The Leonard Award Address Presented 1996 July 25, Berlin,Germany: The elemental composition of stony cosmic spherules

Abstract— Five hundred stony cosmic spherules collected from deep-sea sediments, polar ice, and the stratosphere have been analyzed for major and some minor element composition. Typical spherules are products of atmospheric melting of millimeter sized and smaller meteoroids. The samples are small and modified by atmospheric entry, but they are an important source of information on the composition of asteroids. The spherules in this study were all analyzed in an identical manner, and they provide a sampling of the solar system's asteroids that is both different and less biased than provided by studies of conventional meteorites. Volatile elements such as Na and S are depleted due to atmospheric heating, while siderophiles are depleted by less understood causes. The refractory nonsiderophile elements appear not to have been significantly disturbed during atmospheric melting and provide important clues on the elemental composition of millimeter sized meteoroids colliding with the Earth. Typical spherules have CM-like composition that is distinctively different than ordinary chondrites and most other meteorite types. We assume that C-type asteroids are the primary origin of spherules with this composition. Type S asteroids should also be an important source of the spherules, and the analysis data provide constraints on their composition. A minor fraction of the spherules are melt products of precursor particles that did not have chondritic elemental compositions. The most common of these are particles that are dominated by olivine. The observed compositions of spherules are inconsistent with the possibility that an appreciable fraction of the spherules are simply chondrules remelted during atmospheric entry.     

Atomic data relevant to line formation in strongly magnetized white dwarf stars

The discovery of magnetic field strengths in the range of 500 million Gauss in the objects Grw+70°8247 and PG1031+224 has given enormous impetus to investigations of magnetic white dwarf stars. We have determined intensities of Balmer transitions for B>10⁸ Gauss as a function of field and find strong oscillations of the transitions strengths, which are of importance to the quantitative analysis of the observed spectra and the interpretation of polarimetric measurements in these objects.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.     

THE ANALYTICAL ORIENTATION OF A LUNAR MODEL

An analytical relative orientation of a stereo-pair of photographs was computed in an unusual system of co-ordinates. The disparity in the widely mismatched photographs, their tilts and narrow angles subtended resulted in a rather weak solution from which sections of the lunar surface have been plotted. The results were not good but were better than expected. The main outcome of the work is a, probably unique, demonstration of the versatility of analytical photogrammetry.     

Models of the Southern Oscillation in the 300–100 mb layer and the basis of seasonal forecasting

Summary The geometry of the principal Upper High (near the Indian Occean) in the 300–100 mb layer appears to account for the Southern Oscillation (S.O.), and models of its behaviour are presented. Significant features of these models include the equatorial points of upper convergence (C) and divergence (D), a pressure discontinuity (CNDS) forming «arcs» and an «enclosure» around the high, and, lastly, encircling «crescents» both outside and inside the enclosure. The geography of the seasonal sucession can thus—in a qualitative manner—be interpreted in the light of known wind and contour patterns near the tropopause. With a few general principles, the established empirical rules of long-range forecasting then follow by deduction. The models and the terminology are useful likewise in the interpretation of solar-terrestrial relations and of climatic fluctuations.     

Lagrangian diffusion equation and its application to oceanic dispersion

The Lagrangian diffusion equation appropriate for the dispersion of current followers (e. g., floats, drogues, drifters) is proposed. The analytical solution to the equation is obtained for a uniform deformation field, characterized by Lagrangian deformations and anisotropic eddy diffusivities both varying with time. Expressions are derived for the patch area and its elongation and rotation. For small values of elapsed time after the initial release the patch area can be accounted for by the exponential of the cumulative value of the horizontal divergence; the relative rate of change of the patch area can be accounted for by the horizontal divergence.     

Sea-structure interaction for tripod-type steel gravity platform

The paper deals with a numerical integrated procedure to calculate the effects of the interaction between sea waves and a tripod-type steel gravity platform. The main aspects to be taken into account for a reliable wave loading analysis of such a new type of platform are emphasized. Among them, the field perturbation effect due to the large bodies presence is analysed. Finally, some principal results in terms of structure global loads obtained by the numerical integrated procedure are presented.     

Harpacticoida taxocen diversity in the silty-sandy littoral zone of Kandalaksha Bay of the White Sea

The fauna composition, ecological groups, and life forms of Harpacticoids of soft littoral grounds from 15 sites off the Karelian coast in Kandalaksha Bay of the White Sea were studied. Six types of harpacticoid taxocens with different sets of dominating species are described. On silty sands with clear signs of desalination, the Stenchelia palustris taxocen is common; medium-grained sands are characterized by the Heterolaophonte minuta, Paraleptastacus kliei — Huntemannia jadensis, and Amphiascoides nanus — Scottopsyllus minor taxocens; while on coarse sands, the Ameira parvula and Ameira scotti — Mesochra lilljeborgi taxocens have developed. The diversity of the taxocens is partly explained by the differences in the grain-size composition and salinity at different sites. In addition, groups of various taxocens dwelling on the same type of the sediments were found in different minor bights of the coastline.