Fine structure of the low‐latitude mesospheric turbulence

Abstract

[1] Rocket-borne measurements of electron density were conducted from Sriharikota (13.7°N, 80.2°E) to study the fine structure of low-latitude mesospheric neutral turbulence. Spectra of electron density fluctuations were obtained using the continuous wavelet transform (CWT), and the turbulence parameters were estimated. The present study shows that turbulence is not present continuously in the mesosphere but exists in layers of different thicknesses varying from 100 m to 3 km, interspersed by regions of stability. The most important results are the following: (1) Identification of thin layers of turbulence with 100-200 m of thickness over low latitudes. These thin layers are found to lie on the edges of the thick layers of turbulence. (2) Sharp gradients in turbulence parameters at the edge regions are detected from experimental observations for the first time. This was seen earlier in simulation studies only. (3) Satellite-observed temperatures show enhanced gravity wave activity, and it is suggested that deep convections over the continental landmass in the lower atmosphere are the major source of these gravity waves responsible for generation of turbulence.

First Na lidar measurements of turbulence heat flux, thermal diffusivity, and energy dissipation rate in the mesopause region

“…The k H profile shown in Figure b also exhibits a general decrease with increasing altitude, from 52 m 2 s −1 at 85 km to 10 m 2 s −1 at 100 km, with a local maximum of 71 m 2 s −1 at 93 km. These measured k H values are generally consistent with the k z z values measured by other techniques in other latitudes [e.g., Lübken , ; Das et al , ; Bishop et al , ] and larger than the k z z values used in WACCM (Whole Atmosphere Community Climate Model) which has a maximum of about 20 m 2 s −1 [ Smith , , Figure 7]. ϵ was calculated based on equation and is shown in Figure c.…”

Spectral characteristics and scatter cross-section of low latitude mesospheric echoes measured by the Indian MST radar at Gadanki

“…If interpreted as turbulent echoes, they correspond to 20-200 mW kg −1 turbulent energy dissipation rates. Chandra et al (2008) and Uma Das et al (2009) reported energy dissipation rates of 1-100 mW kg −1 for the same altitude range, which were derived from the rocket measurements from Sriharikota located about 100 east of Gadanki. The LLME spectral widths for our three cases are close to those (2-3 m s −1 ) measured by Chandra et al (2008) with the same radar in July 2004.…”

Multi-scale dynamics of glow discharge plasma through wavelets: Self-similar behavior to neutral turbulence and dissipation

“…The Heisenberg model exhibits these power laws, where a smooth transition takes place between them. We expect the possibility of neutral turbulence and dissipation in our system, which is revealed with the Heisenberg fit of different exponents shown in figure 10 [26]. The slopes obtained are -5/3 and -7, which give the turbulent and dissipative nature of the system respectively.…”