Physics of auroral phenomena : proceedings of the 40th annual seminar, Apatity, 13-17 March, 2017 / [ed. board: N. V. Semenova, A. G. Yahnin]. - Апатиты : Издательство Кольского научного центра РАН, 2017. - 143 с. : ил., табл.

V.С. Roldugin et al already extremely rare. Therefore modernization of the patrol all sky camera and expansion of its dynamic range have allowed increasing the period of optical observations in the Lovozero observatory. Regular observations can be made since the beginning of August now that gives more opportunities to register NLCs appearance in high latitudes. С JZ DO *3 82^_ XIkm V v / i v A " I f k к Г у V/ Wv .. H Hi M . ... ____ ГА ' UT, hour Figure 2. The ordinary wave amplitude of the radar (left) and its variations at different heights (right). D a ta In 2016 observations have been begun since August 1, time of observations was 2-3 hours in the first days. It was succeeded to record NLCs by the upgraded all sky camera at 8 , 9 and 12 August 2016. Because of bad weather these observations there were not acceptable for detailed researches except only data for 12 August. In Fig. 1 the shot of the all sky camera at 22:25:00 UT 12 August 2016 constructed using blue pixels is presented. The white cross is the zenith above the all sky camera, and black one is the zenith over the Tumanny observatory at the height of 84 km. It is visible that NLC were observed also in the neighborhood of the Tumanny observatory over PRR. Tropospheric clouds can be seen at the picture also. NLCs in this area have wavy structure, they are extended along the horizon. Other pictures show that NLCs move to the south - southwest direction. The characteristic distance between maxima of brightness is 50-100 km, and the speed is about 3-4 km/min at the height of 84 km. In the left bottom comer o f the figure the wavy structure with the period about 20 km is visible. During NLCs appearance records of ordinary wave amplitude of PRR have been received. The two-dimensional picture of the amplitude is presented on the left panel of Fig. 2. According to the all sky camera between 22:00 and 23:00 UT the area over the radar became covered by NLCs, and, during the same time interval, additional reflections at the heights about 82-87 km appeared. We connect the appearance of these sporadic reflections with NLCs. On the right panel the ordinary wave amplitudes for heights of 81-87 km are given; it is clearly visible that reflections happen, mainly, from the heights of 83-86 km and have sometimes quasiperiodic structures. The maximum amplitude is observed at the height of 84 km. For this reason when determining wavelength and speed of NLCs this height was accepted. The variations of sky intensity in the circle with the radius of 5° above the radar were calculated and the course o f sky luminescence intensity in this area was drawn. In Fig. 3 sky luminescence intensity and ordinary wave amplitude during 21:30-22:30 UT are shown. At that time according to ascafilms NLCs were above the radar. As we can see from the figure, there is no good compliance between curves of luminescence and the reflected signal: the signal o f the radar is late for 15-20 minutes after the photographic data show covering the chart of the antenna by NLCs. According to ascafilms, before growth of amplitude of the radar there was a change of the NLCs form in the field of the chart of the antenna. In Fig. 4 parts of ascafilms for the moments 21:45, 21:53 and 22:00 UT are shown. Circular sections of the chart of the antenna at the height of 84 km are shown by lines. At 21:45 the area over the radar is covered with a uniform cloud, a veil on the standard classification, and the signal at this time reflected in the radar was at the quiet level. At 21:53 UT on northern border of the directional pattern appears wavy structure with wavelength about 15 km, and signal amplitude slightly increases. At 22:00 UT in the field of the directional pattern of the radar the NLCs are non-uniform, the dimensions of irregularities of NLCs are less than the Figure 3. Sky luminescence variations in the circle with the radius of 5° above the radar (the simple line) and ordinary wave amplitude of the radar at the height of 84 km (the bold line with crosses). 113