V. V. Bychkov

Lidar Observations and Formation Mechanism of the Structure of Stratospheric and Mesospheric Aerosol Layers over Kamchatka

Lidar observations during 2007–2008 in Kamchatka revealed aerosol layers in the upper stratosphere at heights of 35–50 km and in the mesosphere at heights of 60–75 km. It is well known that forces of gas-kinetic nature, i.e., photophoretic forces, act on aerosol particles that absorb solar radiation and terrestrial IR radiation; these forces can counteract the gravitational force and even lead to the levitation of these particles at particular heights. The accumulation of particles at these heights may lead to the formation of aerosol layers. We calculated these forces for the conditions of lidar observations in Kamchatka. Aerosol layers were observed at heights where particle levitation can occur. Thus, the stratospheric and mesospheric aerosol layers, detected at heights of 30–50 and 60–75 km, respectively, may be due to the effect of the photophoretic force on aerosol particles.

Lidar observations of aerosol occurrence in the middle atmosphere of Kamchatka in 2007–2011

The lidar observations, performed in Kamchatka during period from October 2007 to December 2010, are used to analyze the behavior of the vertical aerosol structure in the altitude interval of 30–80 km. The data obtained revealed a regular occurrence of the aerosol scattering during winter in the upper stratosphere and mesosphere at altitudes of 60–75 km. The aerosol scattering in these regions becomes apparent in late October and disappears in March-April. During the warm season (from April to October), the lidar signals correspond well to Rayleigh molecular scattering.

Lidar returns from the upper atmosphere of Kamchatka according to observations in 2008

We present the experimental data which show that backscattered signals at the wavelength of 532 nm correlate with parameters which determine the plasma content in the nocturnal F2 layer of the ionosphere. Based on analysis of lidar data and the geophysical situation, we discuss the hypothesis of a possible role of highly excited Rydberg atoms in the formation of lidar returns from ionospheric altitudes.

Dynamics of Lidar Reflections of the Kamchatka Upper Atmosphere and Its Connection with Phenomena in the Ionosphere

The results of Rayleigh lidar sounding of the upper atmosphere over Kamchatka are analyzed in comparison with ionosonde data. A correlation between light backscattering signals at a wavelength of 532 nm and parameters determining the content of plasma in the nocturnal F2 layer of the ionosphere is found. Based on the performed analysis of lidar data and the geophysical situation, a hypothesis about the possible role of Rydberg atoms in the formation of lidar reflections at ionospheric heights is discussed.

Lidar returns from the upper atmosphere and possible causes of their generation

New experimental data which confirm episodic occurrence of the correlation of light backscattering lidar signals from a 150–300 km altitude region with the plasma content in the nighttime F2 layer of the ionosphere are presented. Analysis results of lidar observation data for 2008–2014 are given. A conclusion is drawn that these correlations occur when additional sources for ionosphere ionization appear. A hypothesis is discussed that the resonance scattering by excited atomic nitrogen ions is a possible cause of generation of these signals.

Seasonal features of the appearance of aerosol scattering in the stratosphere and mesosphere of Kamchatka from the results of lidar observations in 2007–2009

The behavior of the vertical aerosol structure (profiles of the ratio of the coefficients of the backward total and molecular scattering) in the height interval 30–80 km is analyzed from the results of lidar observations in Kamchatka over the period from October 2007 through December 2009. The obtained data revealed a regular two-layer aerosol structure in this height range with the maxima of the ratio of the scattering coefficients in the upper stratosphere at heights 35–50 km and in the mesosphere at heights of 60–75 km, as well as a relation between seasonal variations in the aerosol stratification and the circumpolar vortex affecting dynamic processes in the atmosphere of midlatitudes. The procedure of including the aftereffect of the Hamamatsu-M8259-01 PEM, which influences the error in the calculation of the ratio of scattering coefficients, is described.

Lidar investigations of the scattering of the upper and middle atmosphere

The results of two-frequency lidar investigation of the atmosphere scattering are presented. The observations were carried out at the wavelength of 561 and 532 nm. The radiation band of lasers covers two emission lines of atomic oxygen (561.106 and 561.346 nm) and three emission lines of atomic nitrogen (532.020, 532.087 and 532.095 nm). The lines correspond to the transitions between the exited states of ions of atomic oxygen or nitrogen. The possibility of application of the lidar method for ionosphere investigations is discussed. The physical basis of such method may be the resonance scattering on upper atmosphere ions. The authors discuss the conditions when the impact of the resonance scattering into the lidar signal at the mesosphere heights is observed.

Resonance scattering at excited atoms and ions of the upper atmosphere as a possible mechanism for ionosphere investigations

According to the results of lidar observations in 2014, new experimental data are presented. They confirm the possibility of correlation of lidar signals backscattering at the wavelength of 532 nm with the parameters determining plasma content in the nighttime ionospheric F2 layer. The possibility of application of the lidar method in ionosphere investigations is discussed. The physical basis of this method may be the resonance scattering on the exited atoms and ions of the upper atmosphere.

Lidar and satellite temperature measurements during the sudden stratospheric warmings over Siberia and the Russian Far East in 2008–2012

This article presents a comprehensive study of disturbances of the temperature regime of the Earth’s stratosphere, which are related to sudden stratospheric warmings over Western and Eastern Siberia and the Russian Far East in the winters of 2008–2012. This study is based on data obtained using temperature remote-sensing techniques (lidar and satellite ones). The analysis rests on data on vertical temperature distribution in the stratosphere, obtained from lidar measurements over regions of Tomsk (56°N, 85°E), Yakutsk (61°N, 130°E), and Paratunka, the Kamchatka territory (53°N, 158°E). For complex analysis of the spatial–temporal temperature distribution in the middle atmosphere, the lidar measurement data are applied along with satellite data on temperature acquired by the microwave limb sounder on the Earth Observing System Aura satellite. We consider the regional effects of sudden stratospheric warmings that were observed over the Asian region of Russia (~85–160°E) in the winters of 2008–2012. There were stratospheric warmings over the Asian region of Russia each winter during the period under consideration, as deduced from lidar and satellite measurements of temperature. Lidar and satellite measurements of temperature have evidenced the previously known peculiarities of the development of winter stratospheric warmings. On the whole, lidar and satellite measurements of height distribution of temperatures agree. Possible reasons for the divergences under consideration are discussed.

Some statistically average characteristics of occurrence of aerosol scattering in the middle Atmosphere of Kamchatka

We study the scattering ratio profiles obtained at the lidar station of Institute of Cosmophysical Research and Radio Wave Propagation (ICRR), Far Eastern Branch, Russian Academy of Sciences (Kamchatka) from 2007 to 2011, during the cold period of October-March. The statistically average profiles obtained in the mesosphere have well-defined maxima at altitudes of 65, 69, and 75 km. Negative correlations are found between the average scattering ratio and the temperature in the mesosphere during stratospheric warmings, and in the stratosphere during calm days.