The seasonal cycle of interhemispheric oscillations in mass field of the global atmosphere

• 来源期刊: 科学通报(英文版)
• 年，卷（期）: 2008,（20）
• 页码范围: 3226-3234
• 页数: 9页
• 语种: 英文
• DOI: 10.1007/s11434-008-0316-3

摘要

Using the daily and monthly data of surface air pressure, meridional wind, radiation and water vapor from NCEP/NCAR reanalysis for the period of 1979--2006, we have examined the seasonal variations of the interhemispheric oscillations (IHO) in mass field of the global atmosphere. Our results have dem-onstrated that IHO as observed in surface air pressure field shows the distinct seasonal cycle. This seasonal cycle has an interhemispheric seesaw structure with comparable annual ranges of surface air pressure in the Southern and Northern Hemispheres. Mass of water vapor changes out-of-phase be-tween the Southern and Northern Hemispheres, showing clearly a seasonal cycle with its annual range almost equivalent to annual range of the IHO seasonal cycle. Amazingly, the cross-equatorial flow is found to be induced by annual changes in water vapor mass as a response of the atmosphere to sea-sonal cycle of forcing from hemispheric net surface short- and long-wave radiations. The IHO season-ality exhibits its larger variations in magnitude in mid-latitudes other than in other regions of the globe. Additionally, our results also show that the global air mass is redistributed seasonally not only between the Northern and Southern Hemispheres but also between land and sea. This land-sea air mass redis-tribution induces a zonal pattern of surface air pressure in the Northern Hemisphere but the meridional pattern in the Southern Hemisphere.