SM13C-2508
Transport of Solar Wind Across Earth’s Bow Shock
Monday, 14 December 2015
Poster Hall (Moscone South)
George K Parks1, Ensang Lee2, Zhongwei Yang3, Ying Liu3, Suiyan Fu4, Patrick Canu5, Melvyn L Goldstein6, Iannis S Dandouras7, Henri Reme7 and Jinhy Hong8, (1)University of California Berkeley, Berkeley, CA, United States, (2)Kyung Hee University, Yongin, South Korea, (3)NSSC National Space Science Center, CAS, Beijing, China, (4)Peking University, School of Earth and Space Sciences, Beijing, China, (5)Laboratoire de Physique des Plasmas, Palaiseau, France, (6)NASA Goddard SFC, Greenbelt, MD, United States, (7)IRAP, Toulouse, France, (8)Kyung Hee University, School of Space Research, Yongin, South Korea
Abstract:
Observations have established that about 20% of the solar wind (SW) is reflected and 80% directly transmitted across Earth’s bow shock (Skopke et al, Adv. Space Sci., 15, No. 8/9, 269, 1995). The transmitted SW is not immediately thermalized and the magnetosheath plasma distribution can remain non-Maxwellian for a long time. Cluster observations have further established that most of the magnetosheath bulk flow remains super-Alfvenic except in the polar altitudes near the cusp region (Longmore et al., Anna. Geophysicae, 23, 3351–3364, 2005). We have studied SW ion distributions before and after entering the bow shock to examine the details of the solar wind-bow shock interaction. Preliminary findings indicate that a typical SW H+ beam with thermal kT ~10 eV drifting at 400 km/s in front of the bow shock appears as ~12 eV beam drifting at 250 km/s after it penetrates the shock barrier. The small kT increase is possibly due to wave-particle interaction at the boundary. While the He++ ion beam kT behaves similarly as H+ ions, the drift velocities of He++ ions do not always slow down as H+ ions. These observations indicate the physics of SW-bow shock interaction is much more complicated than the models that explain SW slow down as resulting from an electrostatic potential at the shock that decelerates the SW. We have started PIC simulation of SW transport across the bow shock and the results will be presented together with observations.
