作　　者： ; ;

机构地区： 中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室

出　　处： 《气象学报》 2003年第2期180-195,共16页

摘　　要： 通过对 1998年 7月副热带高压短期结构及其演变的诊断 ,指出 5 0 0hPa西太平洋副热带高压内并非均一的下沉运动 ,而是多处、多时存在上升运动 ,这是由西太平洋副热带高压的复杂的动力和热力性所决定。诊断还发现 ,在西太平洋副热带高压脊区下方的近地面层 ,多存在一个辐散下沉层 ,这是副热带高压内天气一般多晴空或少云的主要原因。利用动力学理论 ,研究副热带高压的复杂结构的成因 ,指出在 5 0 0hPa副热带高压的西部 ,高低空风场的分布决定了该区域必然多上升运动 ; The diagnosis of the short-term structure of the subtropical anticyclone over the Western Pacific(SAWP) in the summer of 1998 shows that, other than uniform descent, ascent at 500hPa often exists within the area of SAWP. These features are determined by the complicated dynamic and thermodynamic structures of the SAWP. Under the 500hPa SAWP ridge, along the ridge line in the planetary boundary layer, there always exist divergence and descent, which greatly accounts for the usual clearness in the SAWP area. This complicated structure was also studied by employing atmospheric dynamic theory. It was found that vertical wind shear over the west part of the SAWP that is forced by external forcing should be accompanied by ascent. On the other hand, the negative vorticity advection at higher levels is the major forcing for the appearance of descent over the west of the SAWP.

关 键 词： 年 夏季 副热带高压 短期结构 动力 热力 强迫机制

领　　域： [天文地球]