Urban wind field analysis from the Jack Rabbit II Special Sonic Anemometer Study. (15th December 2020)

• Record Type: Journal Article
• Authors: Pirhalla, Michael; Heist, David; Perry, Steven; Hanna, Steven; Mazzola, Thomas; Arya, S. Pal; Aneja, Viney
• Is Part Of: Atmospheric environment. Volume 243(2020)
• Publication Date: 2020-12-15
• Subjects: Jack rabbit II -- Turbulence -- Microscale meteorology -- Sonic anemometry -- Urban dispersion -- Building wakes; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2020.117871
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: The Jack Rabbit II Special Sonic Anemometer Study (JRII-S), a field project designed to examine the flow and turbulence within a systematically arranged mock-urban environment constructed from CONEX shipping containers, is described in detail. The study involved the deployment of 35 sonic anemometers at multiple heights and locations, including a 32 m tall, unobstructed tower located about 115 m outside the building array to document the approach wind flow characteristics. The purpose of this work was to describe the experimental design, analyze the sonic data, and report observed wind flow patterns within the urban canopy in comparison to the approaching boundary layer flow. We show that the flow within the building array follows a tendency towards one of three generalized flow regimes displaying channeling over a wide range of wind speeds, directions, and stabilities. Two or more sonic anemometers positioned only a few meters apart can have vastly different flow patterns that are dictated by the building structures. Within the building array, turbulence values represented by normalized vertical velocity variance ( σ w 2 ) are at least two to three times greater than that in the approach flow. There is also little evidence that σ w 2 measured at various heights or locations within the JRII array is a strong function of stability type in contrast to the approach flow. The results reinforce how urban areas create complicated wind patterns, channeling effects, and localized turbulence that can impact the dispersion of an effluent release. These findings can be used to inform the development of improved wind flow algorithms to better characterize pollutant dispersion in fast-response models. Highlights: Jack Rabbit II Special Sonic Anemometer Study is described in detail. Wind within the mock-urban building array is characterized by three flow regimes. Turbulence and mixing increase within the array while overall wind speed decreases. Flow at adjacent sonics varies strongly reinforcing urban dispersion complexity. Atmospheric stability effects are moderated within the mock-urban array.