Properties of spectra of atmospheric turbulence at 100 metres

Abstract

SUMhWRYThe properties of spectra of vertical and horizontal turbulence and of their cross-spectra, at elevations near 100 m, are summarized ; a few spectra from lower levels are considered. The following tentative conclusions are drawn :At frequencies of the order of 100 c/hr and above, the spectral intensity is proportional to the square of the mean wind speed and essentially independent of the radiation intensity. At lower frequencies, the ratio of spectral intensity to the square of the wind speed increases with increasing incoming radiation.2. The intensity-ratio of the co-spectrum of vertical and horizontal velocity to the spectrum of vertical velocity increases with increasing wind shear. It also decreases with increasing frequency, n, approximately as n-'. 3. At low frequencies, the spectral intensity of the horizontal velocity components is generally much larger than that of the vertical velocity. At high frequencies, the spectral intensities of all velocity components are of the same order of magnitude. At low frequencies, the ratio of vertical to horizontal spectral density increases with increasing radiation.The quadrature spectra at a given frequency tend to be negative with large radiation, positive with little radiation. This indicates that eddies are low and wide with little radiation, and tall with much radiation.The frequency at the maximum of the vertical velocity spectrum decreases with increasing height and increasing radiation intensity.The ratio of turbulent to mean energy is somewhat larger for air with over-land trajectories than for air with oceanic trajectories. 1. 4. 5.6.

Data-driven decomposition of the streamwise turbulence kinetic energy in boundary layers. Part 1. Energy spectra

“…In relevance to our work, it is worth noting that the LCS has previously been applied to meteorological ASL-type data for wind engineering purposes and investigations of atmospheric stability/stratification (e.g. Panofsky & McCormick 1954;Davenport 1961;Krug et al 2018), as well as to laboratory TBL data for investigating the local isotropy of the turbulence (e.g. Saddoughi & Veeravalli 1994).…”

Parameterization of wind evolution using lidar

“…Based on their theoretical discussion, the decay parameter for longitudinal separation is supposed to be a function of turbulence intensity, which is a function of roughness length and the Richardson number (a measure of atmospheric stability) (Lumley and Panofsky, 1964). Extending the study, Panofsky and Mizuno (1975) found that the relationships between coherence and other parameters were rather complicated. A model for the decay parameter was proposed based on its empirical properties.…”

“…Figure 3 shows a misalignment between wind direction and lidar measurement direction, at an angle α. The coherence of the line-ofsight wind speed is γ 2 12 , which is no longer the longitudinal coherence but the horizontal coherence as defined by Panofsky and Mizuno (1975). γ 2 13 and γ 2 23 are the longitudinal and lateral coherence, respectively.…”

Guide to Local Diffusion of Air Pollutants

“…The value of x which is a solution of Equation (19) is naturally smaller than the value obtained from Equation (16). Figure 38 furnishes the solution for Equation (19) in terms of the solution of Equation (16) Another possible concern is the fact that some materials, such as h•ydrochloric acid (HCI) and fluorine compounds, are hygroscopic and could be diluted by the condensation of water vapor.…”