Adam Jaczewski (Poland) 1
1 - Institute of Meteorology and Water Management - National Research Institute
Current projections show that the number of people living in cities is expected to double by 2030. At the scale of the whole city the energy exchange between the ground and atmosphere is manifested by the rise of urban heat island (UHI) phenomena accelerated by changing climate. There is a high demand for mitigation and adaptation actions but these cannot be efficiently achieved without accurate numerical models. For adequate representation of the meteorological conditions prevailing in the urban area it is necessary to implement special parameterization of the meteorological processes in the scale of buildings and streets. In the course of this study, such demand was achieved through running COSMO-CLM model with TERRA_URB parameterization which is bulk scheme with a prescribed anthropogenic flux (Wouters et al., 2016). Last few years (2013-2016) was chosen for simulations based on availability of the observational data. The years since 2014 are the ones of the warmest in the 20th and 21th centuries in Poland. The city also experienced a couple severe flash flooding events in this period.
The model was driven by ERA-Interim Reanalysis dataset in the extended metropolitan area (250 km X 250 km). For model evaluation 2-m temperature and precipitation data at hourly resolution was taken from the database of Institute of Meteorology and Water Management (Polish meteorological and hydrological service). For comparison, additional model run without TERRA_URB was performed.
The results show that application of urban parameterization scheme has significantly improved prediction. The model captured the UHI features and enhanced its effects on convective precipitation but there are still spatial differences and discrepancies in diurnal cycles.
1.Wouters, H. et al. The efficient urban canopy dependency parametrization (SURY) v1.0 for atmospheric modelling: description and application with the COSMO-CLM model for a Belgian summer. Geosci. Model Dev. 9, 3027_3054 (2016).