TY - JOUR
T1 - State analysis using the Local Ensemble Transform Kalman Filter (LETKF) and the three-layer circulation structure of the Luzon Strait and the South China Sea Topical Collection on the 5th International Workshop on Modelling the Ocean (IWMO) in Bergen, Norway 17-20 June 2013
AU - Xu, Fang Hua
AU - Oey, Lie Yauw
N1 - Funding Information:
We are grateful to the three reviewers and the editor for their comments and suggestions that improved the manuscript. We thank Y.-L. Chang, Y.-C. Lin, and M.-C. Chang of the ATOP Group for their assistance in running the mpiPOM. The supports for FHX from the National Basic Research Program of China (973 Program, Grant No. 2013CB956603) and from the start-up funds of the Tsinghua University are acknowledged. LYO is grateful for the award from the Taiwan’s Foundation for the Advancement of Outstanding Scholarship and acknowledges partial supports from the National Science Council and the National Central University.
PY - 2014/6
Y1 - 2014/6
N2 - A new circulation model of the western North Pacific Ocean based on the parallelized version of the Princeton Ocean Model and incorporating the Local Ensemble Transform Kalman Filter (LETKF) data assimilation scheme has been developed. The new model assimilates satellite data and is tested for the period January 1 to April 3, 2012 initialized from a 24-year simulation to estimate the ocean state focusing in the South China Sea (SCS). Model results are compared against estimates based on the optimum interpolation (OI) assimilation scheme and are validated against independent Argo float and transport data to assess model skills. LETKF provides improved estimates of the western North Pacific Ocean state including transports through various straits in the SCS. In the Luzon Strait, the model confirms, for the first time, the three-layer transport structure previously deduced in the literature from sparse observations: westward in the upper and lower layers and eastward in the middle layer. This structure is shown to be robust, and the related dynamics are analyzed using the results of a long-term (18 years) unassimilated North Pacific Ocean model. Potential vorticity and mass conservations suggest a basin-wide cyclonic circulation in the upper layer of the SCS (z>-570 m), an anticyclonic circulation in the middle layer (-570 m≥z>-2,000 m), and, in the abyssal basin (<-2,000 m), the circulation is cyclonic in the north and anticyclonic in the south. The cyclone-anticyclone abyssal circulation is confirmed and explained using a deep-layer reduced-gravity model as being caused by overflow over the deep sill of the Luzon Strait, coupled with intense, localized upwelling west of the strait.
AB - A new circulation model of the western North Pacific Ocean based on the parallelized version of the Princeton Ocean Model and incorporating the Local Ensemble Transform Kalman Filter (LETKF) data assimilation scheme has been developed. The new model assimilates satellite data and is tested for the period January 1 to April 3, 2012 initialized from a 24-year simulation to estimate the ocean state focusing in the South China Sea (SCS). Model results are compared against estimates based on the optimum interpolation (OI) assimilation scheme and are validated against independent Argo float and transport data to assess model skills. LETKF provides improved estimates of the western North Pacific Ocean state including transports through various straits in the SCS. In the Luzon Strait, the model confirms, for the first time, the three-layer transport structure previously deduced in the literature from sparse observations: westward in the upper and lower layers and eastward in the middle layer. This structure is shown to be robust, and the related dynamics are analyzed using the results of a long-term (18 years) unassimilated North Pacific Ocean model. Potential vorticity and mass conservations suggest a basin-wide cyclonic circulation in the upper layer of the SCS (z>-570 m), an anticyclonic circulation in the middle layer (-570 m≥z>-2,000 m), and, in the abyssal basin (<-2,000 m), the circulation is cyclonic in the north and anticyclonic in the south. The cyclone-anticyclone abyssal circulation is confirmed and explained using a deep-layer reduced-gravity model as being caused by overflow over the deep sill of the Luzon Strait, coupled with intense, localized upwelling west of the strait.
KW - Data assimilation
KW - Local Ensemble Transform Kalman Filter (LETKF)
KW - Ocean modeling
KW - Three-layer Luzon Strait transport
KW - Three-layer circulation of South China Sea
UR - http://www.scopus.com/inward/record.url?scp=84902273385&partnerID=8YFLogxK
U2 - 10.1007/s10236-014-0720-y
DO - 10.1007/s10236-014-0720-y
M3 - 期刊論文
AN - SCOPUS:84902273385
SN - 1616-7341
VL - 64
SP - 905
EP - 923
JO - Ocean Dynamics
JF - Ocean Dynamics
IS - 6
ER -