|
| |
|
|
The Evaluation of the Heavy Convective Precipitation Forecast
Zacharov, Petr ; Řezáčová, Daniela (advisor) ; Brechler, Josef (referee) ; Pešice, Petr (referee)
The thesis deal with the evaluation of the quantitative convective precipitation forecast and its uncertainty. Five convective events that produced heavy local rainfall in the Czech Republic were studied. The nonhydrostatic local model LM COSMO was run with a horizontal resolution of 2.8 km and an ensemble of 13 forecasts was created by modifying the initial and boundary conditions. Forecasts were verified by gauge-adjusted radar-based rainfalls. Ensemble skill and ensemble spread were determined using the Fractions Skill Score (FSS). The spread represents the differences between the control forecast and the forecasts provided by each ensemble member, while the skill evaluates the difference between the precipitation forecast and radar-based rainfalls. The numerical experiments used the FSS-skill and spread values related to four events to estimate the skill-spread relationship. The relationship was applied to a fifth event to estimate the QPF ensemble skill given the ensemble FSS-spread. A couple of test of FSS computing were performed. The analysis of these events proved, that the application of the new fuzzy verification scores in high resolution QPF is highly advisable. The new scores are more suitable then the traditional verification scores based on the contingency table. In order to asses the...
|
|
|
Evalution of information from Meteosat 8 and the CZRAD network of meteorological radars in selected significant convective situations
Hajáková, Jaroslava ; Pešice, Petr (advisor) ; Kastner, Jiří (referee)
KAPITOLA ABSTRACT Abstract Topic of Mc. S. Thesis: Evaluation of information from Meteosat 8 and the CZRAD network of meteorological radars in selected significant convective situations. Abstract: This paper focused on comparing the information from the satellite Meteosat 8 and the CZRAD network of meteorological radars in selected significant convective situations. The main goals of this study were to assess how satellite and radar data respond on development of convection and if the satellite data responds on intenzifying convection before the radar data. For this purpose, four significant convective situations and associated areas (72 x 72 km) were selected, and the satellite and radar data were preprocessed. Appropriate differences of spectral channels (i.e. satellite methods) and radar products were chosen. The preprocessing involved data synchronization in time and location. The parallax correction was used for satellite data. Seven satellite methods were used - spectral channel IR 10.8 (TIR10.8), difference of channels WV 0.6 and IR 10.8 (TWV6.2 - TIR10.8), IR 13.4 and IR10.8 (TIR13.4 - TIR10.8), IR 12.0 and IR 10.8 (TIR12.0 - TIR10.8), IR 8.7 and IR 10.8 (TIR8.7 - TIR10.8,), NIR 1.6 and VIS 0.6 (REFNIR1.6 - REFVIS0.6) and the trispectral method. The trispectral method resulted from measurements of...
|
|
|
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.
|
|
|
Influence of the satellite spatial resolution and scan time on convective storms'overshooting tops detection
Růžičková, Markéta ; Setvák, Martin (advisor) ; Pešice, Petr (referee)
This paper deals with the possibilities of convective storms' overshooting tops detection as seen from satellites. These tops are characterized by a rapid development, their size is only a few kilometres in diameter and they are connected with the presence of hazardous weather. They can be identified as small clusters of very low temperatures in satellite imagery, but this nature depends on the scan time and the scan frequency of the specific satellite and on the other features presence at tops of convective storm. The temporal variability of minimum IR brightness temperatures at the cloud tops of selected convective storms is studied in this paper, namely on the basis of the Meteosat Second Generation (MSG) satellite datasets. But the main emphasis of this work is to analyse the influence of the operative meteorological satellites' spatial resolution on the minimal IR brightness temperature, which is related to height of the cloud top. The datasets acquired by the sensors SEVIRI, AVHRR and MODIS have been chosen for these purposes. Mostly the convective storms that occurred over the Europe in the year 2008 have been diagnosed. The scan time difference must be taken into account when datasets from MSG and the other polar orbit satellites are compared and this difference should be minimal. The minimum IR...
|
|
|
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.
|
|
|
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.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_C22019110512030 - PDF
|
|
|
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.
Fulltext: content.csg - PDF
Plný tet: SKMBT_C22018110212450 - PDF
|
|
|
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.
|
guest ::
