National Repository of Grey Literature 21 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Dependence of activated aerosol on horizontal hydrometeor type.
Zíková, Naděžda ; Pokorná, Petra ; Pešice, Petr ; Sedlák, Pavel ; Ždímal, Vladimír
Atmospheric aerosol (AA) affects not only cloud formation, but also other cloud properties such as droplet size distribution, chemical composition, etc. The interaction between AA and cloud does not have to be investigated only by aerial measurements, but the same processes can be observed in fog and low clouds. An example of a station suitable for such research is Milešovka station, where the fog (or low clouds) is 55% of the time. Here, measurements were made to describe the effect of fog on the number size distributions of AA and activated nucleation nuclei.
Study of Wet Deposition of Atmospheric Aerosol using Horizontal Hydrometeors.
Zíková, Naděžda ; Pokorná, Petra ; Pešice, Petr ; Sedlák, Pavel ; Ždímal, Vladimír
Processes between atmospheric aerosol (AA) and clouds, source of large uncertainty in weather and climate changes estimations, were described on fogs at Milešovka, meteorological observatory of the Institute of Atmospheric Physics. For the description of the AA properties, online measurement of outdoor particle number size distribution (PNSD) in the size range 10 nm – 20 μm was conducted using SMPS and APS spectrometers. The sampling system consisted of a heated whole air inlet, and PM2.5 sampling head, being switched by an automatic valve. From the difference between PNSD sampled by whole air inlet and by PM2.5 inlet, PNSD of activated particles (aPNSD) was calculated. The aPNSDs differ with hydrometeor type and depend on air mass history, with a stronger influence on freezing fog AA.
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Cloud Processing of Atmospheric Aerosol Spectra.
Zíková, Naděžda ; Pokorná, Petra ; Pešice, Petr ; Sedlák, Pavel ; Ždímal, Vladimír
Atmospheric aerosol (AA), and its influence on the cloud formation, lifetime and other properties, remains the most uncertain (with low confidence level) element in the IPCC radiative forcing estimations (Stocker et al., 2013). The AA, however, is influenced by the cloud processing as well (Collett et al., 2008., Zíková and Ždímal, 2016). Cloud processing of AA (and vice versa) can be described on fogs, or on low clouds present at a suitable station. An example of such a station is Milešovka, where fog is present for almost 55 % of the time (Fišák et al., 2009), giving a great opportunity to explore the changes in the particle size distributions due to the cloud processing.
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Earth-space path propagation characteristics in the climatic conditions of the Czech Republic from Alphasat Ka/Q band experiment
Fišer, Ondřej ; Brázda, Vladimír ; Pešice, Petr ; Grabner, M.
The objective of the activity is to prepare, realize and conduct experimental research of the influence of atmospheric phenomena on the Earth-space path propagation characteristics at 20 and 40 GHz (Ka/Q) bands in the specific climatic conditions of the Czech Republic (CR). The scientific approach is based on the comprehensive measurements of physical parameters of atmosphere together with concurrent measurements of propagation characteristics on the Earth-space path and on 10 collocated terrestrial paths with star configuration. The proposed activity will utilize the ESA Alphasat Mission Ka/Q experiment that is designed to investigate the propagation characteristics on slant paths in Europe and elsewhere.
Experimental measurements at the meteorological observatory Milešovka
Pešice, Petr
The Milešovka Observatory was established in 1905 and has since been continuously performing standard meteorological and climatological\nobservations and measurements that are the primary mission of the station.\nMilešovka but like Lysá hora or other mountain observatory attracts experimentalists whether thanks to their exposed\nlocation and harsh weather conditions, frequent occurrence of strong winds, low cloud cover,\nor the abundant occurrence of storms and atmospheric discharges. The Milešov Measure Report summarizes current and planned experiments conducted at the Observatory.
Effects of orography on spatial distribution of convective precipitation in Banská Bystrica district (Slovakia)
Kvak, Róbert ; Müller, Miloslav (advisor) ; Pešice, Petr (referee)
Effects of orography on spatial distribution of convective precipitation in Banská Bystrica district (Slovakia) Abstract The presented diploma thesis deals with the issue of spatial distribution of convective precipitation over complex terrain in Banská Bystrica district in the middle part of the Slovak Republic. The primary aim of this thesis is to verify the relation between areal precipitation characteristics caused by deep convection, and morphometric terrain parameters in the study area. The next goal is to identify how the existence of terrain influences the precipitation mechanisms. Eight precipitation events with maximum areal daily totals in the warm part of years between 2005 and 2015 are studied in this thesis. The events are split into the four groups (S, W, E, N) with respect to prevailing direction of storm motion during respective days. The precipitation rating is based on rain gauge measurements and adjusted radar precipitation estimates produced in the INCA model. The spatial relation between convective precipitation and topography is quantified in radar pixels' network 1 x 1 km and in the closest surroundings (20 x 20 km squares) of the rain gauge stations. The products are using DEM with the 50 m, 1 km and 2 km spatial resolution. The strongest correlation is proved in the relation with...
Cloud-top morphology of convective storms as observed by meteorological satellites
Radová, Michaela ; Setvák, Martin (advisor) ; Pešice, Petr (referee) ; Sokol, Alois (referee)
Title: Cloud-top morphology of convective storms as observed by meteorological satellites Author: Michaela Radová Department: Department of Atmospheric Physics Supervisor: RNDr. Martin Setvák, CSc., Czech Hydrometeorological Institute Abstract: This work focuses on study of features occurring at tops of convective storms, namely embedded warm areas, cold rings, cold-U/Vs and overshooting tops (OTs), mainly from the perspective of satellite observations. We have assembled a database of 104 subjectively detected cold rings and cold-U/Vs from the area of Europe. We discuss relationship between satellite- observed brightness temperature and cloud top height determined from radar measurements for storms with distinct cold-rings. Our results support the hypothesis that the warm area is a consequence of presence of central elevated dome reaching warmer lower stratosphere. Moreover, a storm with transformation of cold ring into cold-U is studied and an elevated plume above storm anvil in the warmer lower stratosphere is found to be a likely explanation of the warm area inside the cold-U. Both analyses confirm that thermal inversion above the tropopause is a necessary prerequisite for occurrence of cold rings and cold-U/Vs. We also propose a method for automated objective determination of spatial characteristics of...
Factors determining bad thermal conditions in the Czech Republic
Venclová, Markéta ; Chládová, Zuzana (advisor) ; Pešice, Petr (referee)
This presented work deals with a weak thermal convection over the Czech Republic. The main objective is to identify areas and meteorological conditions which determined weak thermal convection in the atmosphere. Another objective is to describe surfaces and situations that are characterized with occurrence of decreasing air currents. This work may be useful for non-motorized aircraft pilots for which the occurrence of weak thermal convection and decreasing air currents will be very dangerous during the flight. In the first part there are described different ways of spreading heat through the atmosphere, this is followed by a general description of thermal convection, its distribution, origin and course. The second part deals with weak thermal convection, describes the decreasing thermal current, meteorological conditions and factors causing weak thermal convection. The third part contains the results of a questionnaire, which was sent among aeroclubs in the Czech Republic. The results of the questionnaire were compared with the information reported in the literature and in most cases they coincide. The cases which differed from the literature are more detailed in the discussion.
Vertical temperature profile in atmospheric boundary layer
Gvoždíková, Blanka ; Pešice, Petr (advisor) ; Sedlák, Pavel (referee)
Submitted bachelor thesis discusses the issue of the atmospheric boundary layer. First of all, it addresses the boundary layer's thermal characteristics which are very variable near the Earth's surface. For this purpose we have chosen the observatory in Kopisty near Most where a tower meteorological measurement is performed. In addition the air temperature measurements from Milešovka observatory were included to a dataset, too. It is assumed that this mountain weather station due to its position can represent conditions of the free atmosphere. But if we compare some thermal characteristics of the air at different height levels, we'll figure out that the air temperature measurements at Milešovka are highly influenced by radiation balance of the Earth's surface. Despite this fact, the analysis of air layer between Kopisty and Milešovka gives an idea of a continuous-time behavior of air temperature characteristics. This bachelor thesis describes in detail the air temperature variations and the temperature lapse rate variations in several height levels, the variability of thermal stratification or the incidence and extent of air temperature inversions.
The exploitation of remote sensing for the analysis and progress of rainfalls
Bližňák, Vojtěch ; Sokol, Zbyněk (advisor) ; Setvák, Martin (referee) ; Pešice, Petr (referee)
The thesis is divided in two parts. The first part deals with the areal distribution of short-term convective rainfalls with regard to the influence of altitude. Precipitation estimates based on combination of rain gauge and radar data are used for this purpose. Statistical tests proved that the areal distribution of hourly convective rainfalls does not depend on altitude. Besides data containing precipitation events only, all measured data were statistically analysed regardless of the fact whether precipitation occurred or not. In this case it was found out that the relationship between hourly rainfall totals and altitude depends on the considered threshold of rainfall totals. When all data were considered, i.e. a threshold value was set to zero, an increase of rainfall totals well correlated with altitude. The dependence slowly disappeared with an increasing threshold. The areal distribution of 6 hour rainfall totals proved higher values in the area of south Bohemia. The most frequent synoptic patterns were northwest cyclonic situations (NWC) and cyclone over the Central Europe (C). The second part of the thesis is focused on satellite data exploitation, as measured by meteorological satellite Meteosat Second Generation, for convective precipitation estimates. The Convective Rainfall Rate (CRR) algorithm,...

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