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1.
基于1960—2017年2 000多个气象台站逐日降水数据和中国气象局热带气旋(TC)最佳路径资料集,采用客观天气图分析法(OSAT)识别得到TC降水。研究表明,中国TC降水总体呈显著下降趋势,较12年前的研究结果下降趋势变缓;TC盛期(7~9月)降水占到TC总降水的78.5%,TC盛期降水和TC非盛期降水均呈显著下降趋势。TC降水气候趋势在空间分布上以减少为主要特征,并表现出明显的地域差异,自南向北呈"减少—增多—减少"的分布型,减少趋势中心位于广东和海南。按TC影响期最大强度分级(弱TC、中等强度TC和强TC)研究不同强度TC降水的变化,结果显示,强TC降水表现出显著减少趋势,主要决定着TC总降水的影响范围和趋势等主要特征。进一步分析发现,影响TC频数在1960—2017年呈显著减少趋势,并在1995年发生突变;对1995年前后2个时期的对比研究显示,与前一时期(1960—1994年)相比,后一时期(1995—2017年)影响TC活动频次在20°N以南的海域呈现出显著的减少趋势,减少大值中心位于南海北部,而且这一特征也主要由影响TC中的强TC所决定;强TC的这一变化趋势导致了华南地区尤其是广东和海南TC降水日数的减少,进而使得TC降水减少。 相似文献
2.
Based on the daily precipitation data of more than 2 000 meteorological stations from 1960 to 2017 and the tropical cyclone (TC) best-track data of the China Meteorological Administration, the TC precipitation was identified by the Objective Synoptic Analysis Technique (OSAT). The research shows that the TC precipitation in China has a significant downward trend, which is slower than that of the research results 12 years ago. The TC precipitation in the peaking season (July to Sepember) accounted for 78.5% of the total TC precipitation. Both TC precipitation in peaking season and other months showed a significant downward trend. The TC precipitation climate trend is mainly characterized by reduction in spatial distribution, and shows obvious regional differences. From south to north, there is a distribution of “decreasing-increasing-decreasing”, and the decreasing trend centers are located in Guangdong and Hainan. According to the maximum intensity in the TC influence period, we classified TCs into three levels (weak TCs, medium intensity TCs and strong TCs) and studied the variations of TC precipitation in different intensities. The results show that the strong TC precipitation shows a significant decrease trend, which mainly determines the influence range and trend of TC total precipitation. Further analysis found that the frequency of affecting TC showed a significant reduction trend during the time period of 1960-2017 and an abrupt shift occurred in 1995. A comparative study of the two periods before and after 1995 showed that compared with the previous period (1960-1994), the frequency of TCs in the latter period (1995-2017) showed a significant decreasing trend in the south of 20°N. The maximum decreasing center was located in the northern part of the South China Sea, and this feature was mainly affected by the strong TC. It was decided that this trend of strong TC led to a decrease trend in the number of precipitation days in South China, especially in Guangdong and Hainan, which led to a decrease trend in TC precipitation. 相似文献
3.
春季热带海温与北疆夏季极端降水的关系研究 总被引：1，自引：0，他引：1
基于1961—2017年北疆47站夏季逐日降水资料、NOAA海温资料和NCEP/NCAR再分析资料,利用90%分位确定北疆夏季单站降水阈值,得出极端降水量,讨论了春季热带海温与北疆夏季极端降水的关系。结果表明：北疆夏季极端降水和春季热带印度洋（20° S~15° N,50°~110° E）及赤道东太平洋（15° S~15° N,90°~180° W）海温呈正相关,两个关键区春季热带海温异常偏暖时,北疆夏季极端降水偏多,仅春季热带印度洋关键区海温异常偏暖时,北疆西北地区夏季极端降水偏多。当春季热带印度洋和赤道东太平洋关键区海温同时异常偏暖时,200 hPa西风急流轴明显偏南,500 hPa西西伯利亚和中亚地区低值系统活跃,南方路径输送的水汽增加,有利于北疆夏季极端降水的发生;仅春季热带印度洋关键区海温异常偏暖时,200 hPa西风急流强度增强,500 hPa西西伯利亚地区低值系统活跃,配合偏东路径的水汽输送,北疆西北地区夏季极端降水偏多。 相似文献
4.
西北地区空中水汽时空分布及变化趋势分析 总被引：69，自引：11，他引：58
使用NCEP/NCAR1958%D2000年再分析格点资料,分析了西北地区空中水汽和水汽输送的时空分布特征和变化趋势.结果表明:1)西北地区空中水汽地域分布主要集中在西北地区东部和西部的天山北部以及塔里木河流域盆地,而西北地区中部水汽含量较少,尤以青海的西部和北部为最;2)西北地区空中水汽主要来自印度洋孟加拉湾、南海以及阿拉伯海的水汽输送,北面还有一支来自西伯利亚和蒙古方向的水汽输送;3)西北地区空中水汽含量自50年代末至80年代中期呈明显下降趋势,而从80年代后期开始水汽又呈波动上升趋势.水汽增加地区主要在新疆北部沿河西走廊至甘肃中部祁连山区中段以及南疆盆地西部,而其它地区近年来水汽明显减少,其中减少幅度最大的地方位于西北中部的甘肃、青海、新疆交界处以及东部的陕西省;4)从空中水汽年代际变化趋势看,60～70年代西北大部分地区呈现减少趋势,而80～90年代全区普遍呈现增多趋势,以西北地区西部水汽增多趋势最为明显.最后讨论了影响西北地区水汽分布及输送的气候动力因子. 相似文献
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6.
A total of 269 tropical storms and hurricanes originated in the North Atlantic basin from 1960–1989. Of these, 76 made landfall on the continental United states. This study divides the 76 tropical storms into their month of formation. Seasonal shifts in the principal areas of tropical cyclone formation over the Atlantic basin have been recognized for many decades. The results of the study suggest that the early and late season tropical cyclones develop in areas which are first affected by the position of the sun, resulting in an increase in water temperatures. These cyclones normally make landfall along the Gulf Coast and usually are of low intensity. Formation areas shift eastward in mid-summer with a slight increase in intensity. By late August and early September, the formation areas have extended to the Cape Verde Islands. These storms tend to strike the east coast of the US and are normally more intense. By the end of the hurricane season, the primary formation area has shifted back to the Gulf of Mexico, with low intensity storms affecting the Gulf Coast. 相似文献
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The genesis of tropical cyclones (TCs) over Indian seas comprising of Bay of Bengal (BoB) and Arabian Sea (AS) is highly seasonal with primary maximum in postmonsoon season (mid-September to December) and secondary maximum during premonsoon season (April and May). The present study is focused to demonstrate changes in genesis and intensity of TCs over Indian seas in warming environment. For this purpose, observational data of TCs, obtained from the India Meteorological Department (IMD), are analyzed. The sea surface temperature (SST), surface wind speed, and potential evaporation factor (PEF), obtained from the International Comprehensive Ocean Atmosphere Data Set (ICOADS), are also analyzed to examine the possible linkage with variations in TC activities over Indian seas. The study period has been divided into two epochs: past cooling period (PCP, period up to 1950) and current warming period (CWP, period after 1950) based on SST anomaly (became positive from 1950) over the BoB and AS. The study reveals that the number of severe cyclones (SCS) increases significantly (statistically significant at 99% confidence level) by about 41% during CWP though no such significant change is observed in cyclonic disturbances (CDs) and cyclones (CS) over Indian seas. It is also observed that the rate of dissipation of CS and SCS over Indian seas has been decreasing considerably by about 63 and 71%, respectively, during CWP. The analysis shows that the BoB contributes about 75% in each category of TCs and remaining 25% by the AS towards total of Indian seas. A detailed examination on genesis and intensity of TC over both the basins and the seasons illustrates that significant enhancement of SCS by about 65% during CWP is confined to the postmonsoon season of the BoB. Further, the BoB is sub-divided into northern, central, and southern sectors and the AS into western and eastern sectors based on genesis of TCs and SST gradient. Results show that in postmonsoon season during CWP, the number of SCS increases significantly by about 71% in southern BoB and 300% over western AS. 相似文献
9.
提出了确定东亚夏季风活动区域、划分热带季风和副热带季风活动区域的指标,利用大气对流层风速、位势高度、湿度、温度、OLR以及TBB等NCEP/NCAR资料,从月、候和过程平均多种时间尺度,诊断分析了2005年6月(简称“0506”)华南持续性暴雨的季风环流活动变化特征.结果表明:副热带高压强度偏强,西脊点位置偏西偏南,热带西太平洋(130°～140°E)区域越赤道气流偏强,华南处于气旋性低压异常区,无论是月时间尺度还是暴雨过程时间尺度都表现出这些明显特征;暴雨过程水汽除了来源于孟加拉湾和南海外,水汽通量异常部分主要来自南海和热带西太平洋,热带西太平洋水汽随着副高边缘气流经过南海向华南输送,从而为暴雨过程提供了丰富的水汽来源;2005年6月热带季风前沿在华南沿海地区停滞时间比气候平均偏长(2候),该特征是华南暴雨预报值得参考的信号;6月整个南海地区平均季风偏强,主要体现于经向风明显偏强,但华南持续性暴雨过程开始于南海地区夏季风非活跃期,这与热带季风季节内振荡向北传播到华南有关.以上季风活动变化特征为华南强降水提供了有利的动力条件和丰富的水汽来源. 相似文献
10.
Manoj Kumar Thakur T. V. Lakshmi Kumar Sanjeev Dwivedi M. S. Narayanan 《Natural Hazards》2018,94(2):819-832
In the present study, we have used TRMM multi-satellite precipitation analysis (TMPA) 3B42 and global precipitation mission (GPM): IMERG “precipitation Cal” products to identify and quantify the asymmetry and distribution of rainfall in tropical cyclones formed over Bay of Bengal (BoB). For the period 2010–2013, TMPA products have been made use of and for the period 2014–2017, GPM–IMERG products are used to study the aforementioned features. Overall, 17 cyclones covering 75 events/days ranging from depression to very severe cyclonic stage of the system have been analysed. Our analysis revealed some interesting features on asymmetry, direction of maximum rain-receiving zones, relation of T-number with maximum and total rainfall in rain-receiving areas. The study reveals the direction of rainfall zone is mostly towards west and southwest directions of the storm centre in BoB. This point gains importance in the context of earlier reports, where it is mentioned that the direction of maximum rainfall is in east. The study also infers that the maximum rainfall and total rainfall need not be dependent on the intensity (indicated by T-number). We also attempted to classify the rain-receiving zones, based on both the rainfall-rate window and area covered in each window of rainfall, and a criterion has been proposed. The distribution of rainfall is classified, as sharply falling, slowly falling and nearly constant. 相似文献
11.
《Quaternary Science Reviews》2007,26(19-21):2505-2525
New Zealand's climate during the Last Glacial Maximum (LGM) has been investigated using the United Kingdom Met Office global (HadAM3H) and regional model (HadRM3H). All models were set up according to the glacial conditions as specified by the Paleoclimate Modelling Intercomparison Project (PMIP), although SSTs and sea-ice were supplied from a set of prior coupled model (HadCM3) runs. The simulated climate of New Zealand during the LGM was mainly compared against a control simulation which was set up for pre-industrial conditions. New Zealand's simulated LGM climate was cooler than today, varying spatially between 2.5 and 4 °C. There was an increase in seasonality in temperature with the seasonal cooling being largest during winter. Excluding the Alpine/Fiordland region, the largest cooling geographically took place in the east of the South Island (ESI). Annual mean precipitation was reduced but there were significant regional and seasonal variations. The main band of precipitation along the West Coast shifted westwards, resulting in a reduction in precipitation over those regions in the Southern Alps that receive the largest amount of precipitation in today's climate. The westerly circulation increased considerably over the North Island and the northern part of the South Island, but did not change much over the rest of the South Island. The stronger westerly wind accentuated the cooling over the western and northern parts of the North Island and it probably reduced the occurrence of incursions of tropical lows over the north of the North Island. The westerly winds were weaker over New Zealand during winter, which appears to be related to enhanced blocking activity during that season. The number and the strength of the southerlies increased, and they were capable of bringing very cold polar air over most of the country. The east of the South Island was affected especially by these cold winds.The simulated cooling during the LGM is not sufficient to limit forest growth. It is proposed here, that together with the general drier and colder conditions, it was the increase in seasonality and extremes of climate that limited the growth of certain vegetation types. 相似文献
12.
After the fuzzy clustering method (FCM) that analyzes the tracks of the tropical cyclones (TCs) struck the Korean peninsula (hereafter, K-TC) for a 60-year period (1951?C2010), it is found that both frequency and intensity of K-TC have been increased in recent years. In the order of the cluster number, both K-TC track pattern and its full-track pattern tended to shift southward. That is, while the passage frequency of TC in mainland China and the Manchurian regions decreased, it instead over the sea. Due to this decrease in the topographic effect on TC before reaching Korea, TC intensity around Korea became stronger. The vertical wind shear well reflected a TC intensity around Korea, which became weaker in mid-latitudes of East Asia. On the other hand, the peak month of K-TC frequency lags in the order of the cluster number. The two clusters that most TCs pass through the Korean Peninsula showed a stronger intensity and higher frequency before the 1970s. Meanwhile, another two clusters that most TCs pass through the Straits of Korea or the western region of the Japanese Islands showed those characteristics from the 1980s onward. Consequently, the changes in TC track, recurvature, frequency, and intensity around Korea were related to the southward shift of the western North Pacific high in the order of the cluster number. 相似文献
13.
Analysis of daily rainfall concentration in New Zealand 总被引：1，自引：0，他引：1
Tommaso Caloiero 《Natural Hazards》2014,72(2):389-404
A higher precipitation concentration, represented by greater percentages of the yearly total precipitation in a few very rainy days, has the potential to impact considerably on water resources. In this paper, an investigation of the spatial and temporal patterns of daily precipitation concentration in New Zealand has been carried out by means of a daily precipitation dataset. Results show a different behavior between North Island, with the most critical rainfall concentration, and South Island, where precipitation concentration values on the eastern side are comparable to those of North Island, while the western side presents the lowest values of precipitation concentration. On a seasonal scale, the spatial gradients for summer and autumn are similar to the annual one. The application of the Mann–Kendall test shows a general negative trend detected in the eastern part of North Island, in particular in winter and autumn, and a west/east difference trend in South Island, in particular in winter and summer. 相似文献
14.
大气中的水汽输送对于全球的水分循环、气候系统、生态环境等具有重要意义。水汽输送是影响中国旱涝空间分布的重要因素，其年际和年代际变化与厄尔尼诺-南方涛动、海温、北大西洋涛动、太平洋年代际涛动等因素对东亚大气环流的调控作用有关。本文就近期关于中国地区水汽输送年际和年代际变化的部分研究工作进行了回顾和评述，包括影响中国东部降水年际和年代际变化的水汽输送机制、影响梅雨特征年代际变化的水汽输送机制、热带海温对中国上空水汽输送的影响机制等问题。此外，本文回顾了近期与青藏高原地区水汽输送机制有关的研究进展。 相似文献
15.
大气中的水汽输送对于全球的水分循环、气候系统、生态环境等具有重要意义。水汽输送是影响中国旱涝空间分布的重要因素，其年际和年代际变化与厄尔尼诺-南方涛动、海温、北大西洋涛动、太平洋年代际涛动等因素对东亚大气环流的调控作用有关。本文就近期关于中国地区水汽输送年际和年代际变化的部分研究工作进行了回顾和评述，包括影响中国东部降水年际和年代际变化的水汽输送机制、影响梅雨特征年代际变化的水汽输送机制、热带海温对中国上空水汽输送的影响机制等问题。此外，本文回顾了近期与青藏高原地区水汽输送机制有关的研究进展。 相似文献
16.
黄河、长江源区降水变化的水汽输送和环流特征 总被引：20，自引：8，他引：12
利用黄河、长江源区气象站的降水资料和NCEP/NCAR再分析气候资料,分析了黄河、长江源区降水的年际变化,对黄河、长江源区典型多雨年与少雨年的500 hPa位势高度和风场、600 hPa流场、大气水汽含量和水汽输送进行了合成和对比分析.结果表明:黄河和长江源区的降水在近50 a的长期变化趋势都不明显,但在最近10 a黄河源区的降水有明显的减少趋势.而长江源区的降水则有明显的增加趋势;江河源区在多雨与少雨年有明显的环流差异特征,在多/少雨年,500 hPa蒙古低压减弱/加强,西风风速减弱/增强,600 hPa高原辐合线偏北/南,江河源区大气水汽含量增加/减少,西南季风的偏南水汽输送增加/减少.使得江河源区有较多/少的水汽来源,从而降水增多/减少;黄河和长江源区有相似的多雨与少雨年环流差异特征,只是差异程度不同,长江源区多雨与少雨年环流特征差异的强度不及黄河源区. 相似文献
17.
This study investigates the effects of various combinations of the planetary boundary layer (PBL) schemes and the microphysics schemes on the numerical forecasting of tropical cyclones (TCs). Using different combinations of three PBL schemes (YSU, MYJ and MYNN2) and four microphysics schemes (Ferrier, Goddard, WSM6 and Lin), a number of experiments are carried out for five landed TCs in the South China Sea during 2012. Results show that the combination of the YSU and Ferrier schemes performs the best for the TC track forecasting, although it does not perform the best for the forecast of precipitation. Further analysis reveals that the best performance of the track forecast by the combination of the YSU and Ferrier schemes mainly attributes to a more accurate steering flow as well as TC wind structure produced by this combination. These results provide a valuable reference to the operational numerical forecasting of TC tracks in the future. 相似文献
18.
Based on typhoon best track data of China Meteorological Administration and NCEP global reanalysis data, this study analyzed the characteristics of binary tropical cyclones (TC) in the Northwest Pacific Ocean during 1951 to 2014 by using the objective determine standard. When the distance between the two TCs d≤ 1 800 km, they are defined as binary tropical cyclones or binary typhoons. And binary typhoons are divided into two different types which are typical binary typhoons and atypical binary typhoons. The climatic characteristics of binary tropical cyclones are as follows: There were 699 pairs of binary typhoons in Northwest Pacific Ocean during 1951 to 2014. In these cases, there were 446 pairs of typical binary typhoons and 253 pairs of atypical cases, occupying 63.8% and 36.2%, respectively. The proportion of typical cases increased with the shortest distance decreasing, while the proportion of atypical cases decreased with the shortest distance decreasing. When the speed of typical binary typhoons moving towards each other reached the peak, binary typhoons mainly showed the east to west direction. At this time, typhoons were controlled by easterly stream of the southern edge of the subtropical high. In this situation, the east typhoon moved toward the west typhoon quickly. When the anticlockwise angular velocity of typical binary typhoons reached the peak, binary cases distributed northeast to southwest or east-northeast to west-southwest, appearing in west and southwest edge of the subtropical high and mainly being controlled by southeasterly stream, thus benefiting the anticlockwise rotation between the typical binary typhoons. 相似文献
19.
Every year, Australia experiences tropical cyclones that bring large amounts of rainfall, causing flooding and damage to infrastructure and road closure due to landslips. In March 2017, tropical cyclone Debbie hit the Queensland coast dumping 747 mm of rainfall within 2 days to the Gold Coast region. As a result, multiple shallow landslides occurred in Gold Coast and northern New South Wales due to the increase in soil saturation. A field investigation was conducted from several sites between Gold Coast-Springbrook road and Tallebudgera creek road to identify geological settings and landslide characteristics. Key findings show that slides predominantly occurred in weathered meta-sediments of the Neranleigh-Fernvale Beds within a depth of 1–2 m. Furthermore, a series of shear box tests revealed that the shear strength of the soil significantly decreased when saturation occurred. 相似文献
20.
青藏高原雨季降水的水汽条件研究 总被引：2，自引：2，他引：0
利用1961—2017年青藏高原109站降水量资料、NCEP全球逐月再分析资料,讨论了雨季期间高原的水汽输送特征。结果表明：高原雨季降水呈显著的年际变化特征,高原雨季降水主模态为南北反向型和全区一致型。气候态高原雨季的水汽输送路径为来自阿拉伯海的偏西风水汽输送,在孟加拉湾附近分为三支水汽输送气流：一支向北输送,自高原南缘输入;一支在南海附近转为偏南风水汽输送,自东南侧输入高原;一支受高原大地形的阻挡作用,转为偏西风水汽输送。在全区一致型降水偏多年,高原主体呈现北部弱辐合、南部辐散的分布形态;在全区一致型降水偏少年,来自阿拉伯海偏南水汽输送在25° N附近转为偏东水汽输送,在高原南缘形成较强的水汽辐合中心。雨季期间高原各边界的水汽收支情况表现为西、南、东边界以水汽输入为主,北边界为水汽输出,南边界水汽输入量最大,西边界次之。 相似文献