Relation of internal gravity wave anisotropy with neutral wind characteristics in the upper atmosphere

Abstract

This paper studies the interaction of internal gravity waves (IGW) with neutral wind using the statistics of traveling ionospheric disturbances (TID) from the Radio Physical Complex of the Institute of Solar‐Terrestrial Physics. The complex includes the Irkutsk Incoherent Scatter Radar (IISR), Irkutsk Ionosonde (DPS‐4), and Ekaterinburg HF Radar (EKB). The aim of this study is to give a common explanation for the TID azimuth distributions obtained with the IISR‐ionosonde and HF coherent radar and show that the measurements of 3‐D TID characteristics put into the hands of researchers an important tool to study neutral wind in the thermosphere. The distinctive features of this study are the following: (1) using different TID statistics from independent tools and, correspondingly, independent methods for determining TID characteristics; (2) using the 3‐D TID characteristics for testing the wind‐filtering hypothesis, which allows us to separate the IGW‐induced TIDs from TIDs of other nature and identify three TID types depending on their elevation angles; and (3) using the local time‐azimuth distribution of the TID number for testing the wind‐filtering hypothesis. This study allowed us to conclude that the observed IGW azimuth anisotropy can be mainly explained by the wind filtration mechanism with considering winds at 90–250 km heights. Using the 3‐D IGW characteristics allows us to estimate neutral wind parameters. Proposed methods are applicable for any tool which can obtain TID 3‐D characteristics. Using the proposed methods will enable us to organize a worldwide campaign to improve the existing neutral wind models.

Method for Determining Neutral Wind Velocity Vectors Using Measurements of Internal Gravity Wave Group and Phase Velocities

“…Diurnal and seasonal variations in meridional wind, which were obtained under the assumption of a linear interaction of IGWs with wind by Refs. [6,7], were found to be in satisfactory agreement with the wind variations obtained by the independent method in Ref. [19], which did not use any assumptions about the interaction of IGWs and wind.…”

“…A strong anisotropy of TID azimuths was also shown. In addition, the detected anisotropy was able to be explained by the neutral wind integral effect in the atmosphere on the path of wave propagation [7]. The probability of TID detection is higher for IGWs propagating against a neutral wind acting at the observation height.…”

“…Further development of the technique for TID propagation parameter measurements [5][6][7] has allowed for the automatic processing of long series electron density profiles and the acquisition of representative statistics of parameters related to wave disturbance propagation in the ionosphere (including TID phase velocity and wave vectors). The automatic method of TID detection is based on the assumption that the dominant harmonic-containing most of the energy-can be isolated from the entire spectrum of a wave disturbance.…”

“…The linear approximation for IGW propagation in the upper atmosphere is widely used both in theoretical [10][11][12][13] and experimental [14][15][16][17][18] studies. A study which investigated the interaction of IGWs with neutral wind [7], which was based on representative statistics of traveling ionospheric disturbances, showed that the observed anisotropy of the IGW azimuths could be successfully explained in the framework of the linear interaction of IGW with wind. Diurnal and seasonal variations in meridional wind, which were obtained under the assumption of a linear interaction of IGWs with wind by Refs.…”

Investigation of Nighttime MSTIDS Observed by Optical Thermosphere Imagers at Low Latitudes: Morphology, Propagation Direction, and Wind Filtering

“…These comparisons suggest that the sources of periodic MSTIDs observed in the current study and Paulino et al (, ) are similar, but the location of the source is different. Another explanation for these differences in MSTIDs propagation direction may be related to wind filtering process (e.g., American sector: Paulino et al, , and Asian sector: Medvedev et al, ) and location of the sources (e.g., American sector: Figueiredo et al, and Asian sector: Fukushima et al, ) which, a priori, are different between the American and Asian sectors. Furthermore, Miyoshi et al () show that longitudinal variability of upward gravity waves energy can affect the longitudinal variability in the ionosphere.…”