基于多组定义的南亚高压近40年变化特征的对比分析
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1.南京信息工程大学大气科学学院;2.南京信息工程大学自动化学院

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国家重点研发计划重点专项


A comparison of the South Asian High variations during nearly 40 years based on multiple sets of definitions
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1.College of Atmospheric Sciences,Nanjing University of Information Science and Technology;2.China;3.College of Automation,Nanjing University of Information Science and Technology

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National Key R&D Program of China

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    摘要:

    本文采用四组定义方法表征南亚高压强度、面积和经向、纬向位置,并对四组定义下南亚高压各参数的变化特征进行对比分析。研究结果表明,1979年来基于四组定义的南亚高压经、纬度指数呈年际变化特征,无显著的变化趋势和年代际突变,而南亚高压强度和面积指数表现出显著的变化趋势和年代际突变。当南亚高压偏东(西)时,经向位置偏南(北),偏强(弱)时面积偏大(偏缩小)。基于最大位势高度(F1)和闭合气压系统(F3)的定义方法受全球增暖背景下位势高度整体抬升的影响,特征等值线扩张,导致南亚高压表现为虚假的扩大增强趋势和年代际突变。而扰动位势高度(F2)和变化特征等值线的闭合气压系统(F4)定义方法克服了位势高度整体抬升的干扰,表征的南亚高压强度呈显著减弱缩小的趋势,与所在区域的整层扰动温度显著降低,扰动位势高度显著减小,以及负相对涡度显著增加的热动力特征相对应。可见,去除整体抬升的F2和F4定义方法能够更加客观地反映变暖背景下南亚高压的长期变化趋势。

    Abstract:

    The South Asian High variations for the period of 1979 – 2019 are compared based on four sets of definitions. The results show that the location of the South Asian High have an inter-annual variation characteristic, without significant trend and decadal abrupt in the center indices, whereas the intensity and the area index have significant trend and decadal abrupt. When the South Asia high locates more east (west) than usual, the meridional position is southward (northward). When it is stronger (weaker), the area of the South Asian High is larger (smaller). Based on the maximum geopotential height F1 and the closed-circulation-system index F3, the South Asian High intensity is closely connected with the zonal mean value, which indicates that the increasing trend in those two definitions may be forced by the apparent increment of the geopotential height under global warming. However, after removing the parallel circle geopotential height, the significant weakening trends are observed by the eddy geopotential height definition F2 and the changed-isobar closed-circulation-system index F4. The variation characteristics based on F2 and F4 coincide well with those in the eddy geopotential height field and the relative voracity, indicating that removing the uniform rise in geopotential height is more appropriate to present the long-term variation in the South Asian High.

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  • 收稿日期:2020-09-26
  • 最后修改日期:2020-11-04
  • 录用日期:2020-11-11
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