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Study on mechanism of formation and variability of the Arctic Oscillation

北极涛动形成及变化机制研究

基本信息

批准号：
11640421
负责人：
YAMAZAKI Koji
金额：
$ 1.98万
依托单位：
HOKKAIDO UNVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640421/
关键词：
Arctic Oscillation North Atlantic Oscillation wave-mean flow interaction Troposphere-Stratosphere interaction Sea ice on Sea of Okhotsk 極夜ジェット振動天候レジームプラネタリー波

项目摘要

The Arctic Oscillation the most dominant variation mode of the wintertime sea-level pressure in the Northern extratropics and it is the seesaw variation between the midlatitudes and the Arctic region. It has an equivalent barotropic structure and it has a signal up to the lower stratosphere. This mode resembles the North Atlantic Oscillation, but it is more annular and global. It was named as the Arctic Oscillation by Thompson and Wallace(1998).A perpetual February simulation by an AGCM clearly showed the Arctic Oscillation is not a forced mode but an internal mode of the atmosphere. The composite analysis of the simulation results showed the dominance of the Arctic Oscillation is caused by the wave-mean flow interaction. Mostly planetary-scale wave contributes to the transition to positive and negative phases of the Arctic Oscillation and the synoptic-scale wave also contributes to the transition.The perpetual February experiment also shows that the wintertime Arctic Oscillation is related to the polar night jet oscillation in the stratosphere. When the polar night jet is stronger than normal, the Arctic Oscillation in the troposphere tends to shift to posituve phase.In reality after the stratospheric sudden warming, which corresponds to weak polar night jet and negative phase of the stratospheric Arctic Oscillation, the tropospheric Arctic Oscillation tends to have a negative phase, which bring severe cold weather in midlatitudes.In interannaul and intraseasonal time scales, the Arctic Oscillation has a good correlation with the winter climate over Eurasia, northern Japan and Sea of Okhotsk. Analyzing the sea ice extent over Sea of Okhotsk, it is found that the sea ice extent has a good correlation with the Arctic Oscillation(also with the North Atlantic Oscillation).

北极涛动是北方温带地区冬季海平面气压最主要的变化模式，是中纬度地区与北极地区之间的跷跷板变化。它有一个等效的正压结构，它有一个信号到平流层下层。这种模式类似于北大西洋涛动，但它更具有环形性和全球性。Thompson和Wallace（1998）将其命名为北极涛动。AGCM在2月份的永久模拟清楚地表明，北极涛动不是一个强迫模态，而是一个大气的内部模态。模拟结果的综合分析表明，北极涛动的主导作用是由波均流相互作用引起的。行星尺度波对北极涛动正、负相的过渡起主要作用，天气尺度波对北极涛动正、负相的过渡也起作用。常年2月实验还表明，冬季北极涛动与平流层极夜急流涛动有关。当极夜急流较正常强时，对流层的北极涛动有向正相位偏移的趋势。实际上，在平流层突然变暖后，对应于极夜急流弱和平流层北极涛动负相，对流层北极涛动趋于负相，带来中纬度地区的严寒天气。在年际和季节尺度上，北极涛动与欧亚大陆、日本北部和鄂霍次克海的冬季气候具有良好的相关性。分析鄂霍次克海的海冰范围，发现海冰范围与北极涛动（也与北大西洋涛动）有很好的相关性。