Alfvén Mach number and IMF clock angle dependencies of sunward flow channels in the magnetosphere. Issue 7 (11th April 2013)

• Record Type: Journal Article
• Authors: Eriksson, S.; Rastätter, L.
• Is Part Of: Geophysical research letters. Volume 40:Issue 7(2013:Apr.)
• Page Start: 1257
• Page End: 1262
• Publication Date: 2013-04-11
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/grl.50307
• Languages: English
• ISSNs: 0094-8276

Abstract

<abstract abstract-type="main"> <title> <x xml:space="preserve">Abstract</x> </title> <p>[1] Interplanetary coronal mass ejections associated with strong interplanetary magnetic field (IMF) By have been shown to enhance the neutral density in low Earth orbit. The enhancement has been linked to strong downward Poynting fluxes embedded within ionospheric channels of significant sunward <bold>E</bold>x<bold>B</bold> drift (2000–3000 m/s). Here we present MHD results describing the magnetospheric counterpart of the ionospheric flow channel that Defense Meteorological Satellite Program (DMSP) encountered on 15 May 2005. It is shown that the clock angle of maximum sunward flow (θ_FC) depends on the IMF clock angle θ_FC = α * θ_IMF − 1.3° with α = (0.30, 0.38, 0.43, 0.45) at X = (4, 2, 0, −2) R_E. This is poleward of the magnetic null point region. The flow also depends on the solar wind Alfvén Mach number Vx = Vx0 − δv * M_A. The critical M_A = Vx0 / δV for Vx = 0 decreases from M_A = 3.42 (X = 4 R_E) to M_A = 2.40 (X = −2 R_E). The low M_A and θ_IMF conditions that characterized the X = 2 R_E flow and resulted in strong Poynting flux occurred for 16% of all 167 h in 1998–2008 with <italic>Dst</italic> &lt; −180 nT.</p> </abstract>