Andrea Zonato
Atmospheric Physics Group, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy, Atmospheric Physics Group, Department of Civil, Environmental and Mechanical Engineering, University of Trento, Trento, Italy
Author ProfileAbstract
Urban climate model evaluation often remains limited by a lack of
trusted urban weather observations. The increasing density of personal
weather stations (PWS) make them a potential rich source of data for
urban climate studies that address the lack of representative urban
weather observations. In our study, we demonstrate that PWS data not
only improve urban climate models’ evaluation, but can also serve for
bias-correcting their output prior to any urban climate impact studies.
After simulating near-surface air temperatures over London and
south-east England during the hot summer of 2018 with the Weather
Research Forecast (WRF) model and its Building Effect Parameterization
with the Building Energy Model (BEP-BEM) activated, we evaluated the
modelled temperatures against 407 urban PWS and showcased a
heterogeneous spatial distribution of the model’s cool bias that was not
captured using official weather stations only. This finding indicated a
need for spatially-explicit urban bias corrections of air temperatures,
which we performed using an innovative method using machine learning to
predict the models’ biases in each urban grid cell. Our technique is the
first to consider that urban temperatures are heterogeneously accurate
in space and that this accuracy is not linearly correlated to the urban
fraction. Our results showed that the bias-correction was beneficial to
bias-correct daily-minimum, -mean, and -maximum temperatures in the
cities. We recommend that urban climate modellers further investigate
the use of PWS for model evaluation and derive a framework for
bias-correction of urban climate simulations that can serve urban
climate impact studies.