Improved Surface Urban Heat Impact Assessment using GOES Satellite Data: A Comparative Study with ERA-5

We compare high-resolution land-surface temperature (LST) estimates from the GOES- 16/17 (GOES) satellites to ERA-5 Land (ERA-5) reanalysis data across nine large US cities. We quantify the offset and find that ERA-5 generally overestimates LST compared to GOES by 1.63C. However, this overestimation is less pronounced in urban areas, underscoring the limitations of ERA-5 in capturing the LST gradient between urban and non-urban areas. We then examine three quantities: Surface Urban Heat Island Intensity (SUHII), extreme LST events, and LST exposure by population. We find that ERA-5 does not accurately represent the diurnal variation and magnitude of SUHII in GOES. Furthermore, while ERA-5 was on average too warm, ERA-5 underestimates extreme heat by an average of 2.40°C. Our analysis reveals higher population exposure to high LST in the GOES dataset across the cities studied. This discrepancy is especially pronounced when estimating the population fraction that are most exposed to heat.