Details

Autor(en) / Beteiligte

• Rodríguez‐Zuluaga, J.
• Stolle, C.
• Yamazaki, Y.
• Lühr, H.
• Park, J.
• Scherliess, L.
• Chau, J. L.

Titel

On the Balance Between Plasma and Magnetic Pressure Across Equatorial Plasma Depletions

Ist Teil von

• Journal of geophysical research. Space physics, 2019-07, Vol.124 (7), p.5936-5944

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2019

Quelle

Wiley Online Library

Beschreibungen/Notizen

• In magnetized plasmas such as the ionosphere, electric currents develop in regions of strong density gradients to balance the resulting plasma pressure gradients. These currents, usually known as diamagnetic currents decrease the magnetic pressure where the plasma pressure increases, and vice versa. In the low‐latitude ionosphere, equatorial plasma depletions (EPDs) are well known for their steep plasma density gradients and adverse effect on radio wave propagation. In this paper, we use continuous measurements of the magnetic field and electron density from the European Space Agency's Swarm constellation mission to assess the balance between plasma and magnetic pressure across large‐scale EPDs. The analysis is based on the magnetic fluctuations related to diamagnetic currents flowing at the edges of EPDs. This study shows that most of the EPDs detected by Swarm present a decrease of the plasma pressure relative to the ambient plasma. However, EPDs with high plasma pressure are also identified mainly in the vicinity of the South Atlantic magnetic anomaly. From the electron density measurements, we deduce that such an increase in plasma pressure within EPDs might be possible by temperatures inside the EPD as high as twice the temperature of the ambient plasma. Due to the distinct location of the high‐pressure EPDs, we suggest that a possible heating mechanism might be due to precipitation of particle from the radiation belts. This finding corresponds to the first observational evidence of plasma pressure enhancements in regions of depleted plasma density in the ionosphere. Key Points First observational evidence of high plasma pressure in depleted density regions in the ionosphere High‐pressure plasma depletions are suggested to exhibit temperatures at least twice the background Particle precipitation is a likely heating source due to the longitudinal distribution of the events