Three-dimensional electron density along the WSA and MSNA latitudes probed by FORMOSAT-3/COSMIC

Abstract

In this paper, we employ electron density profiles derived by the GPS radio occultation experiment aboard the FORMOSAT-3/COSMIC (F3/C) satellites to examine the electron density on geographic latitudes of 40°to 80°in the Southern hemisphere and 30°to 60°in the Northern hemisphere at various global fixed local times from February 2009 to January 2010. The results reveal that an eastward shift of a single-peak plasma density feature occurs along the Weddell Sea Anomaly (WSA) latitudes, while a double-peak plasma density feature appears along the northern Mid-latitude Summer Nighttime Anomaly (MSNA) latitudes. A cross-comparison between three-dimensional F3/C electron density and HWM93 simulation confirms that the magnetic meridional effect and vertical effect caused by neutral winds exhibit the eastward shifts. Furthermore, we find that the eastward shift of the peaks when viewed as a function of local time suggests that they could be interpreted as being comprised of different tidal components with distinct zonal phase velocities in local time.

The Midlatitude Trough and the Plasmapause in the Nighttime Ionosphere Simultaneously Observed by DEMETER During 2006–2009

“…Chang et al, ; Klimenko et al, ; Lin et al, ; Liu et al, ), while in the Southern Hemisphere, those departures are over the WSA area (cf. Chang et al, ). Chang et al () reports that equatorward meridional neutral wind significantly affects the MSNA and WSA.…”

“…By contrast, if falling out of ±2 standard deviations, departures are statistically significant. Figure displays in the Northern Hemisphere that the NT N e and NT T e departures are generally small over 0°E to 90°E geomagnetic (−60°E to 30°E geographic, approximately), where is coincident with one of the MSNA (midlatitude summer nighttime anomaly) areas during 2200 LT (Chang et al, ; Lin et al, ; Liu et al, ). In the Southern Hemisphere, departures of ST N e and ST T e are small over 30°E to 60°E geomagnetic (90°E to 0°E geographic), where it is coincident with the WSA (Weddell Sea anomaly) area during 2200 LT (Chang et al, ; Liu et al, ; Lin et al, ; Liu et al, ).…”

“…Note that in the J (summer) month of the Northern Hemisphere, the electron density over the MSNA areas will anomalously enhance, which could significantly move the trough equatorward (green curve in Figure a). This implies the equatorward neutral wind to be essential (Chang et al, ). The departures of ST N e and ST T e are again small over 30° to 60° geomagnetic, where it is coincident with the WSA area.…”

The fast development of solar terrestrial sciences in Taiwan

“…From the first three-dimensional structure of ionospheric WSA, it can be realized that WSA is simpler part of a bigger ionospheric anomaly, namely, the middle latitude summer nighttime anomaly (MSNA) Chen et al 2011Chen et al , 2013. Meanwhile, the MSNA/WSA eastward movement signature have also been comprehensively studied using F3/C observations Liu et al 2015;Chang et al 2015b) and model simulations Sun et al 2015). Also, a new type of low latitude plasma structure located underneath the EIA peaks is discovered, and their corresponding physical mechanism is proposed for the first time (Lee et al 2012b;Chen et al 2014c).…”

Special issue “Coupling of the high and mid latitude ionosphere and its relation to geospace dynamics”

“…It is important to know the distribution of ionospheric plasma densities in order to understand the formation processes of the ionosphere. The characteristics of the distribution of ionospheric plasma density were studied by employing FOR-MOSAT-3/COSMIC satellite data (Chang et al 2015), GPS TEC data (Kumar et al 2015), and SuperDARN HF radar data (Oinats et al 2016a). The results of the analysis of the observation data were compared with HWM93 simulation or International Reference Ionosphere (IRI)-2012 model.…”