1.        Karacostas, T. S. and O. K. Kakaliagou (1991): Objective analysis schemes and their applications to hail measurements network in the Greek NHSP. Geofizika, 8, 3-12.  

 

ABSTRACT:

 

       The objective of this study is to present the investigations and applicability of several objective analysis schemes and to create a detailed, representative and better resolution grid-point hailpad network system retrieved from actual hailpad measurements. The main motivation for this study is the desire to use the equally spaced hailpad measurements in order to be able to theoretically estimate the appropriate hailpad spacing by using either the Monte-Carlo simulation method or any conventional method of statistical analysis.

       To meet the goal, several objective analysis methods are applied to the actual hail impact energy measurements which were obtained from the hailpad network system in the Greek NHSP during the 21st of June 1987 case study, and their effectiveness for the creation of an artificial grid-point hailpad network system is examined. Finally, comparisons between the methods themselves, and each of them against the actual hail impact energy measurements are performed, in order to determine the adequate objective analysis scheme.

  

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2.        Klaić, Z. (1991): Some characteristics of the long-range transport of sulphur dioxide in Croatia and Slovenia. Geofizika, 8, 13-24.

 

ABSTRACT:

 

       The application of a Lagrangian box-model for the calculation of sulphur dioxide concentrations in Yugoslavia is described. Modeled concentrations are then used to estimate dry and wet depositions of the pollutant concerned. Further, two days with high and one with low concentrations, recorded and calculated for the Croatia and Slovenia, are selected. These cases are illustrated by 30-hour backward 850 hPa air trajectories.

 

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 3.        Cerovečki, I., Z. Pasarić, M. Kuzmić, J. Brana and M. Orlić (1991): Ten-day variability of the summer circulation in the North Adriatic. Geofizika, 8, 67-81. 

 

ABSTRACT:

 

       Current, temperature and salinity data, collected during the ASCOP experiment that was carried out in the eastern part of the North Adriatic in summer 1989, have been analyzed together with related meteorological and hydrological data. After dividing the current series into three nearly equal subintervals, residual currents have been calculated for each of them. The major feature this exercise revealed was variability at a time scale of about ten days. A similar phenomenon has been observed by Italian researchers in the northeastern part of the Adriatic during several summers.

       It has been shown in the paper that the wind episodes registered during the experiment, although inducing remarkable changes in temperature and salinity records, did not directly generate the observed current variability. The changes in the Po River outflow have also been ruled out as the cause of the observed current reorientation.

       Temperature data collected in the area have pointed to stratification as the factor controlling the observed current variations. The stratification itself was influenced by buoyancy fluxes and wind forcing. However, further theoretical and empirical work is needed to establish conclusive evidence and elaborate dynamics of the observed phenomenon.   

 

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4.        Herak, D., M. Herak, I. Sović and S. Markušić (1991): Seismicity of Croatia in 1989 and the Kamešnica Mt. earthquake. Geofizika, 8, 83-99. 

 

ABSTRACT:

 

       The seismicity of Croatia and its surrounding areas in 1989 was analysed on the basis of the earthquake catalogue consisting of 361 earthquakes. Its completeness threshold was estimated to be MLC ≥ 3.0. Seismically the most active was the coastal part of Croatia, where the strongest earthquake in 1989 occurred on December 6 with the focus beneath the hill-sides of the Kamešnica Mt. The fault plane solution for this event indicates the presence of a tectonic stress-field directed approximately SW-NE, which is compatible with the assumed anticlockwise rotation on the Adriatic microplate around the pole in Northern Italy, and the associated subduction of the Adriatic plate under the Dinarides. The aftershocks of the Kamešnica Mt. event were numerous, with hypocenters at depth up to 20 km. Macroseismic investigations confirm the frequently observed fact that seismic energy is much more efficiently absorbed perpendicularly to the direction of the Dinaric belt than along it. 

 

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5.        Markušić, S. (1991): Velocities of refracted longitudinal Pn waves in the Dinarides area. Geofizika, 8, 101-113. (in Croatian)

 

ABSTRACT:

 

       The refracted longitudinal wave velocities in the Dinarides area have been determined on the basis of the modified time-term method for the dipping Moho discontinuity. The homogeneity of the Earth crust is assumed. The results (ranging between 7.85 and 8.45 km s-1) divide the research area into three parts and confirm the complexity of the Dinarides region. The arithmetic mean of the Pn wave velocities (calculated for the entire Dinarides area) is 8.10 km s-1. This value is comparable to the average velocity of 8.14 km s-1 obtained for the Dinarides region by deep seismic sounding.

 

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6.        Petkovšek, Z. (1991): Additional bora characteristics according to the frontal model. Geofizika, 8, 25-31. 

 

ABSTRACT:

 

       Similarly to the frontal surface, the upper boundary of the bora must be dynamically balanced in a stationary state. Based on this idea, a special bora model, the frontal bora model, was developed in detail and presented elsewhere (Petkovšek, 1990). The model has given some very interesting results; here additional results of numerical experiments are presented. They show how absolute temperature, height of the ridge, inclination and form of the lee side slope influence the bora thickness and speed.

 

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 7.        Penzar, I. and B. Penzar (1991): Hourly values of solar irradiation in clear skies. Geofizika, 8, 33-42. 

 

ABSTRACT:

 

       Hourly values of global solar irradiation in clear skies are determined as a function of solar elevation using empirical parameters derived from the measurements of radiation in Zagreb (f = 45.828° N, l= 15.992° E) in the period between 1960 and 1985. The estimation was performed on the 15th of every month for geographical latitudes between 41° and 46° N. By means of the well known procedure the global solar radiation is then divided into the direct and diffuse solar radiation and calculated for a south-facing surface inclined at 35°. A possibility of taking into consideration the influence of clouded sky on the decrease in the clear-sky solar irradiation is also presented.

 

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8.        Karacostas, T. S. (1991): Some characteristics of convective cells in the Greek National Hail Suppression Program. Geofizika, 8, 43-50. 

 

ABSTRACT:

 

       The objective of this study is to provide first information on some characteristics of the convective cells observed within the Greek area. To meet this objective, a set of two years (1984 – 1985) of manually digitized weather radar measurements was used. The diurnal and interseasonal distributions of the maximum echo tops height of the convective cells are studied. Unimodal distributions for all the categories of convective cells are found except for those with tops between 12.0 to 13.5 km, which depict a bimodal one. Finally, the life time of the convective cells, a very important factor for the better operations of the NHSP, is investigated. The resulting short-lived characteristics of the observed convective cellsmeans that their probability to become potential hail producers is not very high.

 

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9.        Karacostas, T. S., O. K. Kakaliagou and E. A. Flocas (1991): An objective evaluation of two instability indices associated with forecasting convective storms over the North and Central Greece. Geofizika, 8, 51-59. 

 

ABSTRACT:

 

       Using different methodologies, but the same set of data, two stability indices were derived, with the aim to forecast convective intensities, showers, thundershowers, and hailstorms, over the north and central area of Greece. The indices were derived as analytical expressions of four suitably selected predictor variables, based upon theoretical and statistical arguments.

       The objective of this study is to use a statistically acceptable independent set of data in order to objectively evaluate the creditability of both indices. This will be done by examining the behavior of both indices, and also by performing comparisons between the indices themselves, and the indices against the predicted variable measured in situ by S-band weather radar.

 

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10.   Filipčić, A. (1991): Profiles of mean sea-level pressure along the 100th meridian east and 180th meridian. Geofizika, 8, 61-66. (in Croatian). 

 

ABSTRACT:

 

       The presented profiles of the mean sea-level pressure in high latitudes (including the North and the South Pole) are based on the observed data. In this way in the cold part of the year on the northern hemisphere along the 180th meridian it has been possible to note that the highest air pressure is not centered at the North Pole but about 15° to the south. It is the effect of influence of Islandic minimum, so that the air pressure in the Northern Pacific is still on the rise. In summer because of strong thermal influence of Asia, it is demonstrated that the subtropical high-pressure belt over that part of the northern hemisphere does not exist at all.

 

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