Table 4(a) and (b) shows the correlation values of temperature variables and NDVI and TVDI with the results of soil surface moisture obtained from different data and models for both 2010 and 2014 years. In Table 4, the symbols * and ** at the top of each correlation number indicate the existence of a significant correlation at the level of 1 and 5% between the two comparable variables, respectively. Also, the sign of the positive and negative values of these numbers indicates the existence of direct and inverse correlations between the variables, respectively. As can be seen from the values in the table, in 2010, the soil surface moisture results of ESA-CCI and LPRM as expected are inversely and directly correlated with temperature and NDVI at 1%, respectively, and are inversely correlated with TVDI, for ESA-CCI it is significant at the level of 5% and for LPRM it is significant at the level of 1%. AMSRE radar results due to what has already been discussed about the nature of the captured data of this product, are only directly correlated with the LST variable at the 1% level. Also, as discussed in the previous section, the results of ESA-CCI and LPRM in 2010 have a direct correlation at the level of 1%, but compared to the AMSRE results, both products have an inverse correlation. In 2014, the results of ESA-CCI and GLDAS soil surface moisture variables with the LST variable are inversely correlated at the level of 1%, with the NDVI having a direct correlation at the level of 5% and with the TVDI are inversely correlated at the level of 1%. The results of LPRM model in 2014 have a direct and inverse correlation with the temperature variable and the NDVI at the level of 1%, respectively, and with the TVDI have a direct correlation at the level of 5%. These results are in accordance with what is discussed about the spatial distribution of soil surface moisture in the previous section. The results of ESA-CCI and GLDAS products in 2014 have a direct correlation at the level of 1%, but with the LPRM product (which results from AMSRE radar data) there is an inverse correlation.

Table 4

Statistical correlation values of soil surface moisture obtained from different remote sensing data with NDVI, TVDI, and land surface temperature

a (2010)
LSTNDVITVDIAMSRELPRMESA-CCI
LST −0.497** 0.440* 0.754** −0.696** −0.740** 
NDVI −0.497** −0.379* −0.282 0.712** 0.763** 
TVDI 0.440* −0.379* 0.236 −0.600** −0.445* 
AMSRE 0.754** −0.282 0.236 −0.346* −0.386* 
LPRM −0.696** 0.712** −0.600** −0.346* 0.772** 
ESA-CCI −0.740** 0.763** −0.445* −0.386* 0.772** 
b (2014)
LSTNDVITVDIGLDASLPRMESA-CCI
LST −0.548** 0.681** −0.889** 0.781** −0.872** 
NDVI −0.548** −0.363* 0.392* −0.650** 0.414* 
TVDI 0.681** −0.363* −0.787** 0.428* −0.630** 
GLDAS −0.889** 0.392* −0.787** −0.630** 0.802** 
LPRM 0.781** −0.650** 0.428* −0.630** −0.586** 
ESA-CCI −0.872** 0.414* −0.630** 0.802** −0.586** 
a (2010)
LSTNDVITVDIAMSRELPRMESA-CCI
LST −0.497** 0.440* 0.754** −0.696** −0.740** 
NDVI −0.497** −0.379* −0.282 0.712** 0.763** 
TVDI 0.440* −0.379* 0.236 −0.600** −0.445* 
AMSRE 0.754** −0.282 0.236 −0.346* −0.386* 
LPRM −0.696** 0.712** −0.600** −0.346* 0.772** 
ESA-CCI −0.740** 0.763** −0.445* −0.386* 0.772** 
b (2014)
LSTNDVITVDIGLDASLPRMESA-CCI
LST −0.548** 0.681** −0.889** 0.781** −0.872** 
NDVI −0.548** −0.363* 0.392* −0.650** 0.414* 
TVDI 0.681** −0.363* −0.787** 0.428* −0.630** 
GLDAS −0.889** 0.392* −0.787** −0.630** 0.802** 
LPRM 0.781** −0.650** 0.428* −0.630** −0.586** 
ESA-CCI −0.872** 0.414* −0.630** 0.802** −0.586** 

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