PNNL

Abstract

ERA5-Land reanalysis provides spatiotemporally continuous meteorological data in observation-scarce regions. However, its applicability needs compre- hensive evaluations. To evaluate its performance and assess the propagation of biases into downstream applications, this study conducts evaluations of surface air temperature and dew point of ERA5-Land against hourly obser- vational data in the UK. We investigated the contribution of urbanization to the bias of ERA5-Land and evaluated its efficacy in characterizing the urban heat island (UHI), calculating the heat exposure profile, and model- ing temperature-associated mortality risks and building energy consumption. Our analysis reveals that ERA5-Land does not fully capture the extreme daily and monthly maximum/minimum of both air temperatures and dew point. Further, urbanization affects the performance of ERA5-Land, and a higher impervious surface area ratio leads to a higher underestimation of air temperature. While the dataset successfully reproduces UHI, it tends to un- derestimate the total hours of yearly extreme heat exposure in both urban and rural areas. Nevertheless, the air temperature and dew point of ERA5- Land are reliable proxies for assessing temperature-related mortality risk and driving building energy simulations. This study provides an extensive eval- uation of the application of ERA5-Land data across urban climate studies and the propagation of biases to downstream applications, which guides the application of ERA-Land.