MODIS data assessment of the relationship between vegetation and land surface temperature for central vegetation zone of Adamawa State, Nigeria

Abstract

Global concern over climate change has necessitated the need for the study of the impact of the ever-increasing land surface temperature on the greenness of land covers. Grassland phenological events are dependent on land surface temperature. This work is aimed at assessing the spatio-temporal trend of the relationship between vegetation cover and the day and night-times land surface temperatures in the Northern Guinea Savanna vegetation zone of Adamawa state, Nigeria. Twenty years (2000 to 2019) data series of Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data (MOD09A1), the day-time land surface temperature data (MOD11A), and the night-time land surface temperature (MYOD11A1) were used to spatially compute the Normalized Difference Vegetation Index (NDVI) and day-time and night-time Land Surface Temperatures (LST) for each of the respective years of the study period. The day- and night-time LST were correlated with the NDVI using simple linear regression analysis. The temporal analysis of the results indicate nonlinear changes in both the NDVI, day-time LST, and night-time LST. The results also indicate a negative correlation between LST and NDVI in both cases. Regression analyses of the day-time LST as a function of NDVI revealed a vegetation cover reduction of 0.0063 per Kelvin change in LST (R² = 0.3026, p > 0005, RMSE = 8.1042) and a night-time vegetation cover reduction of 0.0103 per Kelvin rise in LST (R² = 0.3697, p > 0.05, RMSE = 3.7511). The relatively low coefficient of determination and the p values implies a weak relationship between the two variables. The parameters however indicate that the night-time LST is a better predictor of the vegetation greenness of the area. The results revealed that LST is a weak determinant of plant phenological events with respect to the study area.