VERTICAL DISTRIBUTION OF THE CLIMATIC ELEMENTS ON THE BORA DAY

Abstract

The vertical distribution of the climatic elements on the bora day over both sides, windward and leeward, of the Dinar Alps were investigated relating to synoptic patterns. At first, weather maps of the bora day provided by the actual observation in Aj dovscina and Trieste were examined and distinguished into new 6 types. Among these types the cyclonic E (LE) type was taken out of Yoshino's (1971) results because of its higher frequency of occurrences and distinctive value in diurnal variation of climatic elements. The vertical distribution of the wind speed, wind direction, temperature and relative humidity were compared with each other with respect to the occurrence frequency of these or mean value. The results are as follows ; 1) Over Zagreb, a windward station, on the bora days, the winds of 0_??_90 deg. are dominated in the lower layer of the atmosphere. The upper limit of the bora wind tends to appear in different height in accordance with synoptic patterns except LE type. The limits are 1, 500 gpm in HA (anticyclonic A), 2, 000 gpm in HB (anticyclonic B), 2, 500 gpm in LA (cyclonic A), 1, 500 gpm in LB (cyclonic B). Over Split, a leeward station, the bora winds concentrate in lower level than over Zagreb. 2) The height of the upper limits of the bora winds nearly coincides with the heights of mean wind maximum, small lapse rate, and gentle horizontal gradient of temperature. 3) A height of maximum frequency of N to E winds appears at 5000 _??_ 2, 0000 gpm over the windward station and 0_??_500 gpm over the leeward station. 4) On bora days, the inversion often appears between 1, 500 and 2, 000 gpm over the windward station but at the same or lower level over the leeward station. 5) Taking account of the height of inversion layer, wind profile and so on, a model of bora is constructed as in Fig. 4.