Relationship between normalized difference moisture index and land surface temperature

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Remote sensing of urban heat islands(UHIs) has traditionally used the Normalized Difference Vegetation Index(NDVI) as the indicator of vegetation abundance to estimate the relationship land surface temperature(LST) and vegetation.This study investigates the applicability of Normalized Difference Moisture Index(NDMI) as an alternative indicator.This paper compares the Normalized Difference Vegetation Index(NDVI) and Normalized Difference Moisture Index(NDMI) as indicators of surface urban heat island effects in Landsat imagery by investigating the relationships between the Land Surface Temperature(LST),NDMI,and the NDVI.Landsat Thematic Mapper(TM) and Enhanced Thematic Mapper Plus(ETM+) data were used to estimate the LST through the single window algorithm from three different months for the Zhujiang Delta area.Maps of NDVI and NDMI for three different data were generated from band 3,band 4 and band 5 of TM/ETM+ imageries,respectively.The relationships between the LST,NDMI,and the NDVI were analyzed supported by Geographic Information System(GIS).Our analysis indicates that there is stronger linear relationship between LST and NDMI for all three months,whereas the relationship between LST and NDVI is much weaker and varies by different months.With the change of seasons from summer to autumn,the linear correlation relationship between LST and NDMI was gradually lowered.This result suggests that NDMI provides a complementary metric to the traditionally applied NDVI for analyzing LST quantitatively over the three months for surface urban heat island studies using thermal infrared remote sensing in an urbanized environment.