We present the results of studying the influence of geomagnetic storms on the characteristics of the hydroxyl (6-2) emission, which arises at the mesopause heights, and the NmF2 peak electron density. The events of strong geomagnetic storms for which the values of the Dst index were below -100 nT were selected for the analysis. The analysis is based on the observational data of the complex of instruments of the Institute of Solar-Terrestrial Physics SB RAS. It was found, that strong geomagnetic disturbances cause an increase in the OH emission intensity by 50-100 percent with a delay of 2- 5 days after the onset of the storm and oscillating disturbances of the emission intensity and OH rotational temperature decaying with time. In the F2-layer of the ionosphere, during the analyzed periods of geomagnetic storms, significant disturbances of NmF2 were observed.
We present the results of studying variations in the concentrations of the CO and H2O atmospheric constituents over the Baikal Natural Territory from the long-term (2010–2021) data of the MLS Aura satellite measurements. The data were analyzed at the stratospheric heights for pressure levels within 215–10 hPa (~11–32 km) for the locations of Khorinsk (52.17° N, 109.77° E) and Zhigalovo (54.81° N, 105.15° E). We obtained averaged seasonal variations in the concentrations of the analyzed components for each pressure level under day and night conditions for the 2010-2020 period. Comparison of the obtained results with the behavior of the concentrations of atmospheric constituents in 2021 revealed an increased CO concentration for Khorinsk in July–August 2021, when increased smoke from forest fires was observed in the analyzed region.
We present the results of studying year-to-year changes in the variabilities of the mesopause temperature and the peak electron density from the observational data of the complex of instruments of the Institute of Solar-Terrestrial Physics SB RAS in 2008-2020. The analysis involved data on solar and geomagnetic activity, as well as on variations in the Southern Oscillation Index (SOI). We revealed a correlation between the day-to-day variability of the mesopause temperature and SOI variations, with a peak in the La Niña phase and a minimum in the El Niño phase. An analysis of the ionospheric variability and their comparison with changes in geomagnetic and solar activity revealed, that only day-to-day ionospheric variability correlates unambiguously with geomagnetic activity.
We present the results of a comparative analysis of disturbances in the upper atmosphere during the winter sudden stratospheric warmings (SSWs) of various types in January 2013 and February-March 2016 from observations at middle and high latitudes. To investigate the upper mesosphere and low thermosphere (MLT) signatures of the SSWs, we used experimental data on the rotational temperature of the hydroxyl molecule (OH (6-2)) obtained from spectrometric measurements at the Geophysical Observatory of ISTP SB RAS (51.8°N, 103.1°E, Tory). To study the ionospheric disturbances, we analyzed the data on the peak electron density NmF2 obtained from the Irkutsk (52.3°N, 104.3°E) and Norilsk (69.2°N, 88.0°E) DPS-4 Digisondes. The most significant effect of the 2013 January SSW in the MLT was in an increase in the day-to-day variability of the mesopause temperature, due to the intensification of planetary wave activity at these altitudes. During the 2016 February and 2016 March SSWs, the greatest effects were in an increase in the diurnal variability of the mesopause temperature, which can be caused by the influence of tides and internal gravity waves. We revealed strong intra-diurnal NmF2 disturbances over Irkutsk and Norilsk during the 2013 January and 2016 February SSWs. For the February 2016 SSW, the disturbances had a tidal structure. For the 2013 SSW, we found violation of correlation between the variations in NmF2 and solar activity that can be caused by an intensification of the planetary wave activity at the ionospheric heights.
Simple digital filtering is used for studying mesoscale variations of the rotational temperature of excited hydroxyl (OH*) at heights 85 – 90 km according to the data of spectral measurements at observatories Zvenigorod (56°N, 37°E.) in years 2004 – 2016, Tory (52°N, 103°E) in 2012 – 2017 and Maymaga (63°N, 130°E) in 2000 - 2015. Monthly-mean values and standard deviations of OH* temperature disturbances with periods 0.7 – 8 hr are determined, which may reflect the intensity of internal gravity waves in the mesopause region. The filtering of mesoscale variations was performed by calculating the differences between the measured values of OH* temperature separated with time intervals of 0.5 - 2 hr. Seasonal and interannual changes in the mesoscale variances of the temperature at the observational sites are studied.
Using data of the network of chirp sounding radio paths at middle and subauroral latitudes of the Asian region of Russia, we investigated peculiarities of manifestation of medium-scale traveling ionospheric disturbances (MS TIDs) over the Asian region of Russia during solar cycle 24. Typical seasonal dependencies and daily variations in probability of MS TID occurrence and their registration time on one hop radio paths of different directions have been revealed.
We present the results of studying the effects of major winter sudden stratospheric warmings (SSW) in February 2018 and January 2019 in the upper atmosphere over Eastern Siberia. The study was carried out using experimental data on the rotational temperature of the hydroxyl molecule and on the peak electron density NmF2. It was found, that during the SSW periods, a significant increase in the manifestation of the activity of atmospheric waves of different time scales at the heights of the mesopause and the F2-region of the ionosphere was observed, but its nature was different. Thus, the main effect of the major SSW 2018 at the heights of the mesopause and ionospheric F2-region, was in the intensifying the day-to-day variability of the mesopause temperature and NmF2 due to the activity of planetary waves. The most significant effects of the SSW 2019 at the heights of the mesopause were an increase in diurnal temperature variability due to activities of tides and internal gravity waves. In the F2 region of the ionosphere, it was revealed an intensification of the NmF2 day-to-day variability, which may be due to the influence of planetary waves. The observed effects can be caused by intensification of the atmospheric wave activity due to the SSWs.
The systematization and the analysis of long-term data of satellite and rocket measurements of the 5.3-μm nitric oxide emission in the upper atmosphere were carried out. An analysis of photochemical processes leading to the producing of NO emission in the upper atmosphere is performed. Analytical relationships describing the seasonal and latitudinal variations in the intensity of the 5.3 μm NO emission, its altitude distribution, and the dependence on solar activity are obtained.
We present the results of studying the temperature regime and the composition of the mid-latitude atmosphere at the mesopause heights during the periods of minor and final stratospheric warmings in February-March 2016. We used the data from the spectrometric observations of the hydroxyl emission at the Geophysical Observatory (Tory, 51.8°N, 103.1°E ) of the Institute of Solar-Terrestrial Physics (Irkutsk) and at Zvenigorod station (55.7º N, 36.8º E) of the A.M. Obukhov Institute of Atmospheric Physics (Moscow). The technique for calculating the concentrations of atomic oxygen and ozone at the OH emission layer using experimental data on the emission intensity and rotational temperature of the OH molecule, the photochemical model of OH radiation, and MSISE-E-90 model is described. It was found, that during the periods of analyzed stratospheric warmings significant, up to 250%, variations in the OH emission intensity and concentrations of atomic oxygen and ozone in the mesopause region were observed. The longitudional differences in the effects of the stratospheric warmings on the characteristics of the mesopause region were revealed.
We analyzed and systemized the published data on satellite and rocket long-term measurements of the oxygen atom O(3P) (63 μm) and of the СО2 molecule (15 μm) infrared (IR) emissions in the upper atmosphere. We revealed and presented empirical ratios describing the diurnal, seasonal, and latitudinal variations in the intensities of these emissions, their height distribution, as well as their dependence on solar activity. We analyzed photochemical atmospheric processes leading to the emergence of O(3P) (63 μm) and of СО2 (15 μm) emissions in the upper atmosphere.
We present the results of studying the state of the neutral upper atmosphere and the ionosphere over the Eastern Siberia region during minor winter sudden stratosphere warming (SSW) in early February, 2016 and final stratospheric warming in early March, 2016. We used the data from spectrometric measurements of OH (~87 km, 834.0 nm, (6-2)) and At O2 (~94 km, 864.5 nm, (0-1)) emissions from the Geophysical Observatory at the Institute of Solar-Terrestrial Physics SB RAS (51.8°N, 103.1°E, Tory). We also used the vertical sounding data on the peak electron density (NmF2), and on the peak height (hmF2). These data were obtained with the DPS-4 Irkutsk ionosonde (52.3°N, 104.3°E). For the analysis, we also involved the MLS Aura satellite data of measuring vertical temperature profiles and the MERRA reanalysis data. We found the MLT and ionospheric signatures for both analyzed SSWs. At MLT heights, a significant increase in the OH and O2 emission intensities, a decrease in the atmosphere temperature, and an increase in wave activity were found. In the F2-region, we revealed significant (up to ~80 %) NmF2 positive disturbances in the postmidnight hours, which are not associated with geomagnetic activity variations. The revealed effects can be caused by the intensification of the activity of atmospheric waves and the enhancement of vertical transport of atmospheric components caused by stratospheric warmings.
We calculated the absolute integrated intensity of the continuum emission infrared components using the laboratoryobtained rates of photochemical reaction between nitric oxide molecules and oxygen atoms, as well as with non-excited and excited ozone molecules. Altitude distribution of the intensity of continuum radiation in atmosphere in infrared region of a spectrum covers a range of heights of the middle atmosphere from 10 up to 15 km with a maximum at height about 30 km.
On the basis of spectral observations of the hydroxyl emission (band (6-2), 834 nm) in the Eastern Siberia, at Tory (52N, 103E), and in
the European Russia, at Zvenigorod (55.7N, 36.8E), during 2008-2011 the statistically significant seasonal variations of the
mesopause temperature and its day-to-day and night variabilities are revealed. Standard deviations of temperature were used as
parameters of its variability, which allow us to analyze the seasonal activity of planetary waves, tides and internal gravitational waves.
The comparison of the results, obtained in different regions of Russia, shows higher values of variability of the mesopause temperature
in the Eastern Siberia.
On the basis of the photochemical model for atomic oxygen [OI] 558 nm nightglow emission and an approximate
expression for the altitude distribution of the atomic oxygen density in the MLT region at night, we develop a method for
deriving the peak density of atomic oxygen in the MLT region from atomic oxygen [OI] 558 nm nightglow intensity. By
using this method, the peak density of atomic oxygen is derived from the 558 nm airglow data received at the ISTP SB
RAS Geophysical observatory in 2000-2004. The nocturnal variations and the seasonal variations of 558 nm airglow
intensity and the derived peak density of atomic oxygen are considered. The results show that nocturnal variation of the
558 nm airglow intensity changes with season and that the monthly mean 558 nm airglow intensity changes with month,
showing peaks in March, June and October, and larger values in the winter months The nocturnal and the seasonal
variations of the peak density of atomic oxygen are generally similar to those of 558 nm airglow intensity.
We present preliminary analysis of experimental data of the nightglow observation of the atomic oxygen 557.7 nm
(emitting layer height is 85-115 km) and 630 nm (180-250 km) lines emissions in the 23-rd solar cycle. The
experimental data were obtained at ISTP Geophysical observatory near Irkutsk (52° N, 103° E). The 557.7 nm and 630
nm emissions observational data are compared with atmospheric, solar and geophysical parameters. Generally, the 630
nm emission intensity in the 23-rd solar cycle changed in a phase with the solar cycle, increasing from the period of low
solar activity to the period of high solar activity. The difference of correlation coefficient between green line intensity
and F10.7 solar radio flux in various phases of the 23-rd solar cycle was marked. During the increasing and maximum
phases of the solar cycle the negative correlation between monthly mean values of the 557.7 nm emission intensity and
the F10.7 was revealed. The correlation became positive during the descending phase.
Broken phase synchronism of 557.7 nm emission behavior and F10.7 during the growth and maximum phase of the 23-rd solar cycle is preliminary interpreted by high sensitivity of the atmospheric parameters determining 557.7 nm
emission intensity to atmospheric dynamics and various disturbances including the effects from lower atmospheric
layers.
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.
Upper-atmospheric airglow observations were used to investigate the seasonal variation of upper-atmospheric emission in the atomic oyxgen 558 nm line over the region of East Siberia. There is a qualitative agreement with the seasonal variations of 558 nm emission obtained in preceding decades at other mid-latitude stations, as well as with model approximations. Quantitative differences of the seasonal variation of 558 nm emission for the region of East Siberia are considered, which imply a more pronounced autumn maximum and larger values of monthly mean 558 nm emission intensities in the winter months. An analysis of the factors and phenomena that are responsible for the seasonal variation of 558 nm emission, and a comparision with the wind regime dynamics of the upper mesosphere - lower thermosphere as well as with stratospheric warmings in the region of East Siberia suggests the existence regional features in the seasonal variation of 558 nm emission.
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