ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-31-689-2013 The mechanism of mid-latitude Pi2 waves in the upper ionosphere as revealed by combined Doppler and magnetometer observations Pilipenko V. A. https://orcid.org/0000-0003-3056-7465 1 2 Fedorov E. N. 3 Teramoto M. 2 Yumoto K. 4 Space Research Institute, Moscow, Russian Federation Solar-Terrestrial Environment Laboratory, Nagoya University, Japan Institute of Physics of the Earth, Moscow, Russian Federation International Center for Space Weather Science and Education, Kyushu University, Fukuoka, Japan 17 04 2013 31 4 689 695 Copyright: © 2013 V. A. Pilipenko et al. 2013 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/31/689/2013/angeo-31-689-2013.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/31/689/2013/angeo-31-689-2013.pdf

The interpretation of simultaneous ionospheric Doppler sounding and ground magnetometer observations of low-latitude Pi2 waves is revised. We compare the theoretical estimates of the ionospheric Doppler velocity for the same amplitude of the ground magnetic disturbances produced by a large-scale compressional mode and an Alfvén mode. The plasma vertical displacement caused by the wave electric field is shown to be the dominating effect. Taking into account the correction of the previous paper, the observations of low-latitude Pi2 in the F layer ionosphere by Doppler sounding and SuperDARN (Super Dual Auroral Radar Network) radars give consistent results. We suggest that the Doppler response to Pi2 waves is produced by the Alfvén wave component, but not the fast-mode component, whereas the ground magnetic signal is composed from both Alfvén and fast magnetosonic modes.

 References Alperovich, L. S. and Fedorov, E. N.: Hydromagnetic Waves in the Magnetosphere and the Ionosphere, Series: Astrophysics and Space Science Library, 353, XXIV, 418 pp., 2007. Alperovich, L. S., Fedorov, E. N., Volgin, A. V., Pokhil'ko, S. V., Leus, L. A., Pilipenko, V. A., and Karpov, P. N.: Doppler sounding as tool for the study of MHD wave structure in the ionosphere, J. Atmos. Terr. Phys., 53, 581–586, 1991. Chum, J., Hruska, F., Buresova, D., Sindelarova, T., Hejda, P., and Bochnice, J.: Ionospheric oscillations caused by geomagnetic Pi2 pulsations and their observations by multipoint continuous Doppler sounding: First results, Adv. Space Res., 44, 667–676, 2009. Gjerloev, J. W., Greenwald, R. A., Waters, C. L., Takahashi, K., Sibeck, D., Oksavik, K., Barnes, R., Baker, J., and Ruohoniemi, J. M.: Observations of Pi2 pulsations by the Wallops HF radar in association with substorm expansion, Geophys. Res. Lett., 34, L20103, <a href="http://dx.doi.org/10.1029/2007GL030492">https://doi.org/10.1029/2007GL030492</a>, 2007. Grant, J. F. and Cole, K. D.: The height dependence of the perturbation of the mid-latitude F-region by Pi2 pulsations, Planet. Space Sci., 40, 1461–1477, 1992. Han, D. S., Iyemori, T., Nose, M., McCreadie, H., Gao, Y., Yang, F., Yamashita, S., and Stauning, P.: A comparative analysis of low-latitude Pi2 pulsations observed by Oersted and ground stations, J. Geophys. Res., 109, A10209, <a href="http://dx.doi.org/10.1029/2004JA010576">https://doi.org/10.1029/2004JA010576</a>, 2004. Ikeda, A., Yumoto, K., Uozumi, T., Shinohara, M., Nozaki, K., Yoshikawa, A., Bychkov, V. V., and Shevtsov, B. M.: Phase relation between Pi2-associated ionospheric Doppler velocity and magnetic pulsations observed at a mid-latitude MAGDAS station, J. Geophys. Res., 115, A02215, <a href="http://dx.doi.org/10.1029/2009JA014397">https://doi.org/10.1029/2009JA014397</a>, 2010. Keiling, A. and Takahashi, K.: Review of Pi2 models, Space Sci. Rev., 161, 63–148, <a href="http://dx.doi.org/10.1007/s11214-011-9818-4">https://doi.org/10.1007/s11214-011-9818-4</a>, 2011. Kurchashov, Yu. P., Nikomarov, Ya. S., Pilipenko, V. A., and Best, A.: Field-line resonance effects in a local meridional structure of mid-latitude geomagnetic pulsations, Ann.&nbsp;Geophys., 5A, 147–154, 1987. Marshall, R. A. and Menk, F. W.: Observations of Pc 3–4 and Pi 2 geomagnetic pulsations in the low-latitude ionosphere, Ann. Geophys., 17, 1397–1410, <a href="http://dx.doi.org/10.1007/s00585-999-1397-2">https://doi.org/10.1007/s00585-999-1397-2</a>, 1999. Menk, F. W.: Characterization of ionospheric Doppler oscillations in the Pc3–4 and Pi2 magnetic pulsation frequency range, Planet. Space Sci., 40, 459–507, 1992. Menk, F. W., Waters, C. L., and Dunlop, I. S.: ULF Doppler oscillations in the low latitude ionosphere, Geophys. Res. Lett., 34, L10104, <a href="http://dx.doi.org/10.1029/2007GL029300">https://doi.org/10.1029/2007GL029300</a>, 2007. Nishida, A.: Geomagnetic diagnostic of the magnetosphere, Springer-Verlag, New York – Heidelberg – Berlin, 255 p., 1978. Nose, M.: Excitation mechanism of low-latitude Pi2 pulsations: Cavity mode resonance or BBF-driven process?, J. Geophys. Res., 115, A07221, <a href="http://dx.doi.org/10.1029/2009JA015205">https://doi.org/10.1029/2009JA015205</a>, 2010. Pilipenko, V., Fedorov, E., Yumoto, K., Ikeda, A., and Sun, T. R.: An analytical model for Doppler frequency variations of ionospheric HF sounding caused by SSC, J. Geophys. Res., 115, A10228, <a href="http://dx.doi.org/10.1029/2010JA015403">https://doi.org/10.1029/2010JA015403</a>, 2010. Pilipenko, V., Belakhovsky, V., Kozlovsky, A., Fedorov, E., and Kauristie, K.: Determination of the wave mode contribution into the ULF pulsations from combined radar and magnetometer data: Method of apparent impedance, J. Atmos. Solar-Terr. Phys., 77, 85–95, <a href="http://dx.doi.org/10.1016/j.jastp.2011.11.013">https://doi.org/10.1016/j.jastp.2011.11.013</a>, 2012. Pilipenko, V., Fedorov, E., Heilig, B., Engebretson, M. J., Sutcliffe, P., and Luehr, H.: ULF waves in the topside ionosphere: Satellite observations and modeling, in: The Dynamic Magnetosphere, IAGA Special Sopron Book Series, vol. 3, edited by: Liu, W. and Fujimoto, M., Chapter 14, Springer, 257–269, <a href="http://dx.doi.org/10.1007/978-94-007-0501-2">https://doi.org/10.1007/978-94-007-0501-2</a>, 2012. Poole, A. W. V., Sutcliffe, P. R., and Walker, A. D. M.: The relationship between ULF geomagnetic pulsations and ionospheric Doppler oscillations: Derivation of a model, J. Geophys. Res., 93, 14656–14664, 1988. Reddy, C. A., Ravindran, Sudha, Viswanathan, K. S., Krishna Murthy, B. V., Rao, D. R. K., and Araki, T.: Observations of Pc5 micropulsation-related electric field oscillations in the equatorial ionosphere, Ann. Geophys., 12, 565–573, <a href="http://dx.doi.org/10.1007/s00585-994-0565-7">https://doi.org/10.1007/s00585-994-0565-7</a>, 1994. Schunk, R. W. and Nagy, A. F.: Ionospheres: Physics, Plasma Physics, and Chemistry, Cambridge University Press, 2009. Shiokawa, K., Baumjohann, W., Haerendel, G., Paschmann, G., Fennell, J. F., Friis-Christensen, E., Lühr, H., Reeves, G. D., Russell, C. T., Sutcliffe, P. R., and Takahashi, K.: High-speed ion flow, substorm current wedge, and multiple Pi2 pulsations, J. Geophys. Res., 103, 4491–4508, <a href="http://dx.doi.org/10.1029/97JA01680">https://doi.org/10.1029/97JA01680</a>, 1998. Sutcliffe, P. R. and Luhr, H.: A comparison of Pi2 pulsations observed by CHAMP in low Earth orbit and on the ground at low latitudes, Geophys. Res. Lett., 30, 2105, <a href="http://dx.doi.org/10.1029/2003GL018270">https://doi.org/10.1029/2003GL018270</a>, 2003. Sutcliffe, P. R. and Poole, A. W. V.: Low latitude Pc3 pulsations and associated ionospheric oscillations measured by a digital chirp ionosonde, Geophys. Res. Lett., 11, 1172–1175, 1984. Sutcliffe, P. R. and Poole, A. W. V.: Ionospheric Doppler and electron velocities in the presence of ULF waves, J. Geophys. Res., 94, 13505–13514, 1989. Sutcliffe, P. R. and Poole, A. W. V.: The relationship between ULF geomagnetic pulsations and ionospheric Doppler oscillations: model predictions, Planet. Space Science, 38, 1581–1589, 1990. Sutcliffe, P. R. and Yumoto, K.: On the cavity mode nature of low-latitude Pi2 pulsations, J. Geophys. Res., 96, 1543–1551, 1991. Takahashi, K., Ohtani, S.-I., and Anderson, B. J.: Statistical analysis of Pi2 pulsation observed by the AMPTE CCE spacecraft in the inner magnetosphere, J. Geophys. Res., 100, 21929–21941, 1995. Takahashi, K., Ohtani, S., Hughes, W. J., and Anderson, R. R.: CRRES satellite observations associated with low-latitude Pi2 pulsations, J. Geophys. Res., 106, 15567–15581, 2001. Takahashi, K., Lee, D.-H., Nose, M., Anderson, R. R., and Hughes, W. J.: CRRES electric field study of the radial mode structure of Pi2 pulsations, J. Geophys. Res., 108, 1210, <a href="http://dx.doi.org/10.1029/2002JA009761">https://doi.org/10.1029/2002JA009761</a>, 2003. Teramoto, M., Nishitani, N., Ogawa, T., Shiokawa, K., Nagatsuma, T., and Murata, K. T.: Spatial characteristics of Pi2 pulsations in the ionosphere observed by the SuperDARN Hokkaido radar, GEMSIS International Workshop, 12–14 March 2012, Nagoya University, Japan, 2012. Wright, D. M., Yeoman, T. K., and Chapman, P. J.: High-latitude HF Doppler observations of ULF waves. 1. Waves with large spatial scale sizes, Ann. Geophys., 15, 1548–1556, <a href="http://dx.doi.org/10.1007/s00585-997-1548-2">https://doi.org/10.1007/s00585-997-1548-2</a>, 1997. Yeoman, T. K. and Orr, D.: Phase and spectral power of mid-latitude Pi2 pulsations: Evidence for a plasmaspheric cavity resonance, Planet. Space Sci., 38, 1367–1383, 1989. Yumoto, K. and the CPMN Group: Characteristics of Pi2 magnetic pulsations observed at the CPMN stations: A review of the STEP results, Earth Planets Space, 53, 981–992, 2001. Yumoto, K., Ikeda, A., Shinohara, M., Uozumi, T., Nozaki, K., Watari, S., Kitamura, K., Bychkov, V. V., and Shevtsov, B. M.: Electric and magnetic field variations at low and equatorial latitudes during SC, DP2, and Pi2 Events, Adv. Geosci., 14, Solar Terrestrial, edited by: Duldig, M., World Sci. Publ. Comp., 197–212, 2009.