barents seas. Winter anticyclones are most frequent and strongest over Siberia and Alaska/Yukon, with additional frequency maxima of weaker systems found over the central Arctic Ocean and Greenland.During summer, cyclonic activity remains common in the same regions as observed for winter, but increases over Siberia, the Canadian Arctic Archipelago and the Central Aretic, related to cyclogenesis over northern parts of Eurasia and North America. Eurasian cyclones tend to enter the Aretic Ocean from the Laptev Sea eastward to the Chukchi Sea, augmenting the influx of systems from the Norwegian and Barents seas. The Siberian and Alaska/Yukon anticyclone centers disappear, with anticyclone maxima forming over the Kara, Laptev, East Siberian and Beaufort seas, and southeastward across Canada. Summer cyclones and anticyclones exhibit little regional variability in mean central pressure, and are typically 5–10 mb weaker than their winter counterparts.North of 65°N, cyclone and anticyclone activity peaks curing summer, and is at a minimum during winter. Trends in cyclone and anticyclone activity north of 65°N are examined through least squares regression. Since 1952, significant positive trends are found for cyclone numbers during winter, spring and summer, and for anticyclone numbers during spring, summer and autumn.With 11 Figures 相似文献
16.
用Zwack-Okossi方程对一次爆发性气旋的诊断分析 总被引：1，自引：1，他引：0
利用ＥＣＭＷＦ资料作初始场,ＭＭ４模式输出的结果和Ｚｗ ａｃｋ－ Ｏｋｏｓｓｉ方程作诊断工具,对１９８１年１２月２０～２１日生成在西北太平洋的一次爆发性气旋进行了数值试验和诊断分析。得到：气旋的爆发性发展主要是由正涡度平流和非地转场激发,其中涡度平流对气旋发展贡献最大,温度平流的影响则较小,两者主要是在对流层高层起作用,而非地转场则在对流层低层起主要作用。由水汽造成的非绝热加热对本次爆发性气旋的生成影响不大,积云对流潜热的反馈作用更小。另外次天气尺度系统对爆发性气旋形成贡献较小 相似文献
17.
季风涡旋对热带气旋生成影响的理想试验研究 总被引：1，自引：0，他引：1
利用新一代非静力平衡中尺度数值模式WRF_ARW（3.3.1版本）模拟季风涡旋中热带气旋生成的过程,从动力和热力作用两方面分析大尺度季风涡旋对热带气旋生成的影响。结果表明:从动力学角度来看,能提供较大环境场涡度的季风涡旋不利于扰动涡旋快速发展成热带气旋。初始阶段,由于季风涡旋尺度大,垂直涡度径向梯度弱。而垂直涡度径向梯度的强弱可以通过“涡度隔离”效应影响对流单体向涡旋中心的聚集合并过程。随着扰动的组织化,径向入流对涡度的平流作用越来越重要。对流单体相对最大风速半径的位置对热带气旋生成作用明显,当其集中在最大风速半径附近时涡旋容易快速发展。此外,环境场相对涡度与热带气旋的尺度存在显著正相关。初始尺度大的涡旋最终具有较大的外围尺度,其涡度的分布范围也更广。从热力学角度来说,较大的环境场相对湿度有利于热带气旋的生成。虽然较大的环境场湿度能够诱发较强的外围对流,但同时也会使最大风速半径以内存在丰富的对流,后者能够提供充分的内区非绝热加热,降低中心气压,促进涡旋发展。 相似文献
18.
Simple and easily reproducible techniques have been used to construct two objective cyclone climatologies of the North Atlantic-European sector. The goal of this study is to increase understanding of cyclones with the potential to cause damage, in particular, those reaching Beaufort category 7 and above. The two climatologies constructed here span the period 1979–2000 and have been developed from reanalysis mean sea level pressure data from the ECMWF (European Centre for Medium Range Weather Forecasts) and NCEP (National Centres for Environmental Prediction). The ECMWF reanalysis data are only available for 15 years, and have been extended from 1994 using operational analyses. The major temporal and spatial characteristics of North Atlantic cyclones are examined and a comparison between the climatologies developed from the two data sets is carried out. The well-known cyclogenesis regions along the east coast of the United States and to the southeast of Greenland are replicated by both reanalyses, as is the characteristic southwest/northeast orientation of the dominant cyclone track across the Atlantic basin. However, only weak correlations are found between the time series of cyclone frequency produced from the two reanalyses, and this is particularly true for the lower intensity Beaufort Scale category 0–6 cyclones. This result, together with the large differences in the spatial distribution of cyclones over Greenland for Beaufort Scale 0–6 cyclones, indicates the NCEP reanalyses generates fewer systems than the ECMWF reanalyses. The overall conclusion is that the ECMWF mean sea level pressure data produce a more comprehensive climatology of North Atlantic cyclones at all scales. 相似文献
19.
登陆热带气旋研究的进展 总被引：120，自引：12，他引：120
随着大气探测技术的发展 ,登陆热带气旋研究已经成为热带气旋研究中一个新的领域。新的探测技术能初步揭示出热带气旋登陆过程中发生的多种改变。近年来 ,国内外科学家实施了一系列外场科学试验 (Fieldscientificexperi ments) ,对登陆热带气旋进行探测和研究 ,旨在提高预报的准确率。登陆热带气旋研究内容包括 :海岸和内陆山脉地形影响 ,结构和强度变化 ,登陆热带气旋的暴雨强度和分布 ,大风强度和分布 ,风暴潮强度和范围 ,登陆热带气旋在陆上的维持机制 ,陆地涡旋的路径和入海加强 ,边界层结构 ,陆面过程和能量交换 ,变性过程等。研究采用外场科学试验与数值模拟相结合的方法。模拟或预报模式中使用同化资料尤其是卫星同化资料来构造初值场 ,取得较好结果。登陆热带气旋的研究目前正在展开 ,并取得了一些重要结果。研究表明 ,潜热释放和斜压位能释放是近海或登陆热带气旋加强或维持的两种主要能源。这两种能量可分别从水汽输送和热带气旋与中纬度环流的相互作用中获得。另外 ,陆面饱和湿地或水面的潜热输送、热带气旋与中尺度涡旋或热带云团的合并以及高空流出气流强辐散也对其加强和维持有利。世界气象组织的热带气象研究计划 (TMRP)正在组织对这一领域的总结和下一步的研究计划。这项研究将对预报和 相似文献
20.
2007年西北太平洋热带气旋活动综述 总被引：2，自引：2，他引：0
利用热带气旋年鉴、海温和大气环流再分析资料,分析2007年西北太平洋(包括南海)的风暴级以上热带气旋(简称TC)活动状况及海-气条件.结果表明,相对于气候平均值,2007年西北太平洋TC活动的季节峰期推后了约2个月,源地明显偏北,生成点纬度发生了2次明显跃变,年度TC的总体活动较弱,但个体的强度较强,路径以西北行为主,登陆比例偏大.影响上述TC活动特征的一个重要原因是年内ENSO循环的位相使得上半年的大气环流不利因素居多,而下半年大尺度上升运动、热带辐合带均较强,副高偏北、局地垂直风切变较小和对流层低层较强的扰动活动等条件,也十分有利热带气旋活动. 相似文献