A dynamic study on Ekman characteristics by using 1998 SCSMEX and TIPEX boundary layer data is made. The results are as follows: (1) Similar dynamical Ekman characteristics are observed in the Tibetan Plateau and in t...A dynamic study on Ekman characteristics by using 1998 SCSMEX and TIPEX boundary layer data is made. The results are as follows: (1) Similar dynamical Ekman characteristics are observed in the Tibetan Plateau and in the South China Sea and its surrounding area. (2) The thickness of the boundary layer is about 2250 m over the Tibetan Plateau, and considering its variation, the thickness could be up to 2250–2750 m. In the tropical southwest Pacific, the thickness of the boundary layer is about 2000 m, and the variation is smaller; a smaller thickness of the boundary layer is in the plain area of the Bohai Sea. (3) Because of the difference in elevation between the Tibetan Plateau and the tropical ocean area, the influence of the boundary layer on the atmosphere is quite different although the two areas have almost the same thickness for the boundary layer, the height where the friction forcing occurs is quite different. (4) The vertical structure of turbulence friction is quite different in the Plateau and in the tropical ocean area. Calculations by 1998 SCSMEX and TIPEX boundary layer data indicate that even in the lowest levels, eddy viscosity in the Tibetan Plateauan can be 2.3 times than in the tropical ocean area.展开更多
The South China Sea monsoon is not only a main component of Asian monsoon system, but also plays an important role in the weather and climate over the surrounding areas and the globe. However, because of the insuffici...The South China Sea monsoon is not only a main component of Asian monsoon system, but also plays an important role in the weather and climate over the surrounding areas and the globe. However, because of the insufficient observation data, it is self evident that the large-scale field experiment over SCS is very important to deepen understanding East Asian monsoon. In this paper, the composite experiment, modelling and data assimilation, especially the atmospheric observation, oceanic observation, air-sea interface observational network as well as satellite observation are introduced in detail.展开更多
We addressed the mesoscale structure variation of the central South China Sea （SCS） with the measurements by a long-lived Argo float and a high-resolution ATLAS buoy during 1998-2002. T-S diagram indicates cooling a...We addressed the mesoscale structure variation of the central South China Sea （SCS） with the measurements by a long-lived Argo float and a high-resolution ATLAS buoy during 1998-2002. T-S diagram indicates cooling and freshening events in 2000 and 2001 with lower salinity （0.5-0.8） and lower temperature （1-1.7℃）. Significant decrease in the net heat flux and increase in the precipitation suggest that the cooling and freshening is due to extra forcing by the atmosphere. Additional to large year-to-year changes, intraseasonal variability is moderate in the research area. The axis of the maximum intraseasonal temperature and salinity signals are mainly located on the thermocline, Typically, amplitude and period of intraseasonal temperature is about 2℃ and 40-60 days, and that of salinity is 0.34）.5 and 35-60 days. Rapidly-changing winds, heat flux, and precipitation are critical in controlling the intraseasonal fluctuations of the mixed layer of the area. Studies on heat and freshwater balance in the mixed-layer further suggest that horizontal advection plays an important role in intraseasonal fluctuation in the upper ocean. In addition, the energetic mesoscale propagation radiated from the east boundary is linked to the intraseasonal variability in winter.展开更多
The SCSMEX is a joint atmospheric and oceanic experiment by international efforts, aiming at studying the onset, maintenance, and variability of the South China Sea （SCS） summer monsoon, thus improving the monsoon p...The SCSMEX is a joint atmospheric and oceanic experiment by international efforts, aiming at studying the onset, maintenance, and variability of the South China Sea （SCS） summer monsoon, thus improving the monsoon prediction in Southeast and East Asian regions. The field experiment carried out in May-August 1998 was fully successful, with a large amount of meteorological and oceanographic data acquired that have been used in four dimensional data assimilations by several countries, in order to improve their numerical simulations and prediction. These datasets are also widely used in the follow-up SCS and East Asian monsoon study. The present paper has summarized the main research results obtained by Chinese meteorologists which cover six aspects： （1） onset processes and mechanism of the SCS summer monsoon; （2） development of convection and mesoscale convective systems （MCSs） during the onset phase and their interaction with large-scale circulation; （3） low-frequency oscillation and teleconnection effect; （4） measurements of surface fluxes over the SCS and their relationship with the monsoon activity; （5） oceanic thermodynamic structures, circulation, and mesoscale eddies in the SCS during the summer monsoon and their relationship with ENSO events; and （6） numerical simulations of the SCS and East Asian monsoon.展开更多
基金the research item of the Second Tibetan Plateau Experiment.
文摘A dynamic study on Ekman characteristics by using 1998 SCSMEX and TIPEX boundary layer data is made. The results are as follows: (1) Similar dynamical Ekman characteristics are observed in the Tibetan Plateau and in the South China Sea and its surrounding area. (2) The thickness of the boundary layer is about 2250 m over the Tibetan Plateau, and considering its variation, the thickness could be up to 2250–2750 m. In the tropical southwest Pacific, the thickness of the boundary layer is about 2000 m, and the variation is smaller; a smaller thickness of the boundary layer is in the plain area of the Bohai Sea. (3) Because of the difference in elevation between the Tibetan Plateau and the tropical ocean area, the influence of the boundary layer on the atmosphere is quite different although the two areas have almost the same thickness for the boundary layer, the height where the friction forcing occurs is quite different. (4) The vertical structure of turbulence friction is quite different in the Plateau and in the tropical ocean area. Calculations by 1998 SCSMEX and TIPEX boundary layer data indicate that even in the lowest levels, eddy viscosity in the Tibetan Plateauan can be 2.3 times than in the tropical ocean area.
文摘The South China Sea monsoon is not only a main component of Asian monsoon system, but also plays an important role in the weather and climate over the surrounding areas and the globe. However, because of the insufficient observation data, it is self evident that the large-scale field experiment over SCS is very important to deepen understanding East Asian monsoon. In this paper, the composite experiment, modelling and data assimilation, especially the atmospheric observation, oceanic observation, air-sea interface observational network as well as satellite observation are introduced in detail.
基金Supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Nos.KZCX1-YW-12-01,KZCX2-YW-BR-04)the Knowledge Innovation Program of the Chinese Academy of Sciences (Nos.SQ200916,SQ200809)+1 种基金the National Natural Science Foundation of China (No.40806003)the National High Technology Research and Development Program of China (863 Program) (No.2008AA09A402)
文摘We addressed the mesoscale structure variation of the central South China Sea （SCS） with the measurements by a long-lived Argo float and a high-resolution ATLAS buoy during 1998-2002. T-S diagram indicates cooling and freshening events in 2000 and 2001 with lower salinity （0.5-0.8） and lower temperature （1-1.7℃）. Significant decrease in the net heat flux and increase in the precipitation suggest that the cooling and freshening is due to extra forcing by the atmosphere. Additional to large year-to-year changes, intraseasonal variability is moderate in the research area. The axis of the maximum intraseasonal temperature and salinity signals are mainly located on the thermocline, Typically, amplitude and period of intraseasonal temperature is about 2℃ and 40-60 days, and that of salinity is 0.34）.5 and 35-60 days. Rapidly-changing winds, heat flux, and precipitation are critical in controlling the intraseasonal fluctuations of the mixed layer of the area. Studies on heat and freshwater balance in the mixed-layer further suggest that horizontal advection plays an important role in intraseasonal fluctuation in the upper ocean. In addition, the energetic mesoscale propagation radiated from the east boundary is linked to the intraseasonal variability in winter.
基金Supported by the National Key Program: SCSMEX under Grant 98-monsoon-7-3
文摘The SCSMEX is a joint atmospheric and oceanic experiment by international efforts, aiming at studying the onset, maintenance, and variability of the South China Sea （SCS） summer monsoon, thus improving the monsoon prediction in Southeast and East Asian regions. The field experiment carried out in May-August 1998 was fully successful, with a large amount of meteorological and oceanographic data acquired that have been used in four dimensional data assimilations by several countries, in order to improve their numerical simulations and prediction. These datasets are also widely used in the follow-up SCS and East Asian monsoon study. The present paper has summarized the main research results obtained by Chinese meteorologists which cover six aspects： （1） onset processes and mechanism of the SCS summer monsoon; （2） development of convection and mesoscale convective systems （MCSs） during the onset phase and their interaction with large-scale circulation; （3） low-frequency oscillation and teleconnection effect; （4） measurements of surface fluxes over the SCS and their relationship with the monsoon activity; （5） oceanic thermodynamic structures, circulation, and mesoscale eddies in the SCS during the summer monsoon and their relationship with ENSO events; and （6） numerical simulations of the SCS and East Asian monsoon.
