Cyclonic activity in the Asia-Pacific region is largely determined by state of the seasonal centers of atmosphere action. In turn, cyclones themselves influence on conditions in certain «key» areas. Recently the Aleutian Low activity declines in fall-winter and this center is shifted westward, but activity of the Hawaiian High increases in warm season. As the result, heightened air pressure prevails over the Ocean (positive anomalies of the sea level pressure) and lowered pressure (negative anomalies) — over the Far Eastern Seas. In this anomalous situation, the number of cyclones over the Ocean has increased but they become weaker that causes SST increasing in the North Pacific both in winter and summer. Over the Bering Sea, the cyclones become weaker, as well, but this regime causes the ice cover increasing, so SST decreasing in spring. On the contrary, over the Okhotsk Sea and Kuril Islands area, the number of cyclones has decreased gradually but they become stronger in both seasons that causes the ice cover reducing and spring SST rising. In the Japan Sea, cyclonic activity has intensified, too, but this tendency causes cooling in winter and warming in summer.

ОСЕННЕ-ЗИМНИЙ ЦИКЛОГЕНЕЗ НАД ТИХИМ ОКЕАНОМ И ДАЛЬНЕВОСТОЧНЫМИ МОРЯМИ И ЕГО ВЛИЯНИЕ НА РАЗВИТИЕ ЛЕДОВИТОСТИПоказано, что на протяжении последнего 20-летнего периода (с середины девяно-стых годов) в результате постепенного смещения Алеутской депрессии и Сибирского максимума на запад характер осенне-зимней циклонической деятельности над Тихим океаном и прилегающими морями менялся. Если во второй половине 1990-х гг. наи-более активная циклоническая деятельность развивалась над восточными районами Берингова моря, то к концу первой декады 2000-х гг. мощные циклоны стали выходить большей частью в Охотское море и курильский район. В период интенсивного цикло-генеза климатический режим морей, как правило, теплел: до середины нулевых годов в Беринговом море ледовитость была на низком уровне, а в Охотском море -повышенной. Впоследствии, по мере смещения области циклонической активности в охотоморский бассейн, ледовитость в Охотском море уменьшалась, а в Беринговом море, наоборот, возросла. Отмечено, что глубокие охотоморские циклоны могут оказывать «охлажда-ющее» воздействие на акваторию Японского моря, а беринговоморские -на северные районы Тихого океана.Ключевые слова: центры действия атмосферы, количество циклонов, средняя интенсивность циклонов, дальневосточные моря, ледовитость, поверхностная темпе-ратура.

Recent changes of the main oceanographic, chemical, and biological parameters of the Okhotsk Sea ecosystem are considered briefly for the last decades (2000–2010s), mostly on the data obtained in marine expeditions conducted by Pacific Fish. Res. Center (TINRO) annually. Since the mid-2000s, anomalous oceanographic conditions were formed there with prevailing heightened temperature in all layers of the sea and lowered ice cover caused by changes in the atmosphere circulation with northward shift of cyclones tracks in winter and weakening of winter monsoon. The ice cover was below the normal value every year since 2004. In the warmer winter conditions, producing of the high-density water on the northern shelf decreased from 3.2–7.8 . 103 km3 in 1998–2002 to 1.2 . 103 km3 on average in 2004–2015, and the water with density sq > 26.8 was not formed at all in 2007–2009, 2011, and 2014–2015. As the result, winter convection, including the slope convection, became weaker and shallower and ventilated worse the water column, so dissolved oxygen content decreased in the lower portion of the intermediate layer, usually ventilated by slope convection. For the core of the intermediate layer (isopycnal surface 27.0 σθ), positive trend of temperature is estimated as +0.04…+0.16 o/decade, by areas, while the trend of dissolved oxygen content is negative: –0.07…–0.14 mL/L.decade, by areas. From the other hand, spring phytoplankton bloom became less intensive, presumably because of poorer upward flux of nutrients in conditions of weaker vertical mixing, and zooplankton biomass decreased, particularly for phytophages. However, these changes did not cause significant response in fluctuations of stocks for the main commercial fish and crab species. The largest stock of walleye pollock had cyclic fluctuations driven mostly by intra-population regulations, the stocks of pacific herring were rather stable, and the stocks of deep-water fish species, as flounders and halibuts had a slight tendency to growth, possibly because of better conditions for reproduction. Indeed, the densest aggregations of greenland halibut shifted from the depth of 600–700 m to 500–600 m that may be caused by de-oxygenizing of the lower portion of the intermediate layer. Crabs abundance also had positive dynamics obviously because of the effect of protective measures for red king crab in the 2009–2012, though its biomass continued to grow even after restoring the commercial landings. There is concluded that recent changes in the macroecosystem of the Okhotsk Sea correspond to the conception of the sub-polar ecosystems transformation under climate warming toward decreasing of their productivity and increasing of their functioning efficiency that was proposed earlier for the Japan Sea. Thus, from position of commercial exploitation of marine biological resources, the modern reconstruction of the Okhotsk Sea ecosystem under the climate change impact could be considered as a positive process.

Dynamics of the greenland halibut biomass in the fishery districts of the Okhotsk Sea (or subzones) is considered. The biomass variation in the East-Sakhalin subzone has a significant (p < 0.05) negative correlation with the number of 3+ fish in other subzones, with the time lag of 3 years (r = –0.53) and 4 years (r = –0.49), that is interpreted as alternative distribution of the halibut recruitment from the common spawning area either to this district or other ones. From other hand, the recruits abundance in other districts is significantly and positively associated (r = 0.52, p < 0.05) with the index of zonal atmosphere transfer in January and with the index of meridional atmosphere transfer in March of the years of hatching. The recruitment dependence on the spawning stock could be explained by Beaverton-Holt equation with the residuals significantly and positively (r = 0.64, p = 0.03) related with the Arctic Oscillation index. Transport of the eggs, larvae and juveniles of greenland halibut from the spawning grounds at western Kamchatka to the western Okhotsk Sea is considered as the mechanism of its recruitment distribution between the districts in relation with atmospheric indices. The transport was simulated for 1993–2017 using the circulation model JCOPE2 as the movement of 250,000 artificial passive particles, imitating eggs and larvae, with water flows at the depth 40–50 m where their main aggregations are supposed. The particles were released in the area at western Kamchatka where the maximal concentration of spawning females occurred. Number of the particles reached the sections off eastern Sakhalin and their arrival times were computed, their pathways were tracked. The portion of particles released in December and reached northern Sakhalin within 150 days changed in significant positive correlation (r = 0.44, p < 0.05) with dynamics of the halibut stock in the East-Sakhalin subzone, with the time lag 6 years. Even closer correlation (r = 0.94, p < 0.05) could be found for the optimum income of the particles released in October or November in the general additive model of the stock. Using the model results for the recent years, the greenland halibut stock decreasing in the East-Sakhalin subzone is forecasted for the next 6 years.

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