hello
i want to analyse the drought condition using sattelite images
for this i used the MODIS imagery and download EVI , NDVI (250m) and LST (1km) datasets for my sample area in Turkey
in Matlab i generate VCI and TCI indices and define drought classes as suggested generally e.g. www.un-spider.org/advisory-support/recommended-practices/recommended-practice-drought-monitoring/in-detail
aforementioned classes are defined as follow
% 0-10 Extreme Drought
% 10-20 Severe Drought
% 20-30 Moderate Drought
% 30-40 Light Drought
% >40 No Drought
when i generate drought claasification map based on VCI (using NDVI /EVI) the study area is classified mostly as no drought as presented in fig. 1
but when i use TCI dataset, which i resized to 250m in matlab, most of the area classified as severe drought as presented in fig 2
i check all process several times but the calculations are true
as seen i suppose that the 225th day of year could be representative for assessment (12/13Agustos) for both VCI and TCI
am i wrong?
any one can illustrate that
what is the detailed procedure for this purpose ?
can any one describe practically the data preprocessing for analysis?
https://www.un-spider.org/advisory-support/recommended-practices/recommended-practice-drought-monitoring/step-by-step/VCI-R-large-areas
step by step procedure using R studio
I think resampling might not be a suitable option for extracting the indices. Most of the time, your coarser satellite imagery is not helpful and once you resample it to integrate it with others, the results might not be accurate. I suggest you use Landsat-8 OLI and TIRS imagery in order to extract the NDVI and LST(there are lots of videos on how you use Landsat-8 thermal bands to calculate LST) and then use the spatial resolution of 30*30 meters and see how it works.
I hope it helps
best of luck
so thanks Nima Karimi
in fact i was prefered Modis becouse of ease of use of them as i was able to get dataset just for my study area not whole of the scene
but now i start to work on earth engine and now i could try other satellite images
best regards
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