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1.
利用长江上游最近30年(66个测站)蒸发皿蒸发量和最近50年(90个测站)的7种气象要素,分析了蒸发皿蒸发量的区域变化趋势和影响蒸发皿蒸发量变化的因素;针对7个水文站的年径流量变化,探讨了蒸发皿蒸发量变化后对水分循环的影响.结果表明,长江上游蒸发皿蒸发量的变化可以划分为三个分区,研究区域东西两侧(青藏高原和大巴山一带)为显著减少区,分别命名为RⅠ和RⅡ,中间(云贵高原北部到黄土高原南缘以及由二者包围的四川盆地一带)为显著增大区,命名为RⅢ区.影响区域蒸发皿蒸发量变化的原因各有不同,青藏高原一带(RⅠ区)蒸发皿蒸发量减少的原因可归结于太阳辐射强度和风动力扰动减弱所致.大巴山一带(RⅡ区)减少原因是太阳辐射强度、风动力扰动强度、湿度条件都在显著下降所引起的.云贵高原到四川盆地一带(RⅢ区)蒸发皿蒸发量增加是环境气温强烈升高,导致其上空大气水汽含量显著减少,大气很干燥,引发蒸发过程加强所致.蒸发皿蒸发量发生变化的直接后果就是导致水分循环强弱发生变化,对于RⅠ区,尽管蒸发皿蒸发量减少,由于降水量和径流量增加的作用,这一区域的水分循环有所加强.在RⅡ区,降水量、径流量和蒸发量都在减少,因此RⅡ区水分循环显著减弱.在RⅢ区,降水量和径流量同时减少,而蒸发量增大,水量消耗增大,因此RⅢ区水分循环有减弱趋势. 相似文献
2.
依据边界层梯度输送理论和能量守恒原理分析了蒸发皿蒸发量的物理意义，蒸发皿蒸发量是多环境因子共同非线性相互作用的结果，并利用我国有长期太阳辐射观测的62个常规气象站观测资料，通过蒸发皿蒸发量与环境气象因子的相关分析对其进行了验证. 分析了近40年蒸发皿蒸发量和环境气象因子的变化趋势，分析结果也表明只利用单个环境因子的变化来解释蒸发皿蒸发量的气候变化会产生偏颇，譬如将蒸发皿蒸发量的逐年减少归因于地表接收的太阳辐射减少的解释在中国东部比在中国西部较合理. 分析1983～2001年间国际卫星云气候计划观测的资料得出，我国大部分地区的总云量保持微小的减少趋势而总云水路径处于明显的增加趋势，这表明云变得更不透明了,它的物理属性发生了明显的变化;预示着大气可降水量有逐年增加的趋势, 地气系统变得更湿润. 结合水循环过程，利用大气环流模式用数值方法证明地气系统的水汽变化能引起陆地近地层大气相对湿度、地表接收的太阳总辐射和地表潜在蒸发量的明显变化. 相似文献
3.
青海湖流域及周边地区蒸发皿蒸发量变化(1961-2007年)及趋势分析 总被引：3，自引：1，他引：2
采用单调趋势的非参数统计检验Mann-Kendall(M-K)法和灰色关联分析方法对青海湖流域及周边地区1961-2007年20cm小型蒸发皿蒸发量及其影响气候因子的变化趋势进行了分析.结果表明,近47a来青海湖流域及周边地区的蒸发皿蒸发量平均每年减少4.47mm,各季节的蒸发皿蒸发量除秋季变化不显著外,其它各季以0.55-1.83mm/a的速率减小,其中春季减幅最大,其次是夏季,冬季减幅最小;日照时数的减少导致了气温日较差变小和空气饱和差的减小,是造成该研究区域蒸发皿蒸发量减小的主要原因. 相似文献
4.
鄱阳湖夏季水面蒸发与蒸发皿蒸发的比较 总被引：3，自引：1，他引：2
水面蒸发是湖泊水量平衡要素的重要组成部分.基于传统蒸发皿观测蒸发不能代表实际水面蒸发,而实际水面蒸发特征仍不清楚.本研究基于涡度相关系统观测的鄱阳湖水体实际水面蒸发过程,在小时和日尺度分析了水面蒸发的变化规律及其主要影响因子,并与蒸发皿蒸发进行比较.研究表明,实际水面蒸发日变化波动剧烈,变化范围在0~0.4 mm/h之间.水面蒸发的日变化特征主要受风速的影响.鄱阳湖8月份日水面蒸发量与蒸发皿蒸发量在总体趋势上具有很好的一致性.8月份平均日水面蒸发速率(5.90 mm/d)比蒸发皿蒸发速率(5.65 mm/d)高4.6%.水面日蒸发量与蒸发皿蒸发量的比值在8月上、中、下旬平均值分别为1.24、1.00、0.92,呈现下降的趋势.鄱阳湖夏季水面日蒸发量与风速和相对湿度相关性显著,而蒸发皿蒸发与净辐射、气温、饱和水汽压差和相对湿度均呈显著相关.这是由于蒸发皿水体容积小,与湖泊相比其水体热存储能力小,因此更容易受到环境因子的影响. 相似文献
5.
贵州蒸发皿蒸发量变化趋势及影响因素分析 总被引：4，自引：0，他引：4
以贵州境内18个气象站1961-2001年逐日气象观测数据为基础,采用Mann-Kendal非参数检验方法、相关分析和主成分分析方法对贵州近41年来蒸发皿蒸发量及其主要影响因子(太阳净辐射、气温、相对湿度和风速等)进行了相关性及趋势性分析.结果表明:近41年来,贵州年平均蒸发皿蒸发量呈显著下降趋势,通过99%的置信度检验,蒸发量的下降主要表现在冬、春、夏三季.从区域分布来看,蒸发皿蒸发量整体上东部及西北部分地区显著减少,其他地区趋势变化不明显.蒸发皿蒸发量下降的主要原因是太阳净辐射的显著下降. 相似文献
6.
本文以能量守恒原理和边界层梯度输送理论为基础,应用Monin-Obukhov相似函数计算蒸发皿水面感、潜热通量,参数化蒸发皿侧壁热传输能量,建立了一个单层的20 cm蒸发皿蒸发模型.之后利用"古浪非均匀近地层观测试验"中连续14天观测的每小时20 cm蒸发皿数据对所建模型进行检验.研究分析结果表明:模型能够很好地反映蒸发皿水面与地表之间所形成的非均匀性,合理地概括蒸发皿与周围环境之间的相互作用和蒸发皿蒸发的物理过程.另外,模型成功模拟了蒸发皿蒸发的日变化过程,模拟的日蒸发量均方根误差(RMSE)和平均相对误差(MRER)分别为0.44 mm·d-1和3.7%,日蒸发量观测值与模拟值的相关系数为0.998. 相似文献
7.
基于不同再分析资料的全球蒸发量时空变化特征分析 总被引：3，自引：0，他引：3
基于目前使用较为广泛的8套再分析资料,研究了全球蒸发量的时空变化特征,同时对比分析了各套资料的异同点,研究结果表明:各套资料全球蒸发量的空间分布型基本一致,均具有明显的海陆、经向分布差异,并且同纬度陆地上高海拔地区蒸发量小于低海拔地区.各套资料蒸发量的时间变化形势不尽相同,其中MERRA,ERA-Interim,NCEP-R1和NCEP-R2等资料全球平均蒸发量的逐年变化基本一致,而CFSR与ERA-40资料更为接近;各套资料陆地平均蒸发量的逐年变化差异较大,其中MERRA,CFSR和NCEP-R2资料比较相似,而海洋平均蒸发量的变化形势具有较高的一致性,说明再分析资料对海洋蒸发量时空演变特征的再现能力更强.整体而言,MERRA与NCEP-R2资料能够同时较好地反映出全球蒸发量的时空变化特征,具有很好的代表性;此外,CFSR与ERA-40资料也可以较好地刻画出陆地蒸发量的变化特点,而ERA-Interim,NCEP-R1,OAFlux和HOAPS等资料比较适用于对海洋蒸发量的研究.各套资料陆地与海洋平均蒸发量在1958~1978年基本都呈现显著的线性减少趋势,而在1979~2011年时间段内大多是线性增加的,其中海洋地区更加显著.全球蒸发量也同时存在比较显著的年循环特征,尤其是北半球低纬度地区,而且陆地蒸发量逐月变化幅度要高于海洋. 相似文献
8.
1961-2003年间鄱阳湖流域气候变化趋势及突变分析 总被引：19，自引：2，他引：19
本文利用1961-2003年间鄱阳湖流域14个气象站的气温、降水量、蒸发量等观测数据和8个主要水文站的流量数据,研究该时段内鄱阳湖流域的气候变化趋势、突变及其空间分布的差异．研究表明,鄱阳潮流域气温和降水均在1990年发生突变,继而呈现显著的上升趋势；在季节变化上,冬季平均气温在1986年发生突变,增温显著；夏季降水量和夏季暴雨频率均在1992年发生突变增加,暴雨频率增加是夏季降水量增加的主要原因；蒸发皿蒸发量和参照蒸散量均呈现显著下降趋势,该变化在夏季尤为明显．上述变化趋势均以1990s最为显著,这与长江流域气候变化趋势基本一致．在空间分布上,饶河水系、信江水系和赣江下游等气候变化更为显著．笔者认为,鄱阳湖流域气候变化在长江流域中比较突出．该流域1990s暖湿气候在加强；气温的升高、降水量和暴雨频率的增加以及蒸发量的下降强化了五河流量的增加趋势,由此可大致判定鄱阳湖流域气候变化与洪涝灾害之间可能存在的关系,这可为理解气候变化在该流域的响应和预测该流域未来可能的洪涝灾害提供依据． 相似文献
9.
湖泊蒸发量的准确估算对于水文学、气象学和湖泊学等研究有重要的意义.基于2013-2015年太湖水量收支资料、气象观测数据和稳定同位素观测资料,采用稳定同位素质量守恒模型、水量平衡法和Priestley-Taylor模型估算太湖蒸发量,分析太湖蒸发量的季节变化和年际变化特征,并以Priestley-Taylor模型结果为参考值,评价水量平衡法和同位素质量守恒方程的计算精度.结果表明:5-9月太湖蒸发量较高,冬季最低.2013-2015年太湖年总蒸发量分别为1069、894和935 mm,蒸发量的年际变化受到天气条件的影响.2013年12月2014年11月期间,用Priestley-Taylor模型计算的湖泊蒸发量为885 mm;同位素质量守恒模型的估算结果较一致,为893 mm;而水量平衡方程的估算结果明显偏高,为1247 mm. 相似文献
10.
湖泊蒸发对气候变化非常敏感, 是水文循环响应气候变化的指示因子, 因此研究湖泊蒸发的控制因素, 对于理解区域水文循环有重要意义. 本文利用太湖中尺度涡度通量网避风港站观测数据校正JRA-55再分析资料, 驱动CLM4.0-LISSS模型, 并利用2012—2017年涡度相关通量数据和湖表面温度数据检验模型模拟蒸发结果, 验证了该模型在太湖的适用性; 估算了1958—2017年间太湖的湖面蒸发量, 并利用Manner-Kendall趋势检验分析了湖面蒸发的变化趋势, 寻找太湖实际蒸发的年际变化的主控因子. 结果如下: 校正后的JRA-55再分析资料模拟的太湖蒸发与观测值之间存在季节偏差, 但是季节偏差在年尺度上相互抵消, 再分析资料可用于年际尺度太湖蒸发变化的模拟; 1958—2017年间太湖蒸发量以1977年为界, 先下降(-3.6 mm/a), 后增加(2.3 mm/a); 多元逐步回归结果表明, 向下的短波辐射是太湖1958—2017年间太湖蒸发变化的主控因子, 向下的长波辐射、气温、比湿也对湖泊蒸发年际变化有一定影响, 但是风速对蒸发量的年际变化影响不大. 相似文献
11.
Abstract Evaporation is an important reference for managers of water resources. This study proposes a hybrid model (BD) that combines back-propagation neural networks (BPNN) and dynamic factor analysis (DFA) to simultaneously precisely estimate pan evaporation at multiple meteorological stations in northern Taiwan through incorporating a large number of meteorological data sets into the estimation process. The DFA is first used to extract key meteorological factors that are highly related to pan evaporation and to establish the common trend of pan evaporation among meteorological stations. The BPNN is then trained to estimate pan evaporation with the inputs of the key meteorological factors and evaporation estimates given by the DFA. The BD model successfully inherits the advantages from the DFA and BPNN, and effectively enhances its generalization ability and estimation accuracy. The results demonstrate that the proposed BD model has good reliability and applicability in simultaneously estimating pan evaporation for multiple meteorological stations. Citation Chang, F.J., Sun, W., and Chung, C.H., 2013. Dynamic factor analysis and artificial neural network for estimating pan evaporation at multiple stations in northern Taiwan. Hydrological Sciences Journal, 58 (4), 813–825. 相似文献
12.
Guangyong You Yiping Zhang Yuhong Liu Qinghai Song Zhiyun Lu Zhenghong Tan Chuansheng Wu Youneng Xie 《水文研究》2013,27(18):2676-2682
Negative trends of measured pan evaporation are widely reported. Studies of the factors that underlie this reduction in pan evaporation have not reached a consensus about the controlling factors. Most studies employ statistical analysis (correlation analysis or stepwise regression) to identify the controlling climatic variables; in contrast, few studies have employed physical‐based theories. In addition, observations of pan evaporation and related climatic variables are reported to be influenced by anthropogenic activities. Consequently, the observed trends of climatic variables in a nature reserve would be useful for understanding regional climate change. The present study site is located in Ailaoshan National Nature Reserve, SW China, which is free of anthropogenic activity. In this study, we firstly applied the adjusted PenPan model to estimate the pan evaporation. Then, using this physical‐based model, we identified a positive trend in pan evaporation, with a much larger increase in the dry season than in the wet season. The model results indicate that the change in the aerodynamic component is larger than that in the radiative component. In contrast to the reduction in wind speed and sunshine hours that has been reported in previous studies at various sites, we found that wind speed and sunshine hours have increased in recent decades, thereby explaining the increase of the pan evaporation rate. Wind speed made the greatest contribution to the change in pan evaporation, followed by sunshine duration. This study indicates that the potential evaporation has increased at this site despite the widely reported reduction in measured pan evaporation. During the dry season, the availability of water for agriculture and agroforestry could be threatened. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
13.
I. M. Oroud 《Journal of Hydrology》1998,210(1-4):1-10
Lateral heat conduction across a large circular sunken pan located in a hot, dry environment is evaluated using a numerical procedure. Heat flow across the sunken pan–adjacent soil boundary is calculated using a two-dimensional soil plane. Calculations show that a large temperature differential across the pan–substrate boundary develops during the entire diurnal cycle during January and July, leading to consistently positive heat flow from the soil towards the sunken pan. Heat conduction across the pan–substrate boundary represents 10 and 34% of net radiation over the sunken pan during July and January, respectively. This additional heat source, which is not available for shallow lakes, increases annual evaporation from the sunken pan by about 5–8% in July and January, respectively. In hot arid environments, a sunken pan will overestimate evaporation from a nearby shallow lake/dam due to a larger surface roughness and consistently positive conduction heat flow across the pan–substrate boundary. 相似文献
14.
RICHARD N. WEISMAN 《水文科学杂志》2013,58(3):371-377
Abstract The effect that evapotranspiration has on recession curves during low flow periods is explored. Recession constants are obtained from flow data and plotted against the average daily pan evaporation occurring during the recession. The results for the three study basins are similar, showing a decrease in recession constant with an increase in average daily pan evaporation. For low values of average daily pan evaporation, the recession constant approaches a constant value. 相似文献
15.
Temporal changes of warm-season pan evaporation in a semi-arid basin in Western Turkey 总被引：1，自引：1，他引：0
Warm-season (from May to September) pan evaporation series recorded at nine sites in semi-arid Büyük Menderes Basin in Western Turkey were analyzed for evidence of long-term changes using non-parametric Mann–Kendall test. Only two sites showed significant linear trends, one in decreasing direction and the other in increasing direction. Area-averaged normalized anomalies of pan evaporation stayed unchanged over the period 1975–2006. Based on correlation and multiple regression analysis with visual inspection of the time series plots, sunshine duration which is used as a proxy for global radiation was found to be the major factor explaining the change and variability of pan evaporation in warm-season in semi-arid Büyük Menderes Basin. Stepwise multiple regression analysis showed no significant effect of rainfall on pan evaporation, which means that the effect of complementary relationship is rather weak and even non-existent. 相似文献
16.
《水文科学杂志》2013,58(6)
Abstract Abstract Evaporation is one of the fundamental elements in the hydrological cycle, which affects the yield of river basins, the capacity of reservoirs, the consumptive use of water by crops and the yield of underground supplies. In general, there are two approaches in the evaporation estimation, namely, direct and indirect. The indirect methods such as the Penman and Priestley-Taylor methods are based on meteorological variables, whereas the direct methods include the class A pan evaporation measurement as well as others such as class GGI-3000 pan and class U pan. The major difficulty in using a class A pan for the direct measurements arises because of the subsequent application of coefficients based on the measurements from a small tank to large bodies of open water. Such difficulties can be accommodated by fuzzy logic reasoning and models as alternative approaches to classical evaporation estimation formulations were applied to Lake Egirdir in the western part of Turkey. This study has three objectives: to develop fuzzy models for daily pan evaporation estimation from measured meteorological data, to compare the fuzzy models with the widely-used Penman method, and finally to evaluate the potential of fuzzy models in such applications. Among the measured meteorological variables used to implement the models of daily pan evaporation prediction are the daily observations of air and water temperatures, sunshine hours, solar radiation, air pressure, relative humidity and wind speed. Comparison of the classical and fuzzy logic models shows a better agreement between the fuzzy model estimations and measurements of daily pan evaporation than the Penman method. 相似文献
17.
The extremely high rate of evaporation from water surfaces in arid and semi-arid areas greatly reduces optimal utilization of water reservoirs. In Algeria, which is at 80% an arid country, water resources are scarce and renewable due to low annual precipitation. Considering the importance of optimal utilization of renewable water resources, about 70 dams with capacity of 7.4 billion m3 were constructed. One of the biggest problems of water in dams in Algeria is the huge amount of water loss through evaporation due to high evaporation rate. Therefore, applying techniques to reduce evaporation are greatly needed. One of the most recommended techniques for reducing evaporation is the application of a thin chemical film on the surface of the water. The present study aims to investigate the effect of this technique under arid conditions. Experiment was conducted for 20 weeks in Touggourt with three Colorado-type evaporation pans. Fatty alcohol with various doses were used in different pans. First pan was filled with water without adding fatty alcohol while in second pan, fatty alcohols was added with recommended concentration (0.3 kg/104 m2/day) and similarly in third pan fatty alcohol was added with concentration (0.5 kg/104 m2/day). The preliminary results of the study indicated that evaporation rate from surface water was reduced overall up to 16 and 22% in the second pan and the third one, respectively as compared to the non covered pan. 相似文献