Group seminar on 7. May, 14:15
Decomposition of the global circulation related to the atmospheric convection over western North Pacific to different waves
Peishan Chen
The atmospheric convection over Western North Pacific (WNP) plays an important role in affecting the tropical and extratropical circulation. In this study, we use the Normal-mode function to decompose the global circulation related to WNP convection to different waves and compare their contributions. The results suggest that the Rossby waves related to the WNP convection dominantly affect the northern and southern hemisphere circulation compared with other waves, and the baroclinic modes are stronger than the barotropic modes. The first meridional mode of baroclinic Rossby waves, as a symmetrical mode, contributes most to the 850-hPa anticyclonic anomalies and 200-hPa cyclonic anomalies over WNP, and roughly symmetrical circulation anomalies in the tropics of southern hemisphere associated with the WNP convection. In addition, the cross-equatorial flow related to WNP convection is dominantly contributed by MRG and inertio-gravity wave. In the extratropics, the asymmetrical Rossby waves in barotropic modes contribute most to the alternate cyclonic and anticyclonic anomalies extending from East Asia to North America, and asymmetrical circulation anomalies in the southern hemisphere. Moreover, the asymmetrical Rossby waves in baroclinic modes also have a positive contribution to the upper-tropospheric circulation anomalies.