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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.

北极涛动或称北环模(NAM)是冬季北半球最主要的模。研究了北大西洋涛动的季节变化及其与季节的联系。夏季NAM的经向尺度小于冬季NAM，且局限于对流层。冬季NAM与次年夏季NAM呈正相关。我们发现，这种季节性联系在一定程度上是由北部大陆的降雪造成的。冬季NAM的积雪减少了欧亚大陆的降雪量，积雪减少一直持续到晚春。初夏早期融雪加强了欧亚大陆和北冰洋之间的热对比，从而在夏季产生了北冰洋的正位相。这是不结盟运动季节性联系的一种可能机制。另一种可能的机制是与臭氧相关的过程。正NAM年冬季，平流层极涡较强，臭氧从热带向平流层下部温带输送减弱。由于臭氧在平流层下部的光化学寿命很短，减少的臭氧一直持续到初夏。臭氧减少使高纬度地区降温，并在初夏加强平流层低层的纬向风。从而改变了波在对流层中的传播，使对流层NAM变为正值。通过数据分析，我们认为这一机制也适用于季节性联系。2003年夏季欧洲异常炎热，日本异常凉爽。从夏季NAM的角度对这次异常天气进行了分析。7月中旬至8月上旬，夏季NAM值较大，与欧洲和东西伯利亚地区的阻塞相对应。这些阻塞高压造成了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。