Diurnal Variation in Airborne Pollen Concentrations of the Selected Taxa in Zagreb, Croatia

The number of individuals allergic to plant pollen has recently been on a constant increase. The knowledge of diurnal distribution and abundance of allergenic pollen types, their patterns and response to source position and weather is useful to correlate hay fever symptoms with the presence of allergenic pollen in the atmosphere. The aim of this study was to determine diurnal distribution of total airborne pollen, pollen of particular allergenic taxa, possible variation in diurnal pollen distribution at measuring sites placed at different heights, and effect of some meteorological parameters on airborne pollen concentrations. A 7-day Hirst-type volumetric pollen trap was used for pollen sampling. Qualitative and quantitative pollen analysis was performed under a light microscope (magnification x400). Total pollen of all plant taxa (Ambrosia sp., Betula sp., Cupressaceae, Urticaceae, Poaceae, Quercus sp., Fraxinus sp., Alnus sp., Corylus sp., Populus sp., Pinus sp., Picea sp.) observed showed a regular diurnal distribution at both sampling sites in both study years, with a rise in the pollen concentration recorded after 4.00 a.m. and 6.00 a.m., respectively. The peak pollen concentration occurred between 12.00 a.m. and 4.00 p.m., and the lowest diurnal pollen concentrations were recorded overnight. About 50% of the 24-h pollen concentration were released to the atmosphere between 10.00 a.m. and 4.00 p.m. The timing and size of diurnal peaks were closely related to high temperature, low humidity and south-west maximum wind direction

SEASONAL DYNAMICAL DOWNSCALING WITH ERA-4O DATA: A SENSITIVITY STUDY

The Regional Climate Model (RegCM) with 50 km horizontal resolution was used for seasonal dynamical downscaling of ECMWF ERA-40 data over central and southern Europe and the northern Mediterranean region for one winter and one summer season. Various configurations in initial conditions (ICs) and lateral boundary conditions (LBCs) as well as in the model vertical domain were tested. First, the horizontal resolution of ICs and LBCs was increased from T42 to T159 and then a gradual "degradation" was conducted: the frequency of the LBCs update was reduced from 6-hourly to 12-hourly intervals, the model top was lowered from 100 to 200 hPa and the number of vertical levels was reduced from 18 to 14. The latest, most "degraded", configuration is the closest to that available in the ECMWF seasonal forecast archive. The limited number of experiments (a single experiment per configuration and per season) did not allow a thorough statistical assessment of model responses; however, it can be concluded that, though the differences between various configurations and resolutions are generally small, they are far from being negligible. The increase in the ICs and LBCs horizontal resolution yields a reduction in geopotential, in both the upper-air and surface temperature (cooling) and a reduction in the summer convective precipitation. The reduced, 12-hourly, frequency of the LBCs update mostly renders the opposite result, i.e. an increase in geopotential and temperature. However, it was not possible to fully establish how actually detrimental this reduced frequency in LBCs is, because the input ERA-40 upper-air data "osciliate" between consecutive 6 hours due to the difference in the processing of temperatures from satellites and from radiosondes within the ECMWF 3D-Var assimilation system. The model upper troposphere winds are strengthened when the model top is lowered; however, this effect is partly offset when the number of model levels is reduced. Changes in the model vertical configuration cause on average much weaker effects on surface fields than changes in LBCs. The Arakawa-Schubert ciosure in the parameterisation of convection reduces the amount of summer convective precipitation over the northern European lowlands when compared with the Fritsch,Chappel closure. However, in a large portion of the integration domain precipitation is still too high in respect of the CRU observational data

A MODELLING STUDY OF THE UNIVERSAL STABILITY FUNCTIONS IN SIMPLE NUMERICAL MODEL SIMULATIONS OVER IDEALIZED URBAN SURFACE

The aim of this numerical study is to evaluate several formulations of universal stability functions, which characterise turbulent exchange processes in the surface layer in the simple one-dimensional and two-dimensional numerical models. In the first part of the paper the one-dimensional prognostic model illustrates the basic behaviour of the stability functions and in the second part, the ability of the mentioned functions to provide a physical and numerical successful two-dimensional integration of the urban heat island circulation is examined. The results show that the examined formulations did not succeed in describing the development of the urban heat island circulation

DIGITALNA GODIŠNJA TEMPERATURNA KARTA HRVATSKE

U radu su prikazana osnovna temperaturna obilježja na području Hrvatske koja su dobivena izradom digitalne karte srednje godišnje temperature zraka. Za izradu digitalne karte korišteni su podaci sa 161 klimatološke i glavne postaje na području Hrvatske i Slovenije za razdoblje 1961-1990. Karta je izrađena primjenom linearnog regresijskog modela koji daje vezu između temperature kao zavisne veličine te zemljopisne dužine i širine i nadmorske visine kao nezavisnih veličina u točkama mreže. Najniže godišnje temperature zraka javljaju se na vrhovima najviših planina i iznose 2-3ºC. U ravničarskom kontinentalnom dijelu Hrvatske prosječna je godišnja temperatura zraka oko 11ºC, dok je na Jadranu u rasponu od l3ºC na sjeveru do 17ºC na krajnjem jugu

Correlation between biometeorological forecast and the incidence of obstetric admissions in perinatal center during five years: A retrospective study of one center

Background and purpose: The aim of this study was to correlate obstetric admissions at a tertiary perinatal center with biometeorological forecast and weather conditions. Materials and methods: This retrospective study was conducted at the Department of Gynaecology and Obstetrics Clinical Hospital “Sveti Duh” over five years, from January 1, 2014 to December 31, 2018. The hospital’s emergency data was used for record of obstetric admissions on each day. The selected days were sorted in 4 groups based on biometeorological forecast. Results: In the observed period, there were a total of 18,072 obstetric admissions. There were 216 days with fifteen or more admissions. The results showed no significant difference between obstetric admission based on the biometeorological forecast one day before or three days before. Most hospitalization were on days with a favorable biometeorological forecast in the observed period, 68 days with more than fifteen admissions per day. The day before, the biometeorological forecast was mostly favorable or relatively favorable. Conclusion: Our retrospective single-center study did not show a significant difference between obstetric hospital admissions depending on biometeorological conditions, but the higher number of admissions during days with a favorable forecast is definitely the basis for future studies with larger dataset

Association of weather conditions and the day with extreme number of deliveries with spontaneous onset in a tertiary referral perinatal center

Background and purpose: The effect of weather on people’s well-being and health has been previously noticed and has been a subject of interest for medical professionals and laypeople throughout human history. There are many studies connecting gynecology and obstetrics with weather, some of them investigating the weather and physiological processes such as onset of labor.Materials and methods: In this paper we tried to find relationship between weather conditions and the day with extreme number of deliveries with spontaneous onset (contractions and/or rupture of membranes) in a tertiary referral perinatal center. It is still debatable whether we could connect the weather conditions with actual childbirth.Results: A case analysis shows that there could be a connection between the development of the weather situation and the extreme number of deliveries with spontaneous onset.Conclusion: Unfavorable biometeorological conditions were the result of weather conditions that affect people. In our case there was strong cold advection during the analyzed period, especially on the day with an extreme number of deliveries with spontaneous onset, and significant drop of barometric pressure