Spatial and temporal variation of daytime and nighttime MODIS land surface temperature across Nepal

Abstract

Land surface temperature (LST) is an important variable for assessing climate change and related environmental impacts observed in recent decades. Regular monitoring of LST using satellite sensors such as MODIS has the advantage of global coverage, including topographically complex regions such as Nepal. In order to assess the climatic and environmental changes, daytime and nighttime LST trend analysis from 2000 to 2017 using Terra-MODIS monthly daytime and nighttime LST datasets at seasonal and annual scales over the territory of Nepal was performed. The magnitude of the trend was quantified using ordinary linear regression, while the statistical significance of the trend was identified by the Modified Mann–Kendall test. Our findings suggest that the nighttime LST in Nepal increased more prominently compared to the daytime LST, with more pronounced warming in the pre-monsoon and monsoon seasons. The annual nighttime LST increased at a rate of 0.05 K yr−1 (p < 0.01), while the daytime LST change was statistically insignificant. Spatial heterogeneity of the LST and LST change was observed both during the day and the night. The daytime LST remained fairly unchanged in large parts of Nepal, while a nighttime LST rise was dominant all across Nepal in the pre-monsoon and monsoon seasons. Our results on LST trends and their spatial distribution can facilitate a better understanding of regional climate changes.