Bibliography

Planetary Waves and Their Impact on the Mesosphere, Thermosphere, and Ionosphere

Large-scale planetary waves (also known as Rossby waves), such as the Quasi-two day wave, 5 day wave and Kelvin wave, play crucial roles in coupling the lower and middle atmosphere to the mesosphere, thermosphere and ionosphere. Upward propagation and global structure of planetary waves in the stratosphere and mesosphere are affected by the zonal mean winds. Baroclinic or barotropic instability of the background mesospheric winds can amplify the waves en route to the upper atmosphere. Fast traveling planetary waves with deep vertical wavelengths, such as Kelvin waves, are able to reach the upper thermosphere and modulate air density and winds. More commonly, planetary waves influence the thermosphere-ionosphere system by modulating the E-region and F-region dynamo electric fields. Dissipation of planetary waves in the lower thermosphere modifies the background winds, and induces extra meridional circulation, consequently altering thermospheric constituents, such as O/N2, and ionospheric electron densities. Interactions between planetary waves and tides not only provide an additional source of traveling planetary waves in the mesosphere, but are key sources of variability in E-region dynamo electric fields and plasma drift.

Yue, Jia; Lieberman, Ruth; Chang, Loren;

Published by:       Published on:

YEAR: 2021     DOI: 10.1002/9781119815631.ch10

barotropic instability; E-region dynamo electric fields; F-region dynamo electric fields; Kelvin waves; mesosphere; planetary waves; plasma drift; thermosphere-ionosphere system

An empirical model of the drift velocity of equatorial plasma depletions

The Far-Ultraviolet Imager on the IMAGE spacecraft (IMAGE-FUV) has been used to observe O⁺plasma depletions in the post-sunset equatorial ionosphere. Small-scale density irregularities associated with such depletions are believed to adversely affect trans-ionospheric radio signals such as GPS. Prediction of the motion of these plasma depletions is a necessary component of the ability to forecast the occurrence of such radio signal interference. An automated method has recently been developed to identify and track the position and zonal drift velocity of these depletions. Here we use this method to create a large database of the zonal drift velocities of these depletions. We present an empirical model based on these observations that describes the observed drift velocities as a function of both local time and magnetic latitude, which is essential to represent their behavior. A comparison of the observed drift velocities with zonal winds from both an empirical model (Horizontal Wind Model; HWM07) and a first-principles model (the TIEGCM) reveals that the plasma depletions\textquoteright drift velocities have a latitudinal gradient that cannot be explained solely by the F-region dynamo in the post-sunset period, at least by these climatological models. This suggests that these plasma depletions may not simply drift with the background F-region plasma. It has previously been suggested that vertical polarization electric fields associated with the plasma depletions are responsible for their zonal drifts exceeding the background flow, which may explain the previously-observed discrepancy in the drift velocities and the discrepancy in their gradients reported here.

England, S.; Immel, T.;

Published by: Journal of Geophysical Research: Space Physics      Published on: 12/2012

YEAR: 2012     DOI: 10.1029/2012JA018091

Ionosphere; plasma drift; scintillation