RF-CLASS - Remote-sensing-based Flood Crop Loss Assessment Service System
The Surface Reflectance Daily L2G Global 250m of MODIS is selected as the input for generating normalized difference vegetation index (NDVI). The L2G product has two bands – Band1 (620-670 nm) and Band2 (841-876 nm) that represent respectively red and near-infrared band. Therefore, the equation for computing daily NDVI is as follows:
Resulted data are in the range of [0, 250].
RVCI stands for the ratio of current NDVI to previous year for the same periods – either weekly or biweekly. The equation is listed as:
RMVCI stands for the ratio of current NDVI to the median of previous years since 2000 for the same periods – either weekly or biweekly. The equation is listed as:
Where, c is the current year.
Vegetation Condition Index (VCI) is an index that represents the weather condition or the vegetation condition. The following is the basic equation:
Where, NDVI is the value at a given pixel, NDVImin is the minimum across multiple years at that pixel, NDVImax is the maximum across multiple years. This is basically normalized across years at a given pixel.
Mean Vegetation Condition index (MVCI) represents the deviation of the vegetation to “normal” vegetation or multiple-year mean. The equation is listed:
In general, the value range should be mainly around -100% to 100% although the actual range can go beyond these limits.