ISSN 1000-0526
CN 11-2282/P
CN 11-2282/P
Archive > Volume 45 Issue 12 > 2019,45(12):1651-1665. DOI:10.7519/j.issn.1000-0526.2019.12.003 Prev Next
Seasonal and Intraseasonal Variation Characteristics of Siberian High South Boundary Eastern Segment and Their Causes
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Abstract:
Based on the NCEP/NCAR reanalysis data and Hadley sea ice concentration data, the winter variation characteristics of Siberian high (SH) south boundary eastern segment (SHSBES) and its relationship with Arctic sea ice during 1951-2017 were analyzed, and the intraseasonal differences were also discussed. The results showed that SHSBES in winter moves to the north from south in the mid1960s, and transfers to the south in the late 1970s, then turns a little southerly than the normal location since 1990s. The interdecadal transition time of SHSBES in December is earlier, the interdecadal variations of SHSBES in January and February of the following year are similar to the one in winter. SHSBES in winter is most closely related to the homochronous Atlantic sector Arctic sea ice whose decreases can induce the appearance of Baikal Lake blocking high in winter. SHSBES in December is most influenced by Atlantic sector Arctic sea ice in September, and the Western Hemisphere Arctic sea ice in March has the most significant impact on SHSBES in January and February of the next year. Less sea ice of the former results in the blocking high of September in Western Europe, and the reduction of the latter brings about the blocking high on the west site of Baikal in January. Three blocking highs are located respectively in Western Europe, Baikal and Kamchatka Peninsula in February during the ensuing year. Under the dynamic action of the atmospheric blocking, the southeast of SH and its south region are situated in a negative zone of the relative vorticity advection, the surface pressure increases with the downdraft, which is favorable for the southward movement of SHSBES, and vice versa. The decrease (increase) of Atlantic sector Arctic sea ice in September and Western Hemisphere Arctic sea ice in March can cause the southeast of SH and its south region to become colder (warmer) in December and the next year’s February respectively, facilitating the increase (decrease) of surface pressure, ultimately leading SHSBES into the south (north).
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