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Astrophysics and Astronomy

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Selected Works

2018

Turbulence

Articles 1 - 3 of 3

Full-Text Articles in Physical Sciences and Mathematics

The Link Between Shocks, Turbulence And Magnetic Reconnection In Collisionless Plasmas, H. Karimabadi, V. Roytershteyn, H. X. Vu, Y. Omelchenko, J. Scudder, W. Daughton, A. Dimmock, Katariina (Heidi) Nykyri, Et Al. Feb 2018

The Link Between Shocks, Turbulence And Magnetic Reconnection In Collisionless Plasmas, H. Karimabadi, V. Roytershteyn, H. X. Vu, Y. Omelchenko, J. Scudder, W. Daughton, A. Dimmock, Katariina (Heidi) Nykyri, Et Al.

Katariina Nykyri

Global hybrid (electron fluid, kinetic ions) and fully kinetic simulations of the magnetosphere have been used to show surprising interconnection between shocks, turbulence and magnetic reconnection. In particular collisionless shocks with their reflected ions that can get upstream before retransmission can generate previously unforeseen phenomena in the post shocked flows: (i) formation of reconnecting current sheets and magnetic islands with sizes up to tens of ion inertial length. (ii) Generation of large scale low frequency electromagnetic waves that are compressed and amplified as they cross the shock. These 'wavefronts' maintain their integrity for tens of ion cyclotron times but eventually …


A Statistical Study Of The Dawn-Dusk Asymmetry Of Ion Temperature Anistrophy And Mirror Mode Occurrence In The Terrestrial Dayside Magnetosheath Using Themis Data, A. P. Dimmock, A. Osmane, T. I. Pulkkinen, K. Nykyri Jan 2018

A Statistical Study Of The Dawn-Dusk Asymmetry Of Ion Temperature Anistrophy And Mirror Mode Occurrence In The Terrestrial Dayside Magnetosheath Using Themis Data, A. P. Dimmock, A. Osmane, T. I. Pulkkinen, K. Nykyri

Katariina Nykyri

We present a statistical study of ion temperature anisotropy and mirror mode activity in the Earth's dayside magnetosheath using 6 years of Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations focusing on the quantification of dawn-dusk asymmetry as a function of upstream conditions and distance from the magnetopause. Our statistical data show a pronounced dusk favored asymmetry of T⊥/T∥ which drives a similar asymmetry of mirror mode activity. T⊥/T∥ decreases with increasing solar wind Alfvén Mach number, whereas mirror mode occurrence increases. In both cases, the relative asymmetry between the dawn and dusk flanks decrease with increasing …


A Statistical Study Of Magnetic Field Fluctuations In The Dayside Magnetosheath And Their Dependence On Upstream Solar Wind Conditions, A. P. Dimmock, K. Nykyri, T. I. Pulkkinen Jan 2018

A Statistical Study Of Magnetic Field Fluctuations In The Dayside Magnetosheath And Their Dependence On Upstream Solar Wind Conditions, A. P. Dimmock, K. Nykyri, T. I. Pulkkinen

Katariina Nykyri

The magnetosheath functions as a natural interface connecting the interplanetary and magnetospheric plasma. Since the magnetosheath houses the shocked solar wind, it is populated with abundant magnetic field turbulence which are generated both locally and externally. Although the steady state magnetosheath is to date relatively well understood, the same cannot be said of transient magnetic perturbations due to their kinetic nature and often complex and numerous generation mechanisms. The current manuscript presents a statistical study of magnetic field fluctuations in the dayside magnetosheath as a function of upstream solar wind conditions. We concentrate on the ambient higher-frequency fluctuations in the …