Improved observations of turbulence dissipation rates from wind profiling radars

Abstract

Abstract. Observations of turbulence dissipation rates in the planetary boundary layer are crucial for validation of parameterizations in numerical weather prediction models. However, because dissipation rates are difficult to obtain, they are infrequently measured through the depth of the boundary layer. For this reason, demonstrating the ability of commonly used wind profiling radars (WPRs) to estimate this quantity would be greatly beneficial. During the XPIA field campaign at the Boulder Atmospheric Observatory, two WPRs operated in an optimized configuration, using high spectral resolution for increased accuracy of Doppler spectral width, specifically chosen to estimate turbulence from a vertically pointing beam. Multiple post-processing techniques, including different numbers of spectral averages and peak processing algorithms for calculating spectral moments, were evaluated to determine the most accurate procedures for estimating turbulence dissipation rates using the information contained in the Doppler spectral width, using sonic anemometers mounted on a 300 m tower for validation. The optimal settings were determined, producing a low bias, which was later corrected. Resulting estimations of turbulence dissipation rates correlated well (R 2 = 0.54 and 0.41) with the sonic anemometers, and profiles up to 2 km from the 449 MHz WPR and 1 km from the 915 MHz WPR were observed.

Estimation of turbulence dissipation rate and its variability from sonic anemometer and wind Doppler lidar during the XPIA field campaign

“…Wind profiling radars have also been used to estimate (McCaffrey et al, 2017a), with the spectral width method. Wind Doppler lidars can also provide an extensive network of measurements of at different locations and at heights which are not accessible to traditional mast measurements.…”

Characteristics of Water Vapor Turbulence Profiles in Convective Boundary Layers During the Dry and Wet Seasons Over Darwin

“…In order to evaluate and improve turbulence parameterizations in weather and climate models, high resolution and accurate measurements of profiles of turbulence throughout the CBL are needed. Vertical profiles of turbulent motion have been studied using various types of instruments including in situ aircraft measurement (Albrecht et al, ; Andrews et al, ; Lenschow et al, ; Stull et al, ; Vogelmann et al, ; Williams & Hacker, ), radiosonde soundings (Cooper & Eichinger, ; Frehlich & Sharman, ; Garcia‐Carreras et al, ; Neves & Fisch, ; Wilson et al, ), wind profiling radars (Angevine et al, ; Cohn, ; Dehghan et al, ; Ecklund et al, ; McCaffrey, Bianco, & Wilczak, ; McCaffrey, Bianco, Johnston, et al, ; Strauch et al, ; White et al, ), and tall towers (Businger et al, ; Kaimal & Gaynor, ; van Ulden & Wieringa, ; Wilczak & Tillman, ). Even though tall towers can take measurements continuously for long periods of time, their vertical coverage is limited to the lowest portion of the CBL due to their limited height.…”

Improved boundary layer height measurement using a fuzzy logic method: Diurnal and seasonal variabilities of the convective boundary layer over a tropical station

“…Due to the convective motion, in fact, the variance of the vertical velocity is larger inside the boundary layer where many up‐ and down‐drafts are present, decreasing at the top, giving an indication on the boundary layer height. The Doppler spectral width of the vertical velocity is also an indicator of the presence of turbulence [ McCaffrey et al ., ], which is more evident inside the convective boundary layer, decreasing at the top, again helping at inferring where the top of the boundary layer is existed. This FL method (here onward referred to as “original FL method,” OFL) has been effectively applied over different sites of California's central valley [ Bianco et al ., ].…”