8–13 μm spectrophotometry of Comet Kohoutek

Spectrophotometry of Comet Kohoutek (1973f) covering the wavelength range 8–13 μm is presented. The spectral shape of the derived flux excess above a blackbody closely resembles that seen in circumstellar and interstellar dust and generally attributed to metallic silicates.     

MHD free-convection flow past an accelerated vertical porous plate in a rotating fluid

The three-dimensional flow of an electrically conducting and incompressible viscous fluid past a uniformly accelerated infinite vertical porous plate is studied in a rotating fluid. The flow is assumed to be at small magnetic Reynolds number so that the induced magnetic field is neglected. An exact solution has been obtained by defining a complex velocity with the help of the Laplace transform method for the Prandtl number equal to unity. The effects of rotation, magnetic and free-convection parameters are discussed for the whole problem. Also, the skin-friction components on the plate are discussed.     

Solar wind induction in Mercury: Constraints on the formation of a magnetosphere

The discovery of Mercury's magnetosphere by Mariner 10 was surprising since the conventional view of regenerative planetary dynamos had been that the spin requirement would likely have been in excess of the observed spin rate of Mercury. Also internal fluid motions were not expected to be sufficiently large. This paper explores the alternative model of the formation of Mercury's magnetosphere via electromagnetic induction forced by the solar wind. It is shown, however, that the constraints are so severe as to limit severely the applicability of such a model. Although induction is easily observed on the Moon, the modification of the magnetic boundary condition associated with a plasma magnetosphere on Mercury rules out its formation via induction except for interplanetary driving fields which are decreasing in amplitude. That model is explored but retains the difficulty that induced magnetospheres tend to be of small radial and temporal extent compared to that inferred by Ness et al. for Mercury.     

AÏOUN EL ATROUSS: A NEW HYPERSTHENE ACHONDRITE WITH EUCRITIC INCLUSIONS

Preliminary investigations have been made on two separate pieces from the Aïoun el Atrouss meteorite that fell on April 17, 1974 in southeast Mauritania. The major portion of the meteorite is a brecciated hypersthene achondrite with orthopyroxene (En₇₄) as the major phase. Clasts of eucrite, up to 7 percent in volume within a single slice, occur within the hypersthene achondrite host. No evidence has been found of reaction between the two meteorite types, nor of the presence of any materials intermediate in composition.     

Radiation pressure — a stabilizing agent of dust clouds in comets?

The internal dynamics of an illuminated dust cloud of finite optical thickness is investigated. The dependence of the radiation pressure on the optical depth makes the individual particles oscillate, in one dimension, around the accelerated centre of gravity of the cloud. The cloud moves as an entity, irrespectively of the velocity dispersion of the particles and their efficiency for radiation pressure. If the optical depth does not change, i.e. if the cloud does not expand laterally, its lifetime is unlimited. A contraction caused by energy dissipation in mechanical collissions between the dust particles is expected. The range of particle sizes which can be transported by such a “coherent cloud” is estimated, as well as the acceleration of the whole cloud. The structure of the cloud in real space and in velocity space is investigated. A comparison with the “striae” observed in the dust tails of great comets shows that the parent clouds of these striae may have been of the kind considered.     

Tidal effects of the galaxy on a globular cluster

Tidal effects of a Schmidt (1965) model galaxy on a typical globular cluster moving in an orbit along the axis of symmetry of the spheroid is studied under the impulsive approximation. Ann-body simulation is made for comparison. Results show that in both cases, a high concentration cluster gains enough energy to be totally dissolved within a distance of 2 kpc. A significant mass loss occurs as the cluster approaches the Roche distance.     

Surface heat fluxes and subsurface heat content at a site over the southeastern Bering Sea shelf, May–July 1996

Observations from a surface mooring, in a weak-flow regime over the southeastern Bering Sea shelf, were used to derive surface heat fluxes for the period May–July 1996. Changes in heat content of the water column also were determined from subsurface temperature measurements. Agreement of net surface heat flux and change in heat content was within 2%. This result provides additional evidence that heat advection and diffusion are small in this region.     

Estimate for radiative forcing of smoke aerosol from 2010 summer fires based on measurements in the Moscow region

Temperature and radiation effects of the 2010 summer fires are estimated on the basis of measurements at the Zvenigorod Scientific Station (ZSS) of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (RAS), in the Moscow region. The surface air temperature during the 2010 summer smoke varied in antiphase with the aerosol mass concentration, and the thermal radiation balance in the surface layer of the atmosphere varied in phase. Under extreme smoke of the surface layer in August 2010, the reduction in surface air temperature at ZSS has been found to reach 4 K with an increase in the downward flux of thermal radiation by an average of 20 W/m² and a decrease in the difference between upward and downward fluxes of thermal radiation by an average of 24 W/m².     

Russian investigations in atmospheric chemistry for 2011–2014

This review covers the most significant Russian studies in atmospheric chemistry conducted from 2011 to 2014. This is part of the Russian National Report on the Meteorology and Atmospheric Sciences prepared for the International Association of Meteorology and Atmospheric Sciences (IAMAS). The report was considered and approved by the XXVI General Assembly of the International Union of Geodesy and Geophysics (IUGG).¹ The review is appended by a list of publications by Russian scientists for 2011–2014 covering the field of atmospheric chemistry research.