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NORTH PACIFIC ISLAND ARCS.
Komandorski & Aleutian Islands
http://pacificinfo.ru/climate/acvad/1/ (in Russian)
The Komandorski & Aleutian Islands are a chain of rugged, volcanic islands, separating
the Bering Sea from North Pacific. The Komandorski Islands or Commander Islands
consist of Bering Island, Medny Island, and two small islets, Sea Lion Rock and Sea
Otter Rock. Geologically, although separated from the rest of the chain by several
hundred miles, the Commander Islands are the westernmost extension of the Aleutian
Islands. The Aleutians comprise four main groups: Fox Islands, nearest to the mainland
USA, including Unimak, Unalaska, Umnak, and Akutan; Andreanof Islands, including
Amlia, Atka, Adak, Kanaga, and Tanaga; Rat Islands, including Amchitka and Kiska;
and Near Islands, the smallest and westernmost group, including Agattu and Attu. The
Semichi Islands, of which Shemya is the largest, are nearby.
This island arc is at the edge of the Pacific Plate and experience a lot of seismic activity.
The great majority of the islands bear evident marks of volcanic origin, and there are
numerous volcanic cones on the north side of the chain, some of them active; many of
the islands, however, are not wholly volcanic, but contain crystalline or sedimentary
rocks, and also amber and beds of lignite. The coasts are rocky and surf-worn, and the
approaches are exceedingly dangerous, the land rising immediately from the coasts to
steep, bold mountains.
The climate of the islands is oceanic, with moderate temperatures and heavy rainfall.
Fogs are almost constant. In the cold season from October through March, northern
winds prevail in the west (Komandorski Islands) and northeastern winds dominate in the
east (Aleutian Islands). Monthly precipitation is about 140-200 mm. Winter air
temperature is about -22C in the west and about -15C in the east but can rise up to
2C with passing cyclones which also bring strong winds and swell. The warm season
lasts from April through September. Summer is cool, with air temperature mostly below
10C and monthly precipitation about 50-100 mm.
Tides (Fig. 1.2) are high, up to 230 cm, diurnal tides in the western and central straits
and semi-diurnal tides in the eastern straits. Tidal currents are up to 20 kt in the narrow
and shallow eastern straits, 6 kt in the central straits and no more than 1 kt in the wide
and deep Kamchatsky and Blizhni Straits in the west.
Thermohaline structure of North Pacific off the Islands
Thermohaline structure of the Bering Sea off the Islands
Circulation
Sea surface temperature Fig. 1.3
Temperature in the dichothermal layer Fig. 1.4
Temperature in the temperature maximum layer Fig. 1.5
Sea surface salinity Fig. 1.6
Sound speed
Surface sound speed Fig. 1.7
Sound speed in the sound speed minimum layer Fig. 1.8
Circulation scheme Fig. 1.9
Typical T-S curves in the straits Fig. 1.10
Data catalogue
References
(Bogdanov and Moroz, 2002)