Alexander B. Beletsky

Simultaneous radio and optical observations of the mid-latitude atmospheric response to a major geomagnetic storm of 6–8 April 2000

Basic properties of the mid-latitude traveling ionospheric disturbances (TIDs) during the maximum phase of a major magnetic storm of 6 –8 April 2000 are shown. Total electron content (TEC) variations were studied by using data from GPS receivers located in Russia and Central Asia. The nightglow response to this storm at mesopause and termospheric altitudes was also measured by optical instruments FENIX located at the observatory of the Institute of Solar-Terrestrial Physics (51:9 ◦ N; 103:0 ◦ E), and MORTI located at the observatory of the Institute of Ionosphere (43:2 ◦ N; 77:0 ◦ E). Observations of the O (557:7 and 630:0 nm) emissions originating from atmospheric layers centered at altitudes of 90 and 250 km were carried out at Irkutsk and of the O2(b 1 + g −X 3 − g ) (0-1) emission originating from an atmospheric layer centered at altitude of 94 km was carried out at Almaty. Our radio and optical measurement network observed a storm-induced solitary large-scale wave with duration of 1 h and a wave front width of no less than 5000 km, while it traveled equatorward with a velocity of 200 m=s from 62 ◦ Nt o 38 ◦ N geographic latitude. The TEC disturbance, basically displaying an electron content depression in the maximum of the F2 region, reveals a good correlation with growing nightglow emission, the temporal shift between the TEC and emission variation maxima being diAerent for diAerent altitudes. A comparison of the auroral oval parameters with dynamic spectra of TEC variations and optical 630 nm emissions in the frequency range 0.4 –4 mHz (250 –2500 s periods) showed that as the auroral oval expands into mid-latitudes, also does the region with a developed medium-sale and small-scale TEC structure. c

Variations of the ground-measured solar ultraviolet radiation during the solar eclipse on March 9, 1997

Abstract Results of investigations of the solar ultraviolet radiation measured on the ground during the solar eclipse observed over Irkutsk on March 9, 1997 are presented. The spectral distribution variations (radiation 296–326 nm) are revealed and discussed in connection with proposed ozone-eclipse effect. It is suggested that variations in spectra observed at the time close to the maximum phase of eclipse can be caused by the multiple scattering effect of the ultraviolet radiation.

An investigation of the upper atmospheric optical radiation in the line of atomic oxygen 557.7 nm in East Siberia

Abstract The observed data of night sky emission in lines 557.7 and 630nm for the 1997–1999 seasons above the East-Siberian region are shown. The abnormal increase of intensity of emission 557.7nm in January–February 1998 is described. The possible connection of this phenomenon with a stratosphere warmings above Eastern-Siberia during this season is discussed.

Comparison of ground-based OH temperature data measured at Irkutsk (52°N, 103°E) and Zvenigorod (56°N, 37°E) stations with Aura MLS v3.3

Data about the variations of mesopause temperature (∼87 km) obtained from ground-based spectrographic measurements of the OH emission (834.0 nm, band (6-2)) at Irkutsk and Zvenigorod observatories were compared with satellite data on vertical temperature distribution in the atmosphere from Aura MLS v3.3. We analyzed MLS data for two geopotential height levels: 0.005 hPa (∼84 km) and 0.002 hPa (∼88 km) as the closest to OH height (∼87 km).We revealed that Aura MLS temperature data have lower values than ground-based (cold bias). In summer periods, that difference increases. Aura cold biases compared with OH(6-2) at Irkutsk and Zvenigorod were calculated. For the 0.002 hPa height level, the biases are 10.1 and 9.4 K, and for 0.005 hPa they are 10.5 and 10.2 K at Irkutsk and Zvenigorod, respectively. When the bias is accounted for, an agreement between Aura MLS and OH(6-2) data obtained at both Irkutsk and Zvenigorod is remarkable.

Features of longitudinal variations in atmospheric temperature at heights of the radiating layer of 557.7-nm emission of atomic oxygen

On the basis of correlations between seasonal variations in the intensity and temperature of 557.7-nm emission, the mean monthly longitudinal variations in temperature are drawn. A comparison is performed with the data of interferometer and lidar measurements of temperature performed at various stations, as well as with the results of satellite studies. The dependences of the amplitudes of seasonal variations in temperature on latitude are obtained.

Influence of stratospheric warming on 557.7 nm airglow variations

We investigate the influence of stratospheric warming on 557.7 nm airglow variations on the basis of the experimental data received at the ISTP SB RAS Geophysical observatory (52°N, 103°E) in 1998-2005. In the researched period some cases of abnormal behavior of 557.7 nm airglow intensity in absence of strong geomagnetic disturbances have been found out. We revealed, that these significant increasing of 557.7 nm airglow intensity concerning to mesosphere-low thermosphere heights, are caused by strong stratospheric warming when disturbances cover the big range of atmosphere heights. It is emphasized, that for the Asian region, and, in particular, for the region of Eastern Siberia, there is a big concentration of stratospheric warming centers that can result in occurring regional features in airglow characteristics.