根据天气预报估算参照腾发量

参照腾发量ET₀的实时预测对实时灌溉预报很重要。通过对普通天气预报信息进行解析,取得可用的合理数据,利用Penman-Monteith方法估算了北京大兴试区近10年逐日参照腾发量,最后与由实测气象数据计算的结果进行了对比分析。结果表明：解析气象因子与实测数据中,日照时数的相关系数为0.99,风速为0.90;t检验值日照时数为376.9042,风速为122.4295,远远大于t分布相应临界值2.576(α＝0.01),表明其可以认为是来自一个近似的总体样本。由日最低气温确定的实际水汽压和由实测相对湿度计算的实际水汽压,二者相关系数达到0.93,t检验值为153.3015。运用天气预报信息计算预测的ET₀与实测数据用Penman-Monteith方法计算的ET₀相比,相关系数达到0.9613,t检验值为209.1194,说明二者具有高度显著的线性相关性。如果日常天气预报准确度能够达到90％以上,用此理论预测参照腾发量将具有较大的参考价值和实际意义。     

根据天气预报估算参照腾发量的模糊神经网络方法

尝试利用日常天气预报中天气情况和日最高气温的预报信息,采用自适应模糊神经推理系统(ANFIS)方法,构建参照腾发量估算方法,预报参照腾发量。用北京市大兴区1995～2003年间的逐日实测气象资料进行模型训练,用2004年逐日气象资料进行预报和模型检验。由天气预报估算的结果(ANFIS-ET₀)与Penman-Monteith方法计算的ET₀值(PM-ET₀)进行了对比分析。结果表明：后者与训练数据的线性相关系数为0.90,检验结果为0.84;t检验结果表明,训练数据和预报数据均具有很高的显著性(α＝0.01)。结果同时说明,在提高日常天气预报准确率、选择最合适的隶属度函数和模糊规则的基础上,运用智能算法解决农田灌溉复杂问题是可行的和方便快捷的。     

Prediction of daily reference evapotranspiration by a multiple regression method based on weather forecast data

Prediction of daily reference evapotranspiration (ET ₀) is the basis of real-time irrigation scheduling. A multiple regression method for ET ₀ prediction based on its seasonal variation pattern and public weather forecast data was presented for application in East China. The forecasted maximum temperature (T _max), minimum temperature (T _min) and weather condition index (WCI) were adopted to calculate the correction coefficient by multilinear regression under five time-division regimes (10 days, monthly, seasonal, semi-annual and annual). The multiple regression method was tested for its feasibility for ET ₀ prediction using forecasted weather data as the input, and the monthly regime was selected as the most suitable. Average absolute error (AAE) and root mean square error (RMSE) were 0.395 and 0.522 mm d^?1, respectively. ET ₀ prediction errors increased linearly with the increase in temperature prediction error. A temperature error within 3 K is likely to result in acceptable ET ₀ predictions, with AAE and average absolute relative error (AARE) <0.142 mm d^?1 and 5.8%, respectively. However, one rank error in WCI results in a much larger error in ET ₀ prediction due to the high sensitivity of the correction coefficient to WCI and the large relative error in WCI caused by one rank deviation. Improving the accuracy of weather forecasts, especially for WCI prediction, is helpful in obtaining better estimations of ET ₀ based on public weather data.     

Estimation of soil heat flux from net radiation during the growth of alfalfa

Soil heat flux studies have indicated that the instantaneous daytime flux can be estimated as a fraction of the net radiation, the ratio ranging from 0.1 to 0.5, depending on the amount of vegetation present and on the time of day. Soil heat flux and net radiation were measured for an alfalfa crop over two regrowth cycles during the fall growing season. For both sparse alfalfa stubble and full vegetative canopy, the surface soil water content did not significantly affect the fraction of net radiation consumed as soil heat flux. The ratio of soil heat flux to net radiation around midday was found to be a linearly decreasing function of crop height only for heights up to 450 mm. As crop growth continued beyond this height, the ratio remained nearly constant at 0.1. The ratio data were also found to be well-fitted by a linearly decreasing function of a spectral vegetation index (near-IR to Red ratio) over both regrowth cycles. These results indicate that both crop height and spectral vegetation indices can be used to estimate soil heat flux from net radiation measurements.     

基于GLEAM遥感模型的中国1980－2011年地表蒸散发时空变化

对中国地表蒸散发时空变化的分析,有助于了解气候变化对水循环的影响及对中国水资源的合理配置。该文基于GLEAM（global land-surface evaporation: the Amsterdam methodology）遥感蒸散发模型,通过对GLEAM产品在站点尺度和流域尺度的精度验证以及中国地表蒸散发时空变化特征的研究,得出以下结论：1）GLEAM产品在中国区域满足精度要求,在站点尺度上,GLEAM产品在草原半干旱区的模拟程度最好,海北、内蒙古、当雄3个草原站皮尔逊相关系数（pearson correlation coefficient,CC）均值为0.77（0.65～0.85）;森林站的CC相关系数均值为0.66（0.40～0.85）,禹城农田站CC值为0.68;在流域尺度上,海河（相对偏差（relative bias,RB）16.2%）、黄河（RB,15.2%）、西北诸河流域（RB,9.2%）的验证结果精度较好。在绿洲或农灌区降水较少的年份,GLEAM产品符合地表实际蒸散发可能大于降水的规律;2）1980－2011年中国的多年平均蒸散发为18～1 400 mm,空间分布呈从西北向东南方向递增,西北地区多年平均蒸散发最少,海南岛与台湾岛是多年平均蒸散发的极大值区;3）1980－2011年中国平均的年地表蒸散发变化范围为349.7～436.0 mm,多年平均年地表蒸散量为397.5 mm。近32 a中国区域平均地表蒸散发呈显著的上升趋势,上升速率为12.3 mm/(10 a);4）1980－2011年中国各栅格地表蒸散量变化速率为?86.5～108.7 mm/(10 a),地表蒸散发减少的面积占28.4%,9.45%的区域地表蒸散发呈明显减少、显著减少及急剧减少趋势,主要位于内蒙古东部、青藏高原西部（新疆西部及东北部、西藏西北部）、甘肃南部等地。地表蒸散发增加的面积占71.6%,18.2%的区域地表蒸散发呈显著增加、急剧增加的趋势,主要位于海河区的河北南部及山东西北部、淮河流域的山东半岛、黄河区的青海东部、长江中下游区的四川东部、山西南部、湖北、湖南、安徽、江西等地、东南诸河区、珠江区及云南南部等;5）各栅格年蒸散发的变化趋势主要由夏季蒸散发变化趋势主导,春季、秋季、冬季对年蒸散发变化趋势的影响较弱。该研究对理解中国气候变化与水资源之间的相互影响具有重要作用,可为中国水资源评价与管理提供参考及决策依据。     

利用MODIS数据计算地表蒸散

地表蒸散影响着地表水分和能量的输送,在水文、气象、地理等诸多领域占有重要地位。该文首先基于大气辐射传输原理,利用MODIS大气产品提供的臭氧、水汽以及550 nm气溶胶含量,运用大气透过率计算模型,进行了太阳总辐射的计算,均方根误差（RMSE）为61.4 W/m2,相比FAO-56透过率模式112.1 W/m2的误差有了明显改进。在此基础上结合MODIS的地表温度、植被指数产品进行了地表蒸散的计算。瞬时显热通量与郑州市大孔径闪烁仪（LAS）观测相比,有较好的一致性,RMSE为29.9 W/m2。应用本文的透过率模型计算得到的日蒸散与观测值相比,RMSE为0.69 mm,应用FAO-56透过率计算式得到的日蒸散RMSE为1.42 mm。从验证结果来看,透过率的准确计算能够比较明显的提高地表蒸散计算精度。     

基于FAO-Blaney-Criddle方法的河套灌区参考作物蒸散发量估算

实时灌溉预报是河套灌区管理科学化与信息化的要求,利用天气预报中相对准确的气温数据估算参考作物蒸散发量对实时灌溉预报非常重要,因此需要建立一种基于温度的参考作物蒸散发量估算方法。利用 FAO-Penman-Monteith方法估算河套灌区解放闸灌域历史参考作物蒸散发量,以此作为标准值率定 FAO-Blaney-Criddle 公式中逐旬的修正系数,得到基于温度的参考作物蒸散发量估算方法。结果表明,在作物的生长季（4－9月）,FAO-Blaney-Criddle 方法与FAO-Penman-Monteith 方法的估算结果相近。率定期各旬相对误差均<5%,标准误差<0.65 mm/d,验证期各旬相对误差均<9%,标准误差<0.70 mm/d。10 d 滑动平均的参考作物蒸散发量估算精度,Nash 效率系数达到0.75,误差0.5 mm/d 的精确度达到了68%,误差在1 mm/d 以内的准确率达到95%。FAO-Blaney-Criddle 方法可以应用于河套灌区的灌溉预报中。另外,FAO-Blaney-Criddle 方法的参数具有较强的地区差异性,需要针对不同地区的气象数据进行率定和验证。     

The performance of a thermometer screen on an automatic weather station

The performance of a Didcot-type thermometer screen on an Automatic Weather Station and a conventional Stevenson screen were compared, both with each other and against an aspirated Assmann psychrometer. Maximum temperature in the Didcot screen exceeded the conventional screen maximum by up to 1 K on calm, sunny days, and Didcot minimum temperatures were as much as 1.5 K less than the screen minima on still, clear nights; mean temperature discrepancies between screens were + 0.3 and − 0.4 K for maxima and minima, respectively. The apparent psychrometric constant for the Didcot screen was 1.0 mbar K⁻¹ which increased to 1.2 mbar K⁻¹ when u < 2 m s⁻¹ in contrast to the value of 0.799 mbar K⁻¹ frequently used for the Stevenson screen.     

Yield prediction in spring barley from spectral reflectance and weather data using machine learning

Accurate preharvest yield estimation is an important issue for agricultural planning purposes and precision farming. Machine learning (ML) based on readily obtained information on the cropping system, typically including spectral reflectance measurements, is an essential approach for achieving practical solutions. We tested in a 9-year soil compaction experiment the accuracy of ML-based yield predictions made up to 2 months before harvest from a Ratio Vegetation Index (RVI) and recordings of precipitation and reference evapotranspiration. The applied data set comprises 224 combinations of plots and years with measured grain yields in the range of 4.22–9.34 Mg/ha. The best ML model [i.e., with the smallest mean absolute error (MAE)] was selected automatically by the AutoML interface included in the R program package H₂O. Its cross-validated predictions made on June 30 more than 1 month before harvest showed an MAE of 0.38 Mg/ha when trained on all data from all years except the one under consideration. MAE increased to about 0.68 Mg/ha when determined 3 weeks earlier on June 10. MAE values in the range of 0.32–0.42 Mg/ha were obtained for predictions made on June 30 when based on data from at least six consecutive years; however, MAE showed no generally decreasing trend with the number of years. Yield estimations were robust towards a considerable soil variation observed within the experimental area due in part to the experimental treatments. The results show a potential of making yield predictions in barley 1–2 months before harvest, which, however, is not sufficiently early to support decisions on top-dress N fertilization.     

基于天气预报的漳河灌区参考作物腾发量预报方法比较

为了提出适合湖北省漳河灌区的参考作物腾发量预报方法,以FAO56-Penman-Monteith公式采用历史气象数据计算出的值为基准,利用天气预报数据,比较Hargreaves-Samani(HS)法、逐日均值修正法及该文改进的逐日均值修正法在该灌区钟祥站点的预报精度,并评价各方法适用性.结果表明:利用这3种方法进行参考作物腾发量预报时,1~7 d预见期平均绝对误差均值分别为0.75、0.80、0.76 mm/d,均方根误差分别为1.00、1.07、1.05 mm/d,相关系数分别为0.82、0.80、0.80.1 d预见期最优预报方法为改进逐日均值修正法,2~7 d预见期的最优方法均为HS法.总体而言,预报精度最好的为HS法、改进逐日均值修正法次之、逐日均值修正法最差.对于漳河灌区,建议采用HS法进行预报,可为灌溉预报提供较为准确的数据基础.     

基于静止气象卫星的河北平原实际蒸散量遥感估算

本文提出利用中国第1 颗可操作性静止气象卫星风云2 号C 星(FY-2C)数据结合中等分辨率航天成像光谱仪MODIS 产品估算河北灌溉农田实际蒸散量(ET)的方法, 其中FY-2C 的第1、2 波段用于反演区域地表温度, 再结合16 d MODIS 合成的植被指数产品(MOD13), 得到地表温度与植被指数的三角空间分布图(Ts-NDVI)。通过Ts-NDVI 空间分布的关系, 利用改良三角算法得到区域的蒸发比(EF)。最后结合MODIS 地表反射率产品MCD43 估算得到的日净辐射量, 根据能量平衡计算得到该地区的日实际蒸散量。模型结果与地表Lysimeter 观测数据比较, 显示该模型估算得到的蒸发比和日蒸散量结果较为合理, 误差在可接受范围。此外, FY-2C 用于估算地表ET, 其时间分辨率具有较强的优势, 从而为获得多幅无云蒸散图提供了有利条件。     

站点密度及插值方法对ET0空间插值精度的影响

流域参考作物蒸发蒸腾量（ET0）插值方法的研究对流域尺度作物耗水时空变化规律有重要意义。该文通过海河流域162个国家农业气象站3a（2003－2005年）旬值气象资料,利用Penman-Monteith公式计算了这些站点ET0,采用ArcGIS软件中常用的Spline、IDW和Ordinary Kriging（OK）法,以及近些年研究较多的线性回归Regression插值法,对不同站点密度条件下的ET0进行空间插值。分析了各空间插值方法在不同站点密度条件下的优劣性,并且给出了本流域内各种站点密度范围条件下计算ET0最适宜的插值方法。结果表明以站点密度1.3个/万km2为界,当站点密度低于此密度时,推荐使用Regression插值法;当站点密度大于1.3个/万km2时,推荐使用IDW和OK插值法;当站点密度大于4.3个/万km2,以上三种插值法并无显著差别;不推荐使用Spline插值法。     

Calculation of solar radiation in mountainous terrain

A study was performed to assess the accuracy of a daily solar radiation model for horizontal or sloping sites in terrain where surrounding ridges and tall trees block both direct beam and diffuse sky short wave radiation. To simulate adequately the major effects of these environments on radiation, the model incorporated (1) standard treatment of solar geometry (after Harris, 1983); (2) separation of direct and diffuse radiation by considering scattering and absorption due to aerosols, water vapor, air molecules and ozone (after Iqbal, 1983); (3) anisotropy of diffuse radiation modeled as a circumsolar component (15–50% of the total clear sky diffuse) plus an isotropic background; and (4) proper calculation of the proportions of sky radiation and ground reflected radiation sensed by both horizontal and inclined sensors. The model was calibrated using data from both horizontal and inclined pyranometers at six sites over four years. Values for the Ångstrom turbidity coefficient and the percentage of circumsolar diffuse radiation were determined using an iterative best fit technique. Mean monthly values of these coefficients and mean monthly ozone and water vapor concentrations from nearby weather service stations could be used for predicting total, cloud free, daily radiation with acceptable accuracy. Required site measurements include slope, aspect, latitude, longitude, date, time, effective horizon for the site, and an assessment of albedo for the surrounding terrain (including vegetation).     

基于遥感蒸发模型的干旱区灌区灌溉效率评价

为评价干旱区灌区的灌溉效率,该文以作物生长期灌溉地的蒸散发扣除降水量作为灌溉水的有效利用量,将灌溉水有效利用量与灌溉净引水量(总引水量减去退、排水量)的比值定义为灌溉水有效利用系数。利用遥感蒸散发模型可以较为准确地估算灌溉地蒸散发,从而可以避免传统灌溉水利用系数评估中难以准确估算通过灌溉到达作物根系层水量的问题。以河套灌区为研究对象,利用遥感蒸散发模型(surface energy balance algorithm for land,SEBAL)计算了区域内灌溉地作物生育期的蒸散发量,并结合降水量与净引水量的观测资料,对节水改造以来(2000-2010年)河套灌区灌溉水有效利用系数进行了分析和评价。结果表明,灌溉水有效利用系数近年来有增加趋势,同时灌溉水有效利用系数随降水量和净引水量的减小而增大,减少供水对灌溉水有效利用系数的影响要大于灌区节水改造工程的影响。另一方面,在灌区净引水量减少的情况下,灌溉地蒸发量能够维持在较稳定的水平,反映了近年来灌区节水改造的效果较好。     

Total reflected solar radiation calculated from multi-band sensor data

Reflected solar radiation is a significant term in the net radiation equation and is the one most strongly affected by surface conditions. The evaluation of net radiation over a heterogeneous area requires a detailed knowledge of the areal distribution of the reflected solar radiation. Remote sensing offers a means to obtain this areal distribution, provided that the total reflected solar spectrum can be estimated from discrete band multispectral radiometric data. A radiative transfer model was used to calculate the irradiance at the earth's surface for a number of atmospheric scattering and adsorption conditions. Response functions of two multiband radiometers were used to obtain the partial spectrum/total spectrum (P/T) ratio for each radiometer at each atmospheric condition. It was found that the P/T ratio was essentially independent of atmospheric scattering and only mildly dependent on water vapor absorption. Reflectance spectral distributions for 14 different surface conditions (bare soil to full green canopy) were used along with the irradiance data to determine the P/T ratio for reflected solar radiation. Multispectral data, with the appropriate P/T ratio, were used to calculate the total incoming radiation and the total reflected radiation from a wheat canopy. The calculated data differed from wide band pyranometer data by about 5%. It was concluded that both total incoming and reflected solar radiation can be evaluated from multispectral radiometric data. This development is a step towards regional net radiation maps, and possibly regional evapotranspiration maps.     

基于气温估算参考作物蒸散量方法的对比与改进

为提高基于气温数据估算参考作物蒸散量（ET0）模型的精度,该研究对比分析了基于温度数据估算ET0的Penman-Monteith（PMT）模型、Hargreaves-Samani（HS）模型和改进HS模型,并运用基于气温数据估算实际水汽压和太阳辐射的最新进展改进PMT模型。结果表明：改进HS模型较传统HS模型提高了半干旱区到湿润区ET0的估算精度; PMT模型与改进HS模型估算的各气候区相关系数（r）均值相似,但与改进HS模型相比,PMT模型提高了除湿润区和亚湿润干旱区外各气候区的ET0估算精度,均方根误差（RMSE）和相对均方根误差（RRMSE）均值分别降低0.01～0.15 mm/d和0～0.05,且模型效率（EF）均值提高了0.01～0.06;本文提出的改进PMT模型可进一步改进PMT模型估算除干旱区和半干旱区外各气候区精度,RMSE和RRMSE均值较原PMT模型分别降低0.04～0.12 mm/d和0.02～0.04,r和EF均值更接近于1;并且改进PMT模型估算各站点全局性能指数（Global Performance Index,GPI）值较好,90%的站点GPI值排名第一。因此,建议在仅有气温数据时,使用改进PMT模型作为估算ET0的推荐模型。研究成果可为区域农业水资源管理提供依据。     

Study of different climatic conditions to assess the role of solar radiation in reference crop evapotranspiration equations

This study aims to assess radiation-based models versus the FAO Penman–Monteith (FPM) model to determine the best model using linear regression under different weather conditions. The reference evapotranspiration was estimated using 22 radiation-based methods and was compared with the FPM. The results showed that the Stephens method estimates the reference evapotranspiration better than other methods in the most provinces of Iran (nine provinces). However, the values of R² were more than 0.9930 for 24 provinces of Iran. The radiation-based methods estimated the reference evapotranspiration near the Caspian Sea better than other regions. The most precise methods were the Berengena–Gavilan, Modified Priestley–Taylor, and Priestley–Taylor methods for the provinces ES (center of Iran), GI and GO (north of Iran) and the Stephens–Stewart method for IL (west of Iran). Finally, a list of the best performance of each method has been presented to use other regions and next research steps according to the values of mean, maximum, and minimum temperature, relative humidity, solar radiation, elevation, sunshine, and wind speed. The best weather conditions to use radiation-based equations are 23.6–24.6 MJ m^?2 day^?1, 12–20°C, 18–24°C, 5–13°C, and <180 hour month^?1 for solar radiation, mean, maximum, and minimum temperature, and sunshine, respectively.     

基于STME模型和MODIS数据的滹滏平原实际蒸散量遥感估算

滹滏平原光、热及土壤资源优越,是华北平原重要的粮食生产基地,灌溉是该区农业获得稳产高产的重要保障,持续抽取地下水和无节制利用地表水已经引起了严重的水资源危机,合理高效利用有限水资源进行农业生产势在必行。本文利用单源梯形遥感蒸散发模型(a single-source trapezoid model for evapotranspiration,STME)和中等分辨率成像光谱仪MODIS(2011—2012年共115期)地表温度和反射率产品估算区域地表土壤缺水状况及实际蒸散量,并利用中国科学院栾城农业生态系统试验站(以下简称"栾城站")和赵县梨园涡度相关系统地表水热通量的观测值对STME模型估算结果进行验证。结果表明该模型可以很好地估算区域蒸散量,误差在可接受范围内。赵县梨园净辐射Rn的观测平均值为4.10 mm,估算平均值为4.69 mm,均方根差RMSD为0.80 mm;赵县梨园蒸散量观测平均值为2.86 mm,估算平均值为3.01 mm,均方根差RMSD为0.95 mm;栾城站蒸散量的观测平均值为2.67 mm,估算平均值为2.44 mm,均方根差RMSD为0.87 mm。将STME模型应用到滹滏平原估算日蒸散量,明确了区域尺度蒸散发的时空变化特征:10月份果园生态系统蒸散量多于农田生态系统;11月份区域蒸散量整体小于1 mm;第2年春季小麦返青、拔节期,农田生态系统蒸散量多于果园生态系统蒸散量;5月份处于植被生长旺盛期,农田和果园生态系统的蒸散量相差不大;6月份小麦收获,玉米播种,农田生态系统蒸散量少于果园生态系统;7月份整个区域蒸散量达到最大,蒸散量不仅与植被长势相关,而且与土壤湿度相关;8、9月份随着植被的成熟和收获,区域蒸散量整体变小。不同时期区域水分亏缺指数不同,可根据其指导区域灌溉量。STME模型继承了基于数理计算确定梯形顶点的方法和水分亏缺指数,使得计算过程得以简化且物理机制明确。     

基于水碳通量耦合的长江中下游稻田蒸散发组分分解

探明稻田生态系统蒸散发（Evapotranspiration,ET）组分特征对于提高稻田水分利用效率、实现农业节水具有重要意义。该研究利用涡度相关（Eddy Covariance,EC）系统对长江中下游典型双季稻田水碳通量进行了连续2 a（2017 -2018年）的观测,使用潜在水分利用效率（Underlying Water Use Efficiency,uWUE）法将稻田ET分解为植株蒸腾（Transpiration,T）和棵间蒸发（Evaporation,E）,揭示了稻田生态系统ET及其组分的季节变化特征,并使用小型蒸渗仪/涡度相关（Micro-lysimeter/Eddy Covariance, ML/EC）法观测结果对uWUE法进行了评估。结果表明：早晚稻植株蒸腾占蒸散发的比例（T/ET）均呈先增大后减少的趋势,水稻生育期T/ET在0.49～0.62之间,其中早稻季T/ET明显低于晚稻季。通过比较uWUE法和ML/EC法两种ET组分分解方法发现,uWUE法与ML/EC法估算T/ET差异主要在水稻生长前期和阴天;在其他时期,uWUE法和ML/EC法估算的T/ET显著线性相关（R2=0.852,P<0.01）,表明uWUE法可以较好地模拟稻田ET组分。以上研究成果可为uWUE法在稻田生态系统的应用以及长江中下游稻田节水灌溉和水资源优化配置提供依据。     

黄河流域典型区域目标ET计算及水资源调配方案评估

为了解决在黄河流域基于径流-蒸散发(runoff-evapotranspiration,R-ET)的水资源管理模式中,区域目标蒸散发(evapotranspiration,ET)的合理确定问题,该文先梳理了目标ET的计算步骤,确定了各分项ET的计算方法,建立了目标ET的评估指标体系,通过研究实例进行验证。目标ET具体的计算步骤和方法为:第一步,根据当地的水资源情况制定方案集;第二步,针对不同的分项目标ET,分别采用分布式水文模型、遥感估算模型及用水定额法等方法进行计算;第三步,通过计算各方案的评估指标体系,进行可持续性、公平性和高效性的评估,确定最优方案。以黄河流域鄂尔多斯地区为研究实例,制定了5个计算方案,经过计算方案1为现状用水方案,目标ET值为468.79 mm;方案2为扩大引黄水方案,目标ET为450.89 mm;方案3为压采地下水方案,目标ET为432.95 mm;方案4为减少引黄水方案,目标ET为406.11 mm;方案5为节水方案,其目标ET为383.27 mm。通过综合评估可知方案5为最优方案。通过实例验证认为,该方法对于区域目标ET的确定是一种适用的、较准确的方法,也会为下一步黄河流域实施基于R-ET的水资源管理模式提供数据基础和技术支撑。