Seasonality of Interannual Inter-hemispheric Oscillations over the Past Five Decades  

作　　者：管兆勇 卢楚翰 梅士龙 丛菁 

机构地区：[1]Key Laboratory of Meteorological Disaster of Ministry of Education, College of Atmospheric Sciences, Nanjing University of Information Science and Technology, Nanjing 210044 [2]Weather Service Division of Jiaxing Meteorological Bureau, Jiaxing 314000 [3]Dalian Municipal Meteorological Bureau, Dalian 116001

出　　处：《Advances in Atmospheric Sciences》2010年第5期1043-1050,共8页大气科学进展（英文版）

基　　金：supported jointlyby the National Key Technology R&D Program (GrantNo. 2007BAC29B02);the National Natural Science Foundation of China (NSFC, Grant No. 40675025);the Key Laboratory of Meteorological Disasters, Nanjing University of Information Science & Technology (NUIST,KLME060101)

摘　　要：Air mass is inter-hemispherically redistributed, leading to an interesting phenomenon known as the Inter-Hemispheric Oscillation （IHO）. In the present article, the seasonality of the interannual IHO has been examined by employing monthly mean reanalyses from NCEP/NCAR, EAR40, and JRA25 for the period of 1958–2006. It is found that the IHO indices as calculated from different reanalyses are generally consistent with each other. A distinct seesaw structure in all four seasons between the northern and southern hemispheres is observed as the IHO signature in both the surface air pressure anomalies （SAPAs） and the leading EOF component of the anomalous zonal mean quantities. When the SAPAs are positive （negative） in the northern hemisphere, they are negative （positive） in the southern hemisphere. Large values of SAPAs are usually observed in mid- and high-latitude areas in all but the solstice seasons. In boreal summer and winter, relatively stronger perturbations of IHO-related SAPA are found in the Asian monsoon region, which shows a large difference from the status in boreal spring and fall. This suggests that seasonal mean monsoon activity is globally linked via air mass redistribution globally on interannual timescales, showing a very interesting linkage between monsoons and the IHO in the global domain. In all seasons, large values of SAPA always exist over the Antarctic and the surrounding regions, implying a close relation with Antarctic oscillations.Air mass is inter-hemispherically redistributed, leading to an interesting phenomenon known as the Inter-Hemispheric Oscillation （IHO）. In the present article, the seasonality of the interannual IHO has been examined by employing monthly mean reanalyses from NCEP/NCAR, EAR40, and JRA25 for the period of 1958–2006. It is found that the IHO indices as calculated from different reanalyses are generally consistent with each other. A distinct seesaw structure in all four seasons between the northern and southern hemispheres is observed as the IHO signature in both the surface air pressure anomalies （SAPAs） and the leading EOF component of the anomalous zonal mean quantities. When the SAPAs are positive （negative） in the northern hemisphere, they are negative （positive） in the southern hemisphere. Large values of SAPAs are usually observed in mid- and high-latitude areas in all but the solstice seasons. In boreal summer and winter, relatively stronger perturbations of IHO-related SAPA are found in the Asian monsoon region, which shows a large difference from the status in boreal spring and fall. This suggests that seasonal mean monsoon activity is globally linked via air mass redistribution globally on interannual timescales, showing a very interesting linkage between monsoons and the IHO in the global domain. In all seasons, large values of SAPA always exist over the Antarctic and the surrounding regions, implying a close relation with Antarctic oscillations.

关 键 词：inter-hemispheric oscillation SEASONALITY interannual variability surface air pressure anomaly 

分 类 号：P426.4[天文地球—大气科学及气象学]