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High-speed Particle Image Velocimetry Near Surfaces
Published on: June 24, 2013
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A Novel Method to Quantify Near-Surface Boundary-Layer Dynamics at Ultra-High Spatio-Temporal Resolution
Michael Haugeneder1,2, Michael Lehning1,2, Dylan Reynolds1,2
1WSL-Institute for Snow and Avalanche Research SLF, Davos, Switzerland.
Boundary-Layer Meteorology
|February 13, 2023
Summary
A new method uses thermal cameras and synthetic screens to measure near-surface wind and temperature. This reveals complex atmospheric layers and heat exchange over heterogeneous surfaces like patchy snow.
Area of Science:
- Atmospheric Science
- Environmental Physics
- Surface Energy Balance Studies
Background:
- Lateral heat transport above land surface temperature steps impacts local energy balance.
- Understanding near-surface atmospheric dynamics over heterogeneous terrain is crucial.
- Existing methods often lack the resolution to capture fine-scale atmospheric stratification.
Purpose of the Study:
- To introduce a novel experimental method for investigating near-surface atmospheric stratification and dynamics.
- To quantify near-surface wind fields and air temperature patterns over heterogeneous land surfaces.
- To demonstrate the method's capability in complex alpine environments with patchy snow cover.
Main Methods:
- Utilized a high-resolution thermal infrared camera to record sequences of synthetic screens.
- Screen surface temperature served as a proxy for local air temperature.
- Developed a pattern-tracking algorithm to estimate 2D wind fields at centimeter resolution, validated with ultrasonic anemometers.
Main Results:
- Revealed an extremely heterogeneous near-surface atmospheric layer over patchy snow.
- Identified a dynamic stable internal boundary layer (SIBL) above snow patch edges.
- Observed entrainment of warm air into the SIBL during gusts, impacting snow surface energy.
Conclusions:
- The screen-based method effectively captures complex in situ near-surface heat exchange processes.
- Measurements confirm the significant role of atmospheric stratification in heterogeneous landscapes.
- The technique provides valuable data for understanding microscale weather phenomena and their impact on surface processes.
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