Original scientific paper
BURA (BORA) AND BURIN AT SPLIT
Dražen Poje
; Meteorological and Hydrological Service Grič 3, HR 10000 Zageb, Croatia
Abstract
In this work, the ten-year hourly values of the main meteorological elements of the Split-Marjan meteorological station for the months of January and July were analysed in order to ascertain the main features of the katabatic winds burin and bura at that location. Using the method of separating the wind speed subgroups belonging to the burin and bura, it was possible to determine the main statistical characteristics of these winds and also their duration and the time of onset. At the beginning of the bura, the temperature falls on average by one degree Celsius and the relative humidity by approximately 15%. The derived pseudopotential temperature, corrected for its daily interhourly changes, was found especially suitable for the determination of both the burin and bura. At the onset of the bura, this temperature drops approximately by two (January) and four (July) degrees Celsius. The average daily courses of the examined elements during the burin and bura show distinctive patterns that are significantly different from'the average course during the two representative months. The daily course of the average wind speed values during the bura in January shows a maximal value of nearly 11 ms-1 at noon and a minimum of 8 ms-1 at midnight. In July, however, the greatest average speed of the bura, nearly 9 ms-1, is achieved just before sunrise and the minimum of approximately 6 ms-1 in the early evening hours. In the last part of the article, the results of an analysis of the connection of weather types with the occurrence of burin and bura are presented. The rate of occurrence of the "clear" and "dark" bura in both January and July is seven to three. In January, during the burin there is only a very small probability of precipitation in the form of short, light rain or snow while during the bura the same types of precipitation may occur with a probability of 30%.In July the occurrence of slight rain during the burin or bura is extremely small.
Keywords
bura (bora); burin; climatic characteristics; Split
Hrčak ID:
67902
URI
Publication date:
19.12.1995.
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