This study investigates the direct influence of urban areas on storm events (heavy rainfall above 17 mm/hr). An 11‐year climatology of summertime precipitation was performed to capture and describe storm events for Berlin, Germany. An hourly radar composite product from the German Weather Service with a 1‐km grid resolution was used for the analysis. Berlin was chosen due to the relatively modest influences of topography and distinct urban‐rural landscape heterogeneity potentially affecting storms. The analysis identified 96 storm events for the period from 2006 to 2016. Individual storm characteristics were evaluated before the city (upwind), over the city, and behind the city (downwind). Both visual and statistical estimations quantified storm modifications caused by the urban area. Around 60% of the events showed typical patterns of storm alteration by the city. In conformance to earlier studies, we found evidence of urban rainfall intensification about 20 to 50 km downwind of the urban center. Most storms were suppressed, deflected, or split by the city, whereas intensification over the city typically occurred at night or when storms formed over the city. In the present study, results indicate an urban influence on storms in and around Berlin. But, unlike other studies, downwind intensification of storm rainfall was not a typical feature. This study on urban rainfall modification marks one of the first observations‐based climatological assessments for the European region.
Even though it is known that urbanization affects rainfall, studies vary regarding the magnitude and location of rainfall change. To develop a comprehensive understanding of rainfall modification due to urbanization, a systematic meta-analysis is undertaken. The initial search identified over 2000 papers of which 489 were carefully analyzed. From these papers, 85 studies from 48 papers could be used in a quantitative meta-analysis assessment. Results were analyzed for case studies versus climatological assessments, observational versus modeling studies and for day versus night. Results highlight that urbanization modifies rainfall, such that mean precipitation is enhanced by 18% downwind of the city, 16% over the city, 2% on the left and 4% on the right with respect to the storm direction. The rainfall enhancement occurred approximately 20–50 km from the city center. Study results help develop a more complete picture of the role of urban processes in rainfall modification and highlight that rainfall increases not only downwind of the city but also over the city. These findings have implications for urban flooding as well as hydroclimatological studies. This meta-analysis highlights the need for standardizing how the results are presented in future studies to aid the generalization of findings.
more » « less- NSF-PAR ID:
- 10149638
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Scientific Reports
- Volume:
- 9
- Issue:
- 1
- ISSN:
- 2045-2322
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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