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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...
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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...
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