PUBLICATION HIGHLIGHT: Improved Observations of Turbulence Dissipation Rates from Wind Profiling Radars

Gopher Rock Fish (Credit: NOAA)
A 449-MHz Wind Profiling Radar antenna

What happens in the lowest part of our atmosphere is directly influenced by the Earth’s surface. The turbulence resulting from the transfer and mixing of energy and moisture in this layer between land and sky strongly impacts the weather that we experience in our daily lives. Weather prediction models are unable to resolve the smallest scales of atmospheric motion, where turbulence is active. Observations of turbulence in this planetary boundary layer (PBL) are sparse, yet crucial for improving weather prediction models.

In a new study, CIRES and NOAA researchers at ESRL’s Physical Sciences Division used two wind-profiling radars to measure one aspect of turbulence—dissipation rate—in the PBL. Performed at the Boulder Atmospheric Observatory, the study also used a 300-m tower during the eXperimental PBL Instrumentation Assessment. The two radars were operated at a uniquely high resolution for accurate measurements of Doppler spectral width to estimate the strength of the turbulence, measured by its dissipation rates. The researchers then used several post-processing techniques to remove noise and other non-atmospheric signals in the data, and compared the results to direct observations made by sonic anemometers (sensors measuring wind at very high frequency) that were mounted on the tower.

The findings, recently published in Atmospheric Measurement Techniques, show the ability of the wind-profiling radars to measure the entire range of dissipation rates observed by the sonic anemometers. Comparisons between instruments showed accurate daily cycles of growth and decay of the turbulent PBL using the dissipation rates.

Authors of Improved Observations of Turbulence Dissipation Rates from Wind Profiling Radars are Katherine McCaffrey, Laura Bianco, and James Wilczak of the ESRL Physical Sciences Division.