B. M. Shevtsov

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.

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.

Atmospheric electric effects during the explosion of Shiveluch volcano on November 16, 2014

The development of a volcanic plume from the Shiveluch volcano explosion on November 16, 2014, is analyzed using a complex of geophysical methods. The start of the explosion was detected by seismic data. The World Wild Lightning Location Network (WWLLN) allowed the localization of volcanic lightning discharges that occurred during the first stage of the eruption plume. Satellite IR monitoring data made the plume structure obvious. An electrostatic fluxmeter mounted 113 km apart from the volcano recorded the first disturbances of the atmospheric electrical potential gradient (PG) at a distance of 90 km from the eruption cloud front. Two distinct PG anomalies, of 50 and 32 min in length and of more than 100 V/m in amplitude, recorded in 2 h, indicate two separate eruption formations formed by this time. The propagation velocities of two parts of the plume close to the wind speeds at altitudes of temperature inversions (9–10 and 12 km), according to balloon sensing, point out to the plume layering and propagation at two altitudes.

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.

Development of a monitoring network for lightning stokes accompanying the eruptions of the Northern group of volcanoes on Kamchatka peninsula

In the region of the Northern group of volcanoes in Kamchatka peninsula, a distributed network is being planned to monitor the VLF range electromagnetic radiation and to locate the lightning strokes. It will allow the researchers to register weaker electromagnetic pulses from lightning strokes in comparison to the World Wide Lightning Location Network. The hardware-software complex of the network under construction is presented. The capabilities of the available and the developing hardware and software to investigate natural phenomena associated with lightning activity are described.

Mesoscale structure of tropical cyclones in the northwestern part of the Pacific ocean according to the data of the WWLLN

The paper investigates lightning activity in the region of tropical cyclones (TC), its structure and changeability during the process of TC development and attenuation according to the data of the World Wide Lightning Location Network (WWLLN) as well as the relation with ocean surface wind fields according to the ASCAT scatterometer data. Distribution of lightning discharges in TC regions and discharge density fields drawn up from them allowed us to detect TC structure elements, such as mesovortexes, eyewalls, cloud bands and spirals, and to trace their change in space and time.

Thunderstorm activity and the structure of tropical cyclones

Synoptic and mesoscale cyclonic systems over the ocean and seas are often accompanied by thunderstorm activity, the intensity and spatial distribution of which is modulated by the dynamic structure of these systems. Lightning discharges are sources of electromagnetic radiation in the range of very low frequencies (VLF) and are detected by VLF location finders. Using the World Wide Lightning Location Network (WWLLN), relations between characteristics of fields of detected lightning discharges in the north-western part of the Pacific Ocean and those of fields of meteorological elements of weather formations estimated by data of remote sensing of the Earth by satellites are studied by an example of tropical cyclones. We illustrate a technique permitting one to connect thunderstorm activity parameters (frequency and intensity, as well as spatial distribution of lightning discharges) with the structure of weather systems over oceans and seas and with the intensity and forms of mesoscale formations distinguished in these systems by fields of the near-water wind vortex (the fields are obtained using a scatterometer) and by satellite images in the visible and infrared ranges. The relations between the frequency and density of lightning discharges in the range of influence of a tropical cyclone (TC) and spatial distribution of the near-water wind vortex are demonstrated by an example of individual TCs of 2005–2013.