Number of Days with Precipitation

The number of days with precipitation is a very important characteristic of the precipitation regime. Three categories of days with precipitation are mostly used: £ 0.1; > 1.0, and > 10.0 mm. In the Arctic, as was mentioned in the previous section, light (< 1.0 mm) precipitation prevails. More intensive amounts of precipitation occur with a significantly lower frequency. Days with precipitation greater than 10.0 mm are particularly rare. Most authors presenting results for large parts of the Arctic give only information about the number of days with measurable precipitation, i.e., > 0.1 mm (e.g., Bryazgin 1971; Maxwell 1980; Atlas Arktiki 1985). The maximum number of days with precipitation in the Arctic throughout the year occurs mainly in one of the months from the second half of the year. On the other hand, the minimum number is observed most often in spring.

In January (Figure 7.11), the greatest number of days with precipitation (> 18) occurs in (he parts of the Arctic with the highest cyclonic activity (the south-western part of the Atlantic region and the southern part of the Baffin Bay region). A high frequency (12-18 days) may also be observed in the central part of the Arctic Ocean, the Kara Sea, the eastern part of the Barents Sea, and the continental areas neighbouring these seas, as well as in the central part of (he Baffin Bay region. Areas with the most continental climate (the Siberian and Canadian Arctic) have fewer than 9 days with precipitation. However, the minimum (< 6 days) occurs in the central part of Greenland.

In July (Figure 7.11), generally speaking, an increase of days with precipitation is observed in the entire Arctic, except the Atlantic and Baffin Bay regions, where even a decrease is noted, particularly in the area stretching from the southern part of the Baffin Bay region through Iceland to Spitsbergen. The greatest number of days with precipitation (> 15) occurs in the vicinity of the North Pole, in the south-eastern Canadian Arctic, and locally in the western and eastern parts of the Russian Arctic. The lowest number (< 6 days), similar to January, is observed in the central part of Greenland, but the area is larger.

The annual number of days with precipitation is, unfortunately, not presented in (he Atlas Arktiki (1985). Only Bryazgin (1971) for the non-Soviet Arctic and Maxwell (1980) for the Canadian Arctic give such information. According to Bryazgin's map, the greatest number of days with precipitation occurs in (he southernmost parts of the Atlantic region (> 240). A high frequency (> 200 days) is also observed in the Atlantic region southward from Spitsbergen and probably in (he southern Baffin Bay region. Ouite a large number of days with precipitation (180-200) occur above 85°N. 1 lowever, Radionov et at. (1997) for the Arctic Basin give a significantly lower number (only 152 days).

90° 100° 110" 120° 130° 140° 150° 160° 170° 180°

90° 100° 110" 120° 130° 140° 150° 160° 170° 180°

90° 100° 110° 120° 130° 140° 150° 160° 170° 100°
Figure 7.1 J. Number of days with precipitation 5 0.1 mm in the Arctic in January and July (after Atlas Arktiki 1985).

The Canadian Arctic, according to Bryazgin's data, has about 120 days with precipitation in the northern part and more than 140 days in the southern part. A significantly lower number of days with precipitation is noted by Maxwell (1980). Generally, on his map, coastal regions in the entire Canadian Arctic have 75-100 days with precipitation. A greater frequency (up to 150 days) is observed only in some mountainous regions neighbouring Baffin Bay and Davis Strait.

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