Solar wind Alfvén waves: a source of pulsed ionospheric convection and atmospheric gravity waves

Abstract

Abstract.A case study of medium-scale travelling ionospheric disturbances (TIDs) that are correlated with solar wind Alfvén waves is presented. The HF radar groundscatter signatures of TIDs caused by atmospheric gravity waves with periods of 20-40 min are traced to a source at high latitudes, namely pulsed ionospheric flows (PIFs) due to bursts in the convection electric field and/or the associated ionospheric current fluctuations inferred from ground magnetic field perturbations. The significance of PIFs and TIDs in the context of solar-terrestrial interaction is that Alfvénic fluctuations of the interplanetary magnetic field (IMF) observed in the solar wind plasma streaming from a coronal hole correlate with PIFs and TIDs. The link between the solar wind Alfvén waves and TIDs is corroborated by the ground magnetic field signatures of ionospheric current fluctuations that are associated with the IMF-B y oscillations and TIDs. The observed PIFs and the associated negative-topositive deflections of the ground magnetic field X component are interpreted as ionospheric signatures of magnetic reconnection pulsed by solar wind Alfvén waves at the dayside magnetopause. Although the clarity of the radar lineof-sight velocity data may have been affected by anomalous HF propagation due to intervening TIDs, the application of a pure state filtering technique to analyze the radar data time series reveals a one-to-one correspondence between PIFs, TIDs and solar wind Alfvén waves. The spectra of solar wind and ground magnetic field perturbations are similar to those of PIFs and TIDs. The ground-scatter signatures indicate TID wavelengths, phase velocities and travel times that are consistent with ray tracing, which shows a subset of possible gravity wave group paths that reach the F region from a source in the E region after the wave energy first travel downward to the upper mesosphere where the waves are reflected upward. The observed one-to-one correspondence between the convection electric field bursts and TIDs is consistent with the modeling results for large-scale TIDs by Millward et al. (1993a,b). The correlation with solar wind Alfvén wavesCorrespondence to: P. Prikryl (paul.prikryl@crc.ca) points to very direct coupling of energy in the solar wind into the subauroral atmosphere.

Polar Ion Temperature Variations During the 22 January 2012 Magnetic Storm

“…These observations demonstrate the role of solar wind (i.e., P dyn ) enhancing T i and upwelling within these FCs. In good agreement with the study of Prikryl et al (), these synchronized increases demonstrate that the episodic P dyn increases, characteristic of Alfven waves, triggered pulsed ionospheric flows appearing as flow channels, and generated a T i peak and an upwelling within each flow channel.…”

Structure, dynamics, and seasonal variability of the Mars‐solar wind interaction: MAVEN Solar Wind Ion Analyzer in‐flight performance and science results

“…We find some observable variation during the MAVEN mission of the normalized cross helicity of low‐frequency fluctuations in solar wind magnetic field and velocity, which may result from a combination of heliocentric and solar cycle effects. If the analogy with the terrestrial system holds, these waves may affect the Martian magnetosphere and possibly even the thermosphere [ Prikryl et al ., ].…”

“…This solar wind Alfvénic turbulence may have implications for the Martian system. At the Earth, solar wind Alfvén waves can affect both the ionosphere and the neutral thermosphere [ Prikryl et al ., ]. Similarly, wave energy may propagate from the solar wind into the Martian magnetosphere, potentially providing an energy source to heat ionospheric particles to escape velocity or beyond [ Ergun et al ., ].…”

Electromagnetic energy deposition rate in the polar upper thermosphere derived from the EISCAT Svalbard radar and CUTLASS Finland radar observations

“…The present electromagnetic energy deposition rate also suggests the existence of the strong heat source in the dayside polar cap/cusp region of the upper thermosphere in association with the dayside magnetospheric phenomena of reconnections and flux transfer events. This heat source/energy input can be a possible source for generating disturbances in the thermosphere/ionosphere as well as TIDs originated from the Alvénic IMF-B y oscillations as shown by Prikryl et al (2005).…”

“…The polar patches, the pulsed ionospheric flows, and the poleward-moving radar auroral forms are well-known phenomena (e.g., Basu and Valladares, 1999;Provan et al, 1999;Wild et al, 2001, and references therein). In addition, traveling ionospheric disturbances (TIDs) caused by various forcings have been frequently observed in the polar cap region (e.g., Macdougall et al,2001;Prikryl et al, 2005). These ionospheric and auroral phenomena indicate the presence of various energy inputs into the dayside polar cap/cusp region and heating processes for not only plasmas in the ionosphere but also neutrals in the thermosphere.…”