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1.
近四十年我国东部盛夏日降水特性变化分析 总被引：45，自引：7，他引：38
基于中国地区740台站的日降水资料,细致分析了近40年我国东部盛夏即7、8月份降水长期趋势和年代际变化特征。按小雨、中雨、大雨以及暴雨降水强度分类,探讨了不同强度降水在我国东部降水变化中的贡献。结果表明,中国东部地区盛夏降水变化主要受暴雨强度降水变化的影响,占总降水变化60%以上。近40年来,盛夏长江流域降水量、 降水频率、极端降水频率以及暴雨降水强度均呈增大趋势,在华北地区则呈减小趋势,除降水频率在长江流域的变化趋势绝对值比华北地区小外,另三个指标在长江流域的趋势变化值大约是后者的2倍。降水强度在中国东部表现出一致的增大趋势,但华北地区增大趋势不显著。华北地区降水的减少主要是小雨强度降水频率减小的结果,强降水的频率和强度在该地区也呈微弱的减小趋势,其中小雨强度降水频率减小趋势大值中心值达到-3%/10a,比中雨以上强度降水频率变化趋势值大一个量级;长江流域降水的增多,是各强度降水频率和强度增大共同作用的结果。长江流域和华北地区在区域平均降水频率、降水强度、极端降水频率、最大降水量的时间序列上,彼此均为负相关关系,其中降水频率和极端降水频率序列在两区域的相关系数通过99%的信度检验。Mann-Kendall检验表明,除华北地区降水强度外,其他降水指标均存在显著的年代际跃变。与1970年代末的气候跃变相对应,华北地区降水频率较之长江流域的跃变明显;但长江流域极端降水在1970年代末的跃变较之华北地区更显著,其降水强度、极端降水频率以及最大降水量均于1970年代末期前后发生显著年代际跃变。 相似文献
2.
Temporal and spatial variability of dryness/wetness in China during the last 530 years 总被引：8，自引：1，他引：8
Summary The main characteristics of spatial and temporal variability of dryness and wetness during the last 530 years (1470–1999) are classified over five centuries. They have been investigated by using 100-site dryness/wetness index data that has recorded the historical weather conditions that affect agriculture and living conditions in eastern China. A set of principal modes of spatial variability and time coefficient series describing the dominant temporal variability are extracted by a diagnostic method, the rotated empirical orthogonal function (REOF) analysis. The long-term precipitation around Beijing, north China and the long-term runoffs in the middle Yangtze River are used to confirm the dry/wet variability in north China and the mid-low Yangtze River over the last two centuries.When considering the data from the last 530 years as a whole, the first two modes of dryness/wetness variability are found in the mid to low sections of two major valleys in eastern China, the Yellow and Yangtze River valleys. These valleys experienced the largest dryness/wetness variability in the history of eastern China. The third and fourth modes are located in northwest and northeast China. The fifth and sixth modes are situated in south and southwest China. However, over the last 500 years the strength and location of principal modes have experienced significant changes. During the 20th century, the first mode is found in the lower Yangtze River valley, the second mode in south China while the third mode is located in the mid-low Yellow River valley. During the 19th century, the first three modes are situated in the mid-low Yellow River, the mid-low Yangtze River and south China, respectively. The first two modes in the 18th century are located in the mid-low Yellow River and the mid-low Yangtze River valleys. The largest change of all modes occurred in the 17th century with the first mode in northeast China, the second mode in northwest China, and the third mode in the mid-low Yangtze River valley. During the 16th century, the first two modes are found in the mid-low Yangtze River and the mid-low Yellow River valleys.In each of the last five centuries, some special dryness/wetness processes are characterized in the mid-low Yangtze River and the mid-low Yellow River (north China). During the 20th century, continuous and severe wetness is experienced in the mid-low Yangtze River in the last two decades. A two-decade wetness period in north China was followed by a severe dry period in the late 19th century. Inter-annual variability, decade and two-decade oscillations of dryness/wetness are experienced in the series of different modes from one century to another. Dry/wet variations in north China and the middle Yangtze River are confirmed by series of data on local precipitation and runoff. 相似文献
3.
Trends in graded precipitation in China from 1961 to 2000 总被引：3，自引：0，他引：3
Daily precipitation rates observed at 576 stations in China from 1961 to 2000 were classified into six grades of intensity, including trace （no amount）, slight （≤ 1 mm d^-1）, small, large, heavy, and very heavy. The last four grades together constitute the so called effective precipitation （〉 1 mm d^-1）. The spatial distribution and temporal trend of the graded precipitation days are examined. A decreasing trend in trace precipitation days is observed for the whole of China, except at several sites in the south of the middle section of the Yangtze River, while a decreasing trend in slight precipitation days only appears in eastern China. The decreasing trend and interannual variability of trace precipitation days is consistent with the warming trend and corresponding temperature variability in China for the same period, indicating a possible role played by increased surface air temperature in cloud formation processes. For the effective precipitation days, a decreasing trend is observed along the Yellow River valley and for the middle reaches of the Yangtze River and Southwest China, while an increasing trend is found for Xinjiang, the eastern Tibetan Plateau, Northeast China and Southeast China. The decreasing trend of effective precipitation days for the middle- lower Yellow River valley and the increasing trend for the lower Yangtze River valley are most likely linked to anomalous monsoon circulation in East China. The most important contributor to the trend in effective precipitation depends upon the region concerned. 相似文献
4.
利用中国1956-2008年逐日降水量资料,以全国主要河流流域为研究区域,分析了年最大日降水量、年暴雨（日降水量≥50.0 mm）日数的多年平均状况及长期变化趋势。分析表明,近53年,全国平均年最大日降水量没有明显的线性变化趋势,但全国范围内多数气象站点年最大日降水量呈现出增加趋势,并存在南方流域增加、北方流域减少的变化趋势,这种变化特征在2001年以来表现更加突出。全国平均年暴雨日数呈不显著的增多趋势,20世纪90年代最多,70年代最少。空间上,我国南北方流域年暴雨日数呈现相反的变化特征,南方流域多呈上升趋势,北方流域呈减少趋势。 相似文献
5.
中国年和季各等级日降水量的变化趋势分析 总被引：18，自引：1，他引：17
通过对中国554个测站1961—2003年的日降水量数据进行线性回归,对我国全年和各个季节的总降水量和各级降水的线性趋势进行分析,并对两种不同的极端降水定义方法所得的变化趋势进行了比较。结果显示,全年总降水量在西北、长江中下游和华南地区具有明显的增加趋势,而在华北和四川盆地地区具有明显的减少趋势。分析各类降水的季节变化趋势可以发现,西北地区各个季节的日降水都是增加的,长江中下游地区的各类降水的增加趋势主要集中在夏季和冬季,而华北地区的各类降水在各个季节基本都呈减少趋势。极端降水趋势方面,西北、长江中下游、西南部分地区和华南沿海地区具有明显的增加趋势,而华北、四川盆地和东北部分地区则有明显的减少趋势。 相似文献
6.
在全球增暖背景下,中国极端降水事件及洪涝、干旱等次生灾害近年来频发,严重影响生态系统、人民的生产生活和社会经济发展。本文基于气候变化检测和指数专家组（ETCCDI）定义的10个降水指数,利用中国台站日降水资料,系统分析了1961～2017年中国及九大流域片降水变化情况,并利用空间场显著性检验考察不同降水指数的显著变化是否与外强迫作用有关。结果表明,各降水指数的变化具有区域性特征。整体而言,全国范围内平均降水、降水强度、极端强降水和连续性强降水呈增强趋势的台站数多于呈减弱趋势的台站数,呈显著增强趋势的台站占比不可能仅由气候系统内部变率引起,还受到外强迫的影响。此外,中国大部分站点连续干旱日数（CDD）减少,观测中CDD呈显著减弱趋势的台站占比也与外强迫作用有关。九大流域片中,内陆河片能够观测到平均降水、降水强度、极端强降水和连续性强降水的增多以及连续干旱日数的减少,有洪涝灾害增多的风险,且上述变化可归因为外强迫的作用。长江流域片、东南诸河片和珠海流域片平均降水、极端强降水和连续性强降水均增强,其中强降水的变化与外强迫作用有关。西南诸河片极端强降水增强,但大部分站点CDD呈增加趋势,有干旱增加的风险。黄河流域片、海河流域片、淮河流域片及松辽河流域片的大部分站点及区域平均结果中,降水指数多无显著变化趋势。增暖背景下,不同流域片呈现出不同的降水变化特征,将面临不同的气候灾害风险。 相似文献
7.
An overview of dry-wet climate variability among monsoon-westerly regions and the monsoon northernmost marginal active zone in China 总被引：7，自引：2，他引：5
Climate in mainland China can be divided into the monsoon region in the southeast and
the westerly region in the northwest as well as the intercross zone, i.e., the monsoon northernmost
marginal active zone that is oriented from Southwest China to the upper Yellow River, North China,
and Northeast China. In the three regions, dry-wet climate changes are directly linked to the
interaction of the southerly monsoon flow on the east side of the Tibetan Plateau and the westerly
flow on the north side of the Plateau from the inter-annual to inter-decadal timescales. Some basic
features of climate variability in the three regions for the last half century and the historical
hundreds of years are reviewed in this paper.
In the last half century, an increasing trend of summer precipitation associated with the enhancing
westerly flow is found in the westerly region from Xinjiang to northern parts of North China and
Northeast China. On the other hand, an increasing trend of summer precipitation along the Yangtze
River and a decreasing trend of summer precipitation along the monsoon northernmost marginal active
zone are associated with the weakening monsoon flow in East Asia.
Historical documents are widely distributed in the monsoon region for hundreds of years and natural
climate proxies are constructed in the non-monsoon region, while two types of climate proxies can be
commonly found over the monsoon northernmost marginal active zone. In the monsoon region, dry-wet
variation centers are altered among North China, the lower Yangtze River, and South China from one
century to another. Dry or wet anomalies are firstly observed along the monsoon northernmost marginal
active zone and shifted southward or southeastward to the Yangtze River valley and South China in
about a 70-year timescale. Severe drought events are experienced along the monsoon northernmost
marginal active zone during the last 5 centuries. Inter-decadal dry-wet variations are depicted by
natural proxies for the last 4--5 centuries in several areas over the non-monsoon region.
Some questions, such as the impact of global warming on dry-wet regime changes in China, complex
interactions between the monsoon and westerly flows in Northeast China, and the integrated multi-proxy
analysis throughout all of China, are proposed. 相似文献
8.
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
9.
Summary Spatial-temporal characteristics of temperature variations were analyzed from China daily temperature based on 486 stations
during the period 1960–2000. The method of hierarchical cluster analysis was used to divide the territory into sub-regional
areas with a coherent evolution, both annually and seasonally. Areas numbering 7–9 are chosen to describe the regional features
of air temperature in mainland China.
All regions in mainland China experienced increasing trends of annual mean temperature. The trend of increasing temperature
was about 0.2–0.3 °C/10 yr in northern China and less than 0.1 °C/10 yr in southern China. In the winter season, the increasing
trend of temperature was about 0.5–0.7 °C/10 yr in northern China and about 0.2–0.3 °C/10 yr in southern China. The increasing
trend of autumn temperature was mainly located in northwestern China and southwestern China including the Tibetan Plateau.
In spring, the rising trend of temperature was concentrated in Northeast China and North China while there was a declining
temperature trend of −0.13 °C/10 yr in the upper Yangtze River. In summer, the declining trend of temperature was only concentrated
in the mid-low valley of the Yangtze and Yellow Rivers while surrounding this valley there were increasing trends in South
China, Southwest China, Northwest China, and Northeast China.
Rapid changes in temperature in various regions were detected by the multiple timescale t-test method. The year 1969 was a rapid change point from a high temperature to a low temperature along the Yangtze River
and South China. In the years 1977–1979, temperature significantly increased from a lower level to a higher level in many
places except for regions in North China and the Yangtze River. Another rapid increasing temperature trend was observed in
1987. In the years 1976–1979, a positive rapid change of summer temperature occurred in northwestern China and southwestern
China while a decreasing temperature was found between the Yellow River and the Yangtze River. A rapid increase of winter
temperature was found for 1977–1979 and 1985–1986 in many places.
There were increasing events of extreme temperature in broad areas except in the north part of Northeast China and the north
part of the Xinjiang region. In winter, increasing temperature of the climate state and weakening temperature extremes are
observed in northern China. In summer, both increasing temperature of the climate state and enhancing temperature extremes
were commonly exhibited in northern China.
Present address: Linfen Meteorological Office, Linfen 041000, Shanxi Province, China. 相似文献
10.
Simulations of Water Resource Changes in Eastern and Central China in the Past 130 Years by a Regional Climate Model 
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下载免费PDF全文 Anthropogenic influences on regional climate and water resources over East Asia are simulated by using a regional model nested
to a global model. The changes of land use/land cover (LULC) and CO2 concentration are considered. The results show that variations of LULC and CO2 concentration during the past 130 years caused a warming trend in many regions of East Asia. The most remarkable temperature
increase occurred in Inner Mongolia, Northeast and North China, whereas temperature decreased in Gansu Province and north
of Sichuan Province. LULC and CO2 changes over the past 130 years resulted in a decreasing trend of precipitation in the Huaihe River valley, Shandong Byland,
and Yunnan-Guizhou Plateau, but precipitation increased along the middle reaches of the Yangtze River, the middle reaches
of the Yellow River, and parts of South China. This pattern of precipitation change with changes in surface evapotranspiration
may have caused a more severe drought in the lower reaches of the Yellow River and the Huaihe River valley. The drought trend,
however, weakened in the mid and upper reaches of the Yellow River valley, and the Yangtze River valley floods were increasing.
In addition, changes in LULC and CO2 concentration during the past 130 years led to adjustments in the East Asian monsoon circulation, which further affected
water vapor transport and budget, making North China warm and dry, the Sichuan basin cold and wet, and East China warm and
wet. 相似文献
11.
人类活动造成的温室气体浓度增加对气候变化的加剧做出了贡献,降水作为重要的气象要素和水循环组成部分,人类活动对其时空变化特征的影响也是当下研究的重要课题。本文以长江流域为例,利用1961～2016年CN05.1逐日降水数据和20世纪气候检测归因计划（C20C+D&A Project）中CAM5.1-1degree模式的逐日降水结果,分析了人类活动对长江流域年降水量及三个极端降水指数时空变化的影响。结果表明:包含人类活动及自然强迫因素的现实情景（All-Hist）的模拟结果与观测结果较为相近。All-Hist情景下的多试验集合平均结果对长江流域降水的模拟能力较为可靠。通过对比两种情景下模拟的长江流域降水量时空变化特征发现:考虑人类活动影响后,长江流域平均降水相对于仅考虑自然强迫情景下时呈现减少趋势,且减少趋势随时间推移加剧;极端降水受人类活动的影响随时间呈现出的增加趋势有所削弱;对平均降水及极端降水变化趋势的影响存在空间差异性,其中受人类活动影响最严重的是上游中部、东南部及中下游东南部地区,均呈现减少趋势;但在长江上游西南部极端降水受人类活动影响显著增加,需要加强该区域洪涝预防工作。另外,人类活动对平均降水的减少贡献最大的时段为2000～2009年,影响最明显季节为秋冬两季;人类活动对极端降水的影响与降水的极端程度成正相关,降水极端性越强,受人类活动影响的变化程度更大,且空间分布上的差异性也更加显著。 相似文献
12.
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
Yangtze. 相似文献
13.
青藏高原东北部强降水天气过程的气候特征分析 总被引：7，自引：2，他引：7
根据青藏高原东北部地区降水特点,定义青藏高原强降水概念,利用该区域内各测站自建站以来的气象资料,分析青藏高原强降水的时空分布特征和相对强度。结果表明:青藏高原东北部地区强降水的分布明显受到地形影响,年降水量和强降水次数自东向西呈阶梯性递减趋势,分别在青藏高原东北部的外流河谷地区和东南部四川北部地区存在大值中心;外流河谷地区两侧山脉的年降雨量较大,年均强降水日数较多,河源处相对较小,具有河谷地形的特点;青藏高原强降水的时段集中,雨强大,局地性强,且具有夜发性的特点;强降水日数和站数具有明显的年代际变化特征,近10年来出现区域性强降水的次数增加;青藏高原东北部外流河谷地区强降水的相对强度较大,同长江以南地区暴雨相对强度差不多。 相似文献
14.
Qiang Zhang Juntai Peng Chong-Yu Xu Vijay P. Singh 《Theoretical and Applied Climatology》2014,115(3-4):703-712
Daily precipitation data during the period of 1960 to 2005 from 147 rain gauging stations over the Yangtze River Basin are analyzed to investigate precipitation variations based on precipitation indices and also consecutive rainfall regimes in both space and time. Results indicate decreasing annual/monthly mean precipitation. Distinct decreases in rainfall days are observed over most parts of the Yangtze River Basin, but precipitation intensity is increasing over most parts of the Yangtze River Basin, particularly the lower Yangtze River Basin. Besides, durations of precipitation regimes are shortening; however, the fractional contribution of short-lasting precipitation regimes to the total precipitation amount is increasing. In this sense, the precipitation processes in the Yangtze River Basin are dominated by precipitation regimes of shorter durations. These results indicate intensified hydrological cycle reflected by shortening precipitation regimes. This finding is different from that in Europe where the intensifying precipitation changes are reflected mainly by lengthening precipitation regimes, implying different regional responses of hydrological cycle to climate changes. The results of this study will be of considerable relevance in basin-scale water resources management, human mitigation of natural hazards, and in understanding regional hydrological responses to changing climate at regional scales. 相似文献
15.
中国东部夏季降水年际变化与东中国海及邻近海域海温异常的关系 总被引：8，自引：0，他引：8
本文首先利用1979～2008年中国756个站点和GPCP2.1的降水资料与Hadley中心的HadISST再分析海温资料以及应用合成和相关分析方法, 分析了中国东部夏季降水年际变化及其与东中国海及邻近海域海温异常的关系。分析结果表明: 当东中国海及邻近海域为暖 (冷) 异常时, 长江中下游、 江淮地区夏季降水减少 (偏多), 而东北南部的降水偏多 (减少)。并且, 本文应用RegCM3区域气候模式对上述关系进行数值试验, 结果表明了东中国海及邻近海域的暖 (冷) 异常, 将使得我国长江、 黄淮流域和华北大部分地区夏季降水的减少 (增加), 而华南地区、 东北南部和朝鲜半岛等地夏季降水的增加 (减少)。此外, 本文还利用NCEP/NCAR再分析资料和数值模拟对上述关系的大气环流变异过程进行了分析, 分析结果揭示了上述海域的升温或降温对东亚地区上空的纬向和经向环流有较明显的影响。当东中国海及邻近海域升温时, 除了在该海域东部引起低空辐合, 高空辐散, 产生上升运动外, 还在其西部的长江、 黄淮流域和华北地区引起低空辐散, 高空辐合, 产生下沉运动, 这将引起长江、 黄淮流域和华北等地夏季降水的减少; 并在华南、 东北南部和朝鲜半岛地区引起低空辐合, 高空辐散, 从而产生上升运动, 这使得华南地区、 东北南部和朝鲜半岛夏季降水的增加。反之, 当东中国海及邻近海域降温时, 上述区域出现相反的现象。这些都说明东中国海及邻近海域的热力状态可能是影响我国东部夏季降水的重要因子之一。 相似文献
16.
利用NCAR的全球气候模式 (CCM3) 及第二次青藏高原边界层观测试验的研究结果, 对青藏高原上大气边界层高度的作用进行了研究, 分析了夏季青藏高原地区与长江流域上空的环流状况。研究表明:青藏高原的边界层高度特征对高原东南部地区以及长江流域出现强烈的垂直上升运动及其低层辐合、高层辐散存在着显著的动力效应, 深厚的高原边界层特征将使长江流域夏季区域性的云量及降水明显增加, 河套地区与黄河流域的夏季云量及降水有所减少。 相似文献
17.
2003夏季淮河流域发生了自1991年以来最为严重的洪涝灾害。为了更进一步认识淮河洪水的历史背景，根据史料反演得到的历史上淮河流域洪涝资料以及降水量观测资料分析了1470-2002年该地区的洪涝发生情况。根据淮河流域的洪水在全国范围降水分布和其他地区的关系分类，淮河降水主要有两种类型：第一种是长江淮河型，雨带集中在长江下游，也包括淮河；第二种是华北南部型，降水主要集中在华北南部和淮河。通过分析这两种类型的降水分布与对应的500hPa高度场的关系，得知淮河洪水和大气环流的异常有着紧密的联系，进一步研究洪水发生的规律，了解其形成的大气环流机制将有助于淮河的防洪抗汛工作。 相似文献
18.
根据我国东部地区（110°E以东）160个观测站100多a的降水资料对我国东部地区包括华北地区、长江流域和华南地区等100多a的降水变化趋势和降水极端偏多和极端偏少年份的分布进行了分析;并通过计算z指数,实现旱涝面积转化,分析我国东部100多a来的旱、涝范围变化和极端旱、涝年份的分布。结果表明：我国东部地区100多a的降水极端偏多年份随时间分布比较均匀,其间隔在20～40a间。降水极端偏少年份在减少。降水量的变化存在着大约40—50a的震荡周期。夏季降水增加明显,秋季降水下降明显。长江流域的年降水量和我国东部年降水量趋势保持较好的一致性,说明长江流域的降水对我国东部降水的贡献显著,华南区域的降水起次要作用。我国东部近100a来雨涝范围和干旱范围都没有表现出明显的增、减趋势,但存在着明显的年际和年代际振动。我国东部干旱覆盖面积最大的时间主要集中在1930年代以前,1969年以后变化趋势不明显。东北和华北极端干旱年份大都出现在1940年以前,长江流域和华南的极端干旱年份则随时间分布比较均匀。 相似文献
19.
利用2006年区域气候模式RegCM3和Streets气溶胶排放源清单,在原模式中引入间接气候效应模块,改进云降水方案,对硫酸盐气溶胶的时空分布、辐射强迫效应进行了模拟研究。结果表明：硫酸盐气溶胶辐射强迫有明显季节变化;直接效应使地表温度降低,冬春季大值区出现在四川盆地,夏季大值区出现在华北平原。对降水的影响,主要表现在西南—东北水汽输送带上降水减少;其间接气候效应主要表现在使南方地区温度上升、北方地区温度下降;珠江流域和黄河流域降水减少,长江流域和东北地区降水增加。总的来说,直接效应大于间接效应。 相似文献
20.
Searching for evidence of changes in extreme rainfall indices in the Central Rift Valley of Ethiopia 总被引：1，自引：0，他引：1
Muluneh Alemayehu Bewket Woldeamlak Keesstra Saskia Stroosnijder Leo 《Theoretical and Applied Climatology》2017,128(3-4):795-809
Extreme rainfall events have serious implications for economic sectors with a close link to climate such as agriculture and food security. This holds true in the Central Rift Valley (CRV) of Ethiopia where communities rely on highly climate-sensitive rainfed subsistence farming for livelihoods. This study investigates changes in ten extreme rainfall indices over a period of 40 years (1970–2009) using 14 meteorological stations located in the CRV. The CRV consists of three landscape units: the valley floor, the escarpments, and the highlands all of which are considered in our data analysis. The Belg (March–May) and Kiremt (June–September) seasons are also considered in the analysis. The Mann-Kendall test was used to detect trends of the rainfall indices. The results indicated that at the annual time scale, more than half (57 %) of the stations showed significant trends in total wet-day precipitation (PRCPTOT) and heavy precipitation days (R10mm). Only 7–35 % of stations showed significant trends, for the other rainfall indices. Spatially, the valley floor received increasing annual rainfall while the escarpments and the highlands received decreasing annual rainfall over the last 40 years. During Belg, 50 % of the stations showed significant increases in the maximum number of consecutive dry days (CDD) in all parts of the CRV. However, most other rainfall indices during Belg showed no significant changes. During Kiremt, considering both significant and non-significant trends, almost all rainfall indices showed an increasing trend in the valley floor and a decreasing trend in the escarpment and highlands. During Belg and Kiremt, the CDD generally showed increasing tendency in the CRV.
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