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Hydrometeorological droughts in the Czech territory since 1851
Kakos, Vilibald ; Müller, Miloslav
Variously long periods of precipitation deficit were studied. In the 20th century, the most intensive drought period was first half of 30s. Nevertheless, the drought in first half of 60s of the 19th century was even stronger from the viewpoint of precipitation as well as outflow characteristics. Hydrological droughts arise generally later than precipitation deficits as was shown by comparison of both types of droughts.
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North Atlantic Oscillation - definitions, manifestations, influence on European climate
Huth, Radan
The paper reviews basic knowledge on the North Atlantic Oscillation (NAO), including its manifestations in the atmospheric pressure and geopotential height fields, definitions, methods of detection, effects on surface climate elements (temperature, precipitation) mainly in Europe, connections to phenological phases of some plant species, and relationships with solar activity.
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Comparison of the rain rate measurements at different localities from the microwave attenuation viewpoint
Fišer, Ondřej
The rain rate distribution is the input data used in models predicting the rain attenuation distribution on microwave links. Some methods partially mitigating the rain attenuation are used in practice. The well known "site diversity" method is described in this contribution. The attenuation is obtained from the rain rates which are converted into the attenuation using the Assis-Einloft model. The rain rates are measured on 4 sites in the Czech Republic at distances from 8 to 150 km. It is shown that the site diversity gain is big (about 10 dB at 0.01% exceedance level at 12 GHz). The gain is increasing with the increasing distance (as expected) and is also a function of the azimuth of 2 sites. The north-south sites position has lower gain in comparison with the west-east position: it is due to the prevailing frontal motion from west to east in our country.
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First results of experimental investigation in frequency band 58 GHz
Kvičera, V. ; Grábner, M. ; Fišer, Ondřej
TESTCOM and Institute of Atmospheric Physics, ASCR launched a common experimental research in the frequency band 58 GHz on the experimental hop Geophysical Institute, ASCR - TESTCOM in the frequency band 58 GHz since December 2000. Our research has been focused on obtaining knowledge concerning attenuation due to hydrometeors in our specific climatic conditions. The path length is 846 m, used frequency is 57 650 MHz with V polarization. Records of received signal were statistical processed and cumulative distributions of attenuation due to hydrometeors for individual month as well as the first year period of observation from December 2000 to November 2001 were obtained. The records of attenuation were compared with the concurrent meteorological situation and attenuation due to rain, snow, fog, rain with snow and rain with hail were separatd. Rain intensities have been measured at both sites of path. Obtained CDs of rain intensities are presented.
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