Zuzanna Bielec-Bąkowska

The long-range transport of Pinaceae pollen: an example in Kraków (southern Poland)

High Pinaceae pollen concentrations in the air and on the surface of puddles before the main pollen season started were observed in Kraków (southern Poland) in May 2013. The paper presents the results of detailed studies of the composition and source of the “yellow rain” in 2013, and as a comparison, the Pinaceae pollen concentrations and samples collected from the ground surface in 2014 were considered. The air samples were collected using the volumetric method (Hirst-type device), while pollen grains sampled from the ground surface were processed using a modified Erdtman acetolysis method. Finally, all samples were studied using a light microscope. In 2013, the period of higher Abies, Picea and Pinus pollen concentrations was observed from the 5 to 12 of May, earlier than the main pollen season occurred. The presence of rainfall on the 12 and 13 of May 2013 caused the pollen deposition on the ground surface, where the prevalence of Pinaceae pollen was found. The synoptic situation and the analysis of the back-trajectories and air mass advection at the beginning of May 2013 indicated that Pinaceae pollen grains could have been transported from Ukraine, Romania, Hungary and Slovakia. In contrast, Pinaceae pollen grains deposited on the ground surface as a “yellow” film in May 2014, originated from local sources.

Atmospheric fronts over Poland (2006-2015)

Abstract The paper presents the spatial and temporal variations in the occurrence of fronts and days with no fronts over Poland in 2006-2015. The research was based on a database of the atmospheric fronts that moved over five selected stations located in the outermost regions of Poland and in the centre of the country. The database was created as a result of an analysis of synoptic charts from the website of the German weather service (Deutscher Wetterdienst; DWD). As is shown by the results, atmospheric fronts moved over Poland on approximately 65% of days of the year. However, their frequency in the individual regions was almost half of this, ranging from 33-39%. The annual variations in the number of fronts depended largely on the location of a given area and the atmospheric circulation prevailing there. In most years the maximum frequency of occurrence of atmospheric fronts was observed in November-January, and the lowest frequency was seen in February and September. The research confirms that there is a clear predominance of cold fronts, with warm and occluded fronts forming at around half the frequency of cold fronts. One characteristic feature is a decrease in the number of occluded fronts and days with different types of fronts moving from the north of Poland southwards. In the period under study, more than 80% of the sequences of days with atmospheric fronts included up to 6 days, even though there were also cases when fronts passed over Poland on 20 consecutive days.

Long-term variability of the frequency and persistence of strong highs over Poland

Abstract The paper discusses the spatial and temporal variability in the occurrence of strong highs over Poland in the period 1951-2015. It focuses in particular on the persistence of the systems in question and the changes in their long-term variability. The study was based on the average daily sea-level air pressure values obtained from NCEP/NCAR Reanalyses for 12 grid points. A day with a strong high was defined as a day with daily average pressure equal to or higher than 1030 hPa. Over the study period, a minor increase in the annual air pressure values (0.17-0.32 hPa/10 years) was identified, as well as evidence of an increase in the number of days with strong highs. These changes were the most distinct in December and in southern Poland. A majority of strong high occurrences were recorded during the cool half of the year, they covered less than the whole territory of the country and typically persisted for no more than two days. The longest spells with pressure equal to or greater than 1030 hPa lasted between 15 and 22 days depending on the region. Such long sequences of days with strong highs coincided with years when strong highs were particularly frequent, especially in the 1980s and 1990s. No specific trends in persistence or seasonality were identified.

Thunderstorms and thunderstorm precipitations in southern Poland

Abstract This paper addresses spatial and temporal variability in the occurrence of thunderstorms and related precipitation in southern Poland between 1951 and 2010. The analysis was based on thunderstorm observations and daily precipitation totals (broken down into the few ranges) from 15 meteorological stations. It was found that precipitation accompanied an overwhelming majority of thunderstorms. The most frequent range of thunderstorm precipitation totals was 0.1–10.0 mm which accounted for 60% of all values while precipitation higher than 20.0 mm accounted only for ca. 8%. During the study period, long-term change in the number of days with thunderstorm precipitation within a certain range displayed no clear-cut trends. Exceptions included: 1) an increase in the number of days with thunderstorm precipitation in the lowest range of totals (0.1–10.0 mm) at Katowice, Tarnów, Rzeszów and Lesko and decrease at Mt. Kasprowy Wierch, 2) an increase in the range 10.1–20.0 mm at Zakopane and 20.1–30.0 mm at Opole, 3) a decrease of the top range (more than 30.0 mm) at Mt. Śnieżka. It was found that the heaviest thunderstorm precipitation events, i.e. totalling more than 30 mm, and those events that covered all or most of the study area, occurred at the time of air advection from the southern or eastern sectors and a passage of atmospheric fronts.