Assessment of the Urban Impact on Surface and Screen-Level Temperature in the ALADIN-Climate Driven SURFEX Land Surface Model for Budapest

Gabriella Zsebeházi,Sándor István Mahó

doi:10.3390/atmos12060709

Gabriella Zsebeházi, Sándor István Mahó

Open Access

https://doi.org/10.3390/atmos12060709

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Abstract

Land surface models with detailed urban parameterization schemes provide adequate tools to estimate the impact of climate change in cities, because they rely on the results of the regional climate model, while operating on km scale at low cost. In this paper, the SURFEX land surface model driven by the evaluation and control runs of ALADIN-Climate regional climate model is validated over Budapest from the aspect of urban impact on temperature. First, surface temperature of SURFEX with forcings from ERA-Interim driven ALADIN-Climate was compared against the MODIS land surface temperature for a 3-year period. Second, the impact of the ARPEGE global climate model driven ALADIN-Climate was assessed on the 2 m temperature of SURFEX and was validated against measurements of a suburban station for 30 years. The spatial extent of surface urban heat island (SUHI) is exaggerated in SURFEX from spring to autumn, because the urbanized gridcells are generally warmer than their rural vicinity, while the observed SUHI extent is more variable. The model reasonably simulates the seasonal means and diurnal cycle of the 2 m temperature in the suburban gridpoint, except summer when strong positive bias occurs. However, comparing the two experiments from the aspect of nocturnal UHI, only minor differences arose. The thorough validation underpins the applicability of SURFEX driven by ALADIN-Climate for future urban climate projections.

Highlights

Urbanized surfaces are characterized by highly different surface properties from natural surfaces, that leads to altered energy budget components and boundary layer properties
Since four measurements per day are available from the end of 2002 in Moderate Resolution Imaging Spectroradiometer Sensor (MODIS) (Table 2), we considered only the SURFace EXternalisée (SURFEX)-EI experiment on the period of 2003–2005 on a domain containing mainly urbanized and cropland areas (Figure 2)
The first part of this study focuses on the spatial and temporal characteristics of surface temperature and surface urban heat island (SUHI) simulated by SURFEX-EI, considering the MODIS land surface temperature (LST) product as reference

Summary

Introduction

Urbanized surfaces are characterized by highly different surface properties (e.g., imperviousness, large roughness, large heat capacity, and heat admittance of materials) from natural surfaces, that leads to altered energy budget components and boundary layer properties. More than half of the world’s population lives in urban settlements, the impervious surfaces occupy less than 0.5% of the Earth [2] Such high population density can be observed in Hungary as well; for example, the Budapest urban agglomeration occupies 2.7% of the territory of Hungary, while its 2.5 million inhabitants represent one quarter of the whole country’s population [3]. As a consequence of the high population density and elevated temperatures, cities are exposed to more severe heat related risks compared to rural areas. With climate change, this exposure may be further exacerbated, negatively affecting for example human health, environment and energy demand [4]

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