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[en] From the power spectrum analysis, we found in the cosmic ray intensity variation two discrete periodicities with 27.12 and 28.26 days. These periods almost coincide respectively with the synodic rotation periods of 27 and 28.5 days pointed out by Svalgaard and Wilcox from the sector structure of interplanetary magnetic field polarity
[en] The 27-day recurrences of neutron monitor data, at 3.1 GV cut-off for the years 1953-1979, have been analysed by the inspection of the harmonic amplitude and phase computed via a new algorithm. The analysis allows us to distinguish for these recurrences two behaviours: the first one appears to have small amplitudes and periodicity of about 28.5 days around the solar minima; the second one appears to have greater amplitudes and periodicity around 27.5 days. We have investigated the possibility that the former behaviour is due to the control of the cosmic ray modulation by medium and high heliolatitude solar activity phenomena such as coronal holes, while the latter is related to the solar activity responsable for phenomena of greater amplitude. (Forbush Decreases)
[en] Monthly average values of both integrated and instantaneous clear sky solar radiation components for Islamabad territory have been presented and discussed. The components include total, direct normal, direct horizontal, global and diffuse radiations, sun hours, number of clear days and temperature for solar energy applications. Beam irradiance values are used to get clear sky (maximum) sun hours by ab-initio. The need for replacing the conventional sunshine recorder is discussed. (author). 8 refs, 1 fig, 2 tabs
[en] Near the past solar activity minimun a recurrency of the enhanced diurnal variation of Cosmic-ray intensity with period of 27-days has been observed. Particularly, data at Deep River and Athens neutron monitor stations show over 16 solar rotations i.e. from 1 Jan. 1973 to 10 March 1974, two series of 27-days recurrences of the diurnal variation characterized by large amplitudes. An examination of the direction and the amplitude of the diurnal variation on a 27-day period shows a dependence upon the interplanetary magnetic field sector polarity. An enhanced mean amplitude of the diurnal anisotropy correlates with positively directed sectors, while the amplitude of this anisotropy seems to decrease during sector boundaries
[en] It has been argued that there are certain idiosyncrasies in Australian petrol price behaviour. To the extent that these idiosyncrasies result in large magnitude differences in petrol prices, they may be exploited by consumers to significantly reduce their household expenditure on the product. Similarly, such seasonalities may influence retailers in their purchase and storage decision. The objective of this paper is to test for seasonalities in the Australian retail petrol market. The approach adopted is similar to that for determining calendar anomalies as documented in the financial and commodity markets literature. We find that a monthly seasonal effect is pronounced with petrol prices lower in the months of February-May and highest in July and August. A day-of-the-week effect is also apparent and is manifest in all petrol prices for capital cities (Adelaide, Brisbane, Melbourne and Sydney) across various years. However, the half-month effect, as is common in stock returns, is not observed. Moreover, contrary to popular belief that petrol prices are higher surrounding holidays, no evidence of the holiday effect is found. In Brisbane and Melbourne, petrol prices also have some relationship to the mood of consumers, as proxied using weather conditions. This is not observed in Adelaide and Sydney. (Author)
[en] Measurements of daily sunshine hours and of global solar radiation for most of the existing stations in Italy, covering a period of (5-30) y, were analysed. Linear correlation coefficients were calculated between the above-cited measurement for 36 stations and for every month of the year. Italy has been divided in area in which such coefficients are not much different among them. The mean values of these coefficients relative to each area were used to estimate the global radiation for the sunshine stations located in the same area. Using so radiation obtained values for about 140 stations, 12 month global radiation maps were realized for the italian territory. Possible errors and limitations of the maps were discussed
[en] This paper deals with the relation of radon gas and daughter produced radiation levels to the cave air flows which mobilize them. These flows are a function of interior cave and exterior ambient air temperatures and pressures and of the cave's geophysical configuration. The low-level, ionizing radiation is produced by minute concentrations of radon and thoron gases which emanate from within caves. Because of confinement, the radiation levels are often appreciably higher than in surface atmospheres. Subsequent radioactive disinegration of the gases into their ionized daughter products, which are particulates, permits distribution of the alpha radiation throughout a cave system. The extent and character of this distribution depends upon the particular cave and the air flows which it produces. Thus, the alpha radiation serves as a tracer to describe the flows
[en] Complete text of publication follows. Characteristics of hourly- or daily-scale short-term variations of the Dst index are well known. Burton et al. (1975) have proposed an empirical model of the temporal evolution of the Dst index which uses some solar-wind parameters as inputs. Their model successfully represents short-term variations of the Dst index. This fact means that most of short-term Dst variations can be sufficiently explained by some mechanisms taken into account in their model. However, this empirical model does not well reproduce the long-term variations such as monthly-scale variation. This suggests that the long-term variation would be controlled by mechanisms which were not taken into account. In order to resolve what mechanism causes the monthly-scale long-term variation, we separate the long-term variation from the short-term variation using state space modeling and the so-called particle filter algorithm. We then compared the estimated monthly-scale variation with various solar parameters, such as solar-wind density, solar radiation, and sunspot number. It was found that the long-term variation of the Dst index is negatively correlated with the solar-wind dynamic pressure. (Note that the short-term Dst variation is positively correlated with the solar-wind dynamic pressure). One possible reason of this negative correlation is as follows. If high solar-wind density and high solar-wind velocity are maintained for a long time, the density of the plasmasheet would be enhanced, which could cause the intense ring current and tail current. This effect might depress the Dst index during the high solar-wind dynamic pressure conditions.
[en] Complete text of publication follows. Julius Bartels introduced in 1949 the planetary geomagnetic activity index Kp and the derived activity numbers ap, Ap, Cp and C9. These activity numbers were accepted by the IAGA as official measures to express the geomagnetic activity. The data series expand back to 1932. Kp and its derived numbers got a world wide usage in geomagnetic science. The 10 International Quietest and 5 Most Disturbed Days of every month are determined on the base of this index. The series of definitive indices is routinely updated twice a month on the web. A quick-look indices calculation runs automatically in order to meet the requests of a near real-time availability. The K numbers of the 13 Kp observatories are calculated on the basis of their minute values every 3 hours with a time delay of about 15 minutes. The Kp are calculated by means of the regular algorithm from these K numbers. The Kp, ap, Ap and Cp calculated this way are immediately provided on the web. The quick-look indices are replaced by the definitive numbers after their usual calculation every half month.
[en] An investigation was carried out to characterize some selected parameters which influence rainfall erosivity in southeastern Nigeria. Rainfall amount, distribution, duration, intensity, storm types, energy loads and frequency of rain events in the region were studied using data from stations located in three major agroecological zones. Raindrop size and detaching capacity were evaluated in one of the stations for two months. The mean annual rainfall erosivity values for southeastern Nigeria point to the fact that rainfall tend to be highly erosive. 25 refs, 6 figs, 8 tabs