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1.
S. K. Dash Archana Anil Nair Makarand A. Kulkarni U. C. Mohanty 《Theoretical and Applied Climatology》2011,105(3-4):563-570
In this paper, changes in the long and short spells of different rain intensities are statistically analyzed using daily gridded rainfall data prepared by the India Meteorological Department for the period 1951–2008. In order to study regional changes, analyses have been conducted over nine selected agro-meteorological (agro-met) divisions, five homogeneous zones, and also over the whole of India. Rain events of different intensities with continuous rainfall of more than or equal to 4 days are classified here as long spells. Those with less than 4 days are termed as short spells. Those results which are statistically significant at 95% confidence level are discussed in this paper. Trend analysis shows that during the summer monsoon months of June to September, short spell rain events with heavy intensity have increased over India as a whole. On the other hand, long spell rain events with moderate and low intensities have decreased in numbers. Results further show that the contributions of long spell moderate and short spell low-intensity rain events to the total rainfall have decreased whereas the contributions of short spell heavy and moderate-intensity rain events to the total seasonal rainfall have increased. Percentage changes in various categories of long and short spells in the decade 1991–2000 compared with the earlier decade 1951–1960, highlight the maximum increase in heavy-intensity short spell category and decrease in moderate-intensity long spell category in India as a whole and in most of the homogeneous zones and agro-met divisions. The changes in different types of rain events differ in the six homogeneous zones and nine selected agro-met divisions. However, in three homogeneous zones and three agro-met divisions, the short spell heavy-intensity rain events dominate as in the entire country. There are also changes observed in the monthly occurrences of above categories of rain events during the 4 months of summer monsoon. Such results with details of changes in rain categories in different parts of India have important implications in agriculture sector in the country. 相似文献
2.
利用河南省1957-2005年逐日降水,最高、最低和日平均气温资料,分析了近50 a河南省极端天气事件的变化趋势。结果表明：1957-2005年河南省暴雨日数、极端降水事件和严重干燥事件发生频率都在增加,但其线性趋势并不显著;暴雨和极端降水的变化趋势呈明显的南北差异;异常高温事件增加而异常低温事件减少,暖冬的趋势比较显著;高温日数和低温日数都显著减少,其变化趋势的空间分布具有很好的一致性。 相似文献
3.
4.
1957-2005年河南省降水和温度极端事件变化 总被引：10，自引：0，他引：10
利用河南省1957-2005年逐日降水,最高、最低和日平均气温资料,分析了近50 a河南省极端天气事件的变化趋势。结果表明：1957-2005年河南省暴雨日数、极端降水事件和严重干燥事件发生频率都在增加,但其线性趋势并不显著;暴雨和极端降水的变化趋势呈明显的南北差异;异常高温事件增加而异常低温事件减少,暖冬的趋势比较显著;高温日数和低温日数都显著减少,其变化趋势的空间分布具有很好的一致性。 相似文献
5.
利用重庆市1961—2012年34个气象观测站的逐日降水资料,采用EOF分析、线性回归及相关分析的方法对重庆市的降水量时空特征、降水频数特征及降水强度特征进行诊断分析研究,并进行了相关讨论.结果表明:重庆市的年总降水量呈逐年减少的变化特征,并且年总降水量存在空间一致性与重庆市东北地区和其他地区反相变化的空间分布形式;各类持续性降水过程频数的空间分布差异较大,持续性降水过程频数的变化趋势表明短期降水过程(持续2 d)逐年增加而持续较长时间(持续5 d及以上)的连阴雨天气过程减少趋势明显;降水强度分析中发现一般降水(小雨、中雨、大雨)的年总降水量呈下降趋势,是引起重庆市年总降水量减少的主要原因,小雨、中雨降水强度逐年减弱而大雨的强度有弱的增强,较强降水等级(暴雨与大暴雨)的年总降水量呈较弱的上升趋势,降水强度也表现为弱的增强趋势;持续5 d及以上降水过程频数的减少可能与当地500 hPa位势高度场的上升及赤道太平洋海表温度的升高相关,大雨及以上等级降水的强度变化可能与El Niño Modoki现象有关. 相似文献
6.
东亚区域极端气候事件变化的数值模拟试验 总被引：62，自引：0，他引：62
使用ResCM2区域气候模式,嵌套澳大利亚CSIRO R21L9全球海气耦合模式,进行了温室效应（二氧化碳加倍）对东亚（主要是中国区域）极端气候事件影响的数值试验。控制试验的结果表明,区域模式能够较好地模拟中国区域的极端气候事件。对温室效应引起的它们的变化进行了信度检验,分析结果表明,温室效应将引起日最高和最低气温增加,日较差减小;使得高温天气增多,低温日数减少。降水日数和大雨日数在一些地区将增加。同时还会引起影响中国的台风活动的变化。 相似文献
7.
Jose A. Marengo Matilde Rusticucci Olga Penalba Madeleine Renom 《Climatic change》2010,98(3-4):509-529
We analyze historical simulations of variability in temperature and rainfall extremes in the twentieth century, as derived from various global models run informing the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC-AR4). On the basis of three indices of climate extremes, we compare observed and modeled trends in time and space, including the direction and significance of the changes at the scale of South America south of 10° S. The climate extremes described warm nights, heavy rainfall amounts and dry spells. The reliability of the GCM simulations is suggested by similarity between observations and simulations in the case of warm nights and extreme rainfall in some regions. For any specific extreme temperature index, minor differences appear in the spatial distribution of the changes across models in some regions, while substantial differences appear in regions in the interior of tropical and subtropical South America. The differences are in the relative magnitude of the trends. Consensus and significance are less strong when regional patterns are considered, with the exception of the La Plata Basin, where observed and simulated trends in warm nights and extreme rainfall are evident. 相似文献
8.
近50年广东省分级降水的时空分布特征及其变化趋势的研究 总被引：6，自引：2，他引：6
利用广东省86个常规气象观测站1961—2010年的逐日降水资料,分析近50年广东省降水气候特征,探讨不同等级降水空间分布及随时间变化特征。结果表明:广东省降水丰沛,年均降水量多为1 500~2 000 mm;降水气候特征的区域差异较大,不同区域降水量与降水日数分布差异显著;各月的降水日数差异没有降水量月分布的差异明显,非汛期的日降水量较小,而汛期降水日数多且日降水量大;小雨日和中雨日的区域差异小,大雨日、暴雨日、大暴雨日的大值中心主要集中在广东省的三大暴雨中心地区 (清远中心、阳江中心、海陆丰中心),雨日量级分布大致由北向南逐渐增强,且随着降水等级的增加降雨日数迅速减少;小雨、中雨和大雨的降水贡献率均由粤北地区向沿海地区递减,暴雨和大暴雨的贡献率由粤北向沿海递增;小雨日数显著减少、大雨以上日数略有增多,总降水日数也呈减少趋势;小雨和中雨的贡献率呈减少趋势,大雨以上贡献率增多,使年均降水量呈增多趋势。 相似文献
9.
A new technique for identifying regional climate events, the Objective Identification Technique for Regional Extreme Events(OITREE), was applied to investigate the characteristics of regional heavy rainfall events in China during the period1961–2012. In total, 373 regional heavy rainfall events(RHREs) were identified during the past 52 years. The East Asian summer monsoon(EASM) had an important influence on the annual variations of China's RHRE activities, with a significant relationship between the intensity of the RHREs and the intensity of the Mei-yu. Although the increase in the frequency of those RHREs was not significant, China experienced more severe and extreme regional rainfall events in the 1990 s. The middle and lower reaches of the Yangtze River and the northern part of South China were the regions in the country most susceptible to extreme precipitation events. Some stations showed significant increasing trends in the southern part of the middle and lower reaches of the Yangtze River and the northern part of South China, while parts of North China, regions between Guangxi and Guangdong, and northern Sichuan showed decreasing trends in the accumulated intensity of RHREs.The spatial distribution of the linear trends of events' accumulated intensity displayed a similar so-called "southern flooding and northern drought" pattern over eastern China in recent decades. 相似文献
10.
Extreme rainfalls in SE South America 总被引：1，自引：0，他引：1
Heavy rainfall trends in a region of south-eastern South America during 1959–2002 were discussed using daily data of 52 meteorological stations of Argentina, Brazil and Uruguay. Changes in intensity and frequency were both studied with different statistical tests and approaches to check the significance of trends of single and regional aggregated rainfall series. There were predominant positive trends in the annual maximum rainfalls, as well as a remarkable increment in the frequency of heavy rainfalls over thresholds ranging from 50 to 150 mm. However, significant positive trends were not shown in the series of annual maximums and shown only in 15% to 30% of the series of frequencies over thresholds. This lack of significance is due to the high variability of heavy rainfalls in space and time, which makes difficult their capture by single rain gauges. Thus, when the assessment of the heavy rainfall indicators of intensity and frequency were conducted at the regional and sub-regional level, it showed significant trends, both in intensity and frequency over thresholds, with a clearer signal in central and eastern Argentina between 30° and 40° S. 相似文献
11.
中国夏季不同强度降水模拟对不同积云对流参数化方案的敏感性研究 总被引：3，自引：2，他引：1
利用PσRCM9区域气候模式, 分析了中国夏季不同强度降水模拟对不同积云对流参数化方案的敏感性。结果表明, 采用四种积云对流参数化方案, 模式能够模拟出小雨、 大雨和暴雨的雨量百分比和雨日百分比空间分布的一致性特征, 但不能模拟出中雨雨量百分比和雨日百分比空间分布的相似性, 这是由于模式不能模拟中雨雨量百分比的空间分布形式所致。还发现模拟的我国夏季降水以小雨和中雨为主, 四种积云对流参数化方案均低估了中国夏季大雨和暴雨对总降水的贡献, 尤其是在我国西部、 东北和华北地区更明显。不同积云对流参数化方案下模拟的极端强降水阈值的空间分布形式基本与观测一致, 但强度与观测存在较大差异。相比较而言, Grell方案较Kuo、 Anthes-Kuo和Betts-Mille积云对流参数化方案更适合中国东南部地区夏季极端强降水的模拟。 相似文献
12.
The evolution of seasonal cycle and interannual rainfall, the number of rainy days and daily rainfall types, dry spells frequency of occurrence, onset/cessation/length of rainy season, sowing dates, and the duration of the cropping period, are investigated at local (individual sites) and sub-regional scales (four different rainfall zones) using daily records of station data (83 sites) over Senegal. In the limits of a case study, these analyses complement and update previous studies conducted in the extreme Western Sahel (11?C16° N and 20° W?C10° E). The results unveil noticeable evolution of some of these rain-based factors in the recent periods as compared to the previous dry years. In the regions recording less than 800?mm/year (Sudan and Sahel sub-regions), the positive and statistically significant trends of rainfall amount are associated with new features of increasing frequency of short dry spell category, increasing number of some classes of extreme daily rainfall amounts and shifts in the peak number of rainy days. At sub-regional scales, the starting years (or change points) the magnitude and the signs of the new trends are unevenly distributed in the period post-1990. Earlier and higher amplitude changes are found at local scales and not less than one third of the sites in each sub-regional network are significantly affected. The extreme Southern sub-region exhibits no significant changes. Statistically significant trends are not observed on daily rain records ??10?mm, onset/cessation dates, successful sowing dates, rainy season length, cropping period, medium and extreme dry spell categories. Rather, some of these factors such as the successful sowing date and the cropping season length exhibit significant variability. The onset (cessation) dates of the rainy season are followed (preceded) by extreme dry spell episodes. In the perspectives of climate impact assessments on the local agriculture a sub-regional periodic synopsis of the major rain-based factors of interest to agricultural applications are provided at the end the paper. They document some important internal variability patterns to reckon with in a multi-decadal work over the 1950?C2008 period for this region. 相似文献
13.
利用93站1951—2002年逐日降水资料，分析了东北地区不同强度降水事件的时空演变特征及其对旱涝的影响。结果表明:52年来，东北地区小雨事件对年降水量的贡献率呈显著增加趋势，中雨的贡献率略为减少，大雨和暴雨的贡献率变化不大；东北年总雨日减少趋势非常明显，雨日的减少主要体现在小雨日数的减少；年降水强度表现为明显的增强趋势，主要体现为小雨和暴雨强度增强；20世纪80年代中期之前多小雨事件，80年代中期之后多中雨以上强度的降水，特别是90年代中期之后多暴雨事件。在显著变暖的20世纪90年代，降水日数明显减少，但暴雨日数基本不变，强度明显增强。对东北地区降水量、降水变幅、降水事件的变化特征分析表明:该区域降水有向不均衡、极端化发展的趋势，旱涝灾害也有加重趋势。 相似文献
14.
华东地区夏季不同等级降水变化特征分析 总被引：10，自引：3，他引：7
采用华东地区78个气象站点逐日降水资料,根据日降水量的5个等级划分,应用线性趋势分析、相关分析等分析了不同等级降水频率和降水量的空间分布及其变化趋势。结果表明:(1)夏季不同等级降水频率在整个华东地区具有明显的地区差异,区域平均的降水频率由大到小依次为小雨、微量降水、中雨、大雨、暴雨。(2)平均的夏季总降水量呈南多北少的分布,各等级降水对总降水量的贡献率由大到小依次为暴雨、大雨、中雨、小雨,暴雨对夏季总降水量的贡献在某些年份可达50%以上。(3)区域平均的夏季降水日数呈下降趋势,但总降水量却有明显的增大趋势。(4)区域平均的某等级降水频率正异常时,华东地区各地该等级降水频率,亦多表现为正异常,尤其中雨以上等级降水频率异常符号在整个华东地区更为一致。(5)华东区域微量降水和小雨发生频率分别与其他等级降水存在显著的反相关关系,而中雨、大雨、暴雨三者发生频率之间无显著相关。 相似文献
15.
利用2008—2016年5—9月中国气象局陆面数据同化系统(CLDAS)格点融合分析降水资料以及降水观测资料,在对CLDAS格点降水融合资料进行验证的基础上,对贺兰山区降水时空分布特征以及与地形的关系进行了分析。结果表明：贺兰山区降水呈“东多西少、南多北少”的分布特征,贺兰山主峰偏西0.1°存在一个超过240 mm的降水高值中心,日降水量极值西侧高于东侧。8月降水量和短时强降水次数最多,11:00—18:00降水次数最多,午后到前半夜短时强降水次数最多。贺兰山区降水以小雨为主,其次是中雨,中雨和小雨雨量占区域总雨量的比例高达85%。贺兰山区降水量随海拔高度的增加而增加,西坡降水随高度的增加率为5.1 mm/hm,东坡降水随高度的增加率为2.1 mm/hm,西坡明显高于东坡。中雨日数与地形高度的相关性较好,其它级别降雨日数与地形相关性不强。 相似文献
16.
Mark W. Shephard Eva Mekis Robert J. Morris Yang Feng Xuebin Zhang Karen Kilcup 《大气与海洋》2014,52(5):398-417
Short-duration (5 minutes to 24 hours) rainfall extremes are important for a number of purposes, including engineering infrastructure design, because they represent the different meteorological scales of extreme rainfall events. Both single location and regional analyses of the changes in short-duration extreme rainfall amounts across Canada, as observed by tipping bucket rain gauges from 1965 to 2005, are presented. The single station analysis shows a general lack of a detectable trend signal, at the 5% significance level, because of the large variability and the relatively short period of record of the extreme short-duration rainfall amounts. The single station 30-minute to 24-hour durations show that, on average, 4% of the total number of stations have statistically significant increasing amounts of rainfall, whereas 1.6% of the cases have significantly decreasing amounts. However, regional spatial patterns are apparent in the single station trend results. Thus, for the same durations regional trends are presented by grouping the single station trend statistics across Canada. This regional trend analysis shows that at least two-thirds of the regions across Canada have increasing trends in extreme rainfall amounts, with up to 33% being significant (depending on location and duration). Both the southwest and the east (Newfoundland) coastal regions generally show significant increasing regional trends for 1- and 2-hour extreme rainfall durations. For the shortest durations of 5–15 minutes, the general overall regional trends in the extreme amounts are more variable, with increasing and decreasing trends occurring with similar frequency; however, there is no evidence of statistically significant decreasing regional trends in extreme rainfall amounts. The decreasing regional trends for the 5- to 15-minute duration amounts tend to be located in the St. Lawrence region of southern Quebec and in the Atlantic provinces. Additional analysis using criteria specified for traditional water management practice (e.g., Intensity-Duration-Frequency (IDF)) shows that fewer than 5.6% and 3.4% of the stations have significant increasing and decreasing trends, respectively, in extreme annual maximum single location observation amounts. This indicates that at most locations across Canada the traditional single station IDF assumption that historical extreme rainfall observations are stationary (in terms of the mean) over the period of record for an individual station is not violated. However, the trend information is still useful complementary information that can be considered for water management purposes, especially in terms of regional analysis. 相似文献
17.
Observed trends in severe weather conditions based on public alert statements issued by Environment Canada are examined for Canada. Changes in extreme heat and extreme cold events represented by various humidex and wind chill indices are analyzed for 1953–2012 at 126 climatological stations. Changes in heavy rainfall events based on rainfall amounts provided by tipping bucket rainfall gauges are analyzed for 1960–2012 at 285 stations. The results show that extreme heat events, defined as days with at least one hourly humidex value above 30, have increased significantly at more than 36% of the stations, most of which are located south of 55°N; days with nighttime hourly humidex values remaining above 20 have increased significantly at more than 52% of the stations, most of which are located south of 50°N. Extreme cold events represented by days with at least one hourly wind chill value below ?30 have decreased significantly at more than 76% of the stations across the country. No consistent changes were found in heavy rainfall events. Because city residents are very vulnerable to severe weather events, detailed results on changes in extreme heat, extreme cold, and heavy rainfall events are also provided for ten urban centres. 相似文献
18.
随着数值预报技术的飞速发展, 模式定量降水预报已成为天气预报业务工作中的主要参考依据。本文对目前在国家气象中心应用的3个业务运行模式T213L31, HLAFS0.25, 华北中尺度模式MM5和德国模式及日本模式的降水预报产品进行了季节空间分布、区域时间序列演变及统计检验, 试图从空间、时间及统计方面对降水预报产品的预报性能进行综合评估。检验结果表明:目前的数值预报模式对短期时效内定量降水预报均具有一定的空间预报能力, 但强降水中心位置有一定的偏差; 从时间序列演变检验来看, 模式对区域强降水过程的发展趋势具有较强的预报能力, 但降水量预报与实况有一定的差距; 从累加统计评分检验结果来看, 模式短期时效的预报性能差别不大, 全球模式在小中雨预报方面有一定优势, 其中日本模式的综合预报性能最好, 大雨以上量级的预报则是国内的模式有一定的优势, 其中华北中尺度MM5模式, T213L31模式各有所长, 但均存在预报量和预报区偏大问题。 相似文献
19.
Frequency, intensity, areal extent (AE) and duration of rain spells during summer monsoon exhibit large intra-seasonal and inter-annual variations. Important features of the monsoon period large-scale wet spells over India have been documented. A main monsoon wet spell (MMWS) occurs over the country from 18 June to 16 September, during which, 26.5 % of the area receives rainfall 26.3 mm/day. Detailed characteristics of the MMWS period large-scale extreme rain events (EREs) and spatio-temporal EREs (ST-EREs), each concerning rainfall intensity (RI), AE and rainwater (RW), for 1 to 25 days have been studied using 1° gridded daily rainfall (1951–2007). In EREs, ‘same area’ (grids) is continuously wet, whereas in ST-EREs, ‘any area’ on the mean under wet condition for specified durations is considered. For the different extremes, second-degree polynomial gave excellent fit to increase in values from distribution of annual maximum RI and RW series with increase in duration. Fluctuations of RI, AE, RW and date of occurrence (or start) of the EREs and the ST-EREs did not show any significant trend. However, fluctuations of 1° latitude–longitude grid annual and spatial maximum rainfall showed highly significant increasing trend for 1 to 5 days, and unprecedented rains on 26–27 July 2005 over Mumbai could be a realization of this trend. The Asia–India monsoon intensity significantly influences the MMWS RW. 相似文献
20.
Recent trends in observed temperature and precipitation extremes in the Yangtze River basin,China 总被引：14，自引：1，他引：14
Summary The present study is an analysis of the observed extreme temperature and precipitation trends over Yangtze from 1960 to 2002
on the basis of the daily data from 108 meteorological stations. The intention is to identify whether or not the frequency
or intensity of extreme events has increased with climate warming over Yangtze River basin in the last 40 years. Both the
Mann-Kendall (MK) trend test and simple linear regression were utilized to detect monotonic trends in annual and seasonal
extremes.
Trend tests reveal that the annual and seasonal mean maximum and minimum temperature trend is characterized by a positive
trend and that the strongest trend is found in the winter mean minimum in the Yangtze. However, the observed significant trend
on the upper Yangtze reaches is less than that found on the middle and lower Yangtze reaches and for the mean maximum is much
less than that of the mean minimum. From the basin-wide point of view, significant increasing trends are observed in 1-day
extreme temperature in summer and winter minimum, but there is no significant trend for 1-day maximum temperature. Moreover,
the number of cold days ≤0 °C and ≤10 °C shows significant decrease, while the number of hot days (daily value ≥35 °C) shows
only a minor decrease. The upward trends found in the winter minimum temperature in both the mean and the extreme value provide
evidence of the warming-up of winter and of the weakening of temperature extremes in the Yangtze in last few decades.
The monsoon climate implies that precipitation amount peaks in summer as does the occurrence of heavy rainfall events. While
the trend test has revealed a significant trend in summer rainfall, no statistically significant change was observed in heavy
rain intensity. The 1-day, 3-day and 7-day extremes show only a minor increase from a basin-wide point of view. However, a
significant positive trend was found for the number of rainstorm days (daily rainfall ≥50 mm). The increase of rainstorm frequency,
rather than intensity, on the middle and lower reaches contributes most to the positive trend in summer precipitation in the
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