Propagation and mechanisms of the quasi-biweekly oscillation over the Asian summer monsoon region |
| |
| Authors: | Meirong Wang Jun Wang Anmin Duan |
| |
| Affiliation: | 1.Center of Data Assimilation for Research and Application/Key Laboratory of Meteorological Disaster of Ministry of Education,Nanjing University of Information Science & Technology,Nanjing,China;2.Plateau Atmosphere and Environment Key Laboratory of Sichuan Province,Chengdu,China;3.International Institute for Earth System Science,Nanjing University,Nanjing,China;4.State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Institute of Atmospheric Physics,Chinese Academy of Sciences,Beijing,China |
| |
| Abstract: | The propagation and underlying mechanisms of the boreal summer quasi-biweekly oscillation (QBWO) over the entire Asian monsoon region are investigated, based on ECMWF Interim reanalysis (ERA-Interim) data, GPCP precipitation data, and an atmospheric general circulation model (AGCM). Statistical analyses indicate that the QBWO over the Asian monsoon region derives its main origin from the equatorial western Pacific and moves northwestward to the Bay of Bengal and northern India, and then northward to the Tibetan Plateau (TP) area, with a baroclinic vertical structure. Northward propagation of the QBWO is promoted by three main mechanisms: barotropic vorticity, boundary moisture advection, and surface sensible heating (SSH). It is dominated by the barotropic vorticity effect when the QBWO signals are situated to the south of 20°N. During the propagation taking place farther north toward the TP, the boundary moisture advection and SSH are the leading mechanisms. We use an AGCM to verify the importance of SSH on the northward propagation of the QBWO. Numerical simulations confirm the diagnostic conclusion that the equatorial western Pacific is the source of the QBWO. Importantly, the model can accurately simulate the propagation pathway of the QBWO signals over the Asian monsoon region. Simultaneously, sensitivity experiments demonstrate that the SSH over northern India and the southern slope of the TP greatly contributes to the northward propagation of the QBWO as far as the TP area. |
| |
| Keywords: | |
| 本文献已被 SpringerLink 等数据库收录！ |
|
