Eddy turbulence parameters inferred from radar observations at Jicamarca

Abstract

Abstract. Significant electron density striations, neutral temperatures 27 K above nominal, and intense wind shear were observed in the E-region ionosphere over the Jicamarca Radio Observatory during an unusual event on 26 July 2005 (Hysell et al., 2007). In this paper, these results are used to estimate eddy turbulence parameters and their effects. Models for the thermal balance in the mesosphere/lower thermosphere and the charged particle density in the E region are developed here. The thermal balance model includes eddy conduction and viscous dissipation of turbulent energy as well as cooling by infrared radiation. The production and recombination of ions and electrons in the E region, together with the production and transport of nitric oxide, are included in the plasma density model. Good agreement between the model results and the experimental data is obtained for an eddy diffusion coefficient of about 1×10 3 m 2 /s at its peak, which occurs at an altitude of 107 km. This eddy turbulence results in a local maximum of the temperature in the upper mesosphere/lower thermosphere and could correspond either to an unusually high mesopause or to a double mesosphere. Although complicated by plasma dynamic effects and ongoing controversy, our interpretation of Farley-Buneman wave phase velocity (Hysell et al., 2007) is consistent with a low Brunt-Väisälä frequency in the region of interest. Nitric oxide transport due to eddy diffusion from the lower thermosphere to the mesosphere causes electron density changes in the E region whereas NO density modulation due to irregularities in the eddy diffusion coefficient creates variability in the electron density.

Combined radar observations of equatorial electrojet irregularities at Jicamarca

“…Turbulence can modify the local composition and the local photochemistry and ionization with it. A detailed discussion of the possible role of neutral turbulence in the event described here can be found in Vlasov et al (2007). The main ideas are outlined below.…”

AMISR‐14: Observations of equatorial spread F

“…In 2004/2005, a seven‐panel AMISR prototype was temporarily deployed at the Jicamarca Radio Observatory (JRO) for tests and observations of low‐latitude ionospheric irregularities. Observations of equatorial electrojet were possible [ Vlasov et al , ; Hysell et al , ; Kelley et al , ; Kagan et al , ], but the system was not sensitive enough for adequate measurements of equatorial spread F (ESF).…”

On the mechanism of seasonal and solar cycleNmF2variations: A quantitative estimate of the main parameters contribution using incoherent scatter radar observations

“…This parameter is very uncertain at present. According to Vlasov et al [2007] and Ginzburg et al [1987], the peak of eddy diffusion is located at 107-110 km with the maximum value of K edd = (7-10) × 10 6 cm 2 s −1 . Therefore the peak of [O] layer at ≈97 km is formed in the area of eddy diffusion but below the maximum of eddy turbulence.…”