Электродинамические процессы в высоких широтах: материалы междунарордного симпозиума «Полярные геомагнитные явления», 25-31 мая 1986 г., Суздаль, СССР / Междунар. геодез. и геофиз. союз, Междунар. ассоц. геомагнетизма и аэрономии ; Акад. наук СССР, Кол. фил. им. С. М. Кирова, Поляр. геофиз. ин-т ; [редкол.: О. М. Распопов (отв. ред.). и др.]. - Апатиты : Кольский филиал АН СССР, 1988.

Figure 3 demonstrates that this temperature enhancement is confined to the region where the MTSI occurs. The most probable explanation of this elec tron temperature increase is the following: The unstable plasma waves crea ted Ъу the MTSI act back on the ambient plasma a nd increase T b y wave part- Э 1 . 0 Ш 14-15 UT T,°fC Figure 3. Elevated electron temperature during a period of drift velocities ѵд^ЮОО m/s observed w i t h ElSCAT (from Igarashi a n d Schlegel, 1986 ). icle-interaction (St-Maurice et a l . , 1981). The formalism to calculate the electron temperature from a given drift velocity developed by St-Mau- rice a nd Schlegel ( 1 9 8 2 ) was also used to v erify electron temperatures meas u r ed i n situ on a rocket (Schlegel et al.,1983). Figure 4 shows the results of these calcula tions ba s ed on simultaneous electric field measurements together w i t h the m easured electron temperature. The good agreement can be regarded as a confirmation of the theoretical f or malism. A n e v e n more simple and elegant approach to calculate T e q uantitatively has been found by Robinson (1986) w h i ch will be desc ribed in detail i n section III. Figure 4. Elevated electron temperatures m easu r e d with, a rocket experiment (dots) and the calculated temperatures (full line) w hi c h should be va li d for an electric field of 44 m V / m (vd ^ 9 0 0 m/s) w hi c h was m easured on the same rocket (from Schlegel et al.,1983). Te (К) It should be noted that on of the most critical parameter of such model calculation is the-neutral density, w h i c h determines the ion-neutral as well as the electron-neutral collision frequency. B o t h quantities enter the dis persion rela t i on ( I) of the MTSI and affect the properties of the unstable waves quite strongly. B. The study of the MTSI b y auroral r a d a r s . It is lon g known that VHF- waves directed perpendicular to the magnetic field lines exhibit a strong backscatter fr o m E - r eg i o n heights during geomagnetically disturbed conditions (e.g. Lange-Hesee, 1967; Egeland,1973 or Fejer and K e l l e y , 1980 for reviews). The tools for investigating this phenomenon, the auroral radars, have become 81