Lidija Srnec

Poaceae pollen in the atmosphere of Zagreb (Croatia), 2002 – 2005

Pollen of grasses (Poaceae) is one of the most important airborne allergen sources worldwide. The aim of the study was to determine diurnal, day‐to‐day, weekly, monthly and annual pollen variation, and the effect of selected meteorological parameters on atmospheric pollen concentrations in Zagreb. A preliminary study was carried out during four seasons (2002 – 2005), using a 7‐day VPPS 2000 Hirst volumetric pollen trap. Total annual grass pollen concentrations in Zagreb were constant (2 673 – 3 074 p.g.m−3), with a relative drop in 2004 (1 196 p.g.m−3). The beginning of the grass pollen season is usually observed when the average daily temperature exceeds 13.5°C (max. daily temp. 19.5°C), without precipitation. In all four study years the absolute peak of concentrations occurs in the second half of May. The length of pollen season during the study period was 157 – 173 days. A high variability was observed in the maximal concentration and in the number of days when grass pollen concentration exceeded the threshold value of 30 p.g.m−3 (9 – 40 days). Statistically significant correlations were found between airborne grass pollen concentrations and air temperature, level of precipitation and relative humidity.

Airborne pollen of Betula, Corylus and Alnus in Zagreb, Croatia. A three‐year record

The aim of this study was to construct a picture of the influence of meteorological conditions on the start and duration of the airborne Betulaceae pollen season and the pollen concentrations in the atmosphere of Zagreb, Croatia. The study during three seasons (2002–2004) used a 7‐day Hirst‐type volumetric pollen and spore trap. Total annual airborne pollen of Alnus, Corylus and Betula greatly varied from year to year. The differences in the dates of onset of airborne pollen presence of Alnus, Corylus and Betula noted in Zagreb in 2002–2004 were controlled by weather conditions, particularly temperature and precipitation. In all years studied, airborne pollen peaks were recorded on days with temperature above 0°C and without or minimal precipitation. The mean number of days with airborne pollen concentrations exceeding levels which provoke symptoms of an allergic reaction was 15, 16 and 29 days for alder, hazel and birch, respectively. The results of the present study may provide useful data for allergologists to reach accurate diagnoses, and timely information on concentrations of airborne pollen types and concentrations for individuals with pollen hypersensitivity.

Atmospheric conditions during high ragweed pollen concentrations in Zagreb, Croatia

We examined the atmospheric conditions favourable to the occurrence of maximum concentrations of ragweed pollen with an extremely high risk of producing allergy. Over the 2002–2009 period, daily pollen data collected in Zagreb were used to identify two periods of high pollen concentration (> 600 grains/m3) for our analysis: period A (3–4 September 2002) and period B (6–7 September 2003). Synoptic conditions in both periods were very similar: Croatia was under the influence of a lower sector high pressure system moving slowly eastward over Eastern Europe. During the 2002–2009 period, this type of weather pattern (on ~ 70% of days), in conjunction with almost non-gradient surface pressure conditions in the area (on ~ 30% of days) characterised days when the daily pollen concentrations were higher than 400 grains/m3. Numerical experiments using a mesoscale model at fine resolution showed successful multi-day simulations reproducing the local topographic influence on wind flow and in reasonable agreement with available observations. According to the model, the relatively weak synoptic flow (predominantly from the eastern direction) allowed local thermal circulations to develop over Zagreb during both high pollen episodes. Two-hour pollen concentrations and 48-h back-trajectories indicated that regional-range transport of pollen grains from the central Pannonian Plain was the cause of the high pollen concentrations during period A. During period B, the north-westward regional-range transport in Zagreb was supplemented significantly by pronounced horizontal recirculation of pollen grains. This recirculation happened within the diurnal local circulation over the city, causing a late-evening increase in pollen concentration.

Destination Climate Adaptation

A key element in the product mix of destinations is climate. Climate represents a critical part of a destination’s economic and resource base such that changes in climate will trigger human responses in terms of demand and the type of activities that the climate will support. This threatens the competitiveness, sustainability, and economic viability of destinations. This research note focuses on destination adaptation to climate change that is anticipatory not reactive, based on projecting future climate scenarios for a destination and then assessing the tourism products that the future climate will support. It outlines an original data-driven approach to adaptation that is generalizable to other destinations. The research note describes an exploratory research collaboration in Croatia between tourism and climate scientists that allows, first, the modeling of a destination’s projected climate conditions and, second, the products and activities that can be supported by these climate scenarios using climate indices for tourism.

Erratum to: Atmospheric conditions during high ragweed pollen concentrations in Zagreb, Croatia

V. MadžarevicAndrija Mohorovicic Geophysical Institute,DepartmentofGeophysics,FacultyofScience,UniversityofZagreb,Horvatovac 95,10000 Zagreb, Croatiae-mail: telisman@gfz.hrL. SrnecMeteorological and Hydrological Service of Croatia, Zagreb,Croatia,Gric 3,10000 Zagreb, CroatiaR. PeternelUniversity of Applied sciences Velika Gorica,Velika Gorica, CroatiaI. Hrga