Estimating regional winter wheat yield with WOFOST through the assimilation of green area index retrieved from MODIS observations
Estimating regional winter wheat yield with WOFOST through the assimilation of green area index retrieved from MODIS observations
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DOI：
10.1016/j.agrformet.2012.04.011
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发表时间：
2012-10-15
影响因子：
6.2
通讯作者：
Defourny, Pierre
中科院分区：
文献类型：
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作者：
de Wit, Allard;Duveiller, Gregory;Defourny, Pierre
在这里，我们描述并测试了一种优化冬小麦绿面积指数（GAI）的方法，该方法是用WOFOST作物模型模拟的，使用MODIS估计比利时瓦隆地区的GAI。使用2000-2009年期间的详细作物类型图，通过仅选择目标作物纯度至少为75%的250 m MODIS像元，获得作物特异性GAI的时间序列。通过最小化每个像素和年份的模拟GAI和观测GAI之间的差异，优化了两个重要的模型参数。所得到的特定年份的联合参数分布随后被用于运行一个作物模拟集合，其中该集合通过从相应年份的联合分布中抽样来初始化。反演参数的半变异图表明，空间格局与农业实践相一致，瓦隆尼亚地区天气模式的季节特征至少可以部分解释反演参数分布的时间变异。最后，将平均集合作物模拟结果汇总到省和区域层面。利用欧盟统计局2000-2009年期间报告的产量进行的验证表明，将MODIS与GAI同化可以改善区域一级模拟结果与报告产量之间的关系。(C) 2012 Elsevier B.V.版权所有
Here, we describe and test a method for optimising winter wheat green area index (GAI) simulated with the WOFOST crop model using MODIS estimates of GAI in the Walloon region of Belgium. Detailed crop type maps during the period of 2000-2009 were used to derive time series of crop-specific GAI by selecting only the 250-m MODIS pixels that have at least 75% purity of the target crop. Two important model parameters were optimised by minimising the difference between the simulated and observed GAI for each individual pixel and year. The resulting year-specific joint parameter distributions were then used to run an ensemble of crop simulations in which the ensemble was initialised by sampling from the joint distribution of the corresponding year. The semi-variograms of the retrieved parameters revealed that the spatial patterns were consistent with agricultural practices and that seasonal characteristics of weather patterns in Wallonia can explain - at least partially - the temporal variability observed in the retrieved parameter distributions. Finally, the results of the average ensemble crop simulation were aggregated to the provincial and regional levels. A validation using yields reported by EUROSTAT over the period 2000-2009 revealed that assimilating MODIS with GAI provides an improved relationship between simulation results and reported yields at the regional level. (C) 2012 Elsevier B.V. All rights reserved.