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1.
Estimate of seasonal changes in the intensity of the infrared atmospheric system of molecular oxygen
A. I. Semenov V. I. Perminov K. V. Lipatov V. Yu. Khomich 《Geomagnetism and Aeronomy》2011,51(3):415-420
On the basis of measurements of the intensity of 1.58-μm emissions of the Infrared Atmospheric System of molecular oxygen
(IRAO2) conducted at the Zvenigorod scientific station of the Institute of Atmospheric Physics of the Russian Academy of Sciences
(φ = 55.7°N, λ = 36.8°E), seasonal variations are estimated for various solar zenith angles. Their amplitude has the maximum
value at the solar zenith angles χ
S
∼ 105–110°. It decreases at χ
S
∼ 125–130° and tends to zero at χ
S
∼ 80–85°. The comparison of currently measured values of the 1.58-μm emission intensity of the Infrared Atmospheric System
of molecular oxygen with published data on the intensity of this emission obtained in 1961–1966 reveals their decrease over
approximately 50 years. This fact is in good agreement with similar behavior of the emission intensity of atomic oxygen (557.7
nm) over the period considered. 相似文献
2.
A. V. Mikhalev 《Geomagnetism and Aeronomy》2010,50(8):1021-1024
The effect of anomalously high average nighttime intensities of the atomic oxygen 557.7-nm atmospheric emission (luminescence
heights 85–115 km) during sudden winter stratospheric warming events (SWEs) in Eastern Siberia is considered. Analysis of
the variations in the 557.7-nm emission intensity (I
557.7) revealed the interdaily I
557.7-nm variations during SWEs and high average monthly I
557.7-nm values in the winter months in conditions of high solar activity. It has finally been found that the variations with periods
of several days, at a maximum of which anomalously high daily values of I
557.7 are observed, are superposed on the average I
557.7-level during SWEs at high solar activity. A high average level of I
557.7 in the winter months in Eastern Siberia can be related to the fact that the atomic oxygen concentration at altitudes of the
557.7 nm emission luminescence increases by a factor of 2–3 in years of high solar activity. 相似文献
3.
The study is based on measuring fluctuations of the intensity and rotational temperatures of the molecular emissions of hydroxyl OH(6,2) and the first atmospheric band of oxygen O2(0–1), excited at approximately 87 and 95 km, respectively. The measurements are conducted at Maimaga station (63°N, 129.5°E), located 150 km north of Yakutsk. The semidiurnal tide parameters were obtained using the database compiled from 1999 to 2005. The data obtained from October to March were analyzed. The measurements conducted during 214 nights were used to determine the semidiurnal tide parameters. The wave amplitude at the height of the molecular oxygen emission (~95 km) is 8 K, which is larger than the amplitude at the height of the hydroxyl emission (~87 km) by approximately 2 K. Except November, the 12-h oscillation at the height of molecular oxygen excitation leads the oscillation at the height of hydroxyl excitation. On average, the phase is ~5.7 h at the OH emission height and ~6.4 h at the O2 emission height. We note that an abrupt increase in the tide amplitude in March at the molecular oxygen height can be related to a seasonal decrease in the so-called “wave” turbopause height. 相似文献
4.
The mesopause kinetic temperature at an altitude of 87 km measured with a SABER broadband radiometer installed on the TIMED
satellite and the hydroxyl molecule rotational temperature measured with a ground-spectrograph installed in high-latitude
eastern Siberia (Maimaga optical station; φ = 63°N, λ = 129.5°E) are compared. The data of the observations performed from
2002 to 2006 have been analyzed. The temperatures measured during the satellite passes at distances not larger than 300 km
from the intersection of the spectrograph sighting line with the hydroxyl emitting layer (∼87 km) have been compared. An analysis
of 130 cases of coincident measurements indicated that the average hydroxyl molecule rotational temperatures are systematically
lower than the average kinetic temperature at an altitude of the hydroxyl layer measured with SABER by 4.4 K (with a standard
deviation of 11.4 K). A seasonal dependence is observed regarding the difference between the ground-based and satellite measurements.
The difference decreases from 10 K in January to zero towards March. However, the time variations in the temperature obtained
with the ground-based device and on the satellite are similar. Based on the performed analysis, it has been concluded that
a series of hydroxyl rotational temperatures can be used to study temperature variations on different time scales, including
long-term trends at the temperature emission altitude (∼87 km). 相似文献
5.
The data of the DMSP F7 spacecraft are used for studying the influence of the geomagnetic dipole tilt angle on the latitudinal position of auroral
precipitation boundaries in the nighttime (2100–2400 MLT) and daytime (0900–1200 MLT) sectors. It is shown that, in the nighttime
sector, the high-latitude zone of soft diffuse precipitation (SDP) and the boundary of the polar cap (PC) at all levels of
geomagnetic activity are located at higher and lower latitudes relative to the equinox period in winter and summer, respectively.
The position of boundaries of the diffuse auroral precipitation zone (DAZ) located equatorward from the auroral oval does
not depend on the season. In the daytime sector, the inverse picture is observed: the SDP precipitation zone takes the most
low-latitude and high-latitude positions in the winter and summer periods, respectively. The total value of the displacements
from winter to summer of both the nighttime and daytime boundaries of the PC is ∼2.5°. A diurnal wave in the latitudinal position
of the nighttime precipitation boundaries is detected. The wave is most pronounced in the periods of the winter and fall seasons,
is much weaker in the spring period, and is almost absent in summer. The diurnal variations of the position of the boundaries
are quasi-sinusoidal oscillations with the latitude maximum and minimum at 0300–0500 and 1700–2100 UT, respectively. The total
value of the diurnal displacement of the boundaries is ∼2.5° of latitude. The results obtained show that, undergoing seasonal
and diurnal variations, the polar cap is shifted as a whole in the direction opposite to the changes in the tilt angle of
the geomagnetic dipole. The seasonal displacements of the polar cap and its diurnal variations in the winter period occur
without any substantial changes in its area. 相似文献
6.
Based on the measurements of the ortho helium 1083 nm emission intensity during twilights and on the calculation of its variations depending on the solar zenith angle, the method for determining the atmospheric temperature at heights of 300–1000 km during the nighttime period of day has been developed, taking into account the diurnal and seasonal conditions. 相似文献
7.
N. Iwagami T. Shibaki T. Suzuki H. Sekiguchi N. Takegawa W. H. Morrow 《Journal of Atmospheric and Solar》2003,65(16-18):1349-1360
Atomic oxygen density and airglow volume emission rate profiles measured in the rocket experiment S-310-29 carried out as a part of the Waves in Airglow Structures Experiment over Kagoshima in 2000 (WAVE2000) campaign are presented, and the excitation processes of the atomic oxygen 557.7 nm line and the molecular oxygen atmospheric band airglow emissions are discussed. The volume emission rate profiles calculated from the measured atomic oxygen densities using the methods and parameters proposed by the ETON campaign (EATON model) are found to well represent the shapes of measured twin-peak emission rate profiles seen during this campaign suggesting that the EATON model is valid for a perturbed atmosphere. There is some discrepancy in the modeled absolute values for the emissions. Applying the model to the current O density measurements results in predicted emission rates that are a factor of 3.2 and 1.5 too high for the 557.7 nm line and Atmospheric band, respectively. This suggests either that the atomic oxygen densities of the present campaign are too large by a factor of 1.2 (=1.51/2) to 1.5 (=3.21/3), or that those of the ETON campaign were too small by the same factor or that the combined errors in both campaigns can account for the discrepancy (the modeled volume emission rates of the 557.7 nm line and atmospheric band are roughly in proportion to [O]3 and [O]2, respectively). Our present data findings do not favor the 2-step more than the 1-step excitation process for the atmospheric band because a calculation of the quantum efficiency based on the observed O density does not show a steep gradient around 100 km. 相似文献
8.
The optical observations on Heiss Island (Φ′ = 75.0°) have been used to study the characteristics of auroras in the near-noon
MLT sector after abrupt increases in the solar wind dynamic pressure at negative and positive polarity of the IMF B
z
component. It has been found out that the 427.8 and 557.7 nm emission intensities considerably increased at B
z
< 0 both equatorward of the dayside red luminosity band and within this band. The value of the emission intensities at a
red luminosity maximum (I
6300/I
5577 ∼ 0.5) indicates that energetic electron precipitation is of the magnetospheric origin. At B
z
> 0, fluxes of harder (E > 1 keV) precipitating electrons were superimposed on the soft spectrum of precipitating particles in the equatorial part
of the red luminosity band. This red band part was hypothetically caused by the low-latitude boundary layer (LLBL) on closed
lines of the geomagnetic field, the estimated thickness of which is ∼3 R
e
. The 557.7 nm emission intensity increased during 3–5 min after SC/SI and was accompanied by the displacement of the red
band equatorward boundary toward lower latitudes. The displacement value was ∼150–200 km when the dynamic pressure abruptly
increased by a factor of 3–5. After SC/SI, the 630.0 nm emission intensity continued increasing during 16–18 min. It is assumed
that the time of an increase in the red line intensity corresponds to the time of saturation of the magnetospheric boundary
layers with magnetosheath particles after an abrupt increase in their density. 相似文献
9.
The seasonal dependences of the response of the hydroxyl ((6–2) band) and molecular oxygen O2(b 1Σ g + ) ((0–1) band) emission intensities, temperature, and density indicator in the region of the hydroxyl emission maximum (87 km) to solar activity have been obtained based on the spectral observations of the mesopause emissions at Zvenigorod observatory during 2000–2007. The ratio of the OH (7–3) and (9–4) band intensities, characterizing the behavior of the vibrational temperature, has been used as an indicator of density. It has been established that the response of the studied mesopause characteristics to solar activity is positive in all seasons. In winter the response is maximal in the intensities and temperature and is minimal in the density indicator. The main mechanisms by which solar activity affects the mesopause characteristics have been considered. The behavior of the internal gravity waves with periods of 0.33–7 h depending on solar activity has been studied. It has been noted that these waves become more active at a minimum of the 11-year solar cycle. 相似文献
10.
G. I. Druzhin V. N. Uvarov V. A. Mullayarov V. I. Kozlov A. A. Korsakov 《Geomagnetism and Aeronomy》2010,50(2):211-218
The effect of the solar eclipse that occurred on August 1, 2008, on the level of the natural electro-magnetic emission signals
in the ELF-VLF range, simultaneously observed at Kamchatka and in Yakutsk, and the variations in the amplitude and phase of
signals from the VLF radiostations, registered in Yakutsk, has been considered. The VLF radiostations in Krasnodar, Novosibirsk,
and Khabarovsk successively emitted signals at frequencies of 11 905, 12 649, and 14 880 Hz. Based on the observations of
the signals from these radiostations, it has been established that the signal amplitudes and phases increased by 3–5% and
30°–45° when the signals crossed the lunar shadow region. The synchronous registration of the ELF-VLF noise emission indicated
that a bay-like increase and the following decrease in the emission to the background level was observed at both receiving
points during the eclipse from ∼1000 to 1130 UT. This effect was registered at frequencies of 0.6–5.6 kHz in Yakutsk and at
lower (30–200 Hz) and higher (2.5–11 kHz) frequencies at Kamchatka. In this case the noise emission intensity maximum was
observed when the lunar shadow maximally approached the registration point. At higher frequencies, the emission maximum was
observed simultaneously at both points (at 1100 UT) but with a delay relative to the maximum at lower frequencies. The possible
causes of the appearance of the solar eclipse effects in the natural ELF-VLF emission are considered. 相似文献
11.
Seasonal temperature variations near the mesopause according to the hydroxyl emission measurements in Zvenigorod 总被引:1,自引:0,他引:1
V. I. Perminov 《Geomagnetism and Aeronomy》2009,49(6):797-804
The rotational temperatures of hydroxyl molecules with different vibrational excitation, which were used to determine the
seasonal variations in the vertical temperature distribution near the mesopause at altitudes of 85–90 km, have been obtained
based on the spectral measurements of the atmospheric nightglow at IFA RAN observatory in Zvenigorod. The obtained characteristics
of the annual and semiannual harmonics have been compared with their lidar and satellite measurements and model representations. 相似文献
12.
Seasonal and year-to-year variability in the intensity of the 557.7 nm line of atomic oxygen atmospheric emission and its
dependence on solar activity in the 23rd solar cycle is considered. The experimental data of the 557.7 nm emission observations
in Eastern Siberia obtained in 1997–2008 and the NRLMSIS-00 atmospheric model are used. For particular considered characteristics
of the 557.7 nm emission, differences between the experimental data and model approximations for the 23rd solar cycle are
noted. Possible causes of the discovered discrepancies are discussed. 相似文献
13.
14.
V. I. Larkina 《Geomagnetism and Aeronomy》2010,50(3):320-328
The complex geophysical pattern of the development of geomagnetic storm in VLF emissions has been studied based on the satellite
data. It has been established that the variations in the LF noise emission intensity (0.1–20.0 kHz) and the energetic electron
(E ≥ 40 keV) flux density reflect the processes of magnetospheric plasma reconstruction during geomagnetic disturbances. It
has been indicated that a distinct structure of the inner and outer radiation belts is observed under quiet conditions, and
the VLF emission maximum was registered at L = 4–5. The inner boundary of the outer radiation belt shifted to lower latitudes, the intensity of the noise VLF emissions
increased, and the intensity maximum was displaced to L = 2.5–3.5 during the geomagnetic storm, when the energetic electron flux density increased. The VLF noise spectrum widened
toward higher frequencies. The VLF noise level continued increasing, the noise maximum shifted to L = 4–5, and the fluxes of precipitating electrons abruptly increased during the storm recovery phase, when the density of
the flux of quasitrapped electrons remained increased for a long time. 相似文献
15.
G. A. Mikhailova Yu. M. Mikhailov O. V. Kapustina S. E. Smirnov 《Geomagnetism and Aeronomy》2010,50(6):814-823
We have performed a spectral analysis of variations in the E
z
component of a quasistatic electric field in the atmospheric surface layer in a wide band of internal gravity waves (from
5 min to 3 h) for quiet and seismically active conditions as well as high thunderstorm activity. Observational data of the
field for September, 1999 and August–September, 2002, were used. It has been shown that, if there are no thunderstorms or
earthquakes, the background spectrum includes oscillations with maxima at periods of T ∼ 1.8 and 1 h, 40, 30, 15, and 10–13 min. Their intensity in the range of periods of 0.5–3.0 h is two or more orders of magnitude
higher than the intensity of maxima in the range of 5–30 min. Before earthquakes, with anomalies in diurnal variations of
field intensity, there is a tendency of increased background spectrum at maxima noted there. In both ranges of oscillation
periods, the spectral intensity increases by one to one and a half orders of magnitude. Under high thunderstorm activity,
the variability is higher as compared to the spectra of earthquake precursors by both locations of maxima and their intensity.
The intensity of maxima exceeds the maxima on the eve of earthquakes one to one and a half orders of magnitude in the range
of periods 0.5–3.0 h and two and more orders of magnitude in the range of periods 5–30 min. 相似文献
16.
Rotational temperatures of the 1.58-μm (0–1) band of the Infrared Atmospheric system of molecular oxygen (IRAO2), measured in Zvenigorod (56° N, 36° E), are systematized and analyzed. An empirical dependence of variations in the temperature of the 1.58-μm emission on the solar zenith angle is derived. The use of parameters of the altitude distribution of emission intensity 1.27 μm of middle atmosphere temperature profiles, received from the AURA satellite, allowed for the study of daily variations in the temperature of the 1.58-μm emission. It is revealed that the behavior of these variations corresponds to daily variations in the atmospheric temperature at altitudes of the radiating layer of IRAO2, received from the AURA satellite. 相似文献
17.
The results of studying the atmospheric and ionospheric variability in the region of Eastern Siberia are presented. The analysis involved data on the atmosphere temperature at mesopause heights (Tm) and vertical sounding data on the peak electron density (NmF2). The data on temperature were obtained by spectrometric observations of the hydroxyl molecule emission (band ОН (6-2), 834.0 nm, maximum emission height ~87 km). The analysis covers the period from 2008 to 2015. Seasonal and year-to-year variations in the variability of Tm and NmF2 were studied and compared in different time periods: day-to-day variations (T > 24 h), tidal variations (8 h ≤ T ≤ 24 h), and variations with periods of internal gravity waves (T < 8 h). Both common features and distinctions in the behavior of the analyzed parameters have been found, and their possible physical causes are analyzed. 相似文献
18.
The characteristics of dayside auroras during the large (16–24 nT) positive values of the IMF B
z
component, observed on January 14, 1988, during the interaction between the Earth’s magnetosphere and the body of the interplanetary
magnetic cloud, have been studied based on the optical observations on Heiss Island. A wide band of diffuse red luminosity
with an intensity of 1–2 kilorayleigh (kR) was observed during 6 h in the interval 1030–1630 MLT at latitudes higher than
75° CGL. Rayed auroral arcs, the brightness of which in the 557.7 nm emission sharply increased to 3–7 kR in the postnoon
sector immediately after the polarity reversal of the IMF B
y
component from positive to negative, were continuously registered within the band. Bright auroral arcs were observed at the
equatorward edge of red luminosity. It has been found out that the red auroral intensity increases and the band equatorward
boundary shifts to lower latitudes with increasing solar wind dynamic pressure. However, a direct proportional dependence
of the variations in the auroral features on the dynamic pressure variations has not been found. It has been concluded that
the source of bright discrete auroras is located in the region of the low-latitude boundary layer (LLBL) on closed geomagnetic
field lines. The estimated LLBL thickness is ∼3 R
e
. It has been concluded that the intensity of the dayside red band depends on the solar wind plasma density, whereas the position
of the position equatorward boundary depends on the dynamic pressure value and its variations. 相似文献
19.
A. V. Frank-Kamenetskii A. L. Kotikov A. A. Kruglov G. B. Burns N. G. Kleimenova O. V. Kozyreva M. Kubitski A. Odzimek 《Geomagnetism and Aeronomy》2012,52(5):629-638
We have analyzed variations in the near-surface atmospheric electric field (Ez) normalized to their daily averages that were simultaneously observed in different high-latitude regions at moderate geomagnetic activity (Kp ∼ 3). The Ez data were measured under fair weather conditions at the Vostok Antarctic research station (Φ′ = −83.5°) in the southern polar cap and at the Hornsund Arctic observatory (Φ′ = 74.0°) on Svalbard close to the polar boundary of the auroral oval in the Northern Hemisphere. It is established that variations in the atmospheric electric field in the polar cap region at the Vostok station are controlled (the correlation coefficient R ∼ 0.7–0.9) by variations in the overhead ionospheric potential. The situation at the Hornsund observatory is more complicated. During intervals when Hornsund occurred below the westward electrojet, the correlation was typically positive with R ∼ 0.60–0.85; however, while this observatory was in the region of the eastern electrojet, the correlation could be negative with R ∼ 0.7–0.8. Normally, during such periods, the westward electrojet was detected polarwards of Hornsund while, according to the SuperDARN radar data, the observatory was located below the negative vortex of the polar ionospheric convection. 相似文献
20.
The peculiarities of the distribution of medium-scale acoustic gravity waves (AGWs) in polar regions according to the data
of measurements on board the Dynamics Explorer 2 satellite are studied. Over polar regions of both hemispheres at heights
of 250–400 km, wave variations in neutral atmospheric parameters were systematically registered. These variations were identified
as AGWs with horizontal wavelengths of 500–650 km. The relative amplitudes of polar AGWs in a neutral concentration reach
10%. Wave trains extend over the polar caps to thousands of kilometers and show a distinct spatial relationship with the auroral
oval. A systematic direction is found in AGW propagation from the nighttime sector of the oval into the day-time sector, where
wave activity is strictly limited. An assumption is formulated that this restriction is caused by dynamic interactions between
AGWs and the zonal wind in the daytime sector of the auroral oval. 相似文献