Regional climate
Final Report Abstract
We implemented the urban parametrization scheme DCEP into the regional climate and weather model COSMO-CLM. In contrast to its predecessor BEP, it considers the radiation exchange of roofs in detail and closes the radiative energy balance. We extensively validated COSMO-CLM/DCEP with measurements and compared it with other parametrization schemes. It is now used and further developed at the Potsdam Institute for Climate Impact Research, at the Geography Department of the Humboldt-Universität zu Berlin and at the Swiss Federal Laboratories for Materials Science and Technology. We used COSMO-CLM/DCEP to study the effects of different coupling approaches to microscale models and the effects of different urban heat island mitigation measures. We found that considering mesoscale atmospheric conditions supplied by COSMO-CLM/DCEP in city-wide simulations of the mean radiative temperature can lead to a more appropriate description of heat-related hazards. During heat waves in Berlin, we found a grid-cell wide decrease of the near-surface temperature of about 0.5 K for an increase of 15% of the vegetation covers and a decrease of about 0.5 K for an increase of roof albedos from 16% to 65%. In order to study the effect of climate change on the urban heat island intensity of cities in Germany, we developed an approach to dynamical downscaling focusing on representative periods. This approach reduces the computational demand considerably and allows consideration of different driving global climate models. We found relatively small climate change signals of the city ensemble’s summer mean hourly urban heat island intensity (0.13 K to 0.16 K), with standard errors of similar magnitude. The analysis showed the importance of the driving global climate as it determines the characteristics in urbanized regional climate simulations.
Publications
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2013. Auswirkungen des Klimawandels auf Deutschlands Städte. In: Gerstengarbe, F. & Welzer, H.. Zwei Grad mehr in Deutschland: Wie der Klimawandel unseren Alltag verändern wird. Fischer Taschenbuch
Grossman-Clarke, S. & Schubert, S.
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2013. The Influence of Green Areas and Roof Albedos on Air Temperatures during Extreme Heat Events in Berlin, Germany. Meteorologische Zeitschrift, Volume 22, pp. 131-143
Schubert, S. & Grossman-Clarke, S.
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2014. Evaluation of the coupled COSMO-CLM/DCEP model with observations from BUBBLE. Quarterly Journal of the Royal Meteorological Society, 140(685), pp. 2465-2483
Schubert, S. & Grossman-Clarke, S.
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2014. Extreme summer heat in Phoenix, Arizona (USA) under global climate change (2041-2070). Die Erde, 145(1-2), pp. 49-61
Grossman-Clarke, S., Schubert, S., Clarke, T. R. & Harlan, S. L.
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2016. The urban land use in the COSMO-CLM model: a comparison of three parameterizations for Berlin. Meteorologische Zeitschrift, Volume 25, pp. 231-244
Trusilova, K. et al.
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2016. Towards city-wide, building-resolving analysis of mean radiant temperature. Urban Climate, Volume 15, pp. 83-98
Jänicke, B. et al.
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2017. Urban effects on temperature in Germany under climate change. International Journal of Climatology, 37(2), p. 905–917
Grossman-Clarke, S., Schubert, S. & Fenner, D.
