Nishino et al. (2026) Future Urban Heat Risk Assessment in Sydney: Integrating Satellite-Derived UTCI with Population Projections

Identification

• Journal: ISPRS annals of the photogrammetry, remote sensing and spatial information sciences
• Year: 2026
• Date: 2026-09-28
• Authors: Akihiko Nishino, Sisi Zlatanova, Naohiko Kohtake
• DOI: 10.5194/isprs-annals-xii-4-w2-2026-137-2026

Research Groups

• School of Built Environment, University of New South Wales
• Graduate School of System Design and Management, Keio University

Short Summary

This study presents a framework for metropolitan-scale future heat risk assessment in Sydney by integrating satellite-derived Universal Thermal Climate Index (UTCI) with demographic projections. The results highlight priority zones where high projected thermal stress coincides with large future resident populations.

Objective

• Investigate the relationship between urban heat stress and population growth in Sydney.
• Develop a reproducible framework for metropolitan-scale future heat risk assessment.

Study Configuration

• Spatial Scale: Metropolitan scale, focusing on the city of Sydney.
• Temporal Scale: Long-term projections to 2031.

Methodology and Data

• Models used:
  • GloUTCI-M global UTCI dataset within Google Earth Engine for trend-based extrapolation.
  • ERA5-HEAT physically consistent UTCI at 28 km resolution.
  • Landsat 8/9 land surface temperature at 30 m resolution.
  • 3D solar radiation modelling.
  • Nine-station BOM bias correction.
• Data sources:
  • Satellite observations (GloUTCI-M, ERA5-HEAT, Landsat 8/9).
  • Demographic projections to 2031.

Main Results

• The UTCI-Population Index (UPI) was developed as a composite indicator of population-weighted heat exposure.
• Two complementary satellite-based approaches were implemented:
  • Approach 1: Trend-based extrapolation of GloUTCI-M within Google Earth Engine to predict 2031 summer UTCI at 1 km resolution.
  • Approach 2: High-resolution spatial downscaling combining ERA5-HEAT with Landsat 8/9 land surface temperature, refined by 3D solar radiation modelling and nine-station BOM bias correction.

Contributions

• The study provides a reproducible framework for metropolitan-scale future heat risk assessment in Sydney.
• The results highlight the importance of considering both thermal stress and population growth when planning urban heat adaptation measures.

Funding

• Not specified in the provided text.

Citation

@article{Nishino2026Future,
  author = {Nishino, Akihiko and Zlatanova, Sisi and Kohtake, Naohiko},
  title = {Future Urban Heat Risk Assessment in Sydney: Integrating Satellite-Derived UTCI with Population Projections},
  journal = {ISPRS annals of the photogrammetry, remote sensing and spatial information sciences},
  year = {2026},
  doi = {10.5194/isprs-annals-xii-4-w2-2026-137-2026},
  url = {https://doi.org/10.5194/isprs-annals-xii-4-w2-2026-137-2026}
}