Temporal variations of reference evapotranspiration in Heihe River basin of China

Li, Zhanling; Li, Zhanjie; Xu, Zongxue; Zhou, Xun

doi:10.2166/nh.2012.125

Cited by 37 publications

(17 citation statements)

References 31 publications

(44 reference statements)

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“…To evaluate the contributions of key meteorological factors to the change trend of ET ref quantitatively, the detrending method, a statistical and mathematical operation of removing trend from the series, was employed in this study [8,30,31]. This is a simple but effective method.…”

Section: Detrending Methodsmentioning

confidence: 99%

“…This mathematical approach has been commonly used to calculate the relative changes in ET ref analysis. For instance, Xu et al [8], Li et al [30], Liu et al [31], and Huo et al [32] used this technique for an attribution analysis of change in ET ref in different regions of China. Similarly, in the present study, we successfully apply this technique to Jiangsu province in eastern China.…”

Section: Introductionmentioning

confidence: 99%

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Changes in Reference Evapotranspiration and Its Contributing Factors in Jiangsu, a Major Economic and Agricultural Province of Eastern China

Chu

Shen

et al. 2017

Water

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Reference evapotranspiration (ET ref) is a key parameter of hydro-meteorological studies as well as water resource planning. In this study, we adopted the Penman-Monteith FAO 56 model to estimate ET ref and through the differential equation and detrending method to determine sensitivities and the contributions of four meteorological parameters to ET ref based on daily weather data from 60 stations of Jiangsu province during 1961-2015. Results reveal that ET ref and its trends in the three sub-regions of the Jiangsu province had a significant spatial heterogeneity. A significant decreasing tendency of ET ref (p < 0.001) was observed in the Huaibei region, while a slightly increasing tendency was identified in the Jianghuai and Sunan regions. These changes of ET ref were caused by a significant increasing trend in air temperature (TA) and significant decreasing trends in wind speed (WS), sunshine duration (SD) as well as a non-significant change trend in actual vapor pressure (VP). However, the VP was the meteorological parameter to which ET ref was most sensitive, whereas ET ref was more sensitive to TA and SD in the summer but less so in the winter; the least sensitive factor, WS, had the opposite trend. Across the whole region, WS contributed most to ET ref , followed by SD, while the positive contribution of TA to ET ref could not offset the negative contributions of WS and SD. Although the effect of VP on changes in ET ref is small, it could not be ignored, especially in the winter. The reverse relationship between increasing TA and decreasing ET ref , namely the "evaporation paradox," occurred in Jiangsu province. Thus, the outcomes of this study will contribute to thorough insight into the response to changes in ET ref to the provincial water planning and management in eastern China.

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Section: Detrending Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Changes in Reference Evapotranspiration and Its Contributing Factors in Jiangsu, a Major Economic and Agricultural Province of Eastern China

Chu

Shen

et al. 2017

Water

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“…,; Li et al . ,). The adoption of MK trend test is started from the calculation of the statistic:

S = \sum_{i = 1}^{n - 1} \sum_{j = i + 1}^{n} sgn (x_{j} - x_{i})

where

sgn (x_{j} - x_{i}) = \{\begin{matrix} left \\ left + 1 & left (x_{j} > x_{i}) \\ left 0 & left (x_{j} = x_{i}) \\ left - 1 & left (x_{j} < x_{i}) \end{matrix}

where x i and x j are the sequential data values and n is the length of the data set.…”

Section: Methodsmentioning

confidence: 99%

Variation of reference evapotranspiration and its contributing climatic factors in the Poyang Lake catchment, China

Liu

et al. 2013

Hydrol. Process.

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Abstract:By using linear regression (parametric), Mann-Kendall (nonparametric) and attribution analysis methods, this study systematically analysed the changing properties of reference evapotranspiration (ETr) calculated using the Penman-Monteith method over the Poyang Lake catchment during 1960-2008 and investigated the contribution of major climatic variables to ETr changes and their temporal evolution. Generally, a significant decreasing trend of annual ETr is found in the catchment. The decrease of annual ETr in the Poyang Lake basin is mostly affected by the decline of summer ETr. Over the study period, climatic variables, i.e. sunshine duration (SD), relative humidity (RH), wind speed (WS) and vapour pressure all showed decreasing trends, whereas mean daily temperature (DT) increased significantly. Multivariate regression analysis indicated that SD is the most sensitive climatic variable to the variability of ETr on annual basis, followed by RH, WS and DT, whereas the effect of vapour pressure is obscure. Although recent warming trend and decrease of relative humidity over the catchment could have increased ETr, the combined effect of shortened SD and reduced WS negated the effect and caused significant decrease of ETr. Our investigation reveals that the relative contributions of climatic variables to ETr are temporally unstable and vary considerably with large fluctuation. In consideration of the changes of climatic variables over time, further analysis indicated that changes of mean annual ETr in 1970-2008 were primarily affected by SD followed by WS, RH and DT with reference to 1960s. However, WS became the predominant factor during the period 2000-2008 compared with reference period 1960s, and followed by SD.

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“…Furthermore, the empirical or semi-empirical f studied because of the lack of measured values, and the FAO56-PM f studies over China [25][26][27][28][29][30][31][32][33] without calibration. However, the param ; (d) FAO24; (e) FAO56-PM; (f) Deng Genyun; (g) Tong Hongliang) and CERES data (h) at the nineteen radiation stations.…”

Section: Assessment Of the Existing R Nl Empirical Formulasmentioning

confidence: 99%

Evaluation and Parameter Optimization of Monthly Net Long-Wave Radiation Climatology Methods in China

et al. 2017

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Based on surface radiation balance data and meteorological observations at 19 radiation stations in China from 1993 to 2012, we assessed the applicability of seven empirical formulas for the estimation of monthly surface net long-wave radiation (R nl ). We then established a revised method applicable to China by re-fitting the formula using new observational data. The iterative solution method and the multivariate regression analysis method with the minimum root mean square error (RMSE) were used as the objective functions in the revised method. Meanwhile, the accuracy of the CERES (Clouds and the Earth's Radiant Energy System) estimated R nl was also evaluated. Results show that monthly R nl over China was underestimated by the seven formulas and the CERES data. The Tong Hongliang formula with lowest errors was the best among the seven formulas for estimating R nl over China as a whole, followed by the Penman and the Deng Genyun formulas. The estimated R nl based on the CERES data also showed relatively higher precision in accordance with the three formulas mentioned above. The FAO56-PM formula (Penman-Monteith formula recommended in the No. 56 report of the Food and Agriculture Organization) without calibration was not applicable to China due to its low accuracy. For individual stations, the Deng Genyun formula was the most accurate in the eastern plain area, while the Tong Hongliang formula was suitable for the plateau. Regional formulas were established based on the geographical distribution of water vapor pressure and elevation over China. The revised national and regional formulas were more accurate than the seven original formulas and the CERES data. Furthermore, the regional formulas produced smaller errors than the national formula at most of the stations. The regional formulas were clearly more accurate than the Deng Genyun formula at stations in Northwestern China and on the Tibetan Plateau. They were also more accurate than the Tong Hongliang formula at the stations located in the eastern area. Therefore, the regional formulas developed in this study are recommended as the standard climatology formulas to calculate monthly R nl over China.

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Temporal variations of reference evapotranspiration in Heihe River basin of China

Cited by 37 publications

References 31 publications

Changes in Reference Evapotranspiration and Its Contributing Factors in Jiangsu, a Major Economic and Agricultural Province of Eastern China

Changes in Reference Evapotranspiration and Its Contributing Factors in Jiangsu, a Major Economic and Agricultural Province of Eastern China

Variation of reference evapotranspiration and its contributing climatic factors in the Poyang Lake catchment, China

Evaluation and Parameter Optimization of Monthly Net Long-Wave Radiation Climatology Methods in China

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