Physics of auroral phenomena : proceedings of the 33rd Annual seminar, Apatity, 02 - 05 March, 2010 / [ed.: A.G. Yahnin, A. A. Mochalov]. - Апатиты : Издательство Кольского научного центра РАН, 2011. - 206 с. : ил.

V.D. Tereshchenko at al. Conclusions The results show that PMSE of the medium waves are formed at the altitudes near to the cold summer mesopause (84-87 km) in conditions of strong reduction of the electron concentration, and PMWE - at the altitudes below 80 km in conditions o f sharp increase of the electron concentration. On basis o f comparison o f experimental and theoretical profiles o f the electron density and the analysis of geophysical environment necessary conditions for appearances of intensive mesospheric reflections are determined. It was shown, that for formation o f PMSE at the heights near to the summer mesopause presence o f negative charged aerosols or dust, and for appearance of PMWE - presence in average D-region of the polar ionosphere of layers o f meteoric ions is necessary. However, these conclusions demand the further experimental studying. Determination o f the effective recombination coefficient at a time of polar mesospheric reflections can be a convenient method for determining the concentration of dust and metal ions in the polar mesosphere. A cknow ledg em en ts. This work was partly supported by the Russian Foundation for Basic Researches (project № 07-05-00012). References Belikovich V.V., Vyakhirev V.D., Kalinina E.E., Tereshchenko V.D., Ogloblina O.F., Tereshchenko V.A. Studies of the ionospheric D-region by the partial reflection method at middle latitudes and in the auroral zone // Izv. universities. Radiofizika. - 2003. - V. 46, № 3. - P. 181-191. Bremer J., Hoffman P., Manson A.H., Meek C.E., Riister R., Singer W. PMSE observations at the three different frequency in northern Europe during summer 1994 // Ann. Geophysicae.-1996. - V. 14. - №12. - P. 1317-11327. Osepian A.P., Dalin P.A., Tereshchenko V.D. Model spectra o f incoherent scattering o f radio waves in the polar winter mesosphere during solar proton events // Abstracts. XIII Regional Conference on Radio Wave Propagation, St. Petersburg, 2007. - P. 18 Smirnova N., Ogloblina O., Vlaskov V. Modelling of the lower ionosphere // Pure Appl. Geophys. - 1988. - V. 127. -P . 353-379. Tereshchenko V.D., Tereshchenko V.A., Kovalevich T.V. Seasonal changes in polar mesospheric echoes o f medium radiowaves // Proc. of the 20th All-Russia Scintific Conference on Radio Propagation, Nizhny Novgorod, 2002, Ed. By N.A. Armand. - P. 135-136. Tereshchenko V.D., Ogloblina O.F., Tereshchenko V.A., Vasiljev E.B., Chemyakov S.M. The structure o f the winter D-region of the polar ionosphere according to radar measurements in 2005-2008 // Proc. of the 22th All- Russia Scintific Conference on Radio Propagation, Rostov-on-Don - Loo, 2008, Ed. By N.A. Armand. - V. 1. - P. 201-204. Tereshchenko V.D., Vasiljev E.B., Ovchinnikov N.A., Popov A.A. Medium wave radar Polar Geophysical Institute for the study of the lower ionosphere // Techniques and methods of geophysical experiment. - Apatity: KSC RAS, 2003. - P. 37-46. Vlaskov V.A., Vasiljev E.B., Semjashkina T.N., Turunen E. A study o f PMSE using partial reflection // Ann Geophysicae. - 1994. - V. 12. - P. 577. 158