Spatiotemporal Analysis of Urban Heat Island Effects in Nigerian Cities Using MODIS Data

Abstract

This study examines the geographical and temporal dynamics of the Urban Heat Island (UHI) effect over ten major Nigerian cities: Lagos, Kano, Ibadan, Benin City, Port Harcourt, Aba, Jos, Ilorin, Abuja, and Kaduna, spanning the period from 2001 to 2023. Ultimately steering urban climate adaptation strategy, the main goal is to assess the intensity and mitigation potential of UHI events through high-resolution remote sensing and climatic indicators. The study is based on three fundamental objectives: (i) to evaluate long-term trends in Land Surface Temperature (LST) and vegetation cover using MODIS satellite data; (ii) to identify and classify UHI hotspots and their vegetation status; and (iii) to quantify the impact of vegetation, albedo, and evapotranspiration in reducing urban heat through the Heat Mitigation Index (HMI). Using MODIS MOD11A1.061 daily LST products at 1 km resolution, MCD43A3 albedo data, and MCD12Q1 land cover datasets, the methodology applied a multi-parameter geospatial framework. While trend analysis was conducted using the altered Mann-Kendall test and Sen’s slope estimator to identify statistically significant changes in both LST and NDVI, NDVI was created to measure plant health. The HMI model geographically mapped areas with high, moderate, and low heat mitigation capacity under both daytime and nighttime settings by combining plant cover, albedo, and crop coefficient (Kc) data. NDVI and LST trends were studied using Pearson correlation analysis. Results show consistent UHI intensification in urban centers, with daytime LST values hitting 34–38°C and corresponding nighttime values staying high in most cities. As demonstrated by negative NDVI trends and R² values over 0.5 in various towns, vegetation decrease, most acute in Lagos, Abuja, and Kano, substantially correlates with increasing surface temperatures. On the other hand, cities like Ibadan and Benin City showed significantly high HMI zones (48–52%), highlighting the cooling capacity of preserved vegetative cover. While Jos and Ibadan exhibited lower albedo (<0.120) in vegetated areas, the albedo study revealed high reflectivity in the urban cores of Lagos, Kano, Ilorin, and Abuja, with values ranging from 0.140 to 0.259, which corresponds to impervious surfaces. The spatial overlap of low vegetation, high albedo, and thermal hotspots highlights even more the combined effect of surface change on UHI intensity. Cities like Kano and Lagos also revealed more than 17% barren or low vegetative Kc areas, which are directly linked to environmental pressure and inadequate cooling capacity. This study emphasises the importance of green infrastructure in reducing urban heat and offers an evidence-based basis for climate-resilient urban development in sub-Saharan Africa. Particularly for fast urbanising areas prone to climate-induced heat stress, the results suggest including vegetation restoration, urban greening programs, and nature-based solutions into long-term UHI mitigation and adaptation plans.