Interpretation and possibilities of applying LHR frequency determined from satellite VLF measurements in middle geomagnetic latitudes

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On the minimum distance between two Keplerian orbits with a common focus

The methods used so far for determination of the closest approach between two orbits are discussed, and corrected versions of two of them are presented.     

Mortar Upscaling for Multiphase Flow in Porous Media

In mortar space upscaling methods, a reservoir is decomposed into a series of subdomains (blocks) in which independently constructed numerical grids and possibly different physical models and discretization techniques can be employed in each block. Physically meaningful matching conditions are imposed on block interfaces in a numerically stable and accurate way using mortar finite element spaces. Coarse mortar grids and fine subdomain grids provide two-scale approximations. In the resulting effective solution flow is computed in subdomains on the fine scale while fluxes are matched on the coarse scale. In addition the flexibility to vary adaptively the number of interface degrees of freedom leads to more accurate multiscale approximations. This methodology has been implemented in the Center for Subsurface Modeling's multiphysics multiblock simulator IPARS (Integrated Parallel Accurate reservoir Simulator). Computational experiments demonstrate that this approach is scalable in parallel and it can be applied to non-matching grids across the interface, multinumerics and multiphysics models, and mortar adaptivity. Moreover unlike most upscaling approaches the underlying systems can be treated fully implicitly.     

An assessment of the search for dusty clouds

Some results concerning the intergalactic dust matter are presented. The results of Tarraro, considered as the first undoubted revelation of intergalactic extinction; and of Zabierowski, treated by him as a trial, seem not to be equivalent. Not experimental data, but their theoretical interpretation is responsible for this non-equivalence.Plates have to be prepared by technically uniform procedures to infer the intergalactic obscuration from pseudo-indices. Significant extragalactic obscuration participates in galaxy correlation function, Rubin-Ford effect, underpopulation of quasars, and Sierpiski's sponge structure of galaxy distribution. Contribution from supermassive pre-stars or Population III to the abundance of elements must be considered as highly plausible.     

Propagation of sprays with deceleration

The dependence of the maximum height achieved by sprays showing deceleration and stopping at the end of their propagation, on the velocity has been examined. It was assumed that the velocity is greatest at the beginning, so this maximum velocity defines the kinetic energy of each investigated knot at its start. The relation between the maximum height and maximum velocity was examined in 32 knots from 23 sprays. The problem of whether the maximum height achieved by a knot is determined by the gravitational field alone has been studied. The problem of stopping is important especially for knots which have initial velocities higher than the velocity of escape from the Sun.     

Grid point surface air temperature calculations with a fast turnaround: Combining the results of IMAGE and a GCM

This paper describes a methodology that combines the outputs of (1) the Integrated Model to Assess the Greenhouse Effect (IMAGE Version 1.0) of the Netherlands National Institute of Public Health and Environmental Protection (RIVM) (given a greenhouse gas emission policy, this model can estimate the effects such as global mean surface air temperature change for a wide variety of policies) and (2) ECHAM-1/LSG, the Global Circulation Model (GCM) of the Max-Planck Institute for Meteorology in Hamburg, Germany. The combination enables one to calculate grid point surface air temperature changes for different scenarios with a turnaround time that is much quicker than that for a GCM. The methodology is based upon a geographical pattern of the ratio of grid point temperature change to global mean values during a certain period of the simulation, as calculated by ECHAM-1/LSG for the 1990 Scenarios A and D of the Intergovernmental Panel on Climate Change (IPCC). A procedure, based upon signal-to noise ratios in the outputs, enabled us to estimate where we have confidence in the methodology; this is at about 23% to 83% of the total of 2,048 grid points, depending upon the scenario and the decade in the simulation. It was found that the methodology enabled IMAGE to provide useful estimates of the GCM-predicted grid point temperature changes. These estimates were within 0.5K (0.25K) throughout the 100 years of a given simulation for at least 79% (74%) of the grid points where we are confident in applying the methodology. The temperature ratio pattern from Scenario A enabled IMAGE to provide useful estimates of temperature change within 0.5K (0.25K) in Scenario D for at least 88% (68%) of the grid points where we have confidence; indicating that the methodology is transferable to other scenarios. Tests with the Geophysical Fluid Dynamics Laboratory GCM indicated, however, that a temperature ratio pattern may have to be developed for each GCM. The methodology, using a temperature ratio pattern from the 1990 IPCC Scenario A and involving IMAGE, gave gridded surface air temperature patterns for the 1992 IPCC radiative-forcing Scenarios C and E and the RIVM emission Scenario B; none of these scenarios has been simulated by ECHAM-1/LSG. The simulations reflect the uncertainty range of a future warming.The work reported by the authors was carried out during their stay at the project Forestry and Climate Change of the International Institute for Applied Systems Analysis, Laxenburg, Austria.     

Response of the outer ionosphere to a magnetic storm at equinox

Summary The observations of the ACTIVE Project satellites in the interval of March 17–23, 1990 were analyzed for the purpose of studying the response of the outer ionosphere to the magnetic storm with SSC on March 20 at 22.43 UT. In particular, measurements of thermal plasma parameters were used, but VLF broadband measurements and data on energetic ion and electron fluxes in the range of 17.7–272 keV were also available. The results of this case study show that the observations in the morning sector at altitudes around 2000 km reflect well the state of the plasmasphere during enhanced activity, namely the depth to which the plasmasphere has been affected by enhanced magnetospheric convection. They also provide the possibility of monitoring the initial phase of recovery. The early evening observations of the plasma parameters in the outer ionosphere at altitudes of 500–1000 km indicate a distinct trough in electron concentration. In the dusk sector, the equatorward edge of this trough can be assumed to be the projection of the equatorial plasmapause. This, combined with the occurrence of electron temperature peaks and with the morning plasmapause position, enables one to judge whether the plasmaspheric bulge has formed and whether an inner plasmapause has occurred.     

The relation between the surges and solar radio emission

The 120 limb surges which have been observed by means of Wrocaw Observatory coronagraph from September 1966 to November 1977 are investigated. The evolution of surges was compared with the radio data during the surges. A correlation between radio bursts and the surges was found, particularly with chains of type I radio bursts, which is the first reliable correlation found of these bursts with non-radio events. The type I correlation only applied for surges without accompanying flare, of which 43% are correlated with this type of radio emission. In 23 of 30 associated events the start of a surge coincided within 5 minutes with the start or an enhancement of the type I storm. If flares were present, the association was not significant.We also compared the maximum height reached by a surge with the frequencies of the radio bursts emitted at the same time and the maximum velocity of the rising surge with the frequency drift of type I chains. No such a correlation was however found.We discuss the possibility that surges are the result of a sudden energy input into the chromosphere related to the type I source in the corona.     

The shock waves and the magnetic field in the corona above the active region on February 17–28, 1969

In this paper the situation above the large active region which passed across the solar disc between February 17 and 28, 1969 is considered. Five dynamical spectra of type II radio bursts registered by CSIRO and by Weissenau Observatory were used. After the elaboration of dynamical spectra, the parameters of shock waves and the values of magnetic field in corona were determined. The magnetic field was obtained using two methods. In the first method the connection between the velocity of shock front and the velocity of the Alfvén waves was used. In the second method the dependence of the frequency split upon the value of the magnetic field was applied.     

IV. Bücher- und Zeitschriftenschau

Ohne Zusammenfassung