ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-29-687-2011 Dayside magnetopause transients correlated with changes of the magnetosheath magnetic field orientation Tkachenko O. 1 Šafránková J. 1 Němeček Z. 1 Sibeck D. G. 2 Charles University, Faculty of Mathematics and Physics, V Holesovickach 2, 180 00 Praha 8, Czech Republic NASA Goddard Flight Center, Greenbelt, MD 20771, USA 19 04 2011 29 4 687 699 Copyright: © 2011 O. Tkachenko et al. 2011 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://angeo.copernicus.org/articles/29/687/2011/angeo-29-687-2011.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/29/687/2011/angeo-29-687-2011.pdf

The paper analyses one long-term pass (26 August 2007) of the THEMIS spacecraft across the dayside low-latitude magnetopause. THEMIS B, serving partly as a magnetosheath monitor, observed several changes of the magnetic field that were accompanied by dynamic changes of the magnetopause location and/or the structure of magnetopause layers observed by THEMIS C, D, and E, whereas THEMIS A scanned the inner magnetosphere. We discuss the plasma and the magnetic field data with motivation to identify sources of observed quasiperiodic plasma transients. Such events at the magnetopause are usually attributed to pressure pulses coming from the solar wind, foreshock fluctuations, flux transfer events or surface waves. The presented transient events differ in nature (the magnetopause surface deformation, the low-latitude boundary layer thickening, the crossing of the reconnection site), but we found that all of them are associated with changes of the magnetosheath magnetic field orientation and with enhancements or depressions of the plasma density. Since these features are not observed in the data of upstream monitors, the study emphasizes the role of magnetosheath fluctuations in the solar wind-magnetosphere coupling.

 References Angelopoulos, V.: The THEMIS mission, Space Sci. Rev., 141, 5, <a href="http://dx.doi.org/10.1007/s11214-008-9336-1">https://doi.org/10.1007/s11214-008-9336-1</a>, 2008. Auster, H. U., Glassmeier, K. H., Magnes, W., Aydogar, O., Baumjohann, W., Constantinescu, D., Fischer, D., Fornacon, K. H., Georgescu, E., Harvey, P., Hillenmaier, O., Kroth, R., Ludlam, M., Narita, Y., Nakamura, R., Okrafka, K., Plaschke, F., Richter, I., Schwarzl, H., Stoll, B., Valavanoglou, A., and Wiedemann, M.: The THEMIS Fluxgate Magnetometer, Space Sci. Rev., 141, 235, <a href="http://dx.doi.org/10.1007/s11214-008-9365-9">https://doi.org/10.1007/s11214-008-9365-9</a>, 2008. Berchem, J. and Russell, C. T.: Flux transfer events on the magnetopause: spatial distribution and controlling factors, J. Geophys. Res., 89, 6689–6703, <a href="http://dx.doi.org/10.1029/JA089iA08p06689">https://doi.org/10.1029/JA089iA08p06689</a>, 1984. Bogdanova, Y. V., Owen, C. J., Dunlop, M. W., Wild, J. A., Davies, J. A., Lahiff, A. D., Taylor, M. G. G. T., Fazakerley, A. N., Dandouras, I., Carr, C. M., Lucek, E. A., and Reme, H.: Formation of the low-latitude boundary layer and cusp under the northward IMF: Simultaneous observations by Cluster and Double Star, J. Geophys. Res., 113, A07S07, <a href="http://dx.doi.org/10.1029/2007JA012762">https://doi.org/10.1029/2007JA012762</a>, 2008. Dungey, J. W.: Interplanetary magnetic field and the auroral zones, Phys. Rev. Lett., 6, 47–48, <a href="http://dx.doi.org/10.1103/PhysRevLett.6.47">https://doi.org/10.1103/PhysRevLett.6.47</a>, 1961. Eriksson, S., Hasegawa, H., Teh, W.-L., Sonnerup, B. U. O., McFadden, J. P., Glassmeier, K.-H., Le Contel, O., Angelopoulos, V., Cully, C. M., Larson, D. E., Ergun, R. E., Roux, A., and Carlson, C. W.: Magnetic island formation between large-scale flow vortices at an undulating postnoon magnetopause for northward interplanetary magnetic field, J. Geophys. Res., 114, A00C17, <a href="http://dx.doi.org/10.1029/2008JA013505">https://doi.org/10.1029/2008JA013505</a>, 2009. Foullon, C., Farrugia, C. J., Fazakerley, A. N., Owen, C. J., Gratton, F. T., and Torbert, R. B.: Evolution of Kelvin-Helmholtz activity on the dusk flank magnetopause, J. Geophys. Res., 113, A11203, <a href="http://dx.doi.org/10.1029/2008JA013175">https://doi.org/10.1029/2008JA013175</a>, 2008. Haerendel, G., Paschman, G., Sckopke, N., Rosenbauer, H., and Hedgecock, P. C.: The frontside boundary layer of the magnetopause and the problem of reconnection, J. Geophys. Res., 83, 3195–3216, 1978. Hudson, P. D.: Discontinuities in an anisotropic plasma and their identification in the solar wind, Planet. Space Sci., 18, 1611–1622, 1970. Jeřáb, M., Němeček, Z., \v Safránková, J., Jel\' {i}nek, K., and Merka, J.: A study of bow shock locations, Planet. Space Sci., 53, 85–94, 2005. Kawano, H., Kokubun, S., and Takahashi, K.: Survey of transient magnetic field events in the dayside magnetosphere, J. Geophys. Res., 97, 10677–10692, 1992. King, J. H. and Papitashvili, N. E.: Solar wind spatial scales in and comparisons of hourly Wind and ACE plasma and magnetic field data, J. Geophys. Res., 110, A02104, <a href="http://dx.doi.org/10.1029/2004JA010649">https://doi.org/10.1029/2004JA010649</a>, 2005. Kuo, H., Russell, C. T., and Le, G.: Statistical studies of flux-transfer events, J. Geophys. Res., 100, 3513–3519, <a href="http://dx.doi.org/10.1029/94JA02498">https://doi.org/10.1029/94JA02498</a>, 1995. Lavraud, B., Thomsen, M. F., Lefebvre, B., Schwartz, S. J., Seki, K., Phan, T. D., Wang, Y. L., Fazakerley, A., Reme, H., and Balogh, A.: Evidence for newly closed magnetosheath field lines at the dayside magnetopause under northward IMF, J. Geophys. Res., 111, A05211, <a href="http://dx.doi.org/10.1029/2005JA011266">https://doi.org/10.1029/2005JA011266</a>, 2006. Li, W., Raeder, J., Oieroset, M., and Phan, T. D.: Cold dense magnetopause boundary layer under northward IMF: Results from THEMIS and MHD simulations, J. Geophys. Res., 114, A00C15, <a href="http://dx.doi.org/10.1029/2008JA013497">https://doi.org/10.1029/2008JA013497</a>, 2009. Lundin, R.: On the magnetospheric boundary layer and solar wind energy transfer into the magnetopause, Space Sci. Rev., 48(2), 263–320, 1988. McFadden, J. P., Carlson, C. W., Larson, D., Ludlam, M., Abiad, R., Elliott, B., Turin, P., Marckwordt, M., and Angelopoulos, V.: The THEMIS ESA plasma instrument and in-flight calibration, Space Sci. Rev., 141, 277, <a href="http://dx.doi.org/10.1007/s11214-008-9440-2">https://doi.org/10.1007/s11214-008-9440-2</a>, 2008. Mitchell, D. G., Kutchko, F., Williams, D. J., Eastman, T. E., Frank, L. A., and Russell, C. T.: An extended study of the low-latitude boundary layer on the dawn and dusk flanks of the magnetosphere, J. Geophys. Res., 92(A7), 7394–7404, 1987. Němeček, Z., Šafránková, J., Přech, L., Šimunek, J., Sauvaud, J.-A., Fedorov, A., Stenuit, H., Fuselier, S. A., Savin, S., Zelenyi, L., and Berchem, J.: Structure of the outer cusp and sources of the cusp precipitation during intervals of a horizontal IMF, J. Geophys. Res., 108(A12), 1420, <a href="http://dx.doi.org/10.1029/2003JA009916">https://doi.org/10.1029/2003JA009916</a>, 2003. Nykyri, K. and Otto, A.: Plasma transport at the magnetospheric boundary due to reconnection in Kelvin-Helmholtz vortices, Geophys. Res. Lett., 28, 3565–3568, <a href="http://dx.doi.org/10.1029/2001GL013239">https://doi.org/10.1029/2001GL013239</a>, 2001. Nykyri, K., Otto, A., Lavraud, B., Mouikis, C., Kistler, L. M., Balogh, A., and Rème, H.: Cluster observations of reconnection due to the Kelvin-Helmholtz instability at the dawnside magnetospheric flank, Ann. Geophys., 24, 2619–2643, <a href="http://dx.doi.org/10.5194/angeo-24-2619-2006">https://doi.org/10.5194/angeo-24-2619-2006</a>, 2006. Øieroset, M., Phan, T. D., Angelopoulos, V., Eastwood, J. P., McFadden, J. P., Larson, D., Carlson, C. W., Glassmeier, K. H., Fujimoto, M., and Raeder, J.: THEMIS multispacecraft observations of magnetosheath plasma penetration deep into the dayside low-latitude magnetosphere for northward and strong By IMF, Geophys. Res. Lett., 35, L17S11, <a href="http://dx.doi.org/10.1029/2008GL033661">https://doi.org/10.1029/2008GL033661</a>, 2008. Onsager, T. G., Scudder, J. D., Lockwood, M., and Russell, C. T.: Reconnection at the high-latitude magnetopause during northward interplanetary magnetic field conditions, J. Geophys. Res., 106, 25467–25488, <a href="http://dx.doi.org/10.1029/2000JA000444">https://doi.org/10.1029/2000JA000444</a>, 2001. Paschmann, G., Papamastorakis, I., Sckopke, N., Haerendel, G., Sonnerup, B. U. O., Bame, S. J., Asbridge, J. R., Gosling, J. T., Russell, C. T., and Elphic, R. C.: Plasma acceleration at the Earth's magnetopause – Evidence for reconnection, Nature, 282, 243–246, 1979. Richardson, J. D. and Paularena, K. I.: Plasma and magnetic field correlations in the solar wind, J. Geophys. Res., 106(A1), 239–251, 2001. Rijnbeek, R. P., Cowley, S. W. H., Southwood, D. J., and Russell, C. T.: A survey of dayside flux-transfer events observed by ISEE-1 and ISEE-2 magnetometers, J. Geophys. Res., 89, 786–800, <a href="http://dx.doi.org/10.1029/JA089iA02p00786">https://doi.org/10.1029/JA089iA02p00786</a>, 1984. Rossolenko, S. S., Antonova, E. E., Yermolaev, Yu. I., Verigin, M. I., Kirpichev, I. P., and Borodkova, N. L.: Turbulent fluctuations of plasma and magnetic field parameters in the magnetosheath and the low-latitude boundary layer formation: Multisatellite observations on March 2, 1996, Cosmic Research, 46(5), 373–382, 2008. Russell, C. T. and Elphic, R. C.: Initial ISEE magnetometer results: magnetopause observations, Space Sci. Rev., 22, 681–715, <a href="http://dx.doi.org/10.1007/BF00212619">https://doi.org/10.1007/BF00212619</a>, 1978. Russell, C. T. and Elphic, R. C.: ISEE observations of flux transfer events at the dayside magnetopause, Geophys. Res. Lett., 6, 33–36, 1979. Russell, C. T., Le, G., and Kuo, H.: The occurrence rate of flux transfer, Adv. Space Res., 18, 197–205, <a href="http://dx.doi.org/10.1016/0273-1177(95)00965-5">https://doi.org/10.1016/0273-1177(95)00965-5</a>, 1996. Šafránková, J., N\v eme\v cek, Z., P\v rech, L., \v Sim\r {u}nek, J., Sibeck, D. G., and Sauvaud, J.-A.: Variations of the flank LLBL thickness as response to the solar wind dynamic pressure and IMF orientation, J. Geophys. Res., 112(A7), A07201, <a href="http://dx.doi.org/10.1029/2006JA011889">https://doi.org/10.1029/2006JA011889</a>, 2007. \v Safránková, J., Hayosh, M., Gutynska, O., N\v eme\v cek, Z., and P\v rech, L.: Reliability of prediction of the magnetosheath Bz component from interplanetary magnetic field observations, J. Geophys. Res., 114(A12), A12213, <a href="http://dx.doi.org/10.1029/2009JA014552">https://doi.org/10.1029/2009JA014552</a>, 2009. Sanny, J., Sibeck, D., Venturini, C., and Russell, C. T.: A statistical study of transient events in the outer dayside magnetosphere, J. Geophys. Res., 103(A3), 4939–4952, 1996. Sanny, J., Beruhe, D., and Sibeck, D.: A statistical study of transient event motion at geosynchronous orbit, J. Geophys. Res., 106(A10), 21217–21229, 2001. Shue, J. H., Song, P., Russell, C. T., Steinberg, J. T., Chao, J. K., Zastenker, G., Vaisberg, O. L., Kokubun, S., Singer, H. J., Detman, T. R., and Kawano, H.: Magnetopause location under extreme solar wind conditions, J. Geophys. Res., 103(A8), 17691–17700, 1998. Sibeck, D. G.: A model for the transient magnetospheric response to sudden solar wind dynamic pressure variations, J. Geophys. Res., 95, 3755–3771, <a href="http://dx.doi.org/10.1029/JA095iA04p03755">https://doi.org/10.1029/JA095iA04p03755</a>, 1990. Sibeck, D. G.: Transient events in the outer magnetosphere – boundary waves or flux-transfer events?, J. Geophys. Res., 97, 4009–4026, <a href="http://dx.doi.org/10.1029/91JA03017">https://doi.org/10.1029/91JA03017</a>, 1992. Sibeck, D. G. and Smith, M. F.: Magnetospheric plasma flows associated with boundary waves and flux transfer events, Geophys. Res. Lett., 19, 1903–1906, <a href="http://dx.doi.org/10.1029/92GL01614">https://doi.org/10.1029/92GL01614</a>, 1992. Sibeck, D. G., Baumjohanann, W., and Lopez, R. E.: Solar wind dynamic variations and transient magnetospheric signatures, Geophys. Res. Lett., 16, 13–16, 1989. Sibeck, D. G., Korotova, G. I., Petrov, V., Styazhkin, V., and Rosenberg, T. J.: Flux transfer events on the high-latitude magnetopause: Interball-1 observations, Ann. Geophys., 23, 3549–3559, <a href="http://dx.doi.org/10.5194/angeo-23-3549-2005">https://doi.org/10.5194/angeo-23-3549-2005</a>, 2005. Sonnerup, B., Paschmann, G., Phan, T.-D., and Luhr, H.: Magnetic field maxima in the low latitude boundary layer, Geophys. Res. Lett., 19(17), 1727–1730, 1992. Sonnerup, B. U. O., Hasegawa, H., and Paschmann, G.: Anatomy of a flux transfer event seen by Cluster, Geophys. Res. Lett., 31, L11803, <a href="http://dx.doi.org/10.1029/2004GL020134">https://doi.org/10.1029/2004GL020134</a>, 2004. Southwood, D. J., Saunders, M. A., Dunlop, M. W., Mierjedrzejowicz, W. A. C., and Rijnbeek, R. P.: A survey of flux-transfer events recorded by the UKS spacecraft magnetometer, Planet. Space Sci., 34, 1349–1359, <a href="http://dx.doi.org/10.1016/0032-0633(86)90071-1">https://doi.org/10.1016/0032-0633(86)90071-1</a>, 1986. Wing, S. and Newell, P. T.: 2D plasma sheet ion density and temperature profiles for northward and southward IMF, Geophys. Res. Lett., 29, A1777, <a href="http://dx.doi.org/10.1029/2002GL015845">https://doi.org/10.1029/2002GL015845</a>, 2002. Zwan, B. J. and Wolf, R. A.: Depletion of the solar wind plasma near a planetary boundary, J. Geophys. Res., 81, 1636–1648, 1976.