A Non-Planar Circular Model for the 4/7 Resonance

An adiabatic approximation for the non-planar, circular, restricted 3BP is presented for the external resonance 4/7. It can be used as a model for resonant Kuiper belt objects. The Hamiltonian is truncated at the fourth order in eccentricities and inclinations. After averaging, we have a system of two degrees of freedom with two frequencies. Numerical calculations show that the ratio of these frequencies is ~10². Having introduced suitable canonical variables, we used the adiabatic approach introduced by Wisdom in a different context. We left slow variables frozen and after solving the pendulum problem for fast variables, we used the averaged effect of fast variables on slow variables. In this way we obtained the guiding trajectories for slow variables as contour lines of adiabatic invariant. We discuss the existence of a chaotic region which is formed by trajectories crossing a critical curve which corresponds to the separatrix of fast pendulum motion, where the assumption of sharp division between fast and slow frequencies is not correct and the adiabatic theory fails. The model works well for e ~ 0.1 and can be used for finding the chaotic regions, but for e~ 0.17 it becomes unsatisfactory due to truncation and bad convergence of the Laplace expansion. Qualitatively it can, however, help us to understand how the protective mechanism works as the interplay of mean motion and Kozai–Lidov resonance.     

Low-energy particle events associated with sector boundaries

Onsets of some 40 to 45 low-energy proton events during the years 1957–1969 coincided in time with transits of well-defined sector boundaries across the Earth. These events can be interpreted as long-lived proton streams filling up some of the magnetic sectors, indicating an acceleration of protons which is not associated with typical proton-producing flares. The sharp onsets of these particle streams, as well as a deficiency of flare-associated particle events shortly before the boundary transit, indicate that in some cases magnetic sector boundaries can inhibit transverse propagation of low-energy particles in the solar corona or in interplanetary space.     

Inversion of seismograms to determine simultaneously the moment tensor components and source time function for a point source buried in a horizontally layered medium

Summary A method of determining simultaneously the moment tensor and source time function in the point source approximation is presented. For trial values of the moment tensor components and of the source time function, parametrized by the sum of overlapping triangles delayed in time, theoretical seismograms can be synthetized and compared with the recorded ones. The iterative procedure determines the adjustment of source parameters until a good correlation of both synthetic and observed records is reached. The Green functions in a horizontally stratified medium are constructed with the use of a modal summation method.The limits of applicability of the algorithm are illustrated by the inversion of four synthetic seismograms constructed for two horizontally stratified models of the structure in Friuli area, Italy. The records constructed for the same structural model as for which the Green functions were computed can be inverted even in the high-frequency range. In the opposite case, when the records and Green functions used corresponded to different structural models, a good correlation of the input records with the final synthetics was obtained for low - pass filtered data only.Additional tests performed with input seismograms contaminated with random noise yielded good resolution of the moment tensor and the duration of the source time function even for a high noise to signal ratio.     

A local climatic model of the temperature-cloudiness relationship

Summary Filtered secular series of temperature at Zagreb (Croatia) are negatively correlated with simultaneous series of solar radiation and positively correlated with cloudiness.The local balance of radiative fluxes, with cloudiness interference included, provides a basis for the evaluation of a local deterministic model, which can describe both the positive and negative impacts of cloud radiative forcing upon surface temperature. A theoretical temperature series, generated by the model simulation, proves a prevailing greenhouse effect of clouds upon recent climatic variations of temperature at Zagreb.With 5 Figures     

Anomalous behaviour of plasma parameters as observed by the intercosmos 24 satellite prior to the iranian earthquake of 20 June 1990

Summary Measurements of plasma parameters were made by the Intercosmos 24 satellite at altitudes between 2300 km and 2500 km in the interval of 16 to 12 hours prior to the initial shock of the destructive Iranian earthquake of 20 June 1990 (210009 UT, 37° N, 49·4° E, M=6·4), and before the strong aftershock of 21 June 1990 (090214 UT, M=5·8). The anomalous behaviour of the light ionospheric ions H⁺ and He⁺ and the cold electron temperature was observed over a wide region of the Northern Hemisphere before the earthquake. Sudden increases of energetic electron fluxes were observed over the Asian zone near the epicentre. These changes appear to be a part of the solid Earth — near space interaction occurring during the preparatory stage of the great seismic event.     

Hydrological characterization and connectivity of proglacial lakes to a stream,Adygine ice-debris complex,northern Tien Shan

ABSTRACT

In this study, we characterized the glacial meltwater flow through a proglacial area with a focus on proglacial lakes, their hydrological regime and their connection to the stream. The studied lakes – the Adygine ice-debris complex, northern Tien Shan – showed a distinct development throughout an ablation season: at Lake 2, the mean daily water-level fluctuation amplitude increased from 0.07 m to 0.18 m (June, August), then dropped to 0.07 m in September. Glacial meltwater flows through the lakes and further downstream through a rock glacier rather fast, moving at 0.085 m s^?1. However, based on the low dye recovery in the stream (0.03%), only a small portion of water was routed efficiently. The complexity of the site’s drainage system was supported by varying isotopic composition of water in the tarns situated on the rock glacier, with Tarn a (δ²H: –36.08‰; δ¹⁸O: –6.25‰) being the most enriched and Tarn c (δ²H: 78.68‰; δ¹⁸O: 11.9‰) the most depleted in heavy isotopes.     

Force function of two general spheroids

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Determination of the correction parameters of an askania gravimetric tidal apparatus

Summary From measurements made with an Askania tidal apparatus at a reference station it is possible to derive the correction parameters k and , if required, for reducing the gravimetric factors and phase lags to a unified system, Eq. (2). It is suggested that several tidal waves be used to determine k and and to take the weighted mean as the resultant value. Suitable weights have also been derived, Eq. (7).Dedicated to RNDr Jan Pícha, CSc., on his 60th Birthday