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1.
Potential evapotranspiration(E_(PET)) is usually calculated by empirical methods from surface meteorological variables,such as temperature, radiation and wind speed. The in-situ measured pan evaporation ET_(pan) can also be used as a proxy for E_(PET). In this study, E_(PET) values computed from ten models are compared with observed ET_(pan) data in ten Chinese river basins for the period 1961-2013. The daily observed meteorological variables at 2267 stations are used as the input to those models, and a ranking scheme is applied to rank the statistical quantities(ratio of standard deviations, correlation coefficient, and ratio of trends) between ET_(pan) and modeled E_(PET) in different river basins. There are large deviations between the modeled E_(PET) and the ET_(pan) in both the magnitude and the annual trend at most stations. In eight of the basins(except for Southeast and Southwest China), ET_(pan) shows decreasing trends with magnitudes ranging between-0.01 mm d~(-1) yr~(-1) and-0.03 mm d~(-1) yr~(-1), while the decreasing trends in modeled E_(PET) are less than-0.01 mm d~(-1) yr~(-1). Inter comparisons among different models in different river basins suggest that PET_(Ham1) is the best model in the Pearl River basin, PET_(Ham2) outperforms other models in the Huaihe River, Yangtze River and Yellow River basins, and PET_(FAO) is the best model for the remaining basins. Sensitivity analyses reveal that wind speed and sunshine duration are two important factors for decreasing E_(PET) in most basins except in Southeast and Southwest China. The increasing E_(PET) trend in Southeast China is mainly attributed to the reduced relative humidity. 相似文献
2.
A high-quality monthly pan evaporation dataset of 60 stations has been developed for monitoring long-term pan evaporation
trends over Australia. The quality control process involved examination of historical station metadata together with an objective
test comparing candidate series with neighboring stations. Identified points of discontinuity were located, including installations
of bird guards, site relocations and changes in exposure. Appropriate inhomogeneity adjustments have been applied using established
methods to produce the first homogeneous pan evaporation dataset for Australia. Analysis of these data reveals that Australian
annual mean pan-evaporation shows large interannual variability with no trend over the 1970–2005 period. Previous studies
using unadjusted data have shown a decline in pan evaporation, highlighting the importance of checking data for homogeneity
before drawing conclusions about long-term trends. A strong inverse correlation is evident between all-Australian means of
pan evaporation and rainfall, while a moderate positive correlation is found between pan evaporation and mean temperature.
The positive correlations between mean temperature and pan evaporation that exist on the interannual time scales are not reflected
in the long-term trends, highlighting that the mechanisms that are responsible for variations on the short and longer time
scales are different. This result cautions against the expectation that large changes in potential evaporation are a natural
consequence of global warming. 相似文献
3.
采用线性倾向估计法和累积距平曲线和完全相关系数法,分析了1951—2001年大连市蒸发量变化特征及其影响因子。结果表明：大连市年蒸发量呈增加趋势,其中夏季蒸发量的增加趋势最为明显,其次为春季,秋季和冬季蒸发量增加趋势不显著;年蒸发量的增加主要来自夏季的贡献。大连市年及四季蒸发量与日照时数、平均地面温度、平均气温日较差和平均风速总体上呈正相关,与平均相对湿度呈负相关。平均相对湿度减小和平均地面温度上升是大连市蒸发量增加的主要原因。 相似文献
4.
利用长江流域147个气象站点1960—2007年的地面观测数据,通过计算,对比分析了长江流域20 cm口径蒸发皿蒸发量与太阳辐射的变化关系.结果表明:长江流域近50年来蒸发皿蒸发量变化和太阳辐射变化呈显著正相关关系,二者均呈现显著下降趋势,蒸发皿蒸发量随太阳辐射的变化产生相应波动变化,而且中下游地区蒸发皿蒸发量变化受太阳辐射变化的影响程度更为明显;就季节变化而言,春夏秋冬4个季节长江流域蒸发皿蒸发量变化和太阳辐射变化同样呈现明显下降趋势,春、夏、秋3个季节二者变化关系高度相关,这三季对于流域全年蒸发皿蒸发量减少的贡献也最大;长江流域太阳辐射的显著下降是导致20 cm口径蒸发皿蒸发量持续降低的主要原因之一. 相似文献
5.
烟台市蒸发量变化趋势及影响因子 总被引：1，自引：0，他引：1
利用烟台市1971—2010年蒸发量、气温、日照、降水和总云量资料,采用线性回归、相关分析、小波分析、逐步回归方法,对蒸发量变化趋势及其影响因子进行分析。结果表明,烟台年蒸发量存在2～3年的主周期和4～8、8～12年的次周期变化,春季、夏季、秋季和冬季蒸发量分别存在3～5、5～7、7～11和2～4年的周期变化。平均相对湿度的增加和日照时数的减少是蒸发量减少的主要原因,而影响各季节蒸发量变化的气象因子各有不同。日照时数和总云量是影响夏秋季节蒸发量变化的最主要因子,秋冬季节的蒸发量主要受平均相对湿度、日照时数和总云量的共同影响。 相似文献
6.
利用海南岛18个气象观测站1966—2001年逐日20cm口径小型蒸发皿蒸发量及气象要素资料,通过数理统计方法分析了海南岛年和四季的蒸发量变化特征及气象因子对蒸发量的影响。结果表明:从时间上看,海南岛年蒸发量变化呈波动式下降,蒸发量的减少主要出现在春季,冬季和夏季次之。从空间上看,年蒸发量呈东北少、西南多的分布,其大值区主要集中在西南部,小值区主要集中在东北部和中部地区。M-K检验说明年与春冬两季蒸发量的变化呈下降趋势且在1994年前后发生突变。影响蒸发量变化的因子中,日照时数和风速是造成蒸发量减小的主要因子,降水量的影响仅次于风速和日照时数,而气温不是造成海南岛蒸发量减小的主要因子,相对湿度可能是海南岛的蒸发量减小的影响因子。 相似文献
7.
利用1971-2010年黑龙江省63个气象站地面气象观测数据,应用气候趋势系数、气候倾向率等方法分析黑龙江省蒸发皿蒸发量和实际蒸发量的时空演变特征。结果表明：近40 a来,黑龙江省蒸发皿蒸发量总体呈下降趋势,气候倾向率达-62.7 mm/10 a,春季和夏季下降显著。从空间分布看,全省蒸发皿蒸发量呈下降趋势,但局部地区与气候变化趋势并不完全同步。在影响蒸发皿蒸发量的气象因子中,风速和气温日较差是影响其下降的关键因素。黑龙江省大部分地区年实际蒸发量占蒸发皿蒸发量的30 %,实际蒸发量呈微弱上升趋势,但不显著。实际蒸发量与降水、日照时数和气温日较差显著相关,日较差是影响其变化的首要原因。 相似文献
8.
近40年京津冀蒸发皿蒸发量变化特征及影响因子 总被引：1，自引：0，他引：1
为了研究京津冀地区蒸发皿蒸发量的变化特征及成因,在京津冀地区200多个气象站中选择资料序列完整且具有较长时间序列、测站环境评分都在70分以上(按照中国气象局对测站探测环境评分标准评分)、均匀分布的87个气象站,利用1970—2013年京津冀地区87个气象站蒸发皿蒸发量以及其他气象要素的观测资料,采用线性倾向估计法和完全相关系数法,分析近44年来京津冀蒸发量变化特征及影响因子。结果表明,近44年来,京津冀地区年、季蒸发量呈明显下降趋势。全年蒸发量减少速率由大到小分别为:山前平原区太行山区冀东平原区燕山丘陵区冀北高原区(蒸发速率由北向南逐渐增大);四季中下降速率为:春季秋季冬季夏季。分析蒸发量与影响因子的完全相关系数发现,气温日较差、日照时数和平均风速是影响京津冀地区蒸发皿蒸发量变化的主要因子,在平原地区,平均风速是主导因子;在山区和高原地区,日照时数是主导因子。 相似文献
9.
1961-2010年青海高原蒸发皿蒸发量变化及其对水资源的影响 总被引：2，自引：0，他引：2
利用1961-2010年青海省气象观测资料,分析了青海高原近50年蒸发皿蒸发量的时空分布特征和变化趋势,并采用偏相关及主成分分析法,探讨了青海高原蒸发皿蒸发量变化的气候成因及其对水资源的影响。结果表明：近50 a来青海高原蒸发皿蒸发量呈显著下降趋势,它是热力、水分、动力因子综合作用的结果,在三类因子中,动力及水分因子对蒸发皿蒸发量的影响较大,而热力因子相对较小;区域分析表明,影响东部农业区和柴达木盆地蒸发量的主导因子是平均风速和相对湿度,三江源区为相对湿度,而唐古拉山区为气温日较差。通过分析黄河上游可能蒸散量与地表水资源的关系发现,蒸散量对地表水资源的负效应十分显著,其中夏季蒸散量对于平均流量的影响最为显著,而秋季平均流量对蒸散量的响应最为敏感。 相似文献
10.
利用广东省86个气象站点1961—2003年的地面气象观测数据,采用经验正交函数分解（EOF）和相关分析法,分析了广东省年蒸发皿蒸发量和实际蒸发量的时空变化。结果表明,粤东沿海、珠三角和粤西南等沿海地区是广东省年蒸发皿蒸发量的主要气候变异中心,广东省沿海年蒸发皿蒸发量具有以年代际变化为主的特征,并且在43 a内总体上呈下降趋势,广东省沿海地区与粤东、粤中地区年蒸发皿蒸发量气候变化趋势的差异,可能是由于饱和差、近地面风速在两个区域的气候变化变幅不同所致。在影响蒸发皿蒸发量的因子中,太阳辐射与蒸发皿蒸发量的相关性最好,呈显著的正相关。对实际蒸发量而言,在全省范围内均表现为以年际变化为主的特征,太阳辐射对广东省年实际蒸发量的影响最为显著,广东省年实际蒸发量一般都占蒸发皿蒸发量的50%左右,并且比值总体上呈现微弱的由沿海地区向粤东、粤中地区递增的趋势。研究结果可为今后探讨广东省水资源异常和旱涝气候灾害的成因提供依据。 相似文献
11.
利用黄河流域内61个气象站逐月观测资料,使用Mann-Kendall非参数检验方法对1961—2010年黄河流域小型蒸发皿蒸发量变化趋势进行了分析,并用SVD和多元回归方法检测影响蒸发量变化的因子。结果表明,黄河流域年蒸发皿蒸发量在1961—2010年显著下降,四季中夏季的下降趋势最显著,年和春、夏季蒸发量均在1979年发生突变。上、中、下游的年蒸发量变化率分别为-2.38 mm/a、-2.35 mm/a、-8.35 mm/a,下游下降幅度较大。空间变化分布上,年和春、夏季蒸发皿蒸发量均在黄河流域河源地区、河套地区西部及北部、河南北部有显著下降趋势,在河套地区东部呈显著上升趋势。利用SVD分析发现蒸发量的空间变化与不同因子作用有着显著关联,通过对不同区域内各影响因子的多元回归分析发现流域内蒸发量上升的地区主要是由气温上升所引起,而下降的地区则与风速减小有关。 相似文献
12.
湘江流域蒸发皿蒸发量的变化趋势及原因分析 总被引：1，自引：0，他引：1
利用1960-2006年湘江流域内44个气象观测站蒸发皿观测资料,采用气候倾向率、相关系数分析法,以及反距离权重插值来分析湘江流域蒸发皿蒸发量的时空变化特征及其影响因子。结果表明：湘江流域年蒸发皿蒸发量在47年间以21.29 mm/10a速率显著减少,通过了90%信度检验;且有75%的站点蒸发皿蒸发量下降趋势显著。从季节变化来看,蒸发皿蒸发量的下降趋势主要在夏季,以15.58 mm /10a的速率显著下降,并通过了99%信度检验。从空间分布来看,湘江流域蒸发皿蒸发量自西南向东北逐渐减少,且下游地区减少趋势最显著。流域饱和差的减小及风速的显著下降导致大部分站点蒸发皿蒸发量呈下降趋势。 相似文献
13.
夏季风影响过渡区是天气和气候的敏感区,随着全球和区域的变暖,该区域特殊的气候环境响应引起人们重点关注。以南昌、定西、乌鲁木齐作为夏季风影响区、夏季风影响过渡区以及非夏季风影响区的代表站,通过对比中国夏季风影响过渡区和其他地区50年来温度、日照时数、相对湿度、降水量、低云量、风速的变化趋势,以及分析各气象因子单独变化对蒸发皿蒸发量的影响,发现在夏季风影响过渡区各个气象因子的变化均使蒸发皿蒸发量增加,而在其他地区,只有温度变化会使蒸发皿蒸发量增加,其他各因子的变化均会造成蒸发皿蒸发量的下降。贡献度更直观的反映各气象因子对不同地区蒸发皿蒸发的作用。结果表明温度变化对夏季风影响过渡区蒸发皿蒸发变率的贡献最大,贡献度为48.93%。风速变化对夏季风影响区蒸发皿蒸发变率的贡献最大,贡献度为51.54%。降水变化对非夏季风影响区蒸发皿蒸发变率的贡献最大,贡献度为58.57%。此外,低云量的变化对夏季风影响过渡区、夏季风影响区和非夏季风影响区的贡献均达到20%以上。因此,不同地区影响蒸发皿蒸发的最主要的因子是不同的,但低云量对任何地区蒸发皿蒸发的影响都非常重要。 相似文献
14.
15.
Multiscale evolution of surface air temperature in the arid region of Northwest China and its linkages to ocean oscillations 总被引：1，自引：0，他引：1
Chen Zhongsheng Chen Yaning Bai Ling Xu Jianhua 《Theoretical and Applied Climatology》2017,130(3-4):945-958
Reference crop evapotranspiration (ETo) is one of the most important links in hydrologic circulation and greatly affects regional agricultural production and water resource management. Its variation has drawn more and more attention in the context of global warming. We used the Penman-Monteith method of the Food and Agriculture Organization, based on meteorological factors such as air temperature, sunshine duration, wind speed, and relative humidity to calculate the ETo over 46 meteorological stations located in the Yangtze River Delta, eastern China, from 1957 to 2014. The spatial distributions and temporal trends in ETo were analyzed based on the modified Mann-Kendall trend test and linear regression method, while ArcGIS software was employed to produce the distribution maps. The multiple stepwise regression method was applied in the analysis of the meteorological variable time series to identify the causes of any observed trends in ETo. The results indicated that annual ETo showed an obvious spatial pattern of higher values in the north than in the south. Annual increasing trends were found at 34 meteorological stations (73.91 % of the total), which were mainly located in the southeast. Among them, 12 (26.09 % of the total) stations showed significant trends. We saw a dominance of increasing trends in the monthly ETo except for January, February, and August. The high value zone of monthly ETo appeared in the northwest from February to June, mid-south area from July to August, and southeast coastal area from September to January. The research period was divided into two stages—stage I (1957–1989) and stage II (1990–2014)—to investigate the long-term temporal ETo variation. In stage I, almost 85 % of the total stations experienced decreasing trends, while more than half of the meteorological stations showed significant increasing trends in annual ETo during stage II except in February and September. Relative humidity, wind speed, and sunshine duration were identified as the most dominant meteorological variables influencing annual ETo changes. The results are expected to assist water resource managers and policy makers in making better planning decisions in the research region. 相似文献
16.
中国北方近45年蒸发变化的特征及与环境的关系 总被引：41，自引：4，他引：37
对整个中国北方及东北、华北、西北区东部和西北区西部四个子区域蒸发皿蒸发时间序列的分析发现,近45年(1960—2004年)中国北方蒸发皿蒸发的下降趋势明显,并且在空间上从东北向西北的下降趋势逐渐增大。同时结合降水、相对湿度、日较差及日照等环境因子对过去45年的变化特征及与蒸发皿蒸发之间的关系进行了分析,结果表明:在中国北方,无论是在半湿润的东北区还是干旱的西北区,气温日较差和风速都是影响蒸发皿蒸发的最重要的因子,这可能是导致蒸发皿蒸发下降的主要原因;而降水、相对湿度、日照等的作用也不可忽视。 相似文献
17.
Non-parametric trend analysis of the aridity index for three large arid and semi-arid basins in Iran 总被引：2，自引：1，他引：1
Hossien Ahani Mehrzad Kherad Mohammad Reza Kousari Lieke van Roosmalen Ramin Aryanfar Seyyed Mashaallah Hosseini 《Theoretical and Applied Climatology》2013,112(3-4):553-564
Currently, an important scientific challenge that researchers are facing is to gain a better understanding of climate change at the regional scale, which can be especially challenging in an area with low and highly variable precipitation amounts such as Iran. Trend analysis of the medium-term change using ground station observations of meteorological variables can enhance our knowledge of the dominant processes in an area and contribute to the analysis of future climate projections. Generally, studies focus on the long-term variability of temperature and precipitation and to a lesser extent on other important parameters such as moisture indices. In this study the recent 50-year trends (1955–2005) of precipitation (P), potential evapotranspiration (PET), and aridity index (AI) in monthly time scale were studied over 14 synoptic stations in three large Iran basins using the Mann–Kendall non-parametric test. Additionally, an analysis of the monthly, seasonal and annual trend of each parameter was performed. Results showed no significant trends in the monthly time series. However, PET showed significant, mostly decreasing trends, for the seasonal values, which resulted in a significant negative trend in annual PET at five stations. Significant negative trends in seasonal P values were only found at a number of stations in spring and summer and no station showed significant negative trends in annual P. Due to the varied positive and negative trends in annual P and to a lesser extent PET, almost as many stations with negative as positive trends in annual AI were found, indicating that both drying and wetting trends occurred in Iran. Overall, the northern part of the study area showed an increasing trend in annual AI which meant that the region became wetter, while the south showed decreasing trends in AI. 相似文献
18.
Changes of pan evaporation and reference evapotranspiration in the Yangtze River basin 总被引：5，自引：2，他引：5
Summary For the upper and mid-lower Yangtze River basin trends of pan evaporation and reference evapotranspiration are analysed from
1961 to 2000 using daily data of 115 stations. Both pan evaporation and reference evapotranspiration decreased during the
summer months contributing most to the total annual reduction. This trend is more significant in the mid-lower than in the
upper Yangtze reaches. The decreasing trends can be associated with trends in net radiation and wind speed. Results are compared
with the 20th century evaporation simulated by the general circulation model (GCM, ECHAM5/MPI-OM). Also the GCM’s actual evaporation
decreases contrasting an overall increase in air temperature. 相似文献
19.
为了研究广东省的气候变化规律及其成因,利用1961—2003年广东省86个气象站点的观测数据,采用Mann—Kendal非参数检验方法、EOF经验正交分解方法和灰色关联分析方法,对广东省近43a来蒸发皿蒸发量及其主要影响因子（日照时数、风速、降水量、饱和差、气温日较差、气温等）进行了相关性及趋势性分析。结果表明：43a来广东省的季蒸发皿蒸发量的下降主要表现在春季、前汛期和后汛期,其减少趋势通过或接近通过99％置信水平的统计检验,而秋季的变化不明显;四季蒸发皿蒸发量的下降主要表现在粤东沿海、珠三角和粤西南等沿海地区,不同季节气候变异中心的位置不同;日照时数下降以及风速、气温日较差的减小可能是近年来广东四季蒸发皿蒸发量下降的主要原因。 相似文献
20.
1961～2013年中国蒸发皿蒸发量时空分布特征及其影响因素 总被引：1，自引：0，他引：1
分析了1961～2013年中国1302个台站的蒸发皿蒸发量（Pan Evaporation,PE）的时空分布特征并探讨了影响PE变化的主要气候因子。结果表明:站点平均PE在全年和四季都呈明显下降趋势,且在1978年发生了突变。PE在华北平原、新疆、广东、广西及海南等地呈现出显著的下降趋势,而在福建、浙江和贵州等地为显著上升的趋势。用年平均PE距平场经验正交函数做经验正交函数（EOF）分解得到:在第一模态（EOF1）中,1981年时间系数由负转正,EOF1的空间模态与PE的变化有较好的一致性;第二模态（EOF2）中PE距平呈南北反向分布,2002年以后PE在北方减小,在南方增大。通过计算PE与近地面5个气象因子（降水、气温、风速、湿度、日照时数）的偏相关系数后发现:除了降水外,其余4个因子都和PE有很好的相关性。风速与PE为显著正相关,且相关系数最大的区域与EOF1中PE变率最大的区域吻合;相对湿度与PE为显著负相关;PE与气温的相关系数都为正值,且相关系数最大的区域对应于PE显著增加的地区,而与日照时数的相关系数在除春季以外的其他季节都大于0.6。进一步分析发现,风速和日照时数与PE的关系受两个气象因子的线性趋势影响较大,以此推断出PE的下降趋势应该很大程度是受风速和日照时数减小的影响。此外,干旱发生时,PE明显偏大,降水、气温、湿度和日照时数的变化也都对PE增大有明显的贡献,PE对干旱有很好的指示作用。 相似文献