| Accurate and timely crop growth monitoring and yield forecasting play a significant role in guiding agricultural production and ensuring food security. Recently, the approach combining remote sensing with crop growth simulation models has been catching on, in that it not only reflects dynamic crop growth processes, but also provides real-time monitoring information at large scale from remote sensing data. Especially in the regional application of crop models at water limited production level, it is possible to estimate some sensitive soil parameters and initial value of some state variables of the crop model by remote sensing data with the rapid development of remote sensing technology. However, up to now, the method of calibrating parameters of soil water balance using the evapotranspiration retrieved from remote sensing data are just studied at local scale. In this paper, the primary objective is to develop a method of integrating the evapotranspiration retrieved from satellite remote sensing data in a crop growth model to simulate winter wheat yield on the regional scale in North China.Based on the existing research with respect to the combination of remote sensing data and crop growth model at potential production level, which is the first step of the NSFC program study on estimating winter wheat yield based on remote sensing and crop model, this paper describes the approach of coupling remote sensing data with crop model at water limited production level as the second step. To begin with, the WOFOST model at water limited production level has been improved in some processes and adjusted by using field experiment data in several agrometeorological stations. And then, the method to calibrate soil parameters of crop model by the evapotranspiration retrieved from MODIS data was tested first on a local scale. Finally, the method was carried out at regional scale, on the basis of interpolated meteorological data and regionalized crop genetic parameters and soil parameters.The main results are as follows.(1) In order to improve the simulation accuracy of WOFOST model about the influences of water stress on crop growth, some processes had been modified, such as estimating the reference crop evapotranspiration, crop coefficient, the lag effect of water stress, and the effect of water stress on specific leaf area, etc. And also some crop genetic parameters and soil parameters were adjusted. It was proved that the adjusted WOFOST model can be used to simulate the winter wheat growth, development, and yield formation under water limited condition in North China.(2) According to the sensitivity of several soil parameters and initial value of state variables in soil water balance process, also considering the role of irrigation to winter wheat growth in North China, the initial amount of available soil water in excess of soil water at wilting point (WAV) and irrigation in earring stage were selected to be calibrated. After reinitializing WAV and attaining the irrigation in earring stage by virtue of the optimization procedure FSEOPT, the relative error of simulated dry matter weight of storage organ on the last observation day in 2001-2002 has been reduced from -83.1% to -22.1% in Zheng Zhou and from -18.5% to -0.1% in Tai An.(3) Weather data and some crop parameters related to temperature were interpolated by using spatial interpolation method IDW. Some crop genetic parameters were regionalized simply according to their climate ecological type. And some soil parameters were also regionalized in the light of soil texture types. Then the WAV, dry matter weight in turn-green and irrigation in earring stage during the winter wheat growth season in North China in 2001-2002 have been calibrated by remote sensing data. The results showed that the agreement between simulated yield and measured yield was better than the one without combining remote sensing data, and the relative error of average yield in Hebei and Shandong Province were reduced from -70.9%, -33.2% to 4.2%, 12.5%, respectively. It can be concluded tha...
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