正压模式大气中西藏高原对副热带东西风切变带影响的数值试验
NUMERICAL EXPERIMENTS ON THE EFFECTS OF THE TIBETAN PLATEAU IN THE BAROTROPIC MODEL ATMOSPHERE
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摘要: 本文利用正压原始方程,对48°S——48°N间的给定的平直副热带西风和东风切变带进行了西风爬越西藏高原为主、西风绕过西藏高原和无西藏高原存在的三种不同情况的数值试验。这些试验表明,由于西藏高原与落基山等大地形的存在,不但能造成副热带高压带的断裂,并且能形成四个副热带高压单体。在北半球,这四个单体具有相当稳定的位置,一个在西太平洋,一个在中太平洋,一个在大西洋,一个在北非。这些试验还表明,当西风以爬越西藏高原为主时,对南半球澳大利亚高压的存在与稳定有一定的作用。西风绕过西藏高原流动时有利于西太平洋高压向西伸展。Abstract: A channel (between 48°S and 48°N) barotropic numerical model was used to investigate the role of the Tibetan Plateau in an undisturbed sub-tropical high belt. Three experiments were done with 1) the westerly jet flow mainly over the top of the Plateau (PJ to be its short name), 2) the Plateau standing like an "island" in the westerly, which means no westerly flows over the Plateau,but around it (RG), and 3) presumed absence of the Plateau (WD).Our model was run until it reached a stable situation for each of the three cases. The results showed that the Plateau and the Rocky Mountains could be among some Primary factors that caused the undisturbed sub-tropical high belt to split into four sub-tropical high cells both in Northern and Southern Hemispheres. In Northern Hemisphere, particularly, the four high cells had their balanced positions. The north-west Pacific high was situated more westward in RG than that in PJ. These experiments also showed that the dynamic influences of Tibetan Plateau could intensify the Australian High and make it more stable, though it was closely connected with thermo-condition.
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