SENSITIVITY AND MODEL VARIANCE ANALYSIS APPLIED TO SOME EVAPORATION AND EVAPOTRANSPIRATION MODELS
SENSITIVITY AND MODEL VARIANCE ANALYSIS APPLIED TO SOME EVAPORATION AND EVAPOTRANSPIRATION MODELS
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DOI：
10.1029/wr012i005p00873
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发表时间：
1976-01-01
影响因子：
5.4
通讯作者：
DECOURSEY, DG
中科院分区：
文献类型：
--
作者：
COLEMAN, G;DECOURSEY, DG
计算了6种蒸发蒸散模型的变量敏感度和误差方差。通过用有限差分逼近偏导数来计算它们的灵敏度。为了比较模型，相对灵敏度ψ由ψi=(100/e1)(ΔE/Δxi)计算，其中i=1，…，n，灵敏度定义为蒸发量的百分比变化输入变量exi中的每单位变化。计算第二相对敏感度ΨRI=[(xi−xio)/e1](ΔE/Δxi)以比较不同输入变量的相对重要性。通过[Var(Z)]=∑i=1n(ΔE/Δxi)2Var(Xi)分析误差方差，以求出由仪器不准确引起的误差的方差，其中Var(Xi)是根据制造商的声明估计的仪器方差。虽然没有进行测试来确定模型的偏差或预测精度，但提出了一种技术，说明如何将仪器误差方差与预测误差方差相加，以确定总体系统方差。在模型开发中，如果没有预测偏差，那么最好的模型将是这两个方差之和最小的模型。
Variable sensitivity and error variance of six evaporation and evapotranspiration models were calculated. Their sensitivity values were computed by approximating the partial derivatives by finite differences. To compare the models, relative sensitivityψwas computed byψi= (100/E1)(ΔE/Δxi), wherei= 1, …,n, with sensitivity defined as the percent change in evaporationEper unit change in the input variablexi. A second relative sensitivity ΨR i= [(xi−xio)/E1](ΔE/Δxi) was calculated to compare the relative importance of the different input variables. Error variance was analyzed to find the variance of error due to instrument inaccuracies byE[Var (Z)] =∑i=1n(ΔE/Δxi)2Var (xi) where Var (xi) is the instrument variance estimated from the manufacturer's statements. Although no tests were conducted to determine the bias or prediction accuracy of the model, a technique was proposed to show how the instrument error variance could be added to the prediction error variance to determine the overall system variance. In model development the best model will be one whose sum of these two variances is a minimum if there is no prediction bias.