The characteristics of the upper ocean response to tropical cyclone wind （TCW） forcing in the northwestern Pacific were in- vestigated using satellite and Argo data, as well as an ocean general circulation model. In...The characteristics of the upper ocean response to tropical cyclone wind （TCW） forcing in the northwestern Pacific were in- vestigated using satellite and Argo data, as well as an ocean general circulation model. In particular, a case study was carried out on typhoon Rammasun, which passed through our study area during May 6-13, 2008. It is found that the local response fight under the TCW forcing is characterized by a quick deepening of the surface mixed layer, a strong latent heat loss to the atmosphere, and an intense upwelling near the center of typhoon, leading to a cooling of the oceanic surface layer that persists as a cold wake along the typhoon track. More interestingly, the upper ocean response exhibits a four-layer thermal structure, including a cooling layer near the surface and a warming layer right below, accompanied by another pair of cooling/warming layers in the thermocline. The formation of the surface cooling/warming layers can be readily explained by the strong vertical mixing induced by TCW forcing, while the thermal response in the thermocline is probably a result of the cyclone-driven upwelling and the associated advective processes.展开更多
The MASNUM wave-tide-circulation coupled model, with 21 layers in the vertical and （1/8） °horizontal resolution, was employed to investigate the oceanic responses to Typhoon Mstsa which traversed the East China...The MASNUM wave-tide-circulation coupled model, with 21 layers in the vertical and （1/8） °horizontal resolution, was employed to investigate the oceanic responses to Typhoon Mstsa which traversed the East China Sea （ECS） during the period of 4 - 6 August, 2005. Numerical experiment results are analyzed and compared with observation. The responses of the sea surface temperature （SST）, in a focused area of （27° -29°N, 121° - 124°E）, include heating and cooling stages. The heating is mainly due to warm Kuroshio water transportation and downwelling due to the water accumulation. In the cooling stage, the amplitude of the simulated cold wake （ -3℃ ）, located on the right side of this typhoon track, is compared quite well with that of the satellite observed SST data. The wave-induced mixing（Bv） plays a key role for the SST cooling. Bv still plays a leading role, which accounts for 36%, for the ocean temperature drop in the upper ocean of 0 - 40 m, while the upwelling is responsible for 84% of the cooling for the lower layer of 40 - 70 m. The mixed layer depth （MLD） increased quickly from 28 to 50 m in the typhoon period. However, the simulated MLD without the wave-induced vertical mixing, evolution from 13 to 32 m, was seriously underestimated. The surface wave is too important to be ignored for the ocean responses to a typhoon.展开更多
Based on in-situ observation,satellite and reanalysis data,responses of the western North Pacific subtropical ocean(WNPSO)to the slow-moving category 5 super typhoon Nanmadol in 2011 are analyzed.The dynamical respons...Based on in-situ observation,satellite and reanalysis data,responses of the western North Pacific subtropical ocean(WNPSO)to the slow-moving category 5 super typhoon Nanmadol in 2011 are analyzed.The dynamical response is dominated by near-inertial currents and Ekman currents with maximum amplitude of 0.39m/s and 0.15m/s,respectively.The near-inertial currents concentrated around 100m below the sea surface and had an e-folding timescale of 4 days.The near-inertial energy propagated both upward and downward,and the vertical phase speed and wavelength were estimated to be 5m/h and 175m,respectively.The frequency of the near-inertial currents was blue-shifted near the surface and redshifted in ocean interior which may relate to wave propagation and/or background vorticity.The resultant surface cooling reaches-4.35℃ and happens when translation speed of Nanmadol is smaller than 3.0m/s.When Nanmadol reaches super typhoon intensity,the cooling is less than 3.0℃ suggesting that the typhoon translation speed plays important roles as well as typhoon intensity in surface cooling.Upwelling induced by the slow-moving typhoon wind leads to typhoon track confined cooling area and the right-hand bias of cooling is slight.The mixed layer cooling and thermocline warming are induced by wind-generated upwelling and vertical entrainment.Vertical entrainment also led to mixed layer salinity increase and thermocline salinity decrease,however,mixed layer salinity decrease occurs at certain stations as well.Our results suggest that typhoon translation speed is a vital factor responsible for the oceanic thermohaline and dynamical responses,and the small Mach number(slow typhoon translation speed)facilitate development of Ekman current and upwelling.展开更多
Based on the Winkler hypothesis, a model for analysis of the flexural response of an ocean trestle embedded in layered soil to horizontal impact of a moving mass is developed. By use of the transfer matrix in Lime dom...Based on the Winkler hypothesis, a model for analysis of the flexural response of an ocean trestle embedded in layered soil to horizontal impact of a moving mass is developed. By use of the transfer matrix in Lime domain, one can calculate the flexural dynamic response of a single pile. Then, by use of the boundary conditions of piles at the pile top, the dynamic response of the structure is analyzed. By use of the model proposed in this paper, the interactive force between the moving mass and the structure can be computed based on Work's kinetic energy theorem and Newton iterative method. Thus the approach does not have to assume the interactive force, while the traditional method have to. The approach more accords with the engineering practice than the traditional method and it is convenient for engineering design.展开更多
基金supported by the National Basic Research Pro-gram of China(Grant No.2013CB430302)the National Natural Science Foundation of China(Grant Nos.91128204,41321004,41475101,41421005)+1 种基金the China Scholarship Council,the CAS Strategic Priority Project(Grant Nos.XDA 11010301,XDA11010104)the National Natural Science Foundation of China-Shandong Joint Fund for Marine Science Research Centers(Grant No.U1406401)
文摘The characteristics of the upper ocean response to tropical cyclone wind （TCW） forcing in the northwestern Pacific were in- vestigated using satellite and Argo data, as well as an ocean general circulation model. In particular, a case study was carried out on typhoon Rammasun, which passed through our study area during May 6-13, 2008. It is found that the local response fight under the TCW forcing is characterized by a quick deepening of the surface mixed layer, a strong latent heat loss to the atmosphere, and an intense upwelling near the center of typhoon, leading to a cooling of the oceanic surface layer that persists as a cold wake along the typhoon track. More interestingly, the upper ocean response exhibits a four-layer thermal structure, including a cooling layer near the surface and a warming layer right below, accompanied by another pair of cooling/warming layers in the thermocline. The formation of the surface cooling/warming layers can be readily explained by the strong vertical mixing induced by TCW forcing, while the thermal response in the thermocline is probably a result of the cyclone-driven upwelling and the associated advective processes.
基金The National Natural Science Foundation of China under contract No.40730842
文摘The MASNUM wave-tide-circulation coupled model, with 21 layers in the vertical and （1/8） °horizontal resolution, was employed to investigate the oceanic responses to Typhoon Mstsa which traversed the East China Sea （ECS） during the period of 4 - 6 August, 2005. Numerical experiment results are analyzed and compared with observation. The responses of the sea surface temperature （SST）, in a focused area of （27° -29°N, 121° - 124°E）, include heating and cooling stages. The heating is mainly due to warm Kuroshio water transportation and downwelling due to the water accumulation. In the cooling stage, the amplitude of the simulated cold wake （ -3℃ ）, located on the right side of this typhoon track, is compared quite well with that of the satellite observed SST data. The wave-induced mixing（Bv） plays a key role for the SST cooling. Bv still plays a leading role, which accounts for 36%, for the ocean temperature drop in the upper ocean of 0 - 40 m, while the upwelling is responsible for 84% of the cooling for the lower layer of 40 - 70 m. The mixed layer depth （MLD） increased quickly from 28 to 50 m in the typhoon period. However, the simulated MLD without the wave-induced vertical mixing, evolution from 13 to 32 m, was seriously underestimated. The surface wave is too important to be ignored for the ocean responses to a typhoon.
基金Supported by the National Natural Science Foundation of China(Nos.41706017,41421005,U1406401,U1133001)the National Program on Global Change and Air-Sea Interaction(No.GASI-IPOVAI-01-06)the National Key Research and Development Program of China(No.2016YFC1402000)
文摘Based on in-situ observation,satellite and reanalysis data,responses of the western North Pacific subtropical ocean(WNPSO)to the slow-moving category 5 super typhoon Nanmadol in 2011 are analyzed.The dynamical response is dominated by near-inertial currents and Ekman currents with maximum amplitude of 0.39m/s and 0.15m/s,respectively.The near-inertial currents concentrated around 100m below the sea surface and had an e-folding timescale of 4 days.The near-inertial energy propagated both upward and downward,and the vertical phase speed and wavelength were estimated to be 5m/h and 175m,respectively.The frequency of the near-inertial currents was blue-shifted near the surface and redshifted in ocean interior which may relate to wave propagation and/or background vorticity.The resultant surface cooling reaches-4.35℃ and happens when translation speed of Nanmadol is smaller than 3.0m/s.When Nanmadol reaches super typhoon intensity,the cooling is less than 3.0℃ suggesting that the typhoon translation speed plays important roles as well as typhoon intensity in surface cooling.Upwelling induced by the slow-moving typhoon wind leads to typhoon track confined cooling area and the right-hand bias of cooling is slight.The mixed layer cooling and thermocline warming are induced by wind-generated upwelling and vertical entrainment.Vertical entrainment also led to mixed layer salinity increase and thermocline salinity decrease,however,mixed layer salinity decrease occurs at certain stations as well.Our results suggest that typhoon translation speed is a vital factor responsible for the oceanic thermohaline and dynamical responses,and the small Mach number(slow typhoon translation speed)facilitate development of Ekman current and upwelling.
文摘Based on the Winkler hypothesis, a model for analysis of the flexural response of an ocean trestle embedded in layered soil to horizontal impact of a moving mass is developed. By use of the transfer matrix in Lime domain, one can calculate the flexural dynamic response of a single pile. Then, by use of the boundary conditions of piles at the pile top, the dynamic response of the structure is analyzed. By use of the model proposed in this paper, the interactive force between the moving mass and the structure can be computed based on Work's kinetic energy theorem and Newton iterative method. Thus the approach does not have to assume the interactive force, while the traditional method have to. The approach more accords with the engineering practice than the traditional method and it is convenient for engineering design.
