Regional winter wheat yield estimation based on the WOFOST model and a novel VW-4DEnSRF assimilation algorithm

Abstract

To further improve the accuracy of regional crop yield estimation based on data assimilation, a novel EnSRF assimilation algorithm based on a variable time window and four-dimensional extension (VW-4DEnSRF) was proposed. In this research, taking Hengshui City of Hebei Province as the study area and winter wheat as the research crop, based on the WOFOST crop model and the proposed VW-4DEnSRF algorithm, a crop yield assimilation system was successfully constructed after parameter sensitivity analysis and parameter calibration of the crop model. Supported by the field-measured crop yield data and based on the effective validation of the yield assimilation system at a single point scale and in a typical experimental area, the scale optimization of grid size for regional yield estimation was effectively selected. Finally, combining the WOFOST model and inverted remotely sensed LAI, the regional winter wheat yield simulation under the optimal grid size of 500 m was carried out effectively through comparison with the field-measured yield data and official statistical yield data at the county level. Among them, the R2, adjusted R2 and RMSE between the simulated yield and ground-measured yield were 0.481, 0.471 and 801.4 kg.ha−1, respectively. The mean value of the estimated yield of winter wheat in Hengshui City was 6787 kg.ha−1, and the RMSE and RE between the estimated yield and official yield were 416.7 kg.ha−1 and 4.56%, respectively. These above results showed that the crop yield assimilation system based on the WOFOST model and proposed VW-4DEnSRF algorithm had good performances at both the single-point level and regional level, which proved that the proposed algorithm was feasible and effective at simulating crop yield over a large area