Urban wind field analysis from the Jack Rabbit II Special Sonic Anemometer Study

Area of Science:

• Atmospheric science
• Fluid dynamics
• Urban meteorology

Background:

• Urban environments significantly alter atmospheric boundary layer characteristics.
• Understanding wind flow and turbulence in urban canopies is crucial for predicting pollutant dispersion.

Purpose of the Study:

• To describe the experimental design of the Jack Rabbit II Special Sonic Anemometer Study (JRII-S).
• To analyze sonic anemometer data and characterize wind flow patterns within a mock-urban environment.
• To compare urban canopy flow with approaching boundary layer flow.

Main Methods:

• Deployment of 35 sonic anemometers within a systematically arranged mock-urban environment.
• Utilized a 32 m tall tower to measure approach wind flow characteristics.
• Collected data on wind speed, direction, and atmospheric stability.

Main Results:

• Identified three generalized flow regimes within the building array, including significant channeling.
• Observed vastly different flow patterns even between anemometers meters apart, dictated by building structures.
• Turbulence intensity (normalized vertical velocity variance) within the array was 2-3 times greater than in the approach flow.
• Turbulence intensity within the array showed little dependence on stability type, unlike the approach flow.

Conclusions:

• Urban areas generate complex wind patterns, channeling effects, and localized turbulence.
• These phenomena critically influence the dispersion of airborne pollutants.
• Findings can improve wind flow models for better pollutant dispersion characterization in urban settings.