Turbulence Studies using MMS: data issues and physics
Abstract
Magnetospheric Multiscale (MMS) Mission offers measurements of magnetic field, proton and electron moments spanning a broad range of length-scales, from energy containing scales to kinetic scales. The very high time-resolution of the plasma instruments onboard MMS along with the availability of simultaneous measurements from four spacecraft, separated by sub-proton scale distances, make MMS observations an excellent case for study of multi-scale turbulence in near-Earth space plasmas. We calculate the energy transfer rate in the Earth's magnetosheath using two different methods at separate scales. A Karman-Howarth decay phenomenology gives the global energy budget at the energy containing scales. An estimation of inertial range cascade rate is made using Politano-Pouqet third-order law for MHD. We find that the estimates of the energy transfer rates at the large scales and in the inertial scales agree well with each other, providing a confirmation of the assumption of constant energy cascade across those scales. We further measure the incompressive channel of the cascade rate at kinetic scales by evaluating the classical incompressible third-order law at the kinetic scales, using a mutil-spacecraft technique. To use MMS data in the pristine solar wind some processing is required. We provide a procedure to use the measurements of FPI moments in the pristine solar wind. After processing the data, we measure the incompressive energy transfer rate in the solar wind using the third-order law, similar to the magnetosheath case. We find that the energy transfer rate in the magnetosheath is about 1000 times larger than the transfer rate in the solar wind. The higher rate of energy decay rate in the magnetosheath is consistent with the fact the plasma in the sheath is hotter than the solar wind plasma.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSH21C3294B
- Keywords:
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- 2149 MHD waves and turbulence;
- INTERPLANETARY PHYSICSDE: 4490 Turbulence;
- NONLINEAR GEOPHYSICSDE: 7509 Corona;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7863 Turbulence;
- SPACE PLASMA PHYSICS