I had estimated the Land surface Temperature and Normalised Difference Vegetation Index, the result shows they have positive relation both increases in lower south part areas and higher in upper part areas in the attached map.
I want your opinion on the result:
1) What does this result suggest?
In other what can you interpret from it and use this result for what kind of study, where these can be relevant?
It is really interesting that you got such results. Basically higher temperatures associated with lower NDVI. At least this is true for my studies. The reason behind that is the water content restored in your vegetation and hence cooler LST would be estimated, however, in your case it is the opposite. I recommend you to again calculate the LST and NDVI, for example, if you are using Landsat TIRS images, try to use the calibrated bottom of atmosphere radiances. In addition, try to find other factors. For example, is there an urban area in the vicinity of your study area? or any anthropogenic effects are highly monitored around the area? Those would be the reasons behind such kind of phenomenon. The results of your study could be applied to understand the cooling effects of vegetation blanket or maybe the heat sinking applications for vegetation cover class. There are many other applications that you can also find from the literature.
Hello Pawan Thapa. Based on your maps, it looks like you are having highest NDVI values at estimated temperatures between approximately 12 and 26°C (optimal temperatures for vegetation growth regarding your study site?). At very high and low temperatures, NDVI values seem to be "lower". Look for instance at the red areas of your LST map. Thus, I think you should analyse your data a little bit more in detail with a higher resolution.
A short overview, that should help to interpret NDVI values: NDVI values smaller than 0.1 correspond to areas without any vegetation, like rocks, sand, water bodies or snow. From 0.1 to 0.2 you have almost no vegetation. Spare vegetation like senescing crops, shrubs and also some types of grassland have moderate NDVI values from approximately 0.2 to 0.5. High NDVI values (higher than 0.6) indicate dense vegetation structures, like forests or crops at their peak growth rate.
I hope this helps
Best regards
Paul
There are many effects to consider. Plants evapotranspiration reduces temperature on sun hours but in arid climates plants are not breathing the whole day. The albedo is also reduced, vegetated areas are darker and usually absorb more sun radiation than nake terrain. The wind speed is also reduced in forested areas. The topographic efect is also very important in temperature. You should expect a reduction of 1 ºC every 154 m in height and should also consider the incidence angle of the sun and how long it was heating the terrain until the image was taken. You can compute the solar irradiance with GRASS. I don't like your color table for NDVI. Green usually means high NDVI.
Dear Pawan Thapa ,
I suggest checking available records of precipitation and discharge for example, in your study area; for this is a delicate matter which differs from one study area to another.
In one study you might encounter results which suggest that significant increasing trend of vegetation cover is associated with increasing trend of LST and vise versa.
Observed NDVI could be affected by handful of variables such as net radiation, type of vegetation, precipitation, runoff, evapotranspiration, overall dominant climate, etc.
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