Please put an active hyperlink to our site (www.rusnature.info) when you copy the materials from this page

Biomes and Regions of Northern Eurasia

The Far East

<<< Tectonics and Endogenic Processes | Biomes & Regions Index | The Maritime Province >>>

Climate

The interaction between the Pacific Ocean and the Asian continent results in a temperate monsoon climate which is found nowhere else in the former Soviet Union (FSU) (Lydolf, 1977). In winter, the atmospheric circulation is controlled by the presence of the Siberian high. Sharp temperature and pressure gradients exist between the extremely cold continental interior and the Bering Sea and Sea of Okhotsk dominated by the extension of the Aleutian low. Although ice-bound, these are still warmer than the Siberian land mass. These contrasts result in high wind velocities and some of the most extreme chill factors across Eurasia. Maritime influence is reduced except for the most exposed peninsulas (e.g., the eastern Kamchatka coast) and islands. In summer, the territory south of 60°N is influenced by the monsoonal circulation. The subtropical high in the Western Pacific expands northwards as the Aleutian low retreats. The Pacific high is augmented by high pressure which develops over the cold waters of the Sea of Okhotsk and in late spring-early summer the marine air circulates over the Sea of Okhotsk, with a localized high causing cool, dry weather over the Maritime Province and Sakhalin. By the middle and late summer, this system weakens and warm marine air, circulating along the periphery of the Pacific high, arrives in the Russian Far East. On the whole, the Maritime Province, the Amur region, Sakhalin, and the adjacent seas have a cold, dry winter and a cool, wet summer with steady winds from the southerly quarter and the passage of typhoons. In the Maritime Province, about 10 mm of precipitation occurs in January and about 150 mm in August. A summer rainfall maximum leads to frequent inundations and summer peaks in river discharge exceed those in spring (Figure 5.6). The mean annual temperatures range from -4°C in the north to +10°C in the south with the absolute minimum of -51°C in the middle Sikhote-Alin. Along the coast north of Vladivostok (43°60'N) floating ice forms every winter and many bays and the Amur estuary freeze. Much higher temperatures should have resulted from the southerly position of the region between 42 and 60°N. The main reasons for this thermal deficiency are the influence of the cold Asian continent in winter; absorption of summer heat by the comparatively cold eastern seas; and reduction of insolation by clouds brought about by the summer monsoon. A combination of low winter temperatures and a thin snow cover results in deep seasonal freezing of soils, which locally reaches 3 m, and the occurrence of permafrost (see above). These peculiarities of climate precondition the development of many boreal species and vegetation communities. However, temperate and subtropical species are widely represented too in the southern Maritime Province, south-western Sakhalin and southern Kurils. Broad-leaved and mixed forests, which are completely absent from Siberia, develop here as a result of both a milder modern climate and the uninterrupted post-Tertiary development.

Northeastwards, in Kamchatka and the Kurils, strong cyclonic activity throughout the year moderates the effects of the monsoon and for this reason it is not unusual to come across different classifications of the regional climate: while some authors describe it as monsoonal others classify it as temperate maritime. Both Kamchatka and the Kurils have more severe climates than might be expected from their geographical position because of their proximity to cold seas, but it is much milder than the climate of the opposite mainland coast (Kondratyuk, 1974). The number of degree days with daily mean temperatures above 10°C is three times lower in the Kurils than at the same latitude in central regions of Eurasia. The large size of the Kamchatka peninsula and its complex topography are important climate-forming factors. A local monsoon develops over Kamchatka itself and its interiors have a comparatively dry climate with strong seasonal variations in temperature. Mean July temperatures in Kamchatka are about 10-15°C while mean January temperatures vary between -8°C in the south-east and -26°C in the northwest. In the Kurils, average summer temperatures vary between 17°C in the southern islands and 9°C in the north while mean winter temperatures vary between -9°C and -5°C. Annual precipitation totals decline from 1500-2000 mm in the south-east to 300-400 mm in the north-west and do not exceed 400 mm in the Central Kamchatka valley. The Kurils receive 700-1400 mm of precipitation annually and while snowfalls and snowstorms are frequent in winter, fogs are usual in summer. A combination of strong cyclonic activity in winter (with which strong winds and frequent blizzards are associated) and monsoon precipitation in summer predetermines its rather uniform distribution throughout the year with a minimum in spring. The wettest month is September when typhoons sweep across the islands. Because of the low summer temperatures, evaporation is reduced. The Kurils and most of Kamchatka are characterized by high humidity, and about 12 per cent of the peninsula is swamped. A cool climate, with high effective precipitation and strong winds, results in the development of the specific coastal meadow-forest landscapes which form a transition between the subarctic and boreal zones.

<<< Tectonics and Endogenic Processes | Biomes & Regions Index | The Maritime Province >>>