关中地区夏玉米和冬小麦不同蒸发蒸腾量估算方法的研究

参考作物蒸发蒸腾量(ET0)是精准估算作物需水量、提高农田水分利用效率的重要依据。基于2013-2017年的田间试验数据以及相关气象观测资料,采用5种计算ET0的方法计算关中地区日平均ET0和年平均ET0,采用Origin对ET0及环境因子进行相关分析,使用标准误差估计(SSE)和决定系数r2,在FAO-56 PM和其他4种简单替代方法之间进行比较。结果表明:对ET0和气象因子的标准分数的分析表明,ET测量值和5种方法的估计值均高度依赖于太阳辐射和温度,但与相对湿度和风速的关系较小。对5种ET0估算方法,即:FAO-56 Penman-Monteith(FAO-56 PM)、Penman-Monteith(PM)、Priestly-Taylor(PT)、Mankink(MK)和Hargreaves(HG)进行了评估。统计分析表明PM可代替FAO-56 PM方法来预测该地区的ET_0值。这与作物蒸发蒸腾量(ETC)的准确估计直接相关,这也取决于作物生理特征和发育阶段、天气参数、环境条件和管理实践。     

陕西关中地区夏玉米作物系数试验研究

依据1999—2003年五年田间试验资料,利用Penman-Montheith公式计算陕西关中地区夏玉米全生育期内参考作物蒸发蒸腾量,并利用大型称重式蒸渗仪监测夏玉米全生育期内作物实际蒸发蒸腾量,由此计算了夏玉米各生育阶段的作物系数,并分析了作物系数变化规律。结果表明：在陕西关中地区的气象条件下,夏玉米的参考作物蒸发蒸...     

日光温室作物蒸发蒸腾量的计算方法研究及其评价

对FAO推荐计算参考作物蒸发蒸腾量的Penman-Monteith(缩写为P-M)公式,在日光温室微气候的条件应用作了详细的分析。将P-M公式分为2个部分,即辐射项(ETrad)和空气动力学项(ETaero),推导出了计算温室内参考作物蒸发蒸腾量的P-M修正公式,解决了P-M公式假定温室内风速为“0”所引起的一系列问题。并根据2004年和2005年温室内实测气象数据和水面蒸发对其进行了验证,通过相关分析得出用修正后的P-M公式计算作物蒸发蒸腾量比FAO推荐的P-M公式计算值误差小、精度高。建议在日光温室里使用修正后的P-M公式计算参考作物的蒸发蒸腾量。     

基于CatBoost的温室日参考作物蒸发蒸腾量估算模型研究

参考作物蒸发蒸腾量(Reference Evapotranspiration,ET₀)是估算作物需水量、制定灌溉制度、提高用水效率,实现农业节水的重要参数。针对传统Penman-Monteith(P-M)公式计算作物蒸发蒸腾量需要参数多,计算复杂等问题,提出了一种基于支持分类特征的梯度提升决策树(CatBoost)算法估算温室日参考作物蒸发蒸腾量。以温室修正型Penman-Monteith公式计算的ET₀作为标准值,通过Pearson’s方法对输入参数与ET₀之间的相关性进行分析,组合不同输入特征向量。当输入参数组合为3参数,即平均室内温度、平均相对湿度、累积太阳辐射时,CatBoost性能最优,测试集估算精度MAE为0.220 mm/d,RMSE为0.310 mm/d。进一步对比了6种其他机器学习模型(XGBoost、AdaBoost、随机森林、决策树、KNN、SVM)的估算精度,结果表明CatBoost模型具有最佳的估算精度和稳定性,能够较好地模拟参考作物蒸发蒸腾量。构建的日参考作物蒸发蒸腾量估算模型为水肥精准化管理、灌溉控制系统研发提供了一种新的思路。     

关中地区夏大豆蒸发蒸腾及作物系数的确定

作物系数-参考作物蒸发蒸腾量法是作物需水量计算最普遍采用的方法。作物系数作为该方法的重要参数,它的确定已成为作物需水量研究的关键问题。依据2005-2007年3年田间试验资料,利用Penman-Monteith公式计算了关中地区夏大豆全生育期间参考作物蒸散量,并利用农田水量平衡方程及土壤水分胁迫系数计算了作物实际蒸发蒸腾量,由此计算了大豆各生育阶段的作物系数,并分析了大豆作物系数变化规律。结果表明:关中地区大豆全生育期间参考作物蒸散量平均为524.6 mm;大豆作物系数全生育期平均为0.82,在开花~结荚阶段最大,平均为1.22,其次为结荚~成熟阶段,平均为1.05,播种~幼苗最小为0.26;在关中气候背景下,大豆作物系数与大于10℃积温具有较好的二次多项式关系。     

春玉米生长中期灌水量差异对其蒸发蒸腾量估算精度的影响

为提高旱区作物蒸发蒸腾量估算精度,以石羊河流域春玉米为研究对象,分析灌水量对FAO-56估算作物蒸发蒸腾量精度的影响,并对估算误差进行讨论,提出使用部分根区含水量平均值用于土壤水分胁迫系数计算.结果表明:FAO-56对不同灌水处理下作物蒸发蒸腾量的估算精度存在较大差异,可较精确地估算低灌水处理下作物蒸发蒸腾量;随着灌水量增大,其估算精度有所降低,对高灌水处理下作物蒸发蒸腾量的估算误差达-14.13%;根区上部土层含水量与土壤水分胁迫状况关系紧密,以缓变层及以上土层含水量平均值代替整个根区含水量平均值用于土壤水分胁迫系数计算,可有效改善高灌水处理下旱区作物蒸发蒸腾量计算精度,亦可较为精确地估算低灌水处理下作物蒸发蒸腾量.     

东北地区参考作物蒸发蒸腾量随时间变化的研究

根据选取的东北地区9个代表站1973-2003年的气象资料,应用Penman-Monteith公式计算了31年间逐月参考作物蒸发蒸腾量(ET0),对参考作物蒸发蒸腾量及气象要素的年际变化特征、月际变化特征及趋势进行了分析,应用统计检验方法分析了影响东北地区参考作物蒸发蒸腾量变化的主要气象因素。结果表明:近31年间东北地区ET0值呈现缓慢下降趋势,年内ET0值分布以5-8月份最高,1月份最低。影响ET0的主要气候要素为日照、风速和温度。     

南方低山丘陵区滴灌葡萄蒸发蒸腾量实时预报

以浙江低山丘陵区永康灌溉试验站为背景,运用Penman-Monteith公式计算分析了永康长系列参考作物腾发量ET0及其变化规律,建立了ET0实时预报模型,并分析了参数A0取值方法对预报精度的影响。采用双作物系数法确定了滴灌葡萄逐日作物系数,建立了滴灌葡萄蒸发蒸腾量实时预报模型。运用实测的土壤含水率资料,根据水量平衡原理分析计算葡萄实际蒸发蒸腾量,与模型的预报值比较表明所建立的模型及其参数合理。     

基于大型蒸渗仪和遗传算法的受旱玉米蒸发蒸腾量估算

受旱胁迫下作物蒸发蒸腾量估算重要且复杂,依托新马桥农水综合试验站6台大型称重式蒸渗仪开展玉米受旱胁迫专项试验,对不同受旱胁迫下玉米蒸发蒸腾量特征进行分析,在双作物系数法估算无受旱胁迫下玉米蒸发蒸腾量的基础上,采用遗传算法优化率定基础作物系数Kcbini、Kcbmid、Kcbend和作物系数上限Kcmax,同时基于试验站实测太阳辐射数据采用遗传算法优化率定了Angstrom公式经验参数a、b,进而优化了参考作物蒸发蒸腾量(ET0)的计算结果,并以此基础运用双作物系数法估算受旱胁迫下玉米蒸发蒸腾量。结果表明:营养生长中前期轻微的水分亏缺可能会刺激玉米适应性机能,复水后各项生理功能恢复正常;水分亏缺加重时不仅会使玉米当期的蒸发蒸腾量减少,而且会产生累积效应,将这种胁迫影响传递到之后的生育阶段;相同受旱胁迫强度对玉米生殖生长阶段影响更为明显,且易造成永久胁迫;Kcbini、Kcbmid、Kcbend、Kcmax的率定结果分别为0.150、1.090、0.152和1.400,在此基础上运用双作物系数法估算无受旱胁迫下玉米全生育期蒸发蒸腾量的均方根误差RMSE和平均绝对误差MAE分别为1.39 mm和0.97 mm,比对应的FAO-56推荐值估算结果小6.74%和8.23%,受旱胁迫下玉米计算的2个处理全生育期RMSE、MAE和MRE均值分别为1.60 mm、1.18 mm和6.73%,整体估算效果虽然没有无受旱胁迫下的好,但仍优于FAO-56推荐值的估算结果。因此,基于双作物系数法和遗传算法的受旱胁迫下玉米蒸发蒸腾量估算合理可靠,该研究可为区域制定适宜灌溉制度和降低农业旱灾损失风险提供理论依据。     

应用Hargreaves公式计算太子河流

应用Hargreaves公式和Penman-Montieth公式计算了太子河流域1960-2005年间逐月参考作物腾发量。将Hargreaves公式计算结果与Penman-Montieth公式结果比较发现，年内3月份-10月份Hargreaves公式计算结果偏高，其余月份偏低。两方法夏季差异最大,冬季差异最小。相对湿度和风速是两方法差异的主要原因，经分析太子河流域相对湿度的影响更大。利用Hargreaves公式计算结果与PM公式计算结果之间良好的线性关系，对Hargreaves公式系数进行了地区修正。修正后的Hargreaves公式简单、准确，为辽阳市及其类似地区ET0的计算提供了新方法。     

北京地区潜在蒸散量计算方法的比较研究

利用北京地区1951—2007年的逐日气象资料,选取常用的7种公式计算日潜在蒸散量,并和利用FAO推荐的Penman-Monteith(PM)标准公式计算日潜在蒸散量进行比较。根据线性回归、平方根误差和平均偏差方法分析得出:Penman公式、Kimberly-Penman公式(KP)和Doorenbos-Pruitt公式(DP)与PM相关性较好,KP公式计算的ET0和标准ET0平均偏差和平方根误差均最小,可直接用来计算北京地区的ET0,而Penman公式和DP公式的平均偏差和平方根误差较大,不适合直接计算北京地区的ET0,利用气象数据提出了修正的Penman公式和DP公式。Makkink公式、Priestley-Taylor公式、Hargreaves公式和Turc公式与PM相关性较差,不适合计算北京地区的ET0。北京地区对ET0影响最大的气象因子为饱和水汽压差和净辐射,基于此,提出了2个适合估算北京地区缺资料条件下ET0的经验公式。     

温室内草皮蒸腾量预测的试验研究

研究了温室内草皮蒸腾量和小气候的关系,用彭蔓公式计算参考作物腾发量,用20cm蒸发皿测定温室内的水面蒸发力,并和测定的草皮蒸腾量进行对比。试验结果表明,草皮蒸腾量与温室小气候的回归系数（R^2）为0．938,明显高于蒸腾量与蒸发皿水面蒸发量的回归系数（R^2）0．8683和蒸发量与彭蔓公式计算的参考作物腾发量的回归系数0．7944,以温室小气候计算温室内的作物蒸腾量要优于以参考作物腾发量计算作物蒸腾量和蒸发皿水面蒸发量的方法。温室内草皮的蒸腾量与温室小气候线性相关,可以此计算温室内作物的蒸腾量。     

腾发量的测定和计算方法研究综述

介绍了测定和计算腾发量的方法，对主要方法的原理特点、适用范围及实际中存在的问题进行了分析。水文法适用性强不受时间和气象下垫面的限制，可用于一周以上或较长时间段的总腾发量的测定；遥感技术的应用大大提高了区域腾发量的测量精度；蒸渗仪法简单易行，结果也比较精确；微气象学法不破坏下垫面，适用于整齐均一的作物与林木腾发量的测定；植物生理学法适用于植物个体腾发量的测定。在计算方法方面，应用Penman-monteith方程等单一模型较多，但研究上已转向可估算不同植物类型腾发的多层模型和SPAC系统模型。互补相关模型也在估算区域腾发上得到应用。     

四川省不同SPEI指数计算方法适用性评价

为探究不同参考作物腾发量(ET₀)算法及相应标准化降水蒸散指数(SPEI)在四川省的适用性,针对四川省3个区域(川西高原、川西南山地和川中盆地),利用34个气象站点1967—2016年的气象资料,以Penman-Monteith(PM)法计算的ET₀为标准,对FAO-24Radiation(FAO-Ra)、Priestley-Taylor(PT)、Makkink(MK)、Hargreaves-Samani(HS)、Blaney-Criddle(BC)、World Meteorological Organization(WMO)、Rohwer(Ro)7种方法的ET₀计算结果进行比较,并选取其中综合表现较好的3种方法进行相应的SPEI计算。通过时间序列分析、误差分析、K-S检验及小波分析等方法,探讨各区域不同ET₀算法下的SPEI适用性。结果表明：7种方法在不同区域计算精度差异显著,在川西高原及川西南山地,PT法均方根误差(RMSE)均在99.11 mm以下,大部分气象站点的相对误差(RE)介于-3.8...     

An analysis of the tendency of reference evapotranspiration estimates and other climate variables during the last 45 years in Southern Spain

Climate change will have important implications in the agriculture of semi-arid regions, such as Southern Spain, where the expected warmer and drier conditions might augment crop water demand. To evaluate these effects, a data set consisting of observed daily values of air temperature, relative humidity, sunshine duration and wind speed from eight weather stations in Andalusia and covering the period 1960-2005 was used for estimating reference evapotranspiration (ET_o). ET_o was calculated using five methods: the more complex Penman-Monteith FAO-56 (PM) equation, considered as a reference in this study, and four alternative methods with fewer data requirements, Hargreaves, Blaney-Criddle, Radiation and Priestley-Taylor. These methods were compared to PM with respect to ET_o average values and trends. The non-parametric Mann-Kendall test was used to evaluate annual and seasonal trends in the main climate variables and ET_o.Due to increases in air temperature and solar radiation, and decreases in relative humidity, statistically significant increases in PM-ET_o were detected (up to 3.5 mm year⁻¹). Although the Hargreaves equation provided the closest average values to PM, this method did not detect any ET_o trend. On the other hand, trends found from Blaney-Criddle and Radiation ET_o values were similar to those obtained from PM. In addition, after a local adjustment, these two methods gave accurate ET_o average values. Therefore, Blaney-Criddle and Radiation methods have shown themselves to be the most accurate approaches for ET_o determination in climate change studies, when available data provided by climate models are limited.     

Water requirements of maize in the middle Heihe River basin, China

As part of an intercomparison study on crop evapotranspiration (ET_c), six methods for estimating ET_c have been applied to maize field in the middle Heihe River basin, China. The ET_c was estimated by the soil water balance and Bowen ratio-energy balance methods while the Priestley-Taylor, Penman, Penman-Monteith and Hargreaves methods were used for estimating the reference evapotranspiration (ET₀). The results showed that the trend of ET_c was very similar, while the differences were significant among the different methods. The variations of ET_c were closely related to the LAI as well as to the meteorological features. The ET_c for the Bowen ratio-energy balance, Penman, Penman-Monteith, soil water balance, Priestley-Taylor and Hargreaves methods totaled 777.75, 693.13, 618.34, 615.67, 560.31 and 552.07 mm, respectively, with the daily mean values for 5.26, 4.68, 4.18, 4.16, 3.79 and 3.73 mm day⁻¹. The Penman-Monteith method provided fairly good estimation of ET_o as compared with the Priestley-Taylor, Penman, Hargreaves methods. By contrast with the Penman-Monteith method, the Bowen ratio-energy balance and Penman methods were 25.8% and 12.0% higher, while the Priestley-Taylor and Hargreaves methods were 9.4% and 10.7% lower, respectively. Therefore, the Hargreaves and Priestley-Taylor methods were the alternative ET_c methods in arid regions of Northwest China.     

干旱荒漠草原应用Penman-Monteith与Penman修正式计算ET0的偏差分析

甘肃天祝草原位于我国西北干旱荒漠草原,应用天祝县二道墩试验站2005年的实测气象资料,利用Penman-Monteith公式和Penman修正式计算参考作物腾发量(ET0)并进行了比较。Penman修正式计算的参考作物腾发量ET0值略小于Penman-Monteith公式计算的值,最大绝对偏差0.5 mm/d。分析发现生育期辐射项ETrad是导致参考作物腾发量ET0产生偏差的主要原因。2种方法计算的空气动力项ETaero差别较小,最大绝对偏差不超过0.2 mm/d。导致计算偏差的原因在于2种公式采用了不同的辐射项和空气动力学项计算公式和参数。2个公式计算的参考作物腾发量具有显著的线性相关性。     

High density NOAA time series of ET in the Gediz Basin, Turkey

An evapotranspiration method comparison was carried out by the International Water Management Institute (IWMI, Sri Lanka), at two locations in the Gediz Basin, Turkey, in the period from May to September 1998. In the IWMI study a number of ground-based techniques were compared with results obtained by remote sensing methods. Recently, a search of the satellite active archive yielded over 70 high quality level 1b images from NOAA/AVHRR over the same time period. The processing of these images with the SEBAL algorithm enabled us to build up a detailed time series of sensible and latent heat fluxes for a period of 120 days. In this paper a comparison is made between the sensible and latent heat fluxes determined from the present series of NOAA-14/AVHRR images and the results obtained earlier from various other prediction methods applied during the 1998 IWMI project. Specifically, the NOAA/SEBAL results are assessed against the scintillometer and temperature fluctuation methods. The results show that the NOAA derived evapotranspiration values follow the seasonal irrigation cycle quite well and correspond closely to the Landsat derived values, although they are lower than the results obtained with the traditional crop factor and Penman–Monteith methods.     

参考作物腾发量计算方法适用性分析

受地区间气象、地形和地貌时空异质性的影响,不同参考作物腾发量计算公式适用性各不相同。以湖南省83个站点1971~2000年气象观测资料为样本,论述了Penm an-Monte ith公式和FAO-Monte ith修正式主要方程、参数以及适用范围的差异性。结果表明:根据生育期作物需水特点,运用标准化的Penm an-Monte ith公式计算南方地区参照作物潜在腾发量是合适的。     

Crop coefficients for winter wheat in a sub-humid climate regime

Estimations of evapotranspiration (ET) from natural surfaces are used in a large number of applications such as agricultural water management and water resources planning. Lack of reliable, cheap and easy-to-use instruments, associated with the chaotic and varying nature of the meteorological and plant physiological factors influencing ET cause these estimations to be based on calculated values rather than the measured ones. The two-step approach where ET from a reference crop is calculated and multiplied by empirical crop coefficients to obtain ET from a crop has gained wide acceptance. Daily coefficients for a winter wheat crop growing under standard conditions, i.e. not short of water and growing under optimal agronomic conditions, were estimated for a cold sub-humid climate regime. One of the two methods used to estimate ET from a reference crop required net radiation (R_n) as input. Two sets of coefficients were used for calculating R_n. Weather data from a meteorological station was used to estimate R_n and ET from the reference crop. The winter wheat ET was measured using an eddy covariance system during the main parts of the growing seasons 2004 and 2005. The meteorological data and field measurements were quality controlled and discarded from the analysis if flagged for errors. Daily values of ET from the reference crop and winter wheat calculated from hourly values were used to calculate the crop coefficients. Average daily crop coefficients were in the 1.1–1.15 range during mid-season with standard deviations ranging from 0.13 to 0.23 for both years. These values exceed values used in some sub-humid climate regime studies, but agree well with values from the international literature.