Du Yan

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  • Article
    Mass-induced sea level change in the northwestern North Pacific and its contribution to total sea level change
    (John Wiley & Sons, 2013-08-02) Cheng, Xuhua ; Li, Lijuan ; Du, Yan ; Wang, Jing ; Huang, Rui Xin
    Over the period 2003–2011, the Gravity Recovery and Climate Experiment (GRACE) satellite pair revealed a remarkable variability in mass-induced sea surface height (MSSH) in the northwestern North Pacific. A significant correlation is found between MSSH and observed total sea surface height (SSH), indicative of the importance of barotropic variability in this region. For the period 2003–2011, MSSH rose at a rate of 6.1 ± 0.7 mm/yr, which has a significant contribution to the SSH rise (8.3 ± 0.7 mm/yr). Analysis of the barotropic vorticity equation based on National Centers for Environmental Prediction/National Center for Atmospheric Research reanalysis product, GRACE, and altimetry data suggests that the MSSH signal is primarily caused by negative wind stress curl associated with an anomalous anticyclonic atmospheric circulation. Regression analysis indicates that trends in MSSH and surface wind are related to the Pacific Decadal Oscillation, whose index had a decreasing trend in the last decade.
  • Article
    Interannual 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, Tangdong
    The 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.
  • Article
    Southern Ocean warming and its climatic impacts
    (Elsevier, 2023-05-12) Cai, Wenju ; Gao, Libao ; Luo, Yiyong ; Li, Xichen ; Zheng, Xiaotong ; Zhang, Xuebin ; Cheng, Xuhua ; Jia, Fan ; Purich, Ariaan ; Santoso, Agus ; Du, Yan ; Holland, David M. ; Shi, Jia-Rui ; Xiang, Baoqiang ; Xie, Shang-Ping
    The Southern Ocean has warmed substantially, and up to early 21st century, Antarctic stratospheric ozone depletion and increasing atmospheric CO2 have conspired to intensify Southern Ocean warming. Despite a projected ozone recovery, fluxes to the Southern Ocean of radiative heat and freshwater from enhanced precipitation and melting sea ice, ice shelves, and ice sheets are expected to increase, as is a Southern Ocean westerly poleward intensification. The warming has far-reaching climatic implications for melt of Antarctic ice shelf and ice sheet, sea level rise, and remote circulations such as the intertropical convergence zone and tropical ocean-atmosphere circulations, which affect extreme weathers, agriculture, and ecosystems. The surface warm and freshwater anomalies are advected northward by the mean circulation and deposited into the ocean interior with a zonal-mean maximum at ∼45°S. The increased momentum and buoyancy fluxes enhance the Southern Ocean circulation and water mass transformation, further increasing the heat uptake. Complex processes that operate but poorly understood include interactive ice shelves and ice sheets, oceanic eddies, tropical-polar interactions, and impact of the Southern Ocean response on the climate change forcing itself; in particular, limited observations and low resolution of climate models hinder rapid progress. Thus, projection of Southern Ocean warming will likely remain uncertain, but recent community effort has laid a solid foundation for substantial progress.