Momentum and Turbulent Kinetic Energy Budgets Within the Park Avenue Street Canyon During the Joint Urban 2003 Field Campaign

Nelson, Matthew A.; Pardyjak, Eric R.; Klein, Petra M.

doi:10.1007/s10546-011-9610-8

Cited by 18 publications

(7 citation statements)

References 25 publications

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“…Here, gradients are approximated by forward finite differences. A thorough discussion on the uncertainties in the evaluation of terms of (9) can be found in Nelson et al (2011). The dissipation rate can be estimated with the method described in Kiely et al (1996), in which…”

Section: Evolution Of Turbulent Kinetic Energymentioning

confidence: 99%

Flow during the evening transition over steep Alpine slopes

Nadeau

Pardyjak

Higgins

et al. 2012

Quart J Royal Meteoro Soc

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A field campaign, the Slope Experiment near La Fouly (SELF-2010), was conducted to monitor the evening transition of slope flows on clear-sky days from July to September 2010 in a narrow valley of the Swiss Alps. A steep west-facing slope with inclinations ranging from 25 • to 45 • was instrumented from 1900 m to 2200 m above sea-level. Detailed measurements were made along a linear transect of the slope with two turbulence towers, two weather stations, five surface temperature measurement stations and a tethered balloon system. The present study focuses on nine exemplary 'convective' days, characterized by weak synoptic flow and clear-sky conditions, during which thermal circulations prevail. The analysis of the observational data shows that topographic shading triggers the evening transition. The topographic configuration around the experimental site results in a sharply defined 'shading front' propagating upslope, causing a sudden decrease in incoming short-wave radiation on the order of several hundreds of W m −2 within a few minutes. The slope surface rapidly responds to the advancing shading front; in some cases, reductions in surface temperatures of some 10 • C in less than 10 min are observed. This is rapidly followed by an early-evening calm period with very small turbulent kinetic energy (TKE< 0.05 m 2 s −2 ) and extremely light wind speeds (< 0.5 m s −1 ). When the inertia-driven upslope flow is fully stopped by the katabatic acceleration, a shallow local drainage flow forms and reaches a quasi-equilibrium 1.5 h after the local sunset. An analysis of the TKE budget close to the surface shows that the buoyancy flux is much greater than the shear production in the last hours before the local sunset, possibly due to valley curvature effects.

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Section: Evolution Of Turbulent Kinetic Energymentioning

confidence: 99%

Flow during the evening transition over steep Alpine slopes

Nadeau

Pardyjak

Higgins

et al. 2012

Quart J Royal Meteoro Soc

Self Cite

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“…Many researchers have investigated the characteristics of turbulent flow in urban areas (Roth and Oke 1993;Rotach 1995;Nelson et al 2007Nelson et al , 2011. Louka et al (2000) showed that turbulent fluctuations comprise a large portion of flow in a street canyon.…”

Section: Introductionmentioning

confidence: 99%

Measurements of Turbulent Flow and Ozone at Rooftop and Sidewalk Sites in a High-Rise Building Area

Park¹,

Kwak²,

Han³

et al. 2015

SOLA

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Turbulent flow and ozone concentration at two (rooftop and sidewalk) sites in a high-rise building area of Seoul, Republic of Korea, were measured for the period of 24−27 June 2013 to examine their characteristics according to site location. During the observation period, the diurnal variations of air temperature, wind speed, and turbulent kinetic energy were distinct at both sites. The time series of ozone concentration exhibits a diurnal variation with daytime double peaks and one nighttime peak at both sites. The horizontal wind direction at the rooftop site has variations related to local winds, while the horizontal wind direction at the sidewalk site is mostly southerly (following a nearby street). The multiresolution spectra of horizontal and vertical velocities at the rooftop site confirm diurnal and turbulence-related variations. A quadrant analysis indicates that turbulence at the rooftop site is characterized by frequent ejections and less frequent but stronger sweeps, while turbulence at the sidewalk site is weaker and less characterizable than turbulence at the rooftop site.

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“…The winds over urban areas are further reduced by surface roughness. However, extra heat together with other factors in urban region results in a relatively neutral boundary layer, which therefore induces stronger turbulent vertical mixing and enhances near-surface winds [44]. This effect of wind increase by momentum transport offsets part of wind decrease by roughness.…”

Section: ∂T ∂Tmentioning

confidence: 99%

Features of Urban Heat Island in Mountainous Chongqing from a Dense Surface Monitoring Network

et al. 2019

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The spatial and temporal features of urban heat island (UHI) intensity in complex urban terrain are barely investigated. This study examines the UHI intensity variations in mountainous Chongqing using a dense surface monitoring network. The results show that the UHI intensity is closely related to underlying surfaces, and the strongest UHI intensity is confined around the central urban areas. The UHI intensity is most prominent at night and in warm season, and the magnitude could reach ~4.5 °C on summer night. Our quantitative analysis shows a profound contribution of urbanization level to UHI intensity both at night and in summer, with regression coefficient b = 4.31 and 6.65, respectively. At night, the urban extra heat such as reflections of longwave radiation by buildings and release of daytime-stored heat from artificial materials, is added into the boundary layer, which compensates part of urban heat loss and thus leads to stronger UHI intensity. In summer, the urban areas are frequently controlled by oppressively hot weather. Due to increased usage of air conditioning, more anthropogenic heat is released. As a result, the urban temperatures are higher at night. The near-surface wind speed can serve as an indicator predicting UHI intensity variations only in the diurnal cycle. The rural cooling rate during early evening transition, however, is an appropriate factor to estimate the magnitude of UHI intensity both at night and in summer.

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Momentum and Turbulent Kinetic Energy Budgets Within the Park Avenue Street Canyon During the Joint Urban 2003 Field Campaign

Cited by 18 publications

References 25 publications

Flow during the evening transition over steep Alpine slopes

Flow during the evening transition over steep Alpine slopes

Measurements of Turbulent Flow and Ozone at Rooftop and Sidewalk Sites in a High-Rise Building Area

Features of Urban Heat Island in Mountainous Chongqing from a Dense Surface Monitoring Network

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