Incompressive Energy Transfer in the Earth’s Magnetosheath: Magnetospheric Multiscale Observations
Russell, C. T.; Torbert, R. B.; Matthaeus, W. H.; Chhiber, R.; Paterson, W. R.; Strangeway, R. J.; Burch, J. L.; Moore, T. E.; Bandyopadhyay, Riddhi; Giles, B. L.; Shay, M. A.; Gershman, D. J.; Pollock, C. J.; Chasapis, A.; Dorelli, J.; Parashar, T. N.; Maruca, B. A.
United States
Abstract
Using observational data from the Magnetospheric Multiscale mission in the Earth’s magnetosheath, we estimate the energy cascade rate at three ranges of length scale, employing a single data interval, using different techniques within the framework of incompressible magnetohydrodynamic (MHD) turbulence. At the energy-containing scale, the energy budget is controlled by the von Kármán decay law. Inertial range cascade is estimated by fitting a linear scaling to the mixed third-order structure function. Finally, we use a multi-spacecraft technique to estimate the Kolmogorov-Yaglom-like cascade rate in the kinetic range, well below the ion inertial length scale, where we expect a reduction due to involvement of other channels of transfer. The computed inertial range cascade rate is almost equal to the von Kármán-MHD law at the energy-containing scale, while the incompressive cascade rate evaluated at the kinetic scale is somewhat lower, as anticipated in theory. In agreement with a recent study, we find that the incompressive cascade rate in the Earth’s magnetosheath is about 1000 times larger than the cascade rate in the pristine solar wind.