Potential monitoring of crop production using a satellite-based Climate-Variability Impact Index

The capabilities of the MODerate resolution Imaging Spectroradiometer (MODIS) present some exciting possibilities for improved and timely monitoring of crop production. A quantitative index is introduced in this paper to study the relationship between remotely sensed leaf area index (LAI) and crop production. The Climate-Variability Impact Index (CVII), defined as the monthly contribution to anomalies in annual growth, quantifies the percentage of the climatological production either gained or lost due to climatic variability during a given month. By examining the integrated CVII over the growing season, this LAI-based index can provide both fine-scale and aggregated information on vegetation productivity for various crop types. Once the relationship between the CVII and crop production is developed based on the historical record, a trained statistical model can be applied to produce homogeneous production forecasts (in which the model is trained and tested for a particular region), as well as heterogeneous forecasts (in which the model is trained in a particular region and applied to a different region). Both the homogeneous and the heterogeneous model predictions are consistent with United States Department of Agriculture (USDA)/FAO estimates at regional scales. Finally, by determining the estimated production as a function of the growing-season months it is possible to determine when in the phenological cycle the predictive value of the CVII plateaus and which months within the phenological cycle provide the greatest predictive capacity. Overall, the high temporal and spatial resolution of the satellite LAI products makes the CVII a useful tool in near real-time crop monitoring and production estimation.