Atmosphere/Ionosphere/Magnetosphere Couplings

At LPC2E, research on the coupling between the atmosphere, the ionosphere and the magnetosphere is based on 3 key space missions: Cluster, DEMETER and TARANIS. The team has instrument responsibilities for each of these missions (WHISPER on Cluster, IMSC on DEMETER, IMM, IME-HF and MEXIC on TARANIS).

Atmospheric Electricity  Atmosphere/Ionosphere coupling

For this theme, our research work is divided into three main classes:

Theoretical research on the physics of Transient Luminous Events (TLEs).

• Theoretical research on the physics of Terrestrial Gamma ray Flashes (TGFs).

Experimental research, based on DEMETER data, to study phenomena associated with thunderstorms such as parent flashes of TLEs, electron precipitation induced by flashes and high energy electron beams.

Among the many results obtained are: the quantification of the role of ionospheric conditions in the production, morphology and polarity of sprite atmospheric discharges; the prediction of light emissions associated with the acceleration of relativistic electrons producing TGFs; the discovery of a storm-induced escape from the upper part of the Earth’s atmosphere.

Atmospheric electricity activity is also a topic of interest for the LPC2E team working on the physics and chemistry of the atmosphere. Accordingly, there are joint actions on this theme: a stratospheric balloon project for the study of storms, research work on modelling the impact of TLEs on the physics and chemistry of the atmosphere above thunderstorms.

Our integration into the scientific community of Atmospheric Electricity leads us to participate in various national and international programs:

Collaborative research programme of the European Science Foundation TEA-IS [Thunderstorm Effects on the Atmosphere-Ionosphere System, 2011-2016].

LAboratory of MUlti-Satellite Studies of Atmosphere-Ionosphere Electric Coupling of the Franco-Russian GdRI Helio-Plasmas 2015-2018].

SOLID Project [Space-basedOptical LIghtning Detection, LA Toulouse].

Ionosphere/Magnetic/Solar Wind Coupling

The research conducted at LPC2E on the coupling between the Ionosphere, the Magnetosphere and the solar wind is organized around data from the Cluster and DEMETER space missions.

Use of DEMETER data: DEMETER is the first space mission for which LPC2E got the mission responsibility (both scientific payload and data centre). The operational phase of the mission lasted 6 years up to the end of 2010 but the data exploitation is stillvery active. It has revealed a very wide variety of waves in the ionosphere at various frequencies not only in the auroral zones but also at medium latitude and in the equatorial region. Although the question of the causal link between seismic activity and ionospheric disturbances is still partly open, DEMETER is an undeniable scientific and technical success, which has been based on numerous collaborations, notably via the FP7 SEMEP project (Search for Electro-Magnetic Earthquake Precursors combining satellite and ground-based facilities, 2010-2012).

Use of Cluster data: the scientific interest for Cluster data is still very high and accordingly the operational phase has now be extended beyond 2020. Within the team, studies on the coupling between Ionosphere and Magnetosphere have yielded important scientific results. Within the framework of CNES/ONERA – CEA contracts, we have generated a database consisting of low-frequency wave measurements in the internal magnetosphere (Cluster, THEMIS, DE1, Polar, CRRES and Akebono data). The analysis of this database has highlighted the importance of oblique whistling waves for the processes of particle diffusion, loss and acceleration (see Figure 1).

Figure 1. Energy distribution of whistler waves in radiation belt [Artemyev et al., 2015].
It is now clear that these waves play a decisive role in the formation and dynamics of the external radiation belt. This work has been the subject of a thesis and 25 articles. The skills acquired in this field have earned us the responsibility of a work package in the H2020 PROGRESS project (Prediction of Geospace Radiation Environment and solar wind parameters, 2014-2016).

Concerning the coupling between the Earth’s magnetosphere and the Solar wind, the analysis of the Cluster data performed during the crossing of the terrestrial shock allowed us to show that the structure of the shock front is similar to that of a non-linear whistler wave. This explains all the observations (generation of “precursor” waves before the shock, distribution of the characteristic scales of magnetic and electric field fluctuations, characteristic scale of the change in electronic temperature during the front crossing). Under the same thematic area, magnetic reconnection at magnetopause has been studied by 3D kinetic numerical simulations and MMS data. In recent years, the study and modelling of the beam-plasma interaction and Langmuir wave production in the solar wind has become a particularly active and productive field of research at LPC2E.

The operation of the four WHISPER instruments on Cluster continues with studies dedicated to the filling and emptying of the plasmasphere. From the WHISPER data an absolute measure of the electron density is derived which is a key plasma quantity highly requested and widely used by the Cluster community.

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