PNA流型的年际变化及温、热带太平洋海温的作用

本文分析了PNA型环流的年际变化和影响因子,发现它存在两种优势周期振荡:一种是3—5年的振荡,另一种是10年左右的振荡.研究表明,前者与赤道太平洋海温的主要振荡周期相对应(同相关系),后者与北太平洋海温的主要振荡周期一致(反相关系).揭示了PNA型环流的变化与北太平洋海温比与赤道太平洋海温具有更密切的联系.并且由于北太平洋海温影响的频带与赤道太平洋海温的不同,它的作用有时与赤道太平洋海温的同相,有时则反相,使得ENSO与太平洋-北美地区大气环流和气候异常的关系变得复杂化.指出当考虑北太平洋海温的共同作用后

lnterannual variation of the PNA flow pattern and impacts of extratroplcal and tropical SSTs

In the present article, the interannual variation and the influential factors on the PNA pattern are analyzed. It is found that the PNA pattern has two predominant oscillations, one is the 3 - 5 year oscillation, the other is the ten-year oscillation. It is shown that the former corresponds to the main oscillation of the equatorial Pacific SST (EPSST) (in phase), the latter is consistent with the main oscillation of the North Pacific SST (NPSST) (out of phase). It is uncovered that the PNA pattern has a much closer association with the NPSST than with the EPSST. The frequency at which the NPSST affects the PNA pattern is different from that of the EPSST. Hence, the impact of the NPSST on the PNA pattern is sometimes in phase with, sometimes out of phase with that of the EPSST, which complicates the relationship between the ENSO and the atmospheric circulation and climate anomaly over the North Pacific through the North America. When the impact of the NPSST is involved, some observational facts can be better explained. At last, the possible evolution process of about ten year scale oscillation of the PNA pattern circulation is discussed.