Longitudinal variations of the hydroxyl emission. 2. Height of the emitting layer,vibrational temperature,and intensity

On the basis of multiyear ground-based, rocket, and satellite studies of characteristics of the hydroxyl emission of the upper atmosphere, information on longitudinal changes in the height of its emitting layer, the vibrational temperature, and the intensity of emission of various vibrational levels of the hydroxyl molecule OH is obtained.     

Seasonal temperature variations near the mesopause according to the hydroxyl emission measurements in Zvenigorod

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.     

Empirical model of variations in the helium 1083 nm emission. 2. Temperature

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.     

Empirical model of variations in the 630 nm atomic oxygen emission. 2. Temperature

A model of the temperature variations of the atomic oxygen 630 nm emission for the nighttime conditions is created on the basis of the ground-based interferometer measurements of the Doppler temperature by Fabry-Pérot interferometers. On the basis of these measurements, various regular variations and their approximations for temperature evaluations for the given solar and geophysical conditions in the nighttime period of the day are obtained.     

Empirical model of variations in the emission of the molecular oxygen Atmospheric system. 2. Temperature

The empirical approximations of variations in the rotational temperature of the emission of the molecular oxygen Atmospheric system, obtained based on the systematization of the long-term ground-based observations under different heliogeophysical conditions, are presented.     

Empirical model of variations in the emission of the Infrared Atmospheric system of molecular oxygen: 3. Temperature

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.     

Empirical model of variations in the OI 630 nm emission. 1. Intensity

The empirical model of variations in the atomic oxygen emission intensity depending on different heliogeophysical conditions such as nighttime, lunar time, lunar phase age, season, year, and solar activity level during the 11-year cycle, as well as on cyclic aperiodic activity variations, level of geomagnetic disturbances, and their manifestations in the form of midlatitude subauroral red arcs, has been developed based on the long-term measurements of this emission intensity.     

Empirical model of variations in the helium 1083 nm emission. 1. Intensity

The model of variations in the orthohelium 1083 nm emission intensity has been constructed based on the measurements at different stations. The analytical approximations of the nighttime intensity variations depending on the phase age of the Moon, season, solar activity during the 11-year cycle, and geomagnetic disturbances are presented.     

Empirical model of variations in the continuum emission in the upper atmosphere. 1. Intensity

The ground-based and satellite measurements of the upper-atmosphere continuum (continuous emission) intensity in the visible and near IR spectral regions have been analyzed. The data were obtained at the geophysical stations, located in different regions of the globe, and at Mir Space Station. The regularities in the spectral distribution of the continuum emission intensity and emission variations have been revealed for different heliogeophysical conditions.     

Empirical model of variations in the emission of the molecular oxygen atmospheric system. 1. Intensity

The data on regular variations in the emission intensity of the molecular oxygen Atmospheric system excited in the region of the lower thermosphere have been systematized based on the long-term studies. The empirical approximations of the emission behavior are presented.     

On rotational temperature of the hydroxyl emission

The method for determining the rotational temperature of the hydroxyl emission of the upper atmosphere is analyzed. It is shown that a discrepancy of up to 14 K appears in the temperature values determined for the region of OH emission (～87 km) since different researchers use the intensity factors (line strengths) of the lines of the rotational structure of hydroxyl bands based on various theoretical calculations. This discrepancy considerably exceeds the error (2–3 K) of direct temperature measurements. The use of the set of such data in the analysis of the time and spatial temperature regime can lead to a distortion of the character of the long-term changes in the mesopause temperature. Analytical expressions are obtained making it possible to calculate a systematic correction for the temperatures determined with the use of various intensity factors. One should also take into account considerable seasonal variations in the dependence of rotational temperature values on the level of the hydroxyl vibrational excitation.     

Empirical model of variations in the emission of the infrared atmospheric system of molecular oxygen: 1. Intensity

On the basis of the data of ground-based spectrometric observations in Zvenigorod (55.7°N, 36.8°E) and published results of measurements of the intensity of the Infrared Atmospheric system of molecular oxygen obtained at other stations, empirical relations describing variations in the intensity of the 1.58-μm emission for various solar and geophysical conditions are calculated.     

Temperature and ozone variations in the stratosphere

Examined are temperature and ozone variations in the Northern Hemisphere stratosphere during the period 1958–77, as estimated from radiosondes rocketsondes, ozonesondes, and Umkehr measurements. The temperature variation in the low tropical stratosphere is a combination of the variation associated with the quasi-biennial oscillation, and a variation nearly out of phase with the pronounced 3-yearly temperature oscillation (Southern Oscillation) present in the tropical troposphere since 1963. Based on radiosonde and rocketsonde data, the quasibiennial temperature oscillation can be traced as high as the stratopause, the phase varying with both height and latitude. However, the rocketsonde-derived temperature decrease of several degrees Celsius in the 25–55 km layer of the Western Hemisphere between 1969 (sunspot maximum) and 1976 (sunspot minimum) is not apparent in high-level radiosonde data, so that caution is advised with respect to a possible solar-terrestrial relation.There has been a strong quasi-biennial oscillation in ozone in the 8–16 km layer of the north polar region, with ozone minimum near the time of quasi-biennial west wind maximum at a height of 20 km in the tropics. A quasi-biennial oscillation in ozone (of similar phase) is also apparent from both ozonesonde data and Umkehr measurements in 8–16 and 16–24 km layers of north temperate latitudes, but not higher up. Both measurement techniques also suggest a slight overall ozone decrease in the same layers between 1969 and 1976, but no overall ozone change in the 24–32 km layer. Umkehr measurements indicate a significant 6–8% increase in ozone amount in all stratospheric layers between 1964 and 1970, and in 1977 the ozone amount in the 32–46 km layer was still 4% above average despite the predicted depletion due to fluorocarbon emissions. The decrease in ozone in the 32–46 km, layer of mid latitudes following the volcanic eruptions of Agung and Fuego is believed to be mostly fictitious and due to the bias introduced into the Umkehr technique by stratospheric aerosols of volcanic origin. Above-average water vapor amounts in the low stratosphere at Washington, DC, appear closely related to warm tropospheric temperatures in the tropics, presumably reflecting variations in strength of the Hadley circulation.     

Orography-caused variations in the 557.7 nm atomic oxygen emission intensity

For the first time, the spatial variations caused by the IGW generated in the troposphere when the air flow around the Kopet-Dag mountain ridge are detected based on the measurements of the spatial distribution of the 557.7 nm atomic oxygen emission intensity. The measurements were carried out at Vannovskii station, the Physicotechnical Institute, Academy of Sciences of the Turkmen SSR.     

Empirical model of the OI 630 nm emission variations. 3. Emitting layer height

The empirical model of variations in the emitting layer height and parameters has been developed based on an analysis of the rocket measurements of the vertical distributions in the 630 nm intensity. The dependences on the solar zenith angle during a day are most substantial. This dependence is responsible for the character of seasonal variations at different latitudes. The height of the emitting layer increases with increasing solar activity, reflecting a temperature rise in the upper atmosphere. The negative trend—0.35 km yr^?1 in the interval 1964–1990—has been revealed.     

Empirical model of variations in 656.3-nm hydrogen emission

Based on the measurements of 656.3-nm emission of atomic hydrogen, we constructed a model of variations in its intensity, which describes the dependence of diurnal, lunar, seasonal, latitudinal, and long-term variations, during the 11-year cycle of solar activity, cyclic aperiodic variations, and variations after geomagnetic disturbances.     

Temperature variations in the mesopause region according to the hydroxyl-emission observations at midlatitudes

The seasonal temperature variations in the mesopause region and the inter-day and nighttime temperature variability, the measure of which is standard deviations, have been studied based on the hydroxyl emission spectral observations at the Zvenigorod station of the Obukhov Institute of Atmospheric Physics in 2000–2011 and Institute of Solar Terrestrial Physics geophysical station (Tory) in 2008–2011. The long-term variations in all temperature variability parameters have been analyzed.     

Seasonal features in the response of the mesopause temperature and emission intensities to solar activity variations

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.     

Temperature variations recovered from tree-rings in the middle Qilian Mountain over the last millennium

During the past 1000 years, there had been sev-eral widespread climate events on the earth, such asthe ‘Medieval Warm Period’, the ‘Little Ice Age’ andthe recent warming from the later part of the nine-teenth century onward[1,2]. To better understand thedetails of climatic history on a regional scale, morehigh-resolution, millennia-length climate reconstruc-tions are needed by intensive, multiproxy investigationof ice cores, sediments of loess and lakes, corals andtree-rings. Since …     

Longitudinal variations in the daytime low-latitude ionosphere according to the data of topside sounding from the intercosmos-19 satellite

Using the data of the topside ionosphere sounding from the Intercosmos-19 satellite, longitudinal variations in foF2 at low latitudes at the daytime hours are considered. It is obtained that these variations in particular days in the majority of cases have a regular wave-like character with periods of about 75°–100° in longitude and amplitudes on the average of 2–4 MHz. In other words, along the valley and crests of the equatorial anomaly, a structure with four maximums and four minimums which have a tendency to be located near certain longitudes (the same in all seasons) is observed. The variations in foF2 along the crests of the equatorial anomaly are usually in anti-phase to variations along its valley. Comparing the characteristics of this wavelike structure at the daytime and nighttime hours, we obtained that the average positions of its extremes at the nighttime hours are shifted eastwards by 10°–50° relative to the daytime extremes. As a cause of formation of such a structure, high harmonics of atmospheric tides are assumed which, uplifting from below to heights of the E region, via the electric currents in this region influence the longitudinal structure of the electrodynamic plasma drift over the equator and by that impact the structure of the entire daytime low-latitude ionosphere.