Wang Dong Xiao
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PreprintInterplay between the Indonesian Throughflow and the Luzon Strait Throughflow( 2006) Liu, Qinyan ; Huang, Rui Xin ; Wang, Dong Xiao ; Xie, Qiang ; Huang, QizhouAnalysis based on the “Island Rule” and ocean assimilation dataset shows that the interannual variability of the Indonesian Throughflow and the Luzon Strait (South China Sea) Throughflow is out of phase. Wind anomaly in the equatorial Pacific plays an important role in setting up this phase relation. During El Niño events, the westerly wind bursts intensify the Northern Equator Current and induce a northward shift of its bifurcation point. As a result, the partition of volume transport between the Kuroshio and the Mindanao Current is changed, with the Kuroshio transport decreased and the Mindanao Current increased. The undershooting/overshooting phenomena occur at the Luzon Strait and the Sulawesi-Mindanao passage, caused by variability of these two currents. Water transport from the Pacific to the South China Sea increases with the Kuroshio transport decreased, and transport from the Pacific to the Indian Ocean decreases with the Mindanao Current transport increased. Therefore, the interannual variability of the Indonesian Throughflow and the Luzon Strait Throughflow is out of phase.
ArticleDecadal changes of wind stress over the Southern Ocean associated with Antarctic ozone depletion(American Meteorological Society, 2007-07-15) Yang, Xiao-Yi ; Huang, Rui Xin ; Wang, Dong XiaoUsing 40-yr ECMWF Re-Analysis (ERA-40) data and in situ observations, the positive trend of Southern Ocean surface wind stress during two recent decades is detected, and its close linkage with spring Antarctic ozone depletion is established. The spring Antarctic ozone depletion affects the Southern Hemisphere lower-stratospheric circulation in late spring/early summer. The positive feedback involves the strengthening and cooling of the polar vortex, the enhancement of meridional temperature gradients and the meridional and vertical potential vorticity gradients, the acceleration of the circumpolar westerlies, and the reduction of the upward wave flux. This feedback loop, together with the ozone-related photochemical interaction, leads to the upward tendency of lower-stratospheric zonal wind in austral summer. In addition, the stratosphere–troposphere coupling, facilitated by ozone-related dynamics and the Southern Annular Mode, cooperates to relay the zonal wind anomalies to the upper troposphere. The wave–mean flow interaction and the meridional circulation work together in the form of the Southern Annular Mode, which transfers anomalous wind signals downward to the surface, triggering a striking strengthening of surface wind stress over the Southern Ocean.
ArticleInterannual variability of the South China Sea throughflow inferred from wind data and an ocean data assimilation product(American Geophysical Union, 2006-07-26) Wang, Dong Xiao ; Liu, Qinyan ; Huang, Rui Xin ; Du, Yan ; Qu, TangdongThe Luzon Strait transport, as an index for the South China Sea throughflow, has attracted much attention. In this study the interannual variability of the Luzon Strait transport is examined, using the Island Rule and results from an ocean general circulation model. Transport variability obtained from these two approaches are consistent with each other. Assessment of contribution from each integral segment involved in the Island Rule indicates that wind stress in the western and central equatorial Pacific is the key factor regulating the interannual variability of the Luzon Strait transport, whereas the effect of local wind stress in the vicinity of the Luzon Strait is secondary. Analysis also shows that when the westerly (easterly) wind anomalies in the tropical Pacific break out, the Luzon Strait transport increases (decreases), consistent with the variations in the North Equatorial Current during El Niño (La Niña) events.
ArticleConnection between the decadal variability in the Southern Ocean circulation and the Southern Annular Mode(American Geophysical Union, 2007-08-22) Yang, Xiao-Yi ; Wang, Dong Xiao ; Wang, Jia ; Huang, Rui XinPrevious studies demonstrated the remarkable upward trend of the Southern Annular Mode (SAM) and Southern Ocean wind stress in association with anthropogenic forcing. An oceanic reanalysis data set is used to investigate the response of the circulation in the Southern Ocean to the decadal variability of SAM. Our results indicate the strengthening and the poleward shift of the northward Ekman velocity as well as the Ekman pumping rate, which led to a corresponding strengthening trend in the Deacon Cell. This strengthening, in turn, intensified the meridional density gradient and the tilting of the isopycnal surfaces. On the interannual time scale, the Antarctic Circumpolar Currents (ACC) transport exhibits a positive correlation with SAM index as seen separately in observations. However, there is no significant trend in the total transport of ACC. Possible reasons are discussed.
PreprintDelayed baroclinic response of the Antarctic circumpolar current to surface wind stress( 2008-01-11) Yang, Xiao-Yi ; Huang, Rui Xin ; Wang, Jia ; Wang, Dong XiaoAntarctic Circumpolar Current (ACC) responds to the surface windstress via two processes, i.e., instant barotropic process and delayed baroclinic process. This study focuses on the baroclinic instability mechanism in ACC. That is, the strengthening of surface zonal windstress causes the enhanced tilting of the isopycnal surface, which leads to the intense baroclinic instability. Simultaneously, the mesoscale eddies resulting from the baroclinic instability facilitate the transformation of mean potential energy to eddy energy, which causes the remarkable decrease of the ACC volume transport with the 2-year lag time. This delayed negative correlation between the ACC transport and the zonal windstress may account for the steadiness of the ACC transport in these two decades.