Frequency Distribution

In climatology, the frequency occurrence of the given element within the arbitrary chosen intervals often supplements the information obtained from the analysis of the mean values. The relative frequency of occurrence of winter, summer, and annual precipitation sums in selected stations representing all distinguished climatic regions in the Arctic, is presented in Figure 7.10. Histograms of the frequency have been drawn for 25 mm and 50 mm intervals for seasonal and annual totals, respectively.

In winter, the precipitation totals in the majority of stations, except the southernmost stations located in the Atlantic region (Jan Mayen and Mys Kamenny), lie in the intervals 0-25 mm or 25-50 mm. In the Canadian Arctic this happens in about 100% of the stations. Jan Mayen is characterised by the greatest range of change of winter precipitation totals (50-300 mm). Precipitation occurs with the highest frequency (only 20%) in the interval 200-225 mm.

CD 40

30 20 10 0

Year lL

TO 30

in 40

100 200 300

200 400 600|mm|

Figure 7.10. Relative frequency (in %) of occurrence of winter (D.IF), summer (JJA) and annual (Year) precipitation in selected stations representing particular climatic regions of the Arctic, 1951-1990 (after Przybylak 1996a):

a) Danmarkshavn, Jan Mayen. Ostrov Vize, Mys Kamenny. and Ostrov Kotelny b) Bartow. Coral Harbour A, Resolute A, and Clyde A.

Year

c ro

riifnlHi rA\\ Fl~h

hj tUtu a

200 300

200 300

400 600 B00[mm]

Figure 7.10. cont.

Frequency distribution of summer precipitation is clearly more flat and also shows a more normal distribution than winter precipitation. The intervals which most often occur rarely exceed 40%. The greatest range of annual sums of precipitation (500-1000 mm) is characteristic of the warmest parts of the Arctic (Jan Mayen), and the lowest (20-200 mm) for the coldest parts (Resolute A). The frequency distribution on the areas with the highest cyclonic activity (Jan Mayen, Clyde A) is bimodal. The frequency of occurrence of annual precipitation sums within the analysed intervals exceeds 50% only in the northern part of the Canadian Arctic (Resolute A).

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