A Hypothesis for Urban Rainfall Anomalies

Changnon, Stanley A.; Semonin, Richard G.; Huff, Floyd A.

doi:10.1175/1520-0450(1976)015<0544:ahfura>2.0.co;2

Cited by 66 publications

(32 citation statements)

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“…Urban areas can modify convection and precipitation through dynamic forcing mechanisms initiated by thermal properties of the UHI and the topography of the built environment (Changnon et al 1976, Bornstein & Lin 2000. Modeling has shown that urban surface roughness, greater sensible heat flux, and complex local wind patterns of UHI-impacted regions may synergistically enhance the formation of updrafts complementary to thunderstorm development (Baik et al 2001, Rozoff et al 2003.…”

Section: Introductionmentioning

confidence: 99%

Cloud-to-ground flash patterns for Atlanta, Georgia (USA) from 1992 to 2003

Stallins¹,

Bentley²,

Rose³

2006

Clim. Res.

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We analyzed the patterns of cloud-to-ground (CG) lightning flashes around Atlanta, Georgia (USA), a region that has undergone an intense conversion from natural to anthropogenic land uses. For the 12 yr period from 1992 to 2003, annual average CG flash densities of 6 to 8 flashes km -2 emerged around Atlanta. These values are 50 to 75% higher than in the surrounding rural areas, and comparable to flash densities along the Atlantic coast of Georgia. High flash densities extended over a large swath of Atlanta, and into Gwinnett County, a heavily suburbanized, rapidly growing county to the northeast. Urban flash production peaked during the summer (May through June) and exhibited more night and early morning activity (18:00 to 06:00 h) than in surrounding rural areas. Atlanta's higher flash densities do not result from isolated flash production over the city; rather they develop when the large scale atmospheric setting favors widespread lightning throughout the region. Maps of flash counts by interval classes also revealed where flash density maxima emerge in different county regions around the city. A large area of reduced positive polarity flashes developed along the arc of Atlanta's loop highway, Interstate 285. This area also trended south along the corridor of Interstate Highway 75 into central Georgia. This pattern suggests that automobiles may be a source of particulate matter, which is hypothesized to reduce the percentage of positive flashes. 30: 99-112, 2006 growth. In this study, we mapped seasonal and diurnal flash characteristics for the Atlanta region for the period 1992-2003 and examined 2 questions common to urban lightning studies: (1) Are areas of greater CG flash occurrence the result of an increase in the number of days when flashes are observed, or the result of enhanced flash production? (2) To what extent do days with large versus small total flash counts contribute to this augmentation? KEY WORDS: Lightning · Urban heat island · Air pollution · GIS · Hazard assessment Resale or republication not permitted without written consent of the publisher OPEN PEN ACCESS CCESSClim Res BACKGROUNDUrban-modified CG flash characteristics occur in cities at various latitudes, from the tropics (São Paulo, Brazil;Naccarato et al. 2003) to the Midwest USA (Westcott 1995). Flash distributions in these cities, as well as for cities along the northern Gulf of Mexico , Steiger & Orville 2003, the Iberian peninsula (Areitio et al. 2001, Soriano & de Pablo 2002 and Brazil (Pinto et al. 2004) are sufficiently documented to conclude that the atmospheric properties of urban areas have the propensity to alter CG flash densities. Although the methods and the spatial and temporal extent of flash observations vary among studies, differences in flash density between urban and rural areas can attain 136% (St. Louis, Missouri; Wescott 1995) to 150-200% (Naccarato et al. 2003). In most cities, flash augmentation develops over the central urban core, or up to 100 km or more downwind (Naccarato et al. 2003). Urban...

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Section: Introductionmentioning

confidence: 99%

Cloud-to-ground flash patterns for Atlanta, Georgia (USA) from 1992 to 2003

Stallins¹,

Bentley²,

Rose³

2006

Clim. Res.

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“…The observed summer increases were up to 30% more rainfall and 45% more thunderstorm days, compared to the regional averages (Changnon et al, 1976;Changnon, 1978). One of the hypothesized causes was enhanced aerosol concentrations (Changnon et al, 1976). Bell et al (2008) found that the average storm rainfall in the afternoon was higher in mid-week (when pollution levels were higher) than on the weekend in the southeastern U.S. Rosenfeld and Bell (2011) also found that tornadoes and hailstorms occur in higher numbers during mid-week in the eastern U.S. A possible mechanism for such effects derives from aerosols' role as nuclei for cloud droplet condensation.…”

Section: Floodsmentioning

confidence: 75%

“…The groundbreaking METROMEX (METROpolitan Meteorological EXperiment) of the 1970s found that precipitation and convective storms were enhanced downwind (east and northeast) of St. Louis, MO. The observed summer increases were up to 30% more rainfall and 45% more thunderstorm days, compared to the regional averages (Changnon et al, 1976;Changnon, 1978). One of the hypothesized causes was enhanced aerosol concentrations (Changnon et al, 1976).…”

Section: Floodsmentioning

confidence: 86%

Changes in weather and climate extremes: State of knowledge relevant to air and water quality in the United States

Peterson

Karl

Kossin

et al. 2013

Journal of the Air & Waste Management Association

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Air and water quality are impacted by extreme weather and climate events on time scales ranging from minutes to many months. This review paper discusses the state of knowledge of how and why extreme events are changing and are projected to change in the future. These events include heat waves, cold waves, floods, droughts, hurricanes, strong extratropical cyclones such as nor'easters, heavy rain, and major snowfalls. Some of these events, such as heat waves, are projected to increase, while others, with cold waves being a good example, will decrease in intensity in our warming world. Each extreme's impact on air or water quality can be complex and can even vary over the course of the event.Implications: Because extreme weather and climate events impact air and water quality, understanding how the various extremes are changing and are projected to change in the future has ramifications on air and water quality management.

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“…Changnon et al [1976] showed statistically significant increases in summer rainfall in and around St. Louis. Braham and Wilson [1978] showed an enhancement in the frequency of tall echoes of radar over the city and near-downwind areas.…”

Section: Introductionmentioning

confidence: 96%

Urban effects on low‐level clouds around the Tokyo metropolitan area on clear summer days

Inoue

Kimura

2004

Geophysical Research Letters

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[1] The frequency distribution of low-level clouds was estimated around the Tokyo metropolitan area on summer days without regional-scale cloud cover using NOAA satellite images from 1200 to 1500 LST during an 11-year period. The urban area is determined by the NDVI obtained by the same satellite. The low-level cloud frequency is higher over this large urban area than over rural areas in the early afternoon, especially over the radially extending urban areas along major highways or railways from the metropolis. We can conclude that the frequency of the low-level clouds is enhanced over the urban area, since the cloud frequency is negatively well correlated with the NDVI and their peaks fit well within a shift of about 2 km. The frequency of low-level clouds, however, is quite low in the coastal zone, even in the urban area, because of sea breezes.

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A Hypothesis for Urban Rainfall Anomalies

Cited by 66 publications

References 0 publications

Cloud-to-ground flash patterns for Atlanta, Georgia (USA) from 1992 to 2003

Cloud-to-ground flash patterns for Atlanta, Georgia (USA) from 1992 to 2003

Changes in weather and climate extremes: State of knowledge relevant to air and water quality in the United States

Urban effects on low‐level clouds around the Tokyo metropolitan area on clear summer days

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