Seasonal variation of the northern annular mode and its inter-seasonal correlation

北环模态的季节变化及其季节间相关性

基本信息

批准号：
16540394
负责人：
YAMAZAKI Koji
金额：
$ 2.11万
依托单位：
HOKKAIDO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2005
项目状态：
已结题

项目摘要

The Arctic Oscillation or the northern annular mode (NAM) is the most dominant mode in the winter Northern Hemisphere. The seasonal variation of the NAM and its seasonal linkage are studied in this research project. The summer NAM has a smaller meridional scale than the winter NAM and confined in the troposphere. The winter NAM has a positive correlation with the following summer NAM. We showed that this seasonal linkage is partly caused by snow over the northern continents. The positive winter NAM produces less snow fall over Eurasia and the reduced snow cover persist until late spring. Early snowmelt enhances heat contrast between Eurasia and the Arctic Ocean in early summer, which produce a positive phase of NAM in summer. This is one possible mechanism for seasonal linkage of the NAM. The other possible mechanism is the ozone-related process. In the winter of positive NAM years, the stratospheric polar vortex is strong and hence the ozone transport from the tropics to the extratropics in the lower stratosphere is reduced. Since the photochemical life time of ozone is ling in the lower stratosphere, the reduced ozone persist until early summer. The reduced ozone cools the high-latitude and strengthen the zonal wind in the lower stratosphere in early summer. Thus the wave propagation in the troposphere is changed and the tropospheric NAM become positive by eddy forcing. By data analysis, we suggested this mechanism is also working for the seasonal linkage.The summer of 2003 was abnormally hot in Europe and cool in Japan. This abnormal weather was analyzed from a viewpoint of summer NAM. From mid-July to early August, the summer NAM showed quite large value, which corresponds to blockings over Europe and east Siberia. These blocking highs caused the abnormal weather in Europe and Japan.

北极振荡或北环模式（NAM）是冬季北半球最主要的模式。该研究项目研究了NAM及其季节性联系的季节性变化。夏季NAM的子午量表比冬季NAM较小，并且限制在对流层中。冬季NAM与第二个夏季NAM有正相关。我们表明，这种季节性连接部分是由北部大陆上的降雪引起的。积极的冬季NAM在欧亚大陆上降雪较少，而降雪覆盖量的减少一直持续到春末。早期的融雪增强了欧亚大陆与北极海洋之间的热对比，夏季在夏季产生了NAM的积极阶段。这是NAM季节性连接的一种可能机制。另一种可能的机制是与臭氧相关的过程。在正NAM年的冬季，平流层极性涡流很强，因此臭氧从热带地区传输到下层平流层中的臭氧。由于臭氧的光化学寿命在下层平流层中延伸，因此臭氧一直持续到初夏。减少的臭氧会在初夏冷却高纬度并增强下层平流层的区域风。因此，对流层中的波传播发生了变化，对流层NAM通过涡流强迫变为正。通过数据分析，我们认为这种机制也用于季节性联系。2003年夏天在欧洲异常热，在日本很酷。从夏季NAM的角度分析了这种异常天气。从7月中旬到8月初，NAM的价值很高，这与欧洲和东西伯利亚的封锁相对应。这些阻碍的高点会导致欧洲和日本的异常天气。

项目成果

期刊论文数量（44）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

The Connectivity of the Winter North Atlantic Oscillation (NAO) and the Summer Okhotsk High

DOI：
10.2151/jmsj.2004.905
发表时间：
2004-06
期刊：
Journal of the Meteorological Society of Japan
影响因子：
3.1
作者：
M. Ogi;Y. Tachibana;K. Yamazaki
通讯作者：
M. Ogi;Y. Tachibana;K. Yamazaki

The Arctic Oscillation and summer climate in Japan

北极涛动与日本夏季气候

DOI：
发表时间：
2005
期刊：
Meteorological Research Note (Meteorological Society of Japan, in Japanese) 210
影响因子：
0
作者：
Yamazaki;K.;M.Ogi;Y.Tachibana
通讯作者：
Y.Tachibana

Seasonal variation of moisuture transport in the polar regions and the relation with annular modes.

极地水分输送的季节变化及其与环模的关系。