ANGEO Annales Geophysicae ANGEO Ann. Geophys. 1432-0576 Copernicus Publications Göttingen, Germany 10.5194/angeo-27-1139-2009 Modelling the tongue-of-ionisation using CTIP with SuperDARN electric potential input: verification by radiotomography Pryse S. E. 1 Whittick E. L. 1 Aylward A. D. 2 Middleton H. R. 1 5 Brown D. S. 1 Lester M. 3 Secan J. A. 4 Institute of Mathematics and Physics, Aberystwyth University, Wales, UK Department of Physics and Astronomy, University College London, UK Department of Physics and Astronomy, University of Leicester, UK NorthWest Research Associates, Inc., Tucson, USA now at: European Space Agency, European Space Astronomy Centre, Madrid, Spain 06 03 2009 27 3 1139 1152 Copyright: © 2009 S. E. Pryse et al. 2009 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/27/1139/2009/angeo-27-1139-2009.html The full text article is available as a PDF file from https://angeo.copernicus.org/articles/27/1139/2009/angeo-27-1139-2009.pdf

Electric potential patterns obtained by the SuperDARN radar network are used as input to the Coupled Thermosphere-Ionosphere-Plasmasphere model, in an attempt to improve the modelling of the spatial distribution of the ionospheric plasma at high latitudes. Two case studies are considered, one under conditions of stable IMF <I>B<sub>z</sub></I> negative and the other under stable IMF <I>B<sub>z</sub></I> positive. The modelled plasma distributions are compared with sets of well-established tomographic reconstructions, which have been interpreted previously in multi-instrument studies. For IMF <I>B<sub>z</sub></I> negative both the model and observations show a tongue-of-ionisation on the nightside, with good agreement between the electron density and location of the tongue. Under <I>B<sub>z</sub></I> positive, the SuperDARN input allows the model to reproduce a spatial plasma distribution akin to that observed. In this case plasma, unable to penetrate the polar cap boundary into the polar cap, is drawn by the convective flow in a tongue-of-ionisation around the periphery of the polar cap.

 References Anderson, D. N., Buchau, J., and Heelis, R. A.: Origin of density enhancements in the winter polar cap ionosphere, Radio Sci., 23, 513–519, 1988. Bowline, M. D., Sojka, J. J., and Schunk, R. W.: Relationship of theoretical patch climatology to polar cap patch observations, Radio Sci., 31, 635–644, 1996. Chisham, G., Lester, M., Milan, S. E., Freeman, M. P., Bristow, W. A., Grocott, A., MacWilliams, K. A., Ruohoniemi, J. M., Yeoman, T. K., Dyson, P., Greenwald, R. A., Kikuchi, T., Pinnock, M., Rash, J., Sato, N., Sofko, G., Villain, J.-P., and Walker, A. D. M.: A decade of the Super Dual Auroral Radar Network (SuperDARN): Scientific achievements, new techniques and future directions, Surv. Geophys., 28, 33–109, https://doi.org/10.1007/s10712-007-9017-8, 2007. Cowley, S. W. H.: Excitation of flow in the Earth's magnetosphere-ionosphere system: observations by incoherent scatter radar, in: Polar Cap Boundary Phenomena, edited by: Moen, J., Egeland, A., and Lockwood, M., NATO Advanced Study Institute Series, Kluwer Academic Press, Dordrecht, The Netherlands, 509, 127–140, 1998. Crowley, G.: Critical review of ionospheric patches and blobs, URSI Review of Radio Science 1993–1996, edited by: Stone, W. R., 619–648, 1996. Foster, J. C., Holt, J. M., and Musgrove, R. G.: Ionospheric convection associated with discrete levels of particle precipitation, Geophys. Res. Lett., 13, 656–659, 1986. Fuller-Rowell, T. J., Rees, D., Quegan, S., Moffett, R. J., and Bailey, G. J.: Interactions between neutral thermospheric composition and the polar ionosphere using a coupled ionosphere-thermosphere model, J. Geophys. Res., 92, 7744–7748, 1987. Fuller-Rowell, T. J. and Rees, D.: Derivation of a conservation equation for mean molecular weight for a two-constituent gas within a three-dimensional, time-dependent, model of the thermosphere, Planet. Space Sci., 31, 1209–1222, 1983. Fuller-Rowell, T. J. and Rees, D.: A three-dimensional, time-dependent, global model of the thermosphere, J. Atmos. Sci., 37, 2545–2567, 1980. Greenwald, R. A., Baker, K. B., Dudeney, J. R., Pinnock, M., Jones, T. B., Thomas, E. C., Villain, J.-P., Cerisier, J.-C., Senior, C., Hanuise, C., Hunsucker, R. D., Sofko, G., Koehler, J., Nielsen, E., Pellinen, R., Walker, A. D. M., Sato, N., and Yamagishi, H.: Darn/Superdarn: A global view of the dynamics of high-latitude convection, Space Sci. Rev., 71, 761–796, 1995. Middleton, H. R., Pryse, S. E., Wood, A. G., and Balthazor, R. L.: The role of the tongue-of-ionisation in the formation of the poleward wall of the main trough in the European post-midnight sector, J. Geophys. Res., 113(A2), A02306, https://doi.org/10.1029/2007JA012631, 2008. Middleton, H. R., Pryse, S. E., Kersley, L., Bust, G. S., Fremouw, E. J., Secan, J. A., and Denig, W. F.: Evidence for the tongue of ionisation under northward IMF conditions, J. Geophys. Res., 110(A7), A07301, https://doi.org/10.1029/2004JA010800, 2005. Milan, S. E., Lester, M., and Yeoman, T. K.: HF radar polar patch formation revisited: summer and winter variations in dayside plasma structuring, Ann. Geophys., 20, 487–499, 2002. Millward, G. H., Moffett, R. J., Quegan, S., and Fuller-Rowell, T. J.: A coupled thermosphere-ionosphere-plasmasphere model (CTIP), Solar-terrestrial energy programme (STEP) handbook of ionospheric models, edited by: Schunk, R. W., 239–279, 1996. Pryse, S. E., Wood, A. G., Middleton, H. R., McCrea, I. W., and Lester, M.: Reconfiguration of polar-cap plasma in the magnetic midnight sector, Ann. Geophys., 24, 2201–2208, 2006. Pryse, S. E., Dewis, K. L., Balthazor, R. L., Middleton, H. R., and Denton, M. H.: The dayside high-latitude trough under quiet geomagnetic conditions: Radio tomography and the CTIP model, Ann. Geophys., 23, 1199–1206, 2005. Pryse, S. E.: Radiotomography: A new experimental technique, Surv. Geophys., 24, 1–38, 2003. Quegan, S., Bailey, G. J., Moffett, R. J., Heelis, R. A., Fuller-Rowell, T. J., Rees, D., and Sprio, R. W.: A theoretical study of the distribution of ionisation in the high-latitude ionosphere and the plasmasphere: first results on the mid-latitude trough and the light-ion trough, J. Atmos. Terr. Phys., 44, 619–640, 1982. Robinson, R. M., Tsunoda, R. T., and Vickrey, J. F.: Sources of F-region ionisation enhancements in the nighttime auroral zone, J. Geophys. Res., 90, 7533–7546, 1985. Rodger, A. S., Pinnock, M., Dudeney, J. R., Baker, K. B., and Greenwald, R. A.: A new mechanism for polar patch formation, J. Geophys. Res., 99, 6425–6436, 1994. Ruohoniemi, J. M. and Baker, K. B.: Large-scale imaging of high-latitude convection with Super Dual Auroral radar Network HF radar observations, J. Geophys. Res., 103, 20797–20811, 1998. Schoendorf, J., Aylward, A. D., and Moffett, R. J.: Modelling high-latitude electron densities with a coupled thermosphere-ionosphere model, Ann. Geophys., 14, 1391–1402, 1996. Sojka, J. J., Bowline, M. D., and Schunk, R. W.: Patches in the polar ionosphere: UT and seasonal dependence, J. Geophys. Res., 99, 14959–14970, 1994. Sojka, J. J., Bowline, M. D., Schunk, R. W., Decker, D. T., Valladares, C. E., Sheehan, R., Anderson, D. N., and Heelis, R. A.: Modelling polar-cap F-region patches using time-varying convection, Geophys. Res. Lett., 20, 1783–1786, 1993. Sojka, J. J., Raitt, W. J., and Schunk, R. W.: A theoretical study of the high-latitude winter F region at solar minimum for low magnetic activity, J. Geophys. Res., 86, 609–621, 1981. Valladares, C. E., Basu, S., Buchau, J., and Friis-Christensen, E.: Experimental evidence for the formation and entry of patches into the polar cap, Radio Sci., 29, 167–194, 1994.