WEATHER CONDITIONS AND THE SINO-BRONCHIAL SYNDROME IN CHILDREN IN ZAGREB

Nada. Pleško

Milica Krstić‑Burić

Maja Medar‑Lasić

Ðurđica Milković

Maja Bašić‑Grbac

Sanja Pleško

Abstract - This paper deals with the dependence of the chronic sino-bronchial syndrome and respiratory tract acute diseases in children and adults (age 0-19) living in Zagreb (a town with developed industry and heavy road traffic) on meteorological elements acting on man's thermal sensation. This study is based on the bioclimatic index i/H (air enthalpy and cooling power rate) and the relevant bioclimatic classification and on those meteorological elements that are included in the bioclimatic index calculation (air temperature, relative humidity, wind speed and barometric pressure). A correlation analysis method has been applied on both daily data and 3-, 5- and 7-day moving average values. All analyses have been done separately for the cold and warm part of the year. The results for the cold and warm parts of the year differ. Chronic patients react earlier to meteorological stress than acute ones. In the cold part of the year the warm periods are critical while in the warm part of the year the cold ones are critical. Along with the air temperature relative humidity is also significant. For acute patients periods with high relative humidity are particularly unfavorable, both in the cold and warm periods of the year, if they last at least three days. SO₂ and smoke concentration in the studied period (1988-90) was within the allowed limits and their correlation with sino-bronchial diseases, chronic or acute, was not significant.

Key words: sino-bronchial syndrome in children, chronic, acute, weather conditions, thermal comfort, meteorological elements, concentration of SO₂ and smoke, correlation analysis.

Sulphur-dioxide concentration in the Northern Adriatic health resort area

Alica Bajić, Sonja Vidič, Vesna Đuričić

Abstract - The series of 1226 samples of 24-hours SO₂ concentration data in Veli Lošinj during the period 1986-1989 have been analysed together with basic meteorological variables measured on Mali Lošinj at 3 climatological terms. The day-to-day synoptic weather types are examined in order to relate synoptic scale flow patterns to the SO₂ concentration data. The pollution level in Lošinj area was found to be considerably lower than the minimum legal value of SO₂ based on public health criteria which is 60 mgm^-3 for 24 hours. Nevertheless, particular meteorological conditions such as anticyclonic situations with slight winds from SW-NW direction in winter and bora favourable conditions in spring produced the limited number of situations with 24-hour SO₂ concentration level greater than 40 mgm^-3. From the analysis of the effects of various meteorological elements wind speed and directions were found to be best correlated with the pollution concentration. It is shown that “the worst cased” air pollution situations in areas of low emission rates are not necessarily stagnation periods but my be periods with good ventilation.

Key words. SO₂ concentration, Northern Adriatic, weather types

SO₂ BACKGROUND AIR POLLUTION IN THE BAKAR BAY

Nadežda Šinik¹ , Edita Lončar², Anton Marki¹

Abstract - A correlation between wind velocity and simultaneous pollutant concentrations at a given locality makes possible to estimate potential background pollution. A simple procedure has been derived which helps to determine the minimum concentration corresponding to a theoretical case when wind velocity approaches infinity. It is applicable to any locality. Such research was carried out in the Bakar bay, on the northern Adriatic coast of Croatia, for simultaneous hourly series of SO₂ concentration and wind velocity. It turned out that the minimum value of SO₂ concentration which could not be cleared away any longer by meteorological factors did not depend upon the change in intensity of the local sea and land breeze circulation and its dispersive potentials. Still, when wind directions were taken into account, the different impact of distant and close emission upon the local background pollution could be detected.

Key words index: estimation of local background pollution, sea and land breeze

Distribution Analysis and Mean Residence Time of ⁹⁰Sr in Wet Fallout in Zagreb

Zdenko Franić

Abstract - The results of the analysis of long‑term measurements of ⁹⁰Sr radioactivity in the wet fallout in the Zagreb area are presented. The data are lognormally distributed and the parameters of the lognormal distribution are interpreted. The mean residence time of ⁹⁰Sr in wet fallout is calculated by means of the obtained distribution parameters.

Key words index: ⁹⁰Sr, wet fallout, distribution analysis, mean residence time.

THE WEATHER TYPES IN CROATIA

Edita Lončar i Alica Bajić

Abstract - This article deals with the analysis of the weather types determined for continental Croatia during the period 1971 - 1990. The common statistics of annual, seasonal and monthly relative frequencies has been evaluated with the addition of ten day values so that the relationship between weather types and meteorological parameters can be defined more realistically. Besides, a scheme of the weather types, partitioning according to their influence upon the weather, has been suggested. An additional statistics of weather type duration, of transition from one type to another and of the variability or, possibly the steadiness of certain weather type appearance in the given period completes this analysis together with various information about weather conditions in the of Croatian hinterland.

Key words: Weather type, statistical analysis, annual, seasonal, monthly and ten day relative frequency, weather type categories

A CURVATURE EFFECT ON THE CRITICAL RICHARDSON NUMBER

Branko Grisogono

Abstract - Transitions from laminar to turbulent flow associated with a critical level in the stratified shear flow are related to the critical (gradient) Richardson number, Ri_c, the minimum value of which is Ri_c»1/4. Based on the linear theory and a modified Taylor-Goldstein equation, here it is plausibly shown that Ri_c may slightly vary from this value if the mean wind speed profile contains a small curvature (parameterized here) around the critical level. The modified Ri_c that depends on the dimensionless curvature aº(U’’z/U’) is

.

Key words index: Richardson number, critical level, Taylor-Goldstein equation, parameterization

METEOROLOGICAL STATIONS NETWORK IN CROATIA AND WARS

Zvonko Katušin

Abstract - The meteorological network in Croatia has been operating continuously since the middle of the 19 century. Wars, as significant historical events have a tendency to interrupt such continuity. This paper presents a diagram of the meteorological stations network development, since 1850 showing the decrease in the total number of meteorological stations during and after World War I, World War II and in the period of aggression on Croatia from 1991 to 1993. The impact of war in the period from 1991 to 1993 is presented in greater detail by a second diagram, showing an evident correlation between actual war activities and the lack of meteorological observations, damage to meteorological equipment and buildings. The horizontal and vertical distribution of meteorological stations within the meteorological network is shown for the year when the distribution was in accordance with criteria recommended by The World Meteorological Organization. If we compare the total number of meteorological stations on 31 December 1993 with the recommended optimum number of meteorological stations, (in accordance with WMO regulations) we can see that only 54.7 % stations were active. Compared to the total number of meteorological stations before the aggression (31 December 1990) 30.4 % stations were destroyed or incapacitated from 1991 to the end of 1993 by war activities. The direct damage (destroyed buildings and instruments of the basic meteorological network) amounts to more than US$ two million. Evidence has been collected from the participants to these events and original reports supplied by the Heads of meteorological stations are quoted. Photographs, diagrams, tables and data from our station catalogues have been used prepare this article. The period analyzed ends on 31 December 1993.

Key words index: meteorological station, network, history, war, observation, destroy, damage, report

WIND SPEED AND ROUGHNESS PARAMETER RELATIONSHIP

Branko Cividini

Abstract - This paper shows the relation, for different wind speed classes, between wind speeds measured at 10 m and 50 m heights near the Konjsko power station. It has been found that gust factors decrease with increasing wind speed, while the mean speed ratio increases, and the gust ratio, except for weak winds, is nearly constant. The relation between gust factor and roughness has been analyzed, together with the possibility of estimating local roughness length from data taken at one measurement level (Wieringa method). The reference method for estimating local roughness was based on the mean wind speed profile in the neutral boundary layer. The Wieringa method is not acceptable in complex terrain conditions because the calculated value z0 are at least one order of magnitude larger than "actual" local roughness.

Key words index: roughness parameter, gust factor, wind speed.

SEVERE ADRIATIC BORA STORMS 1987-1993

Nedjeljka Brzović, Mira Benković

Abstract: In the first part of this paper severe Adriatic bora storms are analysed using the available data from five stations along the Adriatic coast, in the period 1987-1993. The most severe bora storms were registered in Split, while, in contrast to the previous 30-year period, severe bora in Senj was rare .The highest hourly wind speed was registered in Split, with an absolute maximum of 24.7 ms^-1, and the strongest hourly gusts occurred in Senj, with an absolute maximum of 47.6 ms^-1. The longest severe storm duration was 21 hours in Senj, with 17 and 20 hours in Split and Dubrovnik, respectively.

In the second part of the paper, a severe bora case on 31 January-1 February is analysed in more details. Vertical profiles and vertical time cross-sections are presented, using a high resolution isentropic diagnostic model. The synoptic and vertical time cross-section analyses show that the bora appearance in Dubrovnik was connected with the passage of a cold front, while the long bora in Senj was the result of a postfrontal situation with inversion capping the bora layer, which is characteristic for the onset and maintenance of long-lasting bora at this location.

Key word index: severe bora storm, Adriatic wind

ACID RAIN EVENTS AT THE LOŠINJ ISLAND

Sonja Vidič, Vesna Đuričić, Alica Bajić

Abstract: For the period June 1987 - December 1989, daily precipitation samples were collected at Veli Lošinj, health resort located at the southern part of the Lošinj island. The main purpose of the measurement programme was to determine frequency and conditions of acid rain occurrences. Bulk precipitation samples were collected and analysed with regard to precipitation acidity only, which significantly limited the scope of the research. It was found that for the whole period 32 % of samples were acidic, with the average precipitation-weighted pH to be 4.83. It was noted that strong acidity was correlated with larger precipitation amount.

CALCULATION METHODS APPLIED TO LOW WATERS IN OPEN WATER COURSES

Dušan Trninić

D.Sc.Thesis - Zagreb University

Faculty of Civil Engineering, Zagreb, 1994, 183 pp.

Summary: The introduction to the dissertation presents the reasons for choosing the topic Calculation Methods applied to Low Waters in Open Watercourses, one of the reasons being the extensive damage resulting from draught in Croatia in the period 1980-1992. The introduction also stresses the importance of the Hydrologic Data Bank since without the data contained in the bank and the relevant software such a comprehensive and complex analysis would not have been possible. It also mentions the importance of the Geographic Information System as a modern system of storing, processing and interpreting data. The second part presents a summary of the basic factors (natural and anthropologic) influencing low waters. The third part deals with the evaluation of the data used in the low water analysis, for the definition of the necessary data range length, the spatial distribution of hydrologic stations, the analysis of the homogeneity and trends of minimum annual discharges and minimum annual groundwater levels, and a periodicity analysis by means of the correlation and spectral theory of random processes. Measuring data errors are assessed theoretically by using flow curves. The fourth part presents a survey of the mathematical methods used on existing hydrological data. The basic low water parameters are defined and interpreted by using the ArcInfo and ArcView programmes of the Geographic Information System. The time of appearance of minimal 30-day discharge is defined for the basic period 1960-1989. Special emphasis is given to the exhaustion curve (low water forecast and the definition of groundwater reserves). The fifth chapter deals with the definition of low waters when hydrologic data are insufficient or non-existent. The application of the Vladimirov method to such cases is suggested and an example is given based on the low water in Drava catchment area. The sixth and the last chapter deal with climatic changes and their impact on water resources. Although climatologists are not unanimous in the verification of climatic changes, at least one of the existing climatic forecasts, together with its possible repercussions, should be included in all projects.

BIOCLIMATIC CLASSIFFICATION OF CROATIA

Ksenija Zaninović

M.Sc.Thesis - Zagreb University

Faculty of Natural Sciences, Zagreb, 1994, 183 pp.

Summary: This work investigates the bioclimatic conditions in Croatia by means of data measured at six meteorological stations as representatives of different climatic regions (Hvar, Pula, Zavižan, Skrad, Zagreb and Osijek).

In the first part of the work the combined biometeorological index TWH is defined by means of temperature, wind speed and humidity, meteorological parameters influencing thermal comfort. By means of a combination of some known classifications of thermal comfort, the new classification is determined. It contains 9 thermal comfort classes, from "extremely cold" to "extremely hot".

In the second part of the work the theoretical distributions are fitted to observed TWH data distributions for every season (for 7 am, 2 pm and 9 pm local time). The normal distribution was fitted when it was possible, otherwise the adjusted normal or Gumbel distribution was used. The distributions were tested for significance by means of ² test. In some cases none of the distributions fitted significantly the observed data. In these situations the empirical distributions were analyzed.

Bioclimatic conditions in Croatia are analyzed by means of some standard statistical parameters and TWH index distributions. The probability of occurrence of different thermal sensations is analyzed and the limits of normal and extraordinary bioclimatic conditions are determined.

In the last section the TWH index is compared with the results of some classical biometeorological indices and with the thermal comfort model. The results have shown that TWH index estimates the thermal comfort very well. The relation between TWH index and clothing is determined.