Mapping and Assessing the Seasonal Dynamics of Surface Urban Heat Intensity Using LandSAT-8 OLI/TIRS Images

Abstract

Increased heat intensity in urban climate has serious implications on human health, contributing to urban liveability and vitality. As a way of mitigating the effect of excessive heat temperature in the urban area, it is imperative to examine the level of surface temperature in urban areas over time so that the urban heat intensity and its attendant consequences can be put into consideration when under-taking sustainable urban planning. This study examined the spatiotemporal dynamics of surface urban heat intensity in Bosso Local Government Area of Niger State using remotely sensed images. Landsat-8 OLI/TIRS images of the year 2015, 2017, 2019, and 2021 for both dry and wet seasons were used to determine the study area’s Normalized Difference Vegetation Index (NDVI), surface emissivity, land surface temperature (LST), and Normalized Difference Built-up Index (NDBI), using ArcGIS 10.8 software. The result showed that a rise in built-up density, surface emis-sivity, and a decrease in vegetation density yields an increase in LST, while vegetation density proved to be of little effect in dry season when compared to the rainy season because most vegetation experiences draught at this time of the year. The result also showed that LST is higher in rainy season than it was in dry season because the wind, which decreases the effect of LST, is weak at this season of the year. The least value for surface emissivity in dry season was recorded to be 0.98605 while that of rainy is 0.98698, which implies that the emissivity of materials in the study area was observed to be higher in the rainy season than dry season. Furthermore, the result affirmed that a rise in urbanization gives rise to LST, likewise an increase in vegetation density of an area will lead to a decrease in the area’s urban heat intensity. The results also proved that wet periods can be hotter than dry periods of the year due to the presence of weak winds.