The possible influence of urban surfaces on rainfall development: a sensitivity study in 2D in the meso-γ-scale

Thielen, Joanna; Wobrock, W.; Gadian, Alan; Mestayer, P.G.; Creutin, Jean‐Dominique

doi:10.1016/s0169-8095(00)00041-7

Cited by 137 publications

(86 citation statements)

References 24 publications

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“…It is tempting to attribute the anomaly to topography but figure 13b suggests that this particular regions is does not have significant relief. Recalling a previous discussion, Thielen et al (2000) and Baik et al (2001) have shown that weak or small heat islands result in surface sensible heat fluxes, convergence, and buoyancy variations that influence rainfall development being most effective at a distance from the central heat source. According to Sahin and Aksakal (1999) prevailing low-level wind flow during the rainy season is North-Northwesterly.…”

Section: Satellite-based Analysismentioning

confidence: 57%

Evidence of urban-induced precipitation variability in arid climate regimes

Shepherd

2006

Journal of Arid Environments

152

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The study employs a 1 OF(-year precipitation historical data record, global climate observing network observations and satellite data to identify possible anomalies in rainfall in and around two major arid urban areas, Phoenix, Arizona and Riyadh, Saudi Arabia. The analysis reveals that during the monsoon season, locations in northeastern suburbs and exurbs of the Phoenix metropolitan area have experienced statistically significant increases in mean precipitation of 12 to 14 percent from a pre-urban to post-urban ( 1950-2003) period. Further analysis of satellite-based rainfall rates suggests the existence of the anomaly region over a seven-year period. The anomaly cannot simply be attributed to maximum topographic relief and is hypothesized to be related to urban-topographic interactions and possibly irrigation moisture. Temperature records suggest that Riyadh has experienced an adjustment in mean temperature in response to the growth of urban surfaces (e.g., the so-called urban heat island effect).While ground-based precipitation records also indicate an upward trend in mean and total precipitation in and around Riyadh in the last 10-15 years, it is difficult to attribute the increase to urbanization because other less urbanized stations in Saudi Arabia also show a similar increase. Recent satellite-based precipitation estimates indicate an anomaly region 50-100 km north of Riyadh, but this study is not robust enough to conclusively link it to urbanization although certain climate-regime attributes suggests that it might be.

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Section: Satellite-based Analysismentioning

confidence: 57%

Evidence of urban-induced precipitation variability in arid climate regimes

Shepherd

2006

Journal of Arid Environments

152

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“…Many modeling studies support observations of increased convection and precipitation associated with urbanization (Hjelmeft 1982;Yonetani 1983;Thielen et al 2000;Baik et al 2001;Rozoff et al 2003). Three possible causes for urban-induced changes in precipitation are mechanical turbulence resulting from increased surface roughness, additional sensible heat flux, and increased anthropogenic nuclei.…”

Section: Rainfallmentioning

confidence: 77%

Progress in Urban Meteorology :A Review

Kanda

2007

Journal of the Meteorological Society of Japan

101

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This paper reviews the progress made in urban meteorology over the past few decades. The focus is on the impact of urban surfaces on the overlying atmosphere along the conventional meteorological frameworks. Section 1 details the difficulties in generalizing urban surfaces in a meteorological sense because of surface diversity, and considers whether conventional similarity law is applicable. Section 2 describes the characteristics of urban surfaces as the bottom boundary of the atmosphere and includes a discussion of land surface parameters and the resultant surface energy partitioning. Section 3 explains characteristics of the urban atmosphere, including temperature fields, local circulations and rainfall. Section 4 describes recent progress in numerical modeling and promising new technologies, thus revealing a possible future direction for urban meteorological studies.

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“…In southern England, apart from land/sea effects, the largest land-use effects are from urban versus rural areas. Urban areas are expected to increase daytime surface sensible fluxes by up to a factor of two and decrease latent heat fluxes by a factor of between one and six (Thielen et al, 2000). There are, however, no major urban areas in the CSIP area (the largest urban areas have diameters of approximately 15 km).…”

Section: Observed Effects Of the Cirrus Cover On Surface Fluxesmentioning

confidence: 99%

Variable cirrus shading during CSIP IOP 5. I: Effects on the initiation of convection

Marsham

Morcrette

Browning

et al. 2007

Quart J Royal Meteoro Soc

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ABSTRACT:Observations from the Convective Storm Initiation Project (CSIP) show that on 29 June 2005 (Intensive Observation Period 5) cirrus patches left over from previous thunderstorms reduced surface sensible and latent heat fluxes in the CSIP area. Large-eddy model (LEM) simulations, using moving positive surface-flux anomalies, show that we expect the observed moving gaps in the cirrus cover to significantly aid convective initiation. In these simulations, the timing of the CI is largely determined by the amount of heat added to the boundary layer, but weak convergence at the rear edge of the moving anomalies is also significant.Meteosat and rain-radar data are combined to determine the position of convective initiation for all 25 trackable showers in the CSIP area. The results are consistent with the LEM simulations, with showers initiating at the rear edge of gaps, at the leading edge of the anvil, or in clear skies, in all but one of the cases. The initiation occurs in relatively clear skies in all but two of the cases, with the exceptions probably linked to orographic effects.For numerical weather prediction, the case highlights the importance of predicting and assimilating cloud cover. The results show that in the absence of stronger forcings, weak forcings, such as from the observed cirrus shading, can determine the precise location and timing of convective initiation. In such cases, since the effects of shading by cirrus anvils from previous convective storms are relatively unpredictable, this is expected to limit the predictability of the convective initiation.

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The possible influence of urban surfaces on rainfall development: a sensitivity study in 2D in the meso-γ-scale

Cited by 137 publications

References 24 publications

Evidence of urban-induced precipitation variability in arid climate regimes

Evidence of urban-induced precipitation variability in arid climate regimes

Progress in Urban Meteorology :A Review

Variable cirrus shading during CSIP IOP 5. I: Effects on the initiation of convection

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