作物缺水指数法的简化及在干旱遥感监测中的应用

Simplification of crop shortage water index and its application in drought remote sensing monitoring

从能量平衡原理出发 ,对潜在蒸散的计算进行了简化 ,从而对作物缺水指数法干旱遥感监测模型进行了简化 .简化后的模型涉及因子减少 ,计算量明显降低 ,更接近于实际应用 .利用该方法及NOAA/AVHRR卫星遥感资料和有关气象要素资料 ,对陕西省关中地区春季干旱进行了监测 .结果表明 ,简化后的作物缺水指数法仍然充分考虑了下垫面的植被覆盖状况和地面风速、水汽压等气象要素 ,对该区春季干旱的监测效果好于使用植被供水指数法的监测效果 .从简化后模型的计算量、时效响应和实际对比结果来看 ,该简化模型可以进行实际应用 .另外 ,在计算过程中局部出现了CWSI>1的情况 ,这在实际中是不可能的 。

Based on the principle of energy balance, the method for calculating latent evaporation was simplified, and hence, the construction of the drought remote sensing monitoring model of crop water shortage index was also simplified. Since the modified model involved fewer parameters and reduced computing times, it was more suitable for the operation running in the routine services. After collecting the concerned meteorological elements and the NOAA/AVHRR image data, the new model was applied to monitor the spring drought in Guanzhong, Shanxi Province. The results showed that the monitoring results from the new model, which also took more considerations of the effects of the ground coverage conditions and meteorological elements such as wind speed and the water pressure, were much better than the results from the model of vegetation water supply index. From the view of the computing times, service effects and monitoring results, the simplified crop water shortage index model was more suitable for practical use. In addition, the reasons of the abnormal results of C WSI>1 in some regions in the case studies were also discussed in this paper.