Dynamic status of land surface temperature and spectral indices in Imphal city, India from 1991 to 2021

Abstract

The thermal status of northeast Indian cities has a great impact on the sustainability of these places. To meet the research gap in this area, a study is performed in Imphal city, India by investigating the relationship between land surface temperature (LST) and four spectral indices in the summer and winter seasons from 1991 to 2021. The mean LST of the city increases at >1% rate per decade in both seasons. The urban heat island (UHI) develops mostly along the central Imphal. A considerable difference in the mean LST between UHI and non-UHI in summer (3.05 °C in 1991, 2.46 °C in 2001, 3.13 °C in 2011, and 2.49 °C in 2021) and winter (2.01 °C in 1991, 2.63 °C in 2001, 2.64 °C in 2011, and 2.57 °C in 2021) reflects the continuous warming status of the city. Some urban hot spots develop inside the UHI of the central and north Imphal. The dynamic nature of the relationships of spectral indices with LST (moderate negative for MNDWI and NDVI, strongly positive for NDBI, and moderate negative for NDBaI) will be helpful for proper sustainable urban planning. Urban thermal field variance index map shows that the south Imphal attains more ecological comfort than the rest of the parts.