Mjerenja ozona na planinskoj postaji Zavižan (Hrvatska) tijekom 1997. – 2000.

Analysis of ozone concentrations measured at Zavižan, Croatia\u27s highest altitude meteorological station (1594 m a.s.l.), during the spring and summer months of 1997–2000 shows that the actual new Croatian Air Quality standards are severely exceeded. Implication of this and similar findings from other elevated sites call for additional consideration of ozone behaviour at high altitudes in defining ozone standards.Analiza podataka o volumnom udjelu ozona na Zavižanu, najvišoj meteorološkoj postaji u Hrvatskoj (1594 m iznad mora) tijekom proljeća i ljeta 1997. do 2000. godine pokazuje da vrijednosti znatno prelaze granične vrijednosti za kvalitetu zraka važeće nove hrvatske Uredbe o ozonu. Dobiveni rezultati i mjerenja s drugih visinskih postaja ukazuju da potrebu razmatranja uvjeta i na visinskim postajama pri definiranju graničnih vrijednosti za kvalitetu zraka s obzirom na ozon

Mjerenja ozona na brdu Srđ blizu Dubrovnika, Hrvatska

Results and analysis of ozone monitoring at station Sr| (46.25° N, 17.45° E, 412 m a.s.l.) near Dubrovnik from 1998 – 2005 are reported. It is confirmed that this is an unpolluted place despite of high summer solar radiation which could contribute to the photochemical air pollution formation. There is no significant trend in ozone levels found during this time and the overall aver­age ozone fraction is found to be 46 ppb for the summer periodsPrikazani su rezultati i analiza mjerenja ozona na postaji Srđ (46.25° N, 17.45° E, 412 m a.s.l.) blizu Dubrovnika u razdoblju od 1998 do 2005. Potvrđen je neonečišćeni karakter ove lokacije unatoč jakom Sunčevom zračenju ljeti. Mjerenja nisu dala naznake trenda u koncentracijama ozona, a prosječna vrijednost udjela ozona u ljetnom periodu je bila 46 ppb

Mjerenja ozona na brdu Srđ blizu Dubrovnika, Hrvatska

Results and analysis of ozone monitoring at station Sr| (46.25° N, 17.45° E, 412 m a.s.l.) near Dubrovnik from 1998 – 2005 are reported. It is confirmed that this is an unpolluted place despite of high summer solar radiation which could contribute to the photochemical air pollution formation. There is no significant trend in ozone levels found during this time and the overall aver­age ozone fraction is found to be 46 ppb for the summer periodsPrikazani su rezultati i analiza mjerenja ozona na postaji Srđ (46.25° N, 17.45° E, 412 m a.s.l.) blizu Dubrovnika u razdoblju od 1998 do 2005. Potvrđen je neonečišćeni karakter ove lokacije unatoč jakom Sunčevom zračenju ljeti. Mjerenja nisu dala naznake trenda u koncentracijama ozona, a prosječna vrijednost udjela ozona u ljetnom periodu je bila 46 ppb

Analysis of Summer 2006 Ozone Pollution in Zagreb

In the summer of 2006, ozone concentrations were measured at three sites in the Zagreb area. Stations Velika Gorica (VG), Dugave (DUG), and Institute for Medical Research and Occupational Health (IMI) were located at the same elevation along a 15-km stretch from the Zagreb Airport in the south (VG) to about 2.5 km north from the city centre (IMI). At all three sites, ozone volume fractions showed pronounced diurnal variations, peaking between 15 h and 18 h (VG) and between 13 h and 16 h (DUG, IMI) local time (CEST). Average ozone volume fractions measured in the northern and southern residential part of the town (IMI and DUG) were similar and also showed similar daily pattern. In VG daily variations were more pronounced. The analysis of summer 2006 ozone data clearly shows the highest ozone concentrations at the southernmost point (VG). Because the comparison of diurnal variations at all three stations neither confirms nor disproves the transport of ozone precursors to the VG station, it is possible that the source of these high ozone levels at the VG station is local or further south. The wind rose shows there is a low probability of transport from VG station into the city

Modeling of Ozone and Hydrogen Peroxide in Air

Ozone (O3) and hydrogen peroxide (H2O2) volume fractions were calculated using the Master Mechanism (MM) model, author S. Madronich (NCAR, Boulder, CO, USA). MM is an atmospheric “box” model program for calculating the time evolution of atmospheric composition from initial amounts of atmospheric gases under chosen or varying conditions using reaction rate data and other physicochemical parameters. The photolysis coefficients were calculated using the Tropospheric Ultraviolet Visible (TUV) program of the same author. Data gathered during the field measurements in 200419 and modeled with the MM program20 are used here to determine how gradual increase of one initial value of the following eight quantities: NO2, CO, VOC (i.e. some volatile organic compounds), BTX (i.e. benzene, toluene, xylenes), H2O2, O3, temperature and relative humidity, will in the MM modeling affect the volume fractions of either ozone or hydrogen peroxide. According to the model, H2O2 volume fractions in air increase with higher relative humidity and higher initial values of CO, VOC, BTX, H2O2 and O3, and only decrease by NO2. On the other hand, ozone volume fractions do rise with the increase of initial volume fractions of NO2, as well as of CO, VOC, BTX, H2O2 and O3. Temperature does not have any significant influence on the formation of H2O2 and O3. The results also may explain the considerably higher ozone values measured at the airport than in the city of Zagreb (ref. 22)

Estimation of biologically effective UV radiation in Croatia

Background and Purpose: Solar UV radiation is harmful to plants: it reduces photosynthesis, stunts growth, and causes a variety of damage to a plant. The purpose of this study was to estimate solar UV exposure and harmful biologically effective irradiance during the vegetative growth period in Croatia. Biologically effective irradiances were calculated for several action spectra. Data were analyzed in order to establish the relationship between UV exposure, time of a day and week of the year. Simplified formulas were developed that mimic complex radiative transfer models. Methods: UV radiation in Croatia was estimated using the Tropospheric Ultraviolet-Visible (TUV) model, version 4.2. Dose rates harmful to plants (UV-B, UV-A) and also useful photosynthetically active radiation dose rate (PAR) were calculated at 13 h (CEST) at fifty sites during the vegetative growth period (April-October). Daily and monthly variations of UV-B dose rate (irradiance) were calculated (and some approximate formulas were developed) for one representative location. Biologically effective UV daily doses were calculated using data on four different action spectra. Results: In July, at some elevated locations, UV-B irradiance was higher than 2 Wm–2 at 13 h (CEST). The biologically effective UV daily doses ranged from 29 kJ m–2 in October to 72 kJ m–2 in July. The daily doses calculated in this study are the maximum values; all calculations refer to clear-sky conditions and to the total ozone column value 300 DU, which approximately corresponds to the lowest total ozone value measured during the vegetative growth period. Conclusions: UV exposure in Croatia was estimated at one location chosen as representative. Simplified formulas that describe daily and monthly variations of UV-B irradiance may be used instead of the TUV model and produce a relative error of less than 10 %. Corrections for the total ozone column and cloudiness are also possible

Mjerenja ozona na planinskoj postaji Zavižan (Hrvatska) tijekom 1997. – 2000.

Analysis of ozone concentrations measured at Zavižan, Croatia\u27s highest altitude meteorological station (1594 m a.s.l.), during the spring and summer months of 1997–2000 shows that the actual new Croatian Air Quality standards are severely exceeded. Implication of this and similar findings from other elevated sites call for additional consideration of ozone behaviour at high altitudes in defining ozone standards.Analiza podataka o volumnom udjelu ozona na Zavižanu, najvišoj meteorološkoj postaji u Hrvatskoj (1594 m iznad mora) tijekom proljeća i ljeta 1997. do 2000. godine pokazuje da vrijednosti znatno prelaze granične vrijednosti za kvalitetu zraka važeće nove hrvatske Uredbe o ozonu. Dobiveni rezultati i mjerenja s drugih visinskih postaja ukazuju da potrebu razmatranja uvjeta i na visinskim postajama pri definiranju graničnih vrijednosti za kvalitetu zraka s obzirom na ozon

Estimation of Ozone and Peroxide Levels in the Air of Croatia

Volume fractions of different atmospheric gas constituents were modelled using Master Mechanism (MM) model developed by S. Madronich (NCAR, Boulder, CO, USA). Ozone (O3) and hydrogen peroxide (H2O2) seasonal variations were estimated at three different locations in Zagreb. Modelled ozone values showed good agreement with measured values at all three sites. The estimation of H2O2 annual variations with the MM model showed typical H2O2 seasonal variation at a remote location and at an urban location not exposed to traffic, with the highest values over the summer months, due to higher solar radiation. The summer/winter differences were more pronounced at the remote location. At the site exposed to traffic, H2O2 volume fractions did not show seasonal variations and H2O2 levels were determined by the levels of nitrogen oxides. The model was also used to estimate oxidant levels during the heat wave in August 2003. It yielded high hydrogen peroxide (2.5 ppb–3.5 ppb) and ozone (> 100 ppb) levels, followed by increased concentrations of OH radicals. The model confirmed that in extreme conditions (high temperature and solar radiation, elevated CO and NO2 levels) over the summer, the atmospheric oxidizing capacity in Croatia exceedingly rises and may exert harmful effects on the environment

Modeling of Ozone and Hydrogen Peroxide in Air

Ozone (O3) and hydrogen peroxide (H2O2) volume fractions were calculated using the Master Mechanism (MM) model, author S. Madronich (NCAR, Boulder, CO, USA). MM is an atmospheric “box” model program for calculating the time evolution of atmospheric composition from initial amounts of atmospheric gases under chosen or varying conditions using reaction rate data and other physicochemical parameters. The photolysis coefficients were calculated using the Tropospheric Ultraviolet Visible (TUV) program of the same author. Data gathered during the field measurements in 200419 and modeled with the MM program20 are used here to determine how gradual increase of one initial value of the following eight quantities: NO2, CO, VOC (i.e. some volatile organic compounds), BTX (i.e. benzene, toluene, xylenes), H2O2, O3, temperature and relative humidity, will in the MM modeling affect the volume fractions of either ozone or hydrogen peroxide. According to the model, H2O2 volume fractions in air increase with higher relative humidity and higher initial values of CO, VOC, BTX, H2O2 and O3, and only decrease by NO2. On the other hand, ozone volume fractions do rise with the increase of initial volume fractions of NO2, as well as of CO, VOC, BTX, H2O2 and O3. Temperature does not have any significant influence on the formation of H2O2 and O3. The results also may explain the considerably higher ozone values measured at the airport than in the city of Zagreb (ref. 22)