Urban Modification of Convection and Rainfall in Complex Terrain

Freitag, Brian; Nair, U. S.; Niyogi, Dev

doi:10.1002/2017gl076834

Cited by 61 publications

(39 citation statements)

References 42 publications

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“…Other factors like urban size and structure (Kingfield et al, 2018;, different climate zones, or entangling factors can furthermore lead to changes in heavier rainfall regimes. Studies, for example, evaluated urban modification of storms by coastal cities (Comarazamy et al, 2010;Hosannah & Gonzalez, 2014;Shepherd et al, 2010), cities located near artificial reservoirs (e.g., Haberlie et al, 2016), or in deserts (Diem & Brown, 2003;Diem & Mote, 2005), and recently, Freitag et al (2018) cities with complex terrains. Lowry (1998) criticizes that many assumptions of rainfall modification are based on two research campaigns in the second half of the last century.…”

Section: 1029/2018jd028858mentioning

confidence: 99%

Urban Rainfall Modification: Observational Climatology Over Berlin, Germany

et al. 2019

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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.

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Section: 1029/2018jd028858mentioning

confidence: 99%

Urban Rainfall Modification: Observational Climatology Over Berlin, Germany

et al. 2019

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“…Shepherd () proposed that interactions between orographic processes and urban‐induced circulation can produce frequent convergence at the urban interface. Freitag et al () showed that urbanization modifies terrain‐forced convection through dynamic and thermodynamic perturbations to persistent atmospheric forcings. Also, previous studies highlight the importance of considering flow regimes in urban rainfall modification studies (e.g., McLeod et al, ).…”

Section: Introductionmentioning

confidence: 99%

Urban Impacts on Extreme Monsoon Rainfall and Flooding in Complex Terrain

Yang

Smith

Niyogi

2019

Geophysical Research Letters

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Hydrometeorological impacts due to urbanization for cities close to complex terrain are poorly understood due to the complexities of terrain‐related circulation and urban perturbations of atmospheric flow. In this study, we examine urban impacts on extreme monsoon rainfall and the resultant flooding over central Arizona based on high‐resolution atmospheric and hydrological model simulations. Strong positive rainfall anomalies at the urban‐rural interface downwind of the city are mainly related to dynamic effects (increased surface roughness) on convective outflow boundaries. Urban‐related thermodynamic disturbances slightly increase rain rates over the downtown core of Phoenix. Contrasting rainfall anomalies for two consecutive storm episodes highlight the importance of flow regime analysis in understanding urban impacts on extreme rainfall in complex terrain. Urban‐induced rainfall anomalies result in amplification of flood peak magnitudes by as much as a factor of 2 for Phoenix watersheds. Our results highlight the urban impacts on regional flood hydrology through land‐atmosphere interactions.

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“…For example, Freitag et al . () have used WRF and satellite data products to investigate such impacts over San Miguel de Tucumán, Argentina and found that urbanization results in 20–30% less precipitation downwind of the city and that it causes an eastward shift of precipitation upwind.…”

Section: Introductionmentioning

confidence: 99%