Using the conditional nonlinear optimal perturbation(CNOP) approach, sensitive areas of adaptive observation for predicting the seasonal reduction of the upstream Kuroshio transport(UKT) were investigated in the Regio...Using the conditional nonlinear optimal perturbation(CNOP) approach, sensitive areas of adaptive observation for predicting the seasonal reduction of the upstream Kuroshio transport(UKT) were investigated in the Regional Ocean Modeling System(ROMS). The vertically integrated energy scheme was utilized to identify sensitive areas based on two factors: the specific energy scheme and sensitive area size. Totally 27 sensitive areas, characterized by three energy schemes and nine sensitive area sizes, were evaluated. The results show that the total energy(TE) scheme was the most effective because it includes both the kinetic and potential components of CNOP. Generally, larger sensitive areas led to better predictions. The size of 0.5% of the model domain was chosen after balancing the effectiveness and efficiency of adaptive observation. The optimal sensitive area OSen was determined accordingly. Sensitivity experiments on OSen were then conducted, and the following results were obtained:(1) In OSen, initial errors with CNOP or CNOP-like patterns were more likely to yield worse predictions, and the CNOP pattern was the most unstable.(2) Initial errors in OSen rather than in other regions tended to cause larger prediction errors. Therefore, adaptive observation in OSen can be more beneficial for predicting the seasonal reduction of UKT.展开更多
Measured concentrations of dissolved oxygen,phosphate,silicate,total alkalinity and calculated totalCO<sub>2</sub> in a section between 121°E and 125°E across the Kuroshio near 22°N off Taiw...Measured concentrations of dissolved oxygen,phosphate,silicate,total alkalinity and calculated totalCO<sub>2</sub> in a section between 121°E and 125°E across the Kuroshio near 22°N off Taiwan and thegeostrophic velocity were used to estimate the gross transport of oxygen,nutrients and carbonates. The flux of dissolved oxygen is 6.7×10<sup>6</sup> mol/s northward and 0.9×10<sup>6</sup> mol/s southward.The netflux equals 5.8×10<sup>6</sup> mol/s down-stream.The northward flux of phosphate is 22.6×10<sup>3</sup> mol/s;the south-ward flux is 1.4×10<sup>3</sup> mol/s.The net phosphate flux is 21.2×10<sup>3</sup> mol/s northward.The flux of silicateis 967×10<sup>3</sup> northward and 59×10<sup>3</sup> mol/s southward;the net transport is 908×10<sup>3</sup> mol/s down-stream.The flux of alkalinity is 75.5×10<sup>6</sup> mol/s northward,and 10.8×10<sup>6</sup> mol/s southward,the net flux is64.7×10<sup>6</sup> mol/s northward.For total CO<sub>2</sub> the transport is 73.4×10<sup>6</sup> mol/s northward and 10.8×10<sup>6</sup> mol/ssouthward,or a net transport of 62.6×10<sup>6</sup> mol/s northward.展开更多
Owing to lack of observational data and accurate definition,it is difficult to distinguish the Kuroshio intrusion water from the Pacific Ocean into the South China Sea（SCS）.By using a passive tracer to identify the ...Owing to lack of observational data and accurate definition,it is difficult to distinguish the Kuroshio intrusion water from the Pacific Ocean into the South China Sea（SCS）.By using a passive tracer to identify the Kuroshio water based on an observation-validated three-dimensional numerical model MITgcm,the spatio-temporal variation of the Kuroshio intrusion water into the SCS has been investigated.Our result shows the Kuroshio intrusion is of distinct seasonal variation in both horizontal and vertical directions.In winter,the intruding Kuroshio water reaches the farthest,almost occupying the area from 18°N to 23°N and 114°E to 121°E,with a small branch flowing towards the Taiwan Strait.The intrusion region of the Kuroshio water decreases with depth gradually.However,in summer,the Kuroshio water is confined to the east of 118°E without any branch reaching the Taiwan Strait; meanwhile the intrusion region of the Kuroshio water increases from the surface to the depth about 205 m,then it decreases with depth.The estimated annual mean of Kuroshio Intrusion Transport（KIT） via the Luzon Strait is westward to the SCS in an amount of –3.86×106 m3/s,which is larger than the annual mean of Luzon Strait Transport（LST） of –3.15×106 m3/s.The KIT above 250 m accounts for 60%–80% of the LST throughout the entire water column.By analyzing interannual variation of the Kuroshio intrusion from the year 2003 to 2012,we find that the Kuroshio branch flowing into the Taiwan Strait is the weaker in winter of La Ni？a years than those in El Ni？o and normal years,which may be attributed to the wind stress curl off the southeast China then.Furthermore,the KIT correlates the Ni？o 3.4 index from 2003 to 2012 with a correlation coefficient of 0.41,which is lower than that of the LST with the Ni？o 3.4 index,i.e.,0.78.展开更多
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences (Grant No. XDA11010303)the National Natural Science Foundation of China (Grant Nos. 41230420, 41306023 & 41421005)+1 种基金the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers (Grant No. U1406401)the support of K. C. Wong Foundation
文摘Using the conditional nonlinear optimal perturbation(CNOP) approach, sensitive areas of adaptive observation for predicting the seasonal reduction of the upstream Kuroshio transport(UKT) were investigated in the Regional Ocean Modeling System(ROMS). The vertically integrated energy scheme was utilized to identify sensitive areas based on two factors: the specific energy scheme and sensitive area size. Totally 27 sensitive areas, characterized by three energy schemes and nine sensitive area sizes, were evaluated. The results show that the total energy(TE) scheme was the most effective because it includes both the kinetic and potential components of CNOP. Generally, larger sensitive areas led to better predictions. The size of 0.5% of the model domain was chosen after balancing the effectiveness and efficiency of adaptive observation. The optimal sensitive area OSen was determined accordingly. Sensitivity experiments on OSen were then conducted, and the following results were obtained:(1) In OSen, initial errors with CNOP or CNOP-like patterns were more likely to yield worse predictions, and the CNOP pattern was the most unstable.(2) Initial errors in OSen rather than in other regions tended to cause larger prediction errors. Therefore, adaptive observation in OSen can be more beneficial for predicting the seasonal reduction of UKT.
文摘Measured concentrations of dissolved oxygen,phosphate,silicate,total alkalinity and calculated totalCO<sub>2</sub> in a section between 121°E and 125°E across the Kuroshio near 22°N off Taiwan and thegeostrophic velocity were used to estimate the gross transport of oxygen,nutrients and carbonates. The flux of dissolved oxygen is 6.7×10<sup>6</sup> mol/s northward and 0.9×10<sup>6</sup> mol/s southward.The netflux equals 5.8×10<sup>6</sup> mol/s down-stream.The northward flux of phosphate is 22.6×10<sup>3</sup> mol/s;the south-ward flux is 1.4×10<sup>3</sup> mol/s.The net phosphate flux is 21.2×10<sup>3</sup> mol/s northward.The flux of silicateis 967×10<sup>3</sup> northward and 59×10<sup>3</sup> mol/s southward;the net transport is 908×10<sup>3</sup> mol/s down-stream.The flux of alkalinity is 75.5×10<sup>6</sup> mol/s northward,and 10.8×10<sup>6</sup> mol/s southward,the net flux is64.7×10<sup>6</sup> mol/s northward.For total CO<sub>2</sub> the transport is 73.4×10<sup>6</sup> mol/s northward and 10.8×10<sup>6</sup> mol/ssouthward,or a net transport of 62.6×10<sup>6</sup> mol/s northward.
基金The Special Fund of Strategic Leading Science and Technology from Chinese Academy of Sciences under contract Nos XDA11020305 and XDA13030103the National Basic Research Program of China under contract No.2013CB956101+1 种基金the National Science Foundation Council Grant of China under contract Nos 41206009,41430964 and 41521005the Chinese Academy of Sciences/State Administration of Foreign Experts Affairs International Partnership Program for Creative Research Teams under contract No.20140491532
文摘Owing to lack of observational data and accurate definition,it is difficult to distinguish the Kuroshio intrusion water from the Pacific Ocean into the South China Sea（SCS）.By using a passive tracer to identify the Kuroshio water based on an observation-validated three-dimensional numerical model MITgcm,the spatio-temporal variation of the Kuroshio intrusion water into the SCS has been investigated.Our result shows the Kuroshio intrusion is of distinct seasonal variation in both horizontal and vertical directions.In winter,the intruding Kuroshio water reaches the farthest,almost occupying the area from 18°N to 23°N and 114°E to 121°E,with a small branch flowing towards the Taiwan Strait.The intrusion region of the Kuroshio water decreases with depth gradually.However,in summer,the Kuroshio water is confined to the east of 118°E without any branch reaching the Taiwan Strait; meanwhile the intrusion region of the Kuroshio water increases from the surface to the depth about 205 m,then it decreases with depth.The estimated annual mean of Kuroshio Intrusion Transport（KIT） via the Luzon Strait is westward to the SCS in an amount of –3.86×106 m3/s,which is larger than the annual mean of Luzon Strait Transport（LST） of –3.15×106 m3/s.The KIT above 250 m accounts for 60%–80% of the LST throughout the entire water column.By analyzing interannual variation of the Kuroshio intrusion from the year 2003 to 2012,we find that the Kuroshio branch flowing into the Taiwan Strait is the weaker in winter of La Ni？a years than those in El Ni？o and normal years,which may be attributed to the wind stress curl off the southeast China then.Furthermore,the KIT correlates the Ni？o 3.4 index from 2003 to 2012 with a correlation coefficient of 0.41,which is lower than that of the LST with the Ni？o 3.4 index,i.e.,0.78.
