Alfvén waves in the auroral region, their Poynting flux, and reflection coefficient as estimated from Swarm observations
Abstract
The European Space Agency's Swarm constellation can measure electric field, magnetic field, and plasma density on board multiple satellites at altitudes of about 500 km. Based on the data set at high latitudes, we estimate Poynting flux and ionospheric reflection coefficients of Alfvén waves with scale sizes of about 10–100 km. The reflection coefficients are generally higher surrounding the cusp and auroral regions than in the polar cap and higher in the summer than in the winter hemisphere. In the summer (winter) hemisphere the reflection coefficients generally peak on the dayside (nightside). Distributions of the reflection coefficients are not controlled by those of in situ plasma density. Poynting flux of the Alfvén waves maximizes surrounding the cusp and near‐midnight auroral region with magnitudes approaching 1 mW/m2, which are consistent with previous magnetospheric observations. The observed Poynting flux is downward on average for both hemispheres, and the magnitudes do not exhibit clear hemispheric asymmetry.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Feb 01, 2017
- Source ID
- 10.1002/2016ja023527
Entities
People
- D. J. Knudsen
- H. Lühr
- J. K. Burchill
- Jaeheung Park
- Young-Sil Kwak
Organizations
- Air Force Research Laboratory
- Korea Astronomy and Space Science Institute
- Korea University of Science and Technology
- University of Calgary