Vízügyi Közlemények, 1994 (76. évfolyam)

4. füzet - Rövidebb tanulmányok, közlemények, beszámolók

Radaros és felszíni csapadékmérés összehasonlítása 455 Nagy ./.. Az időjárási megfigyelésben használt 3 cm-es clektrom hullámok elnyelődésének vizsgálata. Szakdolgozat. ELTE Met. Tsz. Budapest, 1987. Ryde, J. W.: The attenuation and radar echoes produced at centimatre wavelength by various meteorological phenomena, in Meteorological Factors in Radio Wave Propagation. Physical Society, London, 1946. Comparison of stirficial and radar precipitation measurements by Györgyi GYARMATI, József NAGY and Dr. Tamás PRÁGER, Meteorologisis The objective of the study was to compare the measurement data of the extreme precipitation event that had caused the Tisza River flood of 1993, as measured by traditional rain-gauges and by the Radar-meteorological Observatory of Napkor (Figure 1.) with the purpose of gathering experience for the operation of the network. Maps showing the 24h precipitation sum of the period from 20 Dcceinbcr 1993, 06 UTC to 21 December, 1993, 06 UTC have been prepared on the basis of surficial gauging stations (Figure 2.) and on that of the radar measurement data (Figure 3.). Using radar image and precipitation data processing programme FETIRA the areal average daily precipitation sum data (Table I.) of sub catchments falling into the scanning-field of the radar were calculated. Results obtained on the basis of radar measurement data severely underestimated the actual precipitation due to the superposition of seversú measurement errors of the radar. Л technical fault (setting error) resulted in radar pulse intensities 70% lower than the actual value. Values of the digital maps were corrected accordingly and a modified map of daily précipitation was prepared (Figure 4.). Sub-catchment average data obtained after correction are shown in the third column of Table I. For sub-drainage basins located far from the radar station the deviation between the two maps still remained significant after this correction. In this case the error was caused by the attenuation of the radar signal, caused by the high intensity rain. Further errors may stem from the so called hybrid image generation. The ring-like structure, which can be recognized on the images (Figures 3. and 4.), stems from this error. The main lesson to be learned from this Hooding event is that further methodological and software development, under higher level technical supervision, is needed for generating hybrid images and to correct for the signal attenuation in an on-line calibration process. * * * Niederschlagmessung mittels Radar und an der Oberfläche - ein Vergleich von Dipl.-Meteor. Györgyi GYARMATI. Dipl.-Meteor. József NAGY und Dr.-Meteor. Tamás PRÁGER Zweck der Studie ist es, die im Radarmeteorologischen Observatorium von Napkor (Bild I) über Radar- und Oberflächeninessung gewonnen Daten während den außerordentlich intensiven Niederschlags, der das Thcißhochwasscr von 1993 ausgelöst hat, miteinander zu vergleichen, um die Erfahrungen vom Gesichtspunkt des Betreibenden zu verwerten. Es wurden, einerseits unter Verwendung der Daten der terrestrischen Stationen (Bild 2), andererseites der mit Radar gemessennen Daten (Bild 3) für die Periode zwischen dem 20. Dezember, 06 UTC und den 21. Dezember, 06 UTC, die 24stündigcn Niederschlagshöhen-Bilder zusammengestellt. Auf Grund beider Nicderschlagsverteilungen wurden, mit Hilfe des Radarbildes FETIRA und des Programms der Niederschlagsverarbeitung, die Gebictsmittclwerte des Niederschlags für sämt-