Urban climate
Zusammenfassung der Projektergebnisse
In the context of the Research Unit 1736 UCaHS, Research Module 1 “Outdoor climate and heat-stress hazard” focused on the quantitative analysis of the atmospheric processes causing heat-related hazards, vulnerabilities, and risks. Year-round hourly weather data and statistically aggregated urbanclimate data were generated for a period of more than ten years at high spatial resolution. Cascaded dynamical down-scaling of global reanalysis data resulted in a new gridded data set for Central Europe and Germany called Central Europe Refined analysis (CER) from 2001 to 2010, and for the years beyond. Systematic differences between simulations and observations could be detected particularly concerning air temperature and soil temperature, both showing cold biases, as well as overestimation of net radiation, global radiation, and turbulent fluxes. CER was used for a variety of sensitivity studies. T2 produced by CER was mainly sensitive to PBL schemes, and to a lesser extend to UCMs. All tested UCMs underestimated intra-urban and urban-rural differences as compared to observations. Overall a combination of the PBL scheme Bougeault-Lacarrére scheme with the simple slab UCM showed the best performance in these studies, indicating that a higher degree of complexity of the UCM is not guaranteeing better results. Observational data on indicators of heat-stress risks were used to quantify outdoor heat-stress hazard. Façade greening displayed only a slight reduction of Tmrt during the day. Comparison of these observations with results of micro-scale models could not affirm the reduction. The value of such models for assessing the effectiveness of façade greening seems to be limited, at least for the applied settings. The sub-project contributed to collaborative research on effectiveness and efficiency of actions for reducing heat-stress risks for example by carrying out micro-scale simulations. Simulations with an improved version of the micro-scale model SOLWEIG made it possible to consider both micro-scale urban structures and meso-scale atmospheric conditions by forcing SOLWEIG with gridded meteorological data from the meso-scale atmospheric model COSMO-CLM. Tmrt displayed a high sensitivity to the partitioning of direct and diffuse short-wave radiation. The spatial pattern of T mrt revealed that at midday the city center exhibited low values compared to open areas. Spatial patterns of Tmrt are suitable to identify for planning above mentioned actions. Various simulations with ENVI-met showed the positive effects of vegetation on heat-stress related variables depending on design of vegetation elements or physical dimension, i.e. age of trees in canyons and courtyards.
Projektbezogene Publikationen (Auswahl)
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(2013): Quantification of heat-stress related mortality hazard, vulnerability and risk in Berlin, Germany. DIE ERDE 144, 238- 259
Scherer, D., U. Fehrenbach, T. Lakes, S. Lauf, F. Meier and C. Schuster
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(2013+2014): Special Issue: Urban climate and heat-stress. Part 1+2. DIE ERDE, 144 +145
Scherer D. and W. Endlicher
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(2014): Spatial and temporal air temperature variability in Berlin, Germany, during the years 2001-2010. Urban Climate 10(2), 308-331
Fenner, D., F. Meier, D. Scherer and A. Polze
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(2015): Assessment of indoor heat stress variability in summer and during heat warnings: A case study using the UTCI in Berlin, Germany. International Journal of Biometeorology, 1–14
Walikewitz, N., Jänicke, B., Langner, M. and W. Endlicher
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(2015): Evaluating the effects of façade greening on human bioclimate in a complex urban environment. Advances in Meteorology Volume 2015, Article ID 747259, 15 pages
Jänicke, B., F. Meier, M.-T. Hoelscher, and D. Scherer, D.
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(2016): Spatial variability of human-biometeorological conditions related to heat stress in Berlin, Germany, with focus on air temperature and radiation. Dissertation, Chair of Climatology, Technische Universität Berlin
Jänicke, B.
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(2016): The role of building models in the evaluation of heat-related risks. Natural Hazards and Earth System Sciences, 16: 963-976
Buchin, O., Jänicke, B., Meier, F., Scherer, D. and F. Ziegler
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(2016): Towards city-wide, buildingresolving analysis of mean radiant temperature. Urban Climate 15, 83–98
Jänicke, B., F. Meier, F. Lindberg, S. Schubert and D. Scherer
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(2017): Urban-rural differences in near-surface air temperature as resolved by the Central Europe Refined analysis (CER): sensitivity to planetary boundary layer schemes and urban canopy models. International Journal of Climatology 37(4), 2063-2079
Jänicke, B., F. Meier, D. Fenner, U. Fehrenbach, A. Holtmann and D. Scherer
