Intraseasonal oscillations in East Asian and South Asian monsoons
- 314 Downloads
This study has investigated the relation between the East Asian monsoon and the South Asian monsoon at intraseasonal time scale during the boreal summer. Applying a data adaptive method on daily anomalies of precipitation, two leading intraseasonal oscillations (ISOs) were extracted separately in the regions of South Asia, tropical East Asia and subtropical East Asia. The first ISO has a period of about 45 days and propagates northward and eastward over the South Asian and tropical East Asian regions. The second ISO, with a period of about 26 days, propagates northeastward over South Asia and northwestward over tropical East Asia. Although both the ISOs are also present over the subtropical East Asia, the variance is low while no propagation is evident. The circulation patterns associated with the ISOs were found to be consistent with the corresponding precipitation patterns of the ISOs. The two ISOs also reveal consistency with the space–time evolution of diabatic heating, convection, vertical motion, upper-level divergence and moisture transport. The zonal and meridional propagation of the ISOs provide a strong link between the South Asian monsoon and East Asian monsoon regions. The subtropical East Asian region seems to have a weaker link with the other monsoon regions.
KeywordsEast Asian monsoon South Asian monsoon Intraseasonal oscillations Zonal and meridional propagation
This work was supported by National Science Foundation (Grants 0830068, 1338427), National Oceanic and Atmospheric Administration (Grants NA09OAR4310058, NA14OAR4310160), and National Aeronautics and Space Administration (Grants NNX09AN50G, NNX14AM19G).
- Kripalani RH, Singh SV, Arkin PA (1991) Large-scale features of rainfall and outgoing longwave radiation over Indian and adjoining regions. Beitr Phys Atmosph 64:159–168Google Scholar
- Liebmann B, Smith CA (1996) Description of a complete (interpolated) outgoing longwave radiation dataset. Bull Am Soc 77:1275–1277Google Scholar
- Wang B, Li T, Ding Y, Zhang R, Wang H (2005) East Asian-Western North Pacific monsoon: A distinctive component of the Asian-Australian monsoon system. In: Chang C-P, Wang B, Lau N-CG (eds) The global monsoon system: research and forecast, WMO/TD no. 1266. World Meteorological Organization, Geneva, pp 71–94Google Scholar