Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

Abstract

We present a statistical study of medium-scale traveling ionospheric disturbances (MSTIDs) using the Hokkaido East (43.53°N, 143.61°E) and Ekaterinburg (56.42°N, 58.53°E) high-frequency (HF) radar data. Radar datasets are available from 2007 to 2014 for the Hokkaido and from 2013 to 2014 for the Ekaterinburg radar. In the case of the Hokkaido East radar, we have utilized the elevation angle information to study the MSTIDs propagating at the heights of the E and F ionospheric regions separately. We have analyzed the diurnal and seasonal behavior of the following medium-scale traveling ionospheric disturbance (MSTID) parameters: propagation direction, apparent horizontal velocity and wavelength, period, and relative amplitude. The F region MSTID azimuthal patterns were observed to be quite similar by the two radars. The E region northwestward MSTIDs (from 280°to 320°) were typical of summer daytime. Comparison with the horizontal wind model (HWM07) has showed that the dominant MSTID propagation directions match the anti-wind direction well, at least during sunlight hours. We have also found that the wavelength and period tend to decrease with an increase in solar activity. On the contrary, the relative amplitude increases with an increase in solar activity. Moreover, the relative amplitude tends to increase with increasing auroral electrojet (AE) index, as do the wavelength and velocity.

Medium-scale traveling ionospheric disturbances over Taiwan observed with HF Doppler sounding

“…Recently, MSTIDs have been studied statistically in many places worldwide using various techniques (Frissell et al 2014(Frissell et al , 2016Fukushima et al 2012;Grocott et al 2013;He et al 2004;Ichihara et al 2013;Ishida et al 2008;Klausner et al 2009;Kotake and Otsuka 2007;Medvedev et al 2013;Oinats et al 2015Oinats et al , 2016Otsuka et al 2011Otsuka et al , 2013Shiokawa et al 2003Shiokawa et al , 2009. In this study, we present observations of MSTIDs' horizontal velocities over Taiwan using HF Doppler sounding.…”

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

“…[] presented a statistical study of MSTIDs using midlatitude 630 nm airglow images and reported that most of observed MSTIDs propagate southwestward during all seasons. Similar results were obtained from GPS total electron content (TEC) maps [ Kotake et al ., ; Otsuka et al ., ] and HF radar data [ Ichihara et al ., ; Oinats et al ., ]. Shiokawa et al .…”

“…Our previous studies [ Medvedev et al ., , Oinats et al ., ] considered the EKB radar and IISR‐ionosonde data separately. The aim of this study is to give a common explanation for the TID azimuth distributions obtained with the IISR‐ionosonde and EKB 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.…”

Application of the nudged elastic band method to the point-to-point radio wave ray tracing in IRI modeled ionosphere

“…Travelling ionospheric disturbances (TIDs) have a strong impact on high frequency radio communication (Gershman and Grigorev, 1968;Oinats et al, 2016). The effect of TID on the electron density, N, is modeled by the following equation: Ionosphere irregularity and nonstationarity are modeled as a beam of several travelling monochromatic waves:…”