The enhanced vegetation index (EVI) is improved from the normalized vegetation index (NDVI). It carries out a comprehensive atmospheric correction according to the image factors, atmospheric molecules, aerosols, thin clouds, water vapor and ozone contained in the atmospheric correction. Evi atmospheric correction is divided into three steps. The first step is cloud removal. The second step is atmospheric correction, which includes atmospheric molecules, aerosols, water vapor, etc. in addition to the existing Rayleigh scattering and ozone of NDVI. The third step is to further deal with the impact of residual aerosols by means of the difference between blue and red light passing through aerosols. Since the input NIR, red and blue are subject to relatively strict atmospheric correction, it is unnecessary to use the vegetation index based on NIR / red ratio in order to eliminate multiplicative noise when designing the vegetation index formula. Therefore, the problem of easy saturation of vegetation index and lack of linear relationship with actual vegetation coverage caused by this is solved.
Evi is more sensitive to the changes of canopy structure, including leaf area index (LAI), canopy type, vegetation phase and canopy structure.
Based on MODIS mod13a2 V006 enhanced vegetation index evi data set will cover the framing image of Jinghe River Basin, use MRT tool and python language code to carry out projection conversion and clipping processing, and generate MODIS mod13a2 evi data of Jinghe River Basin from 2000 to 2021. The spatial resolution of this data set is 1km and the temporal resolution is 16 days
The data source of this data set is mod13a2 V006 version data from NASA official website（ https://ladsweb.modaps.eosdis.nasa.gov )。
(1) Test run the MRT tool and generate the PRM file converted by mod13a2 evi projection, with a spatial resolution of 1000 m;
(2) Using MATLAB language program to generate batch file calling MRT tool and run it;
(3) Using the vector boundary of Jinghe River Basin, python batch cutting is adopted, and finally GeoTIFF format is output and saved
This data set is the same as the source data set MODIS mod13a2 V006 consistent quality. The valid range of data is - 2000 to 10000, the scaling factor is 0.0001, and the filling value is - 3000.
This work is licensed under a
Creative
Commons Attribution 4.0 International License.
CSTR:11738.11.ncdc.JRiver.db1967.2022
10.12072/ncdc.JRiver.db1967.2022