Vegetation condition indices for crop vegetation condition monitoring

NDVI maps have been proven valuable in providing a spatially complete view of crop\´s vegetation condition, which manifests disastrous events such as massive flood and drought. It is virtually impossible to obtain from ground survey data. This paper uses NASA MODIS 250m resolution, daily surface reflectance data for crop condition monitoring. The NDVI provides an absolute metrics for vegetation condition. However, a relative measurement of the current vegetation condition against a reference vegetation condition is critical for understanding, interpreting and quantifying the current vegetation condition. In this paper, a new NDVI based vegetation condition index is presented to measure the vegetation condition with respect to the "normal condition", which is characterized by historical average. The proposed new vegetation condition index is empirically compared with several other vegetation indices to evaluate its effectiveness. Its advantages and utility for crop vegetation condition measurement are evidenced by the preliminary results.