Whistler-mode waves inside flux pileup region: Structured or unstructured?
2014 (English)In: Journal of Geophysical Research - Space Physics, ISSN 2169-9380, E-ISSN 2169-9402, Vol. 119, no 11, 9089-9100 p.Article in journal (Refereed) Published
During reconnection, a flux pileup region (FPR) is formed behind a dipolarization front in an outflow jet. Inside the FPR, the magnetic field magnitude and Bz component increase and the whistler-mode waves are observed frequently. As the FPR convects toward the Earth during substorms, it is obstructed by the dipolar geomagnetic field to form a near-Earth FPR. Unlike the structureless emissions inside the tail FPR, we find that the whistler-mode waves inside the near-Earth FPR can exhibit a discrete structure similar to chorus. Both upper band and lower band chorus are observed, with the upper band having a larger propagation angle (and smaller wave amplitude) than the lower band. Most chorus elements we observed are rising-tone type, but some are falling-tone type. We notice that the rising-tone chorus can evolve into falling-tone chorus within <3s. One of the factors that may explain why the waves are unstructured inside the tail FPR but become discrete inside the near-Earth FPR is the spatial inhomogeneity of magnetic field: we find that such inhomogeneity is small inside the near-Earth FPR but large inside the tail FPR.
Place, publisher, year, edition, pages
2014. Vol. 119, no 11, 9089-9100 p.
flux pileup region, dipolarization front, whistler, chorus, structure, magnetic field inhomogeneity
IdentifiersURN: urn:nbn:se:uu:diva-243072DOI: 10.1002/2014JA020204ISI: 000346792100026OAI: oai:DiVA.org:uu-243072DiVA: diva2:787201