Title: Multi-source Remote Sensing of Urban Heat Islands and Mitigation Strategies
Citable Abstract (150–200 words)
This study evaluates urban heat island dynamics and mitigation efficacy using multi-source remote sensing across five cities from 2016 to 2024. Clear-sky summer imagery from Landsat-8 and Sentinel-2 was processed via spatiotemporal registration, cloud detection, and land surface temperature (LST) inversion. We constructed fixed-effects panel models at 500 m built-up grids (≈62,000 samples), incorporating NDVI, surface albedo, and covariates (population density, road density, terrain). Results show that a 0.1 increase in NDVI is associated with a 0.28°C reduction in LST (p<0.01). In roof retrofitting pilots, high-reflectance (“cool roof”) areas exhibited LST that was 0.9°C lower than matched controls (95% CI: 0.6–1.2). Increasing tree canopy coverage from 20% to 30% reduced LST by 1.2°C on peak heatwave days. Findings are robust to alternative window choices, model specifications, and instrumental-variable checks. Limitations include uneven samples due to cloud cover and potential underestimation of micro-scale effects at 500 m resolution. We recommend prioritizing tree canopy expansion and cool roof deployment in identified thermal hotspots, coupled with community-level maintenance to ensure durability and equitable cooling benefits.
Meeting Minutes – Key Points
- Objective: Quantify how vegetation and materials affect urban land surface temperature (LST) and assess mitigation strategies.
- Data: Landsat-8 and Sentinel-2 summer clear-sky imagery (2016–2024).
- Indicators: LST, NDVI, surface albedo.
- Methods: Spatiotemporal registration; cloud detection; LST inversion; panel and regression discontinuity analyses; fixed effects at 500 m built-up grids.
- Sample: Five cities; ≈62,000 grid observations; covariates include population density, road density, terrain.
- Findings:
- NDVI +0.1 → LST −0.28°C (p<0.01).
- Cool roofs → LST −0.9°C vs. controls (95% CI: 0.6–1.2).
- Tree canopy 20%→30% → LST −1.2°C on peak heatwave days.
- Robustness: Results consistent across window changes, alternative models, and instrumental-variable approaches.
- Limitations: Cloud cover reduces spatial-temporal balance; 500 m grids may understate micro-scale cooling.
- Recommendations: Target thermal hotspots for tree canopy expansion and cool roof retrofits; align with community-level maintenance.
Public News Release – Opening Paragraph
As cities grow, summers are getting hotter—and new satellite analysis shows practical ways to cool neighborhoods. Looking at Landsat-8 and Sentinel-2 imagery across five cities, researchers found that greener streets and reflective “cool roofs” significantly lower surface temperatures. Even a modest rise in vegetation reduces heat, while boosting tree canopy from 20% to 30% cools peak heatwave days by about 1.2°C. Roofs with high-reflectance materials were around 0.9°C cooler than similar areas without upgrades. The takeaway is clear: prioritize trees and cool roofs in the hottest zones, and support community maintenance to keep the cooling going.
