Geomagnetic activity as a possible cause of changes in the middle atmosphere and troposphere; observations made in Prague in the years 1932–1987

Summary A possible relation between the 10-day, 1-month, and 2-month geomagnetic as well as solar activity, characterized by Kp and Wolf's number R, and temperatures measured at the Prague-Klementinum meteorological station in January–February of the years 1932–1987 was sought. It was found that:1) Kp correlates with the temperature in Prague better than Wolf's number R.2) If the QBO phase is taken into account, the correlations improve.3) Even if the correlations improves with increasing length of the subintervals into which the individual winter periods (January-February) were derived, their statistical significance declines.     

Palaeoclimatic studies in South Shetland Islands,Antarctica, based on numerous stratigraphic variables in lake sediments

The hitherto longest found lake sediment sequence on Byers Peninsula, Livingston Island, South Shetland Islands, was analysed with respect to lithology, chronology, diatoms, Pediastrum, pollen and spores, mosses, mineralogy, and sediment chemistry. During the ca. 5000 year long development the sediments were influenced by frequent tephra fall-outs. This volcanic impact played a major role in the lake's history during two periods, 4700–4600 and 2800–2500 BP, but was of importance during the lake's entire history with considerable influence on many of the palaeoenvironmentally significant indicators. The large and complex data set was analysed and zonated with different types of multivariate analysis. This resulted in a subdivision of the sequence into 8 time periods and 21 variables. Redundancy analysis (RDA) of this data set, both without and with the tephra periods, and with 4–6 of the variables as explanatory environmental variables, reveal that climatic/environmental signals are detectable. The palaeoclimatic picture that emerged out of the tephra noise suggests that the first 100 years were characterized by mild, humid conditions. This was followed by a less mild and humid climate until ca. 4000 BP when a gradual warming seems to have started, coupled with increased humidity. These mild and humid conditions seem to have reached an optimum slightly after 3000 BP. At ca. 2500 BP a distinct climatic deterioration occurred with colder and drier conditions and long seasons with ice cover. This arid, cold phase probably reached its optimum conditions at ca. 1500 BP, when slightly warmer conditions might have prevailed for a while. Except for the modern sample with rather mild climate, the last 1400 years seem to have been fairly arid and cold, and the effects of the frequent volcanic activity during this period is only vaguely seen in the records.     

Dust particle and solar radiation

Influence of the solar radiation (electromagnetic and corpuscular - solar wind) on the motion of the interplanetary dust particle is investigated. The ratio time of inspiralling toward the Sun: time of inspiralling neglecting the change of mass of the particle is presented as a function of initial eccentricities.     

Problems connected with the tangential metric coefficient in the Schwarzschild metric: A possible solution

Four situations are shown where the Schwarzschild metric cannot be used or is subject to unsurmountable problems. The first is the question of a metric useful for PPN-formalism checking different gravitational theories. The second problem occurs in connection with Mach's principle, when the flatness of the spacetime inside a massive hollow sphere is a generally accepted solution. The metrical discontinuity on the same spherical shell is a third problem. The fourth one is the anisotropy of the mass-energy of a test particle in the gravitational field. Three principles for solution are proposed:

1. The space is not dilated, but rather contracted, in the gravitational field; then the measurement-rods are shorter and measured distances have greater magnitudes.
2. The potential energy is to be related to a potential level where a stationary observer is placed and the general relativistic potential must be used.
3. A new metric must be introduced which is distinct from the Schwarzschild metric, so that the space in the gravitational field is warped isotropically.

Then the problems stated are shown to be easily solvable.     

TheoreticalPKIKP magnitude determination

Summary The estimation of the theoretical magnitude for deep foci based on the vertica component of medium-period PKIKP waves, Earth model PREM and source spectra is presented. The given graphs are valid for period T ranging from 1·6 s to 10 s, source depth of 25 km to 600 km and distance range of 16 500 km to 19 800 km. A simplified method of representing calibration curves is used.     

Investigation of the instability of graveyard orbits due to the earth's gravitational perturbations

Summary The Banach theorem is applied to the Lagrange planetary equation for the semimajor axis of a geostationary satellite orbit to estimate the stability of near-geostationary satellite orbits. To achieve a graveyard (disposal) orbit, which will not interfere (=cross) the initial geostationary orbit, the geostationary semi-major axis a_g have to be increased at least by 50 km. Numerical results for a variety of graveyard orbits show that the increase of a_g by about 100 km will yield sufficiently stable orbits (accounting for the Earth's gravitational perturbations only) during the next 150 years.Dedicated to the 75th Birthday of Professor Academician Tibor Kolbenheyer     

A combined study of macroseismic data and focal mechanisms applied to the West-Bohemian earthquake,Czechoslovakia

The main shock of the West-Bohemian earthquake swarm, Czechoslovakia, (magnitudem=4.5, depthh=10 km) exhibits an irregular areal distribution of macroseismic intensities 6° to 7° MSK-64. Four lobes of the 6° isoseismal are found and the maximum observed intensity is located at a distance of 8 km from the instrumentally determined epicentre. This distribution can be explained by the energy flux of the directS wave generated by a circular source, the hypocentral location and focal mechanism of which are taken from independent instrumental studies. The theoretical intensity, which is assumed to be logarithmically proportional to the integrated squared ground-motion velocity (i.e.,I=const+log v ² (t)dt), fits the observed intensity with an overall root-mean-square error less than 0.5°. It is important that the present intensity data can also be equally well explained by the isotropic source. The fit was attained by means of a horizontally layered model though large fault zones and an extended sedimentary basin suggest a significant lateral heterogeneity of the epicentral region. The results encourage a broader application of the simple modelling technique used.     

Magmatic evolution of the Karmøy Ophiolite Complex,SW Norway: relationships between MORB-IAT-boninitic-calc-alkaline and alkaline magmatism

The polyphasal magmatic evolution of the Caledonian Karmøy Ophiolite Complex includes: (1) formation of an axis sequence from island-arc tholeiitic (IAT) and more MORB-like magmas (493+7/-4 Ma); (2) intrusion of magmas of boninitic affinity (485±2 Ma); (3) intrusion of MORB- and IAT-like magmas; (4) intrusion and extrusion of calc-alkaline magmas (470+9/-5 Ma); (5) intrusion and extrusion of basalts with alkaline trace-element affinity. Repeated intrusion of MORB and IAT-like magmas may be explained by intermittent magmatism involving magma-chamber solidification and remelting of a source characterized by initial _Nd of approximately +6.5. The boninitic rocks may have formed from two LREE-depleted sources: the primary source of the axis-sequence magmas and the residual source left after extraction of these magmas. These sources have been enriched in LREE, Th and Zr from subducted material exhibiting a continental Nd-isotope signature with initial _Nd less than-8. Covariation between _Nd and Th, Zr, Nd, Y and Yb may be explained by metasomatic enrichment of a LREE-depleted mantle source by a LREE-enriched subduction component, followed by partial melting during which the degree of melting of the metasomatized mantle source increased linearly with the amount of subduction component added to the mantle source. The calc-alkaline magmas may have formed by remelting of a highly depleted source, which became enriched in some trace elements derived from the source of the subsequent alkaline magmatism. The geology and geochemistry of the Karmøy Ophiolite Complex suggest growth of an island-arc upon newly-formed oceanic crust, followed by arc-splitting and the development of a new basin.     

Type IV dm bursts: Onset and sudden reductions

The effect of collisions of suprathermal electrons with a thermal background plasma is investigated and is shown to cause flattening of a monotonically descending velocity distribution of fast particles. As a result flare-produced energetic electrons that are trapped in a coronal magnetic arch and that are initially distributed in energy according to a power-law, can give rise to an instability of Langmuir waves in the background plasma and the subsequent emission of continuum radiation as observed in type IV dm bursts.To explain the appearance of sudden reductions observed in type IV dm outbursts the effects both of magnetic compressions of the source region and of renewed injections of fast particles on the continuum source are investigated. It is found that the latter process can explain the observed reductions.