Connectivity of Nocturnal Cold‐Air Flows for Urban Heat Island Mitigation: Introduction of the Cold‐Air Trajectory Calculator KLATra
ABSTRACT Ventilation of cities by local cold‐air flows is an important measure in urban heat island mitigation and climate‐resilient urban planning. We introduce a cold‐air connectivity analysis to identify relevant cold‐air formation areas as well as urban quarters ventilated by cold‐air flows. The...
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| Format: | Article |
| Language: | English |
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Wiley
2025-07-01
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| Series: | Meteorological Applications |
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| Online Access: | https://doi.org/10.1002/met.70080 |
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| author | Paule Hainz Meinolf Kossmann Stephan Weber |
| author_facet | Paule Hainz Meinolf Kossmann Stephan Weber |
| author_sort | Paule Hainz |
| collection | DOAJ |
| description | ABSTRACT Ventilation of cities by local cold‐air flows is an important measure in urban heat island mitigation and climate‐resilient urban planning. We introduce a cold‐air connectivity analysis to identify relevant cold‐air formation areas as well as urban quarters ventilated by cold‐air flows. The nocturnal cold‐air flow trajectories are calculated from numerical model simulations using the single‐layer cold‐air drainage model KLAM_21 and the newly developed trajectory calculator KLATra. The German city of Freiburg im Breisgau is chosen to demonstrate the cold‐air connectivity analysis based on trajectories calculated for two 3‐hourly periods during an idealised night. Hydrological catchment boundaries and land use define eight rural cold‐air formation areas as starting points for forward trajectories, whereas administrative urban district boundaries and land use data are used to define five built‐up quarters potentially prone to overheating as starting points for cold‐air backward trajectories. A rate of connectivity is calculated from the ratio of trajectories connecting cold‐air formation areas with overheated urban quarters to the total number of trajectories. The analysis reveals the potential of cold‐air formation areas to ventilate single or multiple urban quarters at connectivity rates up to 82%. The connectivity analysis therefore supports identification and assessment of the relevance of specific cold‐air formation areas for urban heat island mitigation and may serve as a valuable planning tool and data basis for objective decision making. |
| format | Article |
| id | doaj-art-e8c41b6947ec40e98fedd96d00186aca |
| institution | Kabale University |
| issn | 1350-4827 1469-8080 |
| language | English |
| publishDate | 2025-07-01 |
| publisher | Wiley |
| record_format | Article |
| series | Meteorological Applications |
| spelling | doaj-art-e8c41b6947ec40e98fedd96d00186aca2025-08-26T11:54:48ZengWileyMeteorological Applications1350-48271469-80802025-07-01324n/an/a10.1002/met.70080Connectivity of Nocturnal Cold‐Air Flows for Urban Heat Island Mitigation: Introduction of the Cold‐Air Trajectory Calculator KLATraPaule Hainz0Meinolf Kossmann1Stephan Weber2Climatology and Environmental Meteorology Institute of Geoecology, Technische Universität Braunschweig Braunschweig GermanyClimate and Environment Consultancy, Deutscher Wetterdienst Offenbach am Main GermanyClimatology and Environmental Meteorology Institute of Geoecology, Technische Universität Braunschweig Braunschweig GermanyABSTRACT Ventilation of cities by local cold‐air flows is an important measure in urban heat island mitigation and climate‐resilient urban planning. We introduce a cold‐air connectivity analysis to identify relevant cold‐air formation areas as well as urban quarters ventilated by cold‐air flows. The nocturnal cold‐air flow trajectories are calculated from numerical model simulations using the single‐layer cold‐air drainage model KLAM_21 and the newly developed trajectory calculator KLATra. The German city of Freiburg im Breisgau is chosen to demonstrate the cold‐air connectivity analysis based on trajectories calculated for two 3‐hourly periods during an idealised night. Hydrological catchment boundaries and land use define eight rural cold‐air formation areas as starting points for forward trajectories, whereas administrative urban district boundaries and land use data are used to define five built‐up quarters potentially prone to overheating as starting points for cold‐air backward trajectories. A rate of connectivity is calculated from the ratio of trajectories connecting cold‐air formation areas with overheated urban quarters to the total number of trajectories. The analysis reveals the potential of cold‐air formation areas to ventilate single or multiple urban quarters at connectivity rates up to 82%. The connectivity analysis therefore supports identification and assessment of the relevance of specific cold‐air formation areas for urban heat island mitigation and may serve as a valuable planning tool and data basis for objective decision making.https://doi.org/10.1002/met.70080country breezedrainage windKLAM_21urban planningurban ventilation |
| spellingShingle | Paule Hainz Meinolf Kossmann Stephan Weber Connectivity of Nocturnal Cold‐Air Flows for Urban Heat Island Mitigation: Introduction of the Cold‐Air Trajectory Calculator KLATra Meteorological Applications country breeze drainage wind KLAM_21 urban planning urban ventilation |
| title | Connectivity of Nocturnal Cold‐Air Flows for Urban Heat Island Mitigation: Introduction of the Cold‐Air Trajectory Calculator KLATra |
| title_full | Connectivity of Nocturnal Cold‐Air Flows for Urban Heat Island Mitigation: Introduction of the Cold‐Air Trajectory Calculator KLATra |
| title_fullStr | Connectivity of Nocturnal Cold‐Air Flows for Urban Heat Island Mitigation: Introduction of the Cold‐Air Trajectory Calculator KLATra |
| title_full_unstemmed | Connectivity of Nocturnal Cold‐Air Flows for Urban Heat Island Mitigation: Introduction of the Cold‐Air Trajectory Calculator KLATra |
| title_short | Connectivity of Nocturnal Cold‐Air Flows for Urban Heat Island Mitigation: Introduction of the Cold‐Air Trajectory Calculator KLATra |
| title_sort | connectivity of nocturnal cold air flows for urban heat island mitigation introduction of the cold air trajectory calculator klatra |
| topic | country breeze drainage wind KLAM_21 urban planning urban ventilation |
| url | https://doi.org/10.1002/met.70080 |
| work_keys_str_mv | AT paulehainz connectivityofnocturnalcoldairflowsforurbanheatislandmitigationintroductionofthecoldairtrajectorycalculatorklatra AT meinolfkossmann connectivityofnocturnalcoldairflowsforurbanheatislandmitigationintroductionofthecoldairtrajectorycalculatorklatra AT stephanweber connectivityofnocturnalcoldairflowsforurbanheatislandmitigationintroductionofthecoldairtrajectorycalculatorklatra |