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The impact of initial and boundary conditions on severe weather event simulations using a high-resolution WRF model. Case study of the derecho event in Poland on 11 August 2017

Figurski Mariusz J., Nykiel Grzegorz, Jaczewski Adam, Bałdysz Zofia, Wdowikowski Marcin

Meteorology Hydrology and Water Management. Research and Operational Applications

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2022

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Vol. 10, Iss. 2

60--87

EN

Precise simulations of severe weather events are a challenge in the era of changing climate. By performing simulations correctly and accurately, these phenomena can be studied and better understood. In this paper, we have verified how different initial and boundary conditions affect the quality of simulations performed using the Weather Research and Forecasting Model (WRF). For our analysis, we chose a derecho event that occurred in Poland on 11 August 2017, the most intense and devastating event in recent years. High-resolution simulations were conducted with initialization at 00 and 12 UTC (11 August 2017) using initial and boundary conditions derived from the four global models: Global Forecast System (GFS) from the National Centers for Environmental Prediction (NCEP), Integrated Forecast System (IFS) developed by the European Center for Medium-Range Weather Forecasts (ECMWF), Global Data Assimilation System (GDAS) and ERA5. For the last, we made separate calculations using data at the pressure and model levels. The results were evaluated against surface and radar data. We found that the simulations that used data from the GDAS and GFS models at 12 UTC were the more accurate, while ERA5 gave the worst predictions. However, all models were characterized by a low probability of detection and a high number of false alarms for simulations of extreme precipitation and wind gusts.

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Convective environment and development of a tornadic supercell in the Czech Republic on 24 June 2021

Sulik Sławomir

Meteorology Hydrology and Water Management. Research and Operational Applications

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2022

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Vol. 10, Iss. 1

60--72

EN

This study documents the atmospheric conditions and the development of a tornadic supercell in the Czech Republic, which occurred on the early evening on 24 June 2021. I used the data from the ERA5-reanalysis, vertical atmospheric sounding, synoptic map, and a Sentinel-2 satellite image to determinate the tornado route. As a result of the analysis, it can be concluded that the development of this tornadic supercell was caused by high CAPE values, amounting to around 5,000 J·kg-1, 0-6 km AGL wind shear 30 m·s-1, storm-relative helicity with values of 150 m2·s-2 and a wavy atmospheric front. The tornado occurred around 19:30 local time (1730 UTC) in the town Hrušky and moved north-east, reaching the town Hodonín. Based on satellite image derived from Sentinel-2, the widest point of the tornado reached 70 meters; it traveled a distance of about 20 kilometers and had a force of EF3/T5 on the Fujita/TORRO scale. As a result of this event, 6 people lost their lives, 200 people were seriously injured, and hundreds of buildings and cars were destroyed. Further studies on strong thunderstorm incidents in Europe are necessary for their better understanding and prediction.

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Convective and non-convective wind gusts in Poland, 2001-2015

Kolendowicz L., Taszarek M., Czernecki B.

Meteorology Hydrology and Water Management. Research and Operational Applications

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2016

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Vol. 4, iss. 2

15--21

EN

The main aim of the article is to present the climatology of the peak wind gust frequency in Poland caused by the impact of both atmospheric circulation and the presence of thunderstorm clouds. Nine meteorological stations for the measurement period of 2001-2015 were taken into account. Only SYNOP reports with a peak wind gust higher or equal to 15 m s-1 in thunderstorm and non-thunderstorm days are considered in this study. The results indicate that the highest threat in terms of frequency and strength of peak wind gusts due to convection occurs in July. In winter, thunderstorms are rare, but if they occur, about 80% of them produce wind gusts exceeding a threshold of 15 m s-1. Peak wind gusts in a non-thunderstorm days are the highest and the most frequent in January, and are at a minimum during summer. Comparing both types, peak wind gusts during days with a thunderstorm were on average stronger than those without an involved convection. This indicated that convection was an important factor in enhancing the strength of a wind gust. The highest value in our base was 34 m s-1, recorded in Kraków on 8th July 2015 within the occurrence of a severe thunderstorm, while the highest value in a day without a thunderstorm was 33 m s-1, recorded in Łódź on 31st January 2002.

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Analysis of a storm situation over the southern Baltic Sea using direct hydrometeorological and remote sensing measurements results

Pietrek S. A., Jasiński J. M., Winnicki I. A.

Zeszyty Naukowe / Akademia Morska w Szczecinie

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2014

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nr 38 (110)

81--88

EN

The paper presents results of research concerning meteorological and hydrological conditions in the storm related with the Xaver cyclone moving fast over the Baltic Sea. The analyses were based on remote sensing data from radars in Świdwin and Gdańsk-Rębiechowo and hydrometeorological data from direct measurements conducted at the coastal stations of the Polish Navy, marine stations of the Institute of Meteorology and Water Management, hydrometeorological station on the “Baltic Beta” oil rig and the Coastal Research Station of the Institute of Hydroengineering of the Polish Academy of Sciences in Lubiatowo. The assessment of the synoptic situation was made using surface weather charts, satellite images of cloud cover and meteorological radars products. The measurement data were used to analyze the surface and upper air wind fields for assessment of the hydrological situation (water condition, height and direction of the significant and maximum waves) and evaluation of threats to sea navigation and coastal infrastructure.

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Charakterystyka całkowitej energii chwiejności atmosfery nad Europą w latach 1991-2003

Siedlecki M., Rzepa M.

Przegląd Geofizyczny

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2008

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Z. 1

43-54

PL

Celem opracowania jest przedstawienie warunków całkowitej energii chwiejności atmosfery (CAPE) nad Europą. Dane pomiarowe reprezentują 41 stacji aerologicznych w Europie między 10oW a 50oE oraz 35oN a 65oN. Wartość całkowitej energii chwiejności na wybranych stacjach zostały wyliczone dla sondaży z terminu 00UTC w latach 1991-2003. Przebieg wartości całkowitej energii chwiejności cechuje wyraźny cykl roczny z przypadającymi w lecie wartościami maksymalnymi. Najwyższe wartości powyżej 2500 J/kg zanotowano na stacjach w Mediolanie, na Sycylii, Stambule oraz w Kijowie, natomiast najniższe maksymalne wartości, nieprzekraczające1000 J/kg, na stacjach Brest i Stavanger. Rozkład przestrzenny średnich miesięcznych wartości całkowitej energii chwiejności pozwala na wyróżnienie trzech regionów, cechujących się odmiennym nasileniem niestabilności atmosfery. Pierwszy region, obejmujący obszary zachodniej i północnej Europy zaznacza się najsłabszą chwiejnością atmosfery. Wartości średnie miesięczne CAPE nie przekraczają 50 J/kg. Nie ma tu wyraźnego wzrostu niestabilności atmosfery w lecie. Drugi region, obejmujący wschodnią i środkową Europę, charakteryzuje się silniejsza niestabilnością atmosfery, szczególnie w porze letniej. Wtedy średnie miesięczne całkowitej energii chwiejności przekraczają 50 J/kg w Europie centralnej oraz przekraczają 200 J/kg we wschodniej Europie. Trzeci region, obejmujący południową Europę zaznacza się największymi średnimi miesięcznymi wskaźnika CAPE. W okresie od czerwca do września średnie miesięczne przekraczają 300 J/kg. Rozkład częstości wartości całkowitej energii chwiejności charakteryzuje się silną skośnością. Największą częstością odznaczają się wartości CAPE z przedziału 0-50 J/kg, powyżej 50% wszystkich przypadków, natomiast częstość większych wartości całkowitej energii chwiejności jest znacznie mniejsza. W przypadku stacji śródziemnomorskich szczególnie Mediolan, Sycylia, Stambuł wyróżniają się wzrostem częstości przypadków CAPE powyżej 1000 J/kg. Na tych stacjach w badanym okresie liczba dni z taka chwiejnością przekroczyła 100 przypadków.

EN

The main goal of this study is asses the spatial distribution of convective available potential energy (CAPE) in Europe. The analysis CAPE values is based on data from 41 stations (fig.1) which covered region from 35oN to 65oN and from 35oW to 50oE. The data used in this study were gathered during the thirteen years (1991-2003) measured every day at 00:00 UTC. The annual course of CAPE values shows summer maximum (fig.2). The maximum values reached above 2500 J/kg on Sicilian, Milan, Istanbul and Kiev and only 1000 J/kg on Brest. The spatial distribution and annual course of mean monthly of CAPE values shows three zones. The first one is located in west and north Europe where instability is very week. During all seasons the mean monthly values of CAPE reached minimum lover than 50 J/kg. The second zone, including central end east Europe is characterized by greater instability, especially during summer. During these season the mean monthly values of CAPE are noticed above 50 J/kg, especially in central Europe, and above 200 J/kg in east Europe. The third zone is located in south Europe. Between June to September the mean monthly values reached maximum above 300 J/kg. The frequency distribution of values of CAPE is positively skewed with long tail after the peak. The highest frequency is noticed for 0-50 J/kg in above 50% number of stations. Beyond these CAPE values frequency decreases. The special station are Milan, Sicilian and Istanbul where increases the number of cases above 1000J/kg. The frequency of CAPE index above 1000J/kg is shown (fig.6a) the greatest frequency of strong instability in south Europe (Sicilian, Italy, west Turkey above 100 cases).