Thermal Remote Sensing and WRF simulations-strategy for mitigating the Urban Heat Island effect in Patna and Bangalore, India

Urban Heat Islands (UHI) are a significant hazard in cities, caused by low albedo surfaces, limited green space, narrow streets, and tall buildings that trap heat. This effect intensifies heatwaves and poses health risks, especially for vulnerable populations. Various measures, including increasing green space, have been proposed to mitigate UHI impacts. However, space constraints and poor implementation have limited the effectiveness of these solutions.

A study is being conducted to determine the critical factors to be considered for gaining the optimal benefit of green space and mitigating the impact of UHI. The optimal park configuration for UHI mitigation—whether several small parks distributed across the city or a single large space developed strategically provides more cooling. Further, the temperature gradients as a function of distance from the park core are examined along with the interplay between vegetation density, vegetation canopy, surface albedo, and evapotranspiration rates, etc., through WRF simulations integrated with the Hybrid 100m Land Cover Dataset (CGLC-MODIS-LCZ) and the LANDSAT-8 data analysis.

Two cities with distinct climates and urban morphology are considered for evaluating the consistency in model performance, validating the output with ground-based observations, and assessing the adaptive capacity, transferability, and scalability of the methodology. Patna (eastern India), with a humid subtropical climate, and Bengaluru (southern India), with a tropical savanna climate, are considered for the study.

The analysis shows that Patna City, Didarganj, Bariya Bus Station, Patna Airport, Danapur Industrial area, and the New Secretariat are identified as UHIs characterized by limited greenery and low surface reflectivity. These UHIs exhibit temperatures up to 3.5°C higher when compared to areas with more green cover in the city. WRF simulations show that the strategic introduction of green cover could lower temperatures up to 5°C in these hotspots.