By using the NCEP reanalysis data set in 1979-1995, the fluxes of the latent heat, the sensible heat and the net long-wave radiation in the South China Sea (SCS) are expanded by means of EOF in order to discuss the ba...By using the NCEP reanalysis data set in 1979-1995, the fluxes of the latent heat, the sensible heat and the net long-wave radiation in the South China Sea (SCS) are expanded by means of EOF in order to discuss the basic climatological features in the SCS. The detailed analysis shows that the air-sea heat exchanges in different SCS regions have different seasonal variations. The middle and the north of the SCS are the high value regions of the air-sea heat exchanges during the winter and the summer monsoon periods, respectively, the seasonal variations of air-sea heat exchanges in the south of the SCS are small. In addition, the proportions of different components in the total air-sea heat exchanges have different seasonal variations in different regions. The results show that the SCS monsoon and the air-sea heat exchanges in the SCS region are the accompaniments of each other, the great difference of the sensible heat flux between the Indochina Peninsula and the SCS before the SCS summer monsoon onset may be one of the triggers of the latter. There maintains a high value center of the sensible heat flux before the 13th dekad, its disappearing time consists with that of the summer monsoon onset. It means that as far as the SCS local conditions are concerned, the northwest of the Indochina Peninsula is probably a sensitive region to the SCS summer monsoon onset and the land may play a leading role in the SCS summer monsoon onset.展开更多
In order to explore the interaction be- tween the sea and monsoon in the South China Sea, the heat exchanges at air-sea interface during mon- soon periods in 1986 were calculated using observa- tional data. It shows t...In order to explore the interaction be- tween the sea and monsoon in the South China Sea, the heat exchanges at air-sea interface during mon- soon periods in 1986 were calculated using observa- tional data. It shows that when the summer monsoon bursts and prevails over the South China Sea, the air-sea interface heat exchange is strong and the latent heat rises rapidly in the intertropical conver- gence zone and the tropic cyclone system near 20.49°N, 114.14°E. On May 24, 1986, the sensible heat became positive in the typhoon system. The heating exchange indicates that heat is transported from ocean to atmosphere, with major contribution of latent heat. When the summer monsoon prevails over the South China Sea and the weather is fine, even SST (sea surface temperature) is high, but sensible heat appears to be negative. The heat exchange indicates that heat is transported from atmosphere to ocean, with major contribution of short-wave radiation absorbed by sea surface and sensible heat. When summer monsoon is over and the northeast monsoon prevails over the South China Sea, the heat ex- change at air-sea interface is very strong. The heat- ing exchange shows that the ocean heats the at- mosphere, with major contribution of latent heat when cold air arrives at the sea surface and the sensible heat rises to positive rapidly. Therefore it can be concluded that the heat exchange at air-sea interface is different from the SST in South China Sea. Whenthe summer monsoon prevails over the South China Sea, the main trend is the ocean responding to the atmosphere.展开更多
2°×2° mean monthly COADS grid data in 1974 and 1987 of E1 Nino and La Nina years are used to compute the sensible and latent heat fluxes,the net longwave radiation,the incident solar radiation and heat ...2°×2° mean monthly COADS grid data in 1974 and 1987 of E1 Nino and La Nina years are used to compute the sensible and latent heat fluxes,the net longwave radiation,the incident solar radiation and heat budget on the tropical Pacific surface(30°S—30°N).The difference of the heat budget between El Nino and La Nina mainly occurred on the equatorial ocean surface,especially the water area west of Ecuador and Peru.During El Nino,the sensible and latent heat exchange increased,the net longwave radiation and incident solar radiation decreased and the net gain(loss) of heat reduced(increased) on the ocean surface.During La Nina,the circumstances were opposite.Finally an ideal model of air-sea heat exchange mechanism for the El Nino-La Nina cycle is summarized.展开更多
Surface waves comprise an important aspect of the interaction between the atmosphere and the ocean, so a dynamically consistent framework for modelling atmosphere-ocean interaction must take account of surface waves, ...Surface waves comprise an important aspect of the interaction between the atmosphere and the ocean, so a dynamically consistent framework for modelling atmosphere-ocean interaction must take account of surface waves, either implicitly or explicitly. In order to calculate the effect of wind forcing on waves and currents, and vice versa, it is necessary to employ a consistent formula- tion of the energy and momentum balance within the airflow, wave field, and water column. It is very advantageous to apply sur- face-following coordinate systems, whereby the steep gradients in mean flow properties near the air-water interface in the cross-interface direction may be resolved over distances which are much smaller than the height of the waves themselves. We may account for the waves explicitly by employing a numerical spectral wave model, and applying a suitable theory of wave–mean flow interaction. If the mean flow is small compared with the wave phase speed, perturbation expansions of the hydrodynamic equations in a Lagrangian or generalized Lagrangian mean framework are useful: for stronger flows, such as for wind blowing over waves, the presence of critical levels where the mean flow velocity is equal to the wave phase speed necessitates the application of more general types of surface-following coordinate system. The interaction of the flow of air and water and associated differences in temperature and the concentration of various substances (such as gas species) gives rise to a complex boundary-layer structure at a wide range of vertical scales, from the sub-millimetre scales of gaseous diffusion, to several tens of metres for the turbulent Ekman layer. The bal- ance of momentum, heat, and mass is also affected significantly by breaking waves, which act to increase the effective area of the surface for mass transfer, and increase turbulent diffusive fluxes via the conversion of wave energy to turbulent kinetic energy.展开更多
文摘By using the NCEP reanalysis data set in 1979-1995, the fluxes of the latent heat, the sensible heat and the net long-wave radiation in the South China Sea (SCS) are expanded by means of EOF in order to discuss the basic climatological features in the SCS. The detailed analysis shows that the air-sea heat exchanges in different SCS regions have different seasonal variations. The middle and the north of the SCS are the high value regions of the air-sea heat exchanges during the winter and the summer monsoon periods, respectively, the seasonal variations of air-sea heat exchanges in the south of the SCS are small. In addition, the proportions of different components in the total air-sea heat exchanges have different seasonal variations in different regions. The results show that the SCS monsoon and the air-sea heat exchanges in the SCS region are the accompaniments of each other, the great difference of the sensible heat flux between the Indochina Peninsula and the SCS before the SCS summer monsoon onset may be one of the triggers of the latter. There maintains a high value center of the sensible heat flux before the 13th dekad, its disappearing time consists with that of the summer monsoon onset. It means that as far as the SCS local conditions are concerned, the northwest of the Indochina Peninsula is probably a sensitive region to the SCS summer monsoon onset and the land may play a leading role in the SCS summer monsoon onset.
基金This work was supported by Natural Science Foundation of Guangdong Province(Grant Nos.04102749&04009790)President Foundation of 0ceanological Science and Technology,South China Sea Branch,State 0ceanic Administration of China(Grant Nos.0104&0311)+1 种基金Research Foundation of Tropical 0ceanological and Meteorological Science(Grant No.200414)the Air-Sea Interface Heat Exchange of the Typhoon Project of Shanghai Typhoon Institute Foundation.
文摘In order to explore the interaction be- tween the sea and monsoon in the South China Sea, the heat exchanges at air-sea interface during mon- soon periods in 1986 were calculated using observa- tional data. It shows that when the summer monsoon bursts and prevails over the South China Sea, the air-sea interface heat exchange is strong and the latent heat rises rapidly in the intertropical conver- gence zone and the tropic cyclone system near 20.49°N, 114.14°E. On May 24, 1986, the sensible heat became positive in the typhoon system. The heating exchange indicates that heat is transported from ocean to atmosphere, with major contribution of latent heat. When the summer monsoon prevails over the South China Sea and the weather is fine, even SST (sea surface temperature) is high, but sensible heat appears to be negative. The heat exchange indicates that heat is transported from atmosphere to ocean, with major contribution of short-wave radiation absorbed by sea surface and sensible heat. When summer monsoon is over and the northeast monsoon prevails over the South China Sea, the heat ex- change at air-sea interface is very strong. The heat- ing exchange shows that the ocean heats the at- mosphere, with major contribution of latent heat when cold air arrives at the sea surface and the sensible heat rises to positive rapidly. Therefore it can be concluded that the heat exchange at air-sea interface is different from the SST in South China Sea. Whenthe summer monsoon prevails over the South China Sea, the main trend is the ocean responding to the atmosphere.
文摘2°×2° mean monthly COADS grid data in 1974 and 1987 of E1 Nino and La Nina years are used to compute the sensible and latent heat fluxes,the net longwave radiation,the incident solar radiation and heat budget on the tropical Pacific surface(30°S—30°N).The difference of the heat budget between El Nino and La Nina mainly occurred on the equatorial ocean surface,especially the water area west of Ecuador and Peru.During El Nino,the sensible and latent heat exchange increased,the net longwave radiation and incident solar radiation decreased and the net gain(loss) of heat reduced(increased) on the ocean surface.During La Nina,the circumstances were opposite.Finally an ideal model of air-sea heat exchange mechanism for the El Nino-La Nina cycle is summarized.
文摘Surface waves comprise an important aspect of the interaction between the atmosphere and the ocean, so a dynamically consistent framework for modelling atmosphere-ocean interaction must take account of surface waves, either implicitly or explicitly. In order to calculate the effect of wind forcing on waves and currents, and vice versa, it is necessary to employ a consistent formula- tion of the energy and momentum balance within the airflow, wave field, and water column. It is very advantageous to apply sur- face-following coordinate systems, whereby the steep gradients in mean flow properties near the air-water interface in the cross-interface direction may be resolved over distances which are much smaller than the height of the waves themselves. We may account for the waves explicitly by employing a numerical spectral wave model, and applying a suitable theory of wave–mean flow interaction. If the mean flow is small compared with the wave phase speed, perturbation expansions of the hydrodynamic equations in a Lagrangian or generalized Lagrangian mean framework are useful: for stronger flows, such as for wind blowing over waves, the presence of critical levels where the mean flow velocity is equal to the wave phase speed necessitates the application of more general types of surface-following coordinate system. The interaction of the flow of air and water and associated differences in temperature and the concentration of various substances (such as gas species) gives rise to a complex boundary-layer structure at a wide range of vertical scales, from the sub-millimetre scales of gaseous diffusion, to several tens of metres for the turbulent Ekman layer. The bal- ance of momentum, heat, and mass is also affected significantly by breaking waves, which act to increase the effective area of the surface for mass transfer, and increase turbulent diffusive fluxes via the conversion of wave energy to turbulent kinetic energy.
