Papers by K. Potužníková
Journal of Atmospheric and Solar-Terrestrial Physics, 2015
Abstract The present paper shows results from the summer campaign performed during geomagneticall... more Abstract The present paper shows results from the summer campaign performed during geomagnetically quiet period from June 1 to August 31, 2009. Within time-series of stratospheric and mesospheric temperatures at pressure levels 10–0.1 hPa, mesospheric winds measured in Collm, Germany, and the sporadic E-layer parameters foEs and hEs measured at the Pruhonice station we detected specific coherent wave-bursts in planetary wave domain. Permanent wave-like activity is observed in all analyzed data sets. However, the number of wave-like structures persistent in large range of height from the stratosphere to lower ionosphere is limited. The only coherent modes that are detected on consequent levels of the atmosphere are those corresponding to eigenmodes of planetary waves.
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Journal of Atmospheric and Solar-Terrestrial Physics, 2015
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Atmospheric Science Letters, 2015
In this paper, a wavelet-based methodology is proposed to study the main features of turbulence d... more In this paper, a wavelet-based methodology is proposed to study the main features of turbulence data collected within the crown layer of an even-aged Norway spruce forest at the Bilý Křiž site. The site is situated on a steep (25%) south-southwest-facing slope near the top of a mountain ridge. The periods of organized structures detected when the site is on the downwind (leeward) side of the ridge are significantly shorter than those detected when the site is on the upwind side of the ridge. However, the ‘leeward’ structures have a relatively higher persistence and frequency of occurrence in the 30-min time series.
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ABSTRACT Airflow and turbulence within and above the forest canopy determine the forest - atmosph... more ABSTRACT Airflow and turbulence within and above the forest canopy determine the forest - atmosphere exchange of atmospheric constituents and pollutants. Our investigation is related to the existence of large-scale intermittent coherent structures, which have been detected in turbulence time series measured at the Experimental Ecological Study Site Bílý Kríz (800-900 m a.s.l.) in the Czech Republic. The site is situated on a steep (13°) SSW-faced slope near the top of a mountain ridge forested by a young Norway spruce plantation. Flow directions across the ridge (along the slope) strongly prevail at the site. Results based on a recent study reveal significant differences between the cases when the site is on the upwind vs. downwind side of the ridge. Typical downwind cases are characterized by a low wind speed above the canopy and by relatively higher friction velocity than in the upwind cases. This is explained by the flow retardation by the upslope-directed hydrodynamic pressure gradient and by the large wind shear in the upper part of the wake behind the ridge top. This contribution concentrates on the vertical coherency of the turbulent flow within the forest canopy. Analysed variables include the high-frequency wind velocity components and sonic temperature measured during periods of neutral thermal stratification at two different levels. Wavelet analysis was used for detection of characteristic temporal scale of coherent structures, their persistence and effectivity parameter. Special attention is paid to the differences between the upwind and downwind cases. Acknowledgements: The study is supported by the grant IAA300420803 and IAA300420704 from Grant Agency of Academy of Sciences of the Czech Republic.
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... v průběhu jedné minuty zaznamenávány oscilace a o několik °C oproti průměrným hodnotám). ...... more ... v průběhu jedné minuty zaznamenávány oscilace a o několik °C oproti průměrným hodnotám). ... dceřiné wavelety, pomocí kterých lze v signálu (posuvem podél signálu) lokalizovat tvarem navzájem podobné oscilace s různě velkou periodou. Na Obr. ...
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Journal of Atmospheric and Solar-Terrestrial Physics, 2015
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Papers by K. Potužníková