engleski

Analysis of precipitation appearance in time

The paper analyses the precipitation appearance in time. Elaboration covered the data of continuos precipitation measurement by two automatic float type rainfall recorders (Hellmann type) during ten years period 1984-1993. The measurement increment was 5 minutes with 0.1 mm resolution. The impact of different time increment on precipitation duration in a year has been researched. Calculations showed that smaller time increment diminishes duration of precipitation in a year. If 5 min time increment is used for calculation, precipitation duration is about 3% of the year. If 24 hour time increment is used, the precipitation duration is even 33% of the year. The real mean duration of yearly precipitation has been evaluated as 216 hours, that is 2.47% of the year. It is the impact of time-scale effect on elaboration results. The appearance of precipitation intensity higher of 0.2 mm/min has been researched during the year and over 24 hours. Analyses showed that intensive precipitation appears during warmer part of the year, from June to August. The precipitation distribution is not uniform over a day. In the city of Zagreb, where both raingauging stations are situated, in 90 % of the cases, the precipitation intensity higher of 1.2 mm/min falls during the night, from 9 p.m. to 1 a.m., at the same time causing floods.

precipitation; time-scale effect; time increment; appearance of precipitation in year and day

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