Based on the data obtained from oceanographic surveys at the central and northern parts of the TaiwanStrait during the period from 1983 to 1988, it is showed that the nutrient content in the coastal and bottom waters ...Based on the data obtained from oceanographic surveys at the central and northern parts of the TaiwanStrait during the period from 1983 to 1988, it is showed that the nutrient content in the coastal and bottom waters isrelatively high with an upward and offward decrease, and that the upwelling in the Fujian coastal area controls the distribution of nutrients in summer.The upwelling water is characterized by 2. 29 μmol/dm ̄3 of nitrate; 2. 83 μmol/dm ̄3of silicate; 0. 20 μmol/dm ̄3 of dissolved inorganic phosphate,respectively. Significant correlation between nutrientsand dissolved oxygen content and its degree of saturation, temperature, and salinity, respectively are found in the upweiling area. Average of N/P ratio in the area(15. 9) approaches to Redfield ratio. Their vertical flux is estimated tobe 23. 6 mg/(m ̄2·d) for - P, 223 mg/(m ̄2·d) for NO-N, 302 mg/(m ̄2·d) for SiO-Si, respectively,which is the main source Of nutients in the areas in summer. The mean of the flux of P and NO-N is about86 % and 73% necessary for phytoplankton in the euphotic zone.展开更多
An integrated analysis of internal solitary wave(ISW) observations obtained from two moorings over the continental slope in the northern South China Sea(SCS) leads to an assessment of the vertical heat transport of th...An integrated analysis of internal solitary wave(ISW) observations obtained from two moorings over the continental slope in the northern South China Sea(SCS) leads to an assessment of the vertical heat transport of the ISWs. The clusters of ISW packets are phase-locked to the fortnightly cycle of the semidiurnal tide. The ISWs appear during large semidiurnal tides, and there is a period of 5–6 d when no ISWs are observed. The effect of the ISWs on the continental slope heat budget is observed. The ISWs can modify a local temperature field in which the temperature in the upper layer can be changed by O(100) °C after the ISWs passed the mooring. Both ISWinduced diffusion and ISW-induced advection contribute to the temperature variation. The estimates imply an average vertical heat flux of 0.01 to 0.1 MW/m^2 in the ISWs in the upper 500 m of the water column. The vertical heat transport ranges from 0.56 to 2.83 GJ/m^2 with a mean value of 1.63 GJ/m^2. The observations suggest that the vertical heat transport is proportional to the maximum vertical displacement.展开更多
The transport and diffusion of substances in seawater are limited by the mixing motion of water bodies,while the main forms of mixing in offshore water bodies are advection and eddy diffusion.The eddy diffusion proces...The transport and diffusion of substances in seawater are limited by the mixing motion of water bodies,while the main forms of mixing in offshore water bodies are advection and eddy diffusion.The eddy diffusion process of water indicates the possible transport direction of dissolved substances.However,the complex environment in the coastal zone makes it difficult to quantitatively assess the water diffusion process.^(222)Rn is a useful tool to trace the diffusion process of water bodies.However,studies on the^(222)Rn distribution and its behavior in the Beibu Gulf are scarce.In this study,the activity distribution characteristics of^(222)Rn in surface seawater of the Guangxi shelf area of the Beibu Gulf were measured.Based on the one-dimensional,steady-state model,the vorticity diffusion coefficient of^(222)Rn in the horizontal direction was calculated as(0.42−2.13)×10^(8) m^(2)/d,and the offshore fluxes of^(222)Rn under the influence of water mixing were calculated as 2.00×10^(12) Bq/d.Correspondingly,the horizontal transport fluxes of silicate,phosphate,nitrite and nitrate were 6.28×10^(−3)mol/(m^(2)·d),0.10×10^(−3)mol/(m^(2)·d),0.20×10^(−3)mol/(m^(2)·d)and 4.15×10^(−3)mol/(m^(2)·d),respectively.These results indicate that the study of eddy current diffusion in offshore marine water facilitates a deeper understanding of the water mixing process and nutrient transport and migration.展开更多
Based on the field data obtained during cruises on the shelf of the East China Sea from 1997 to 1999, seasonal variations of coastal upwelling on the inner shelf are discussed by using cross-shelf transect profiles an...Based on the field data obtained during cruises on the shelf of the East China Sea from 1997 to 1999, seasonal variations of coastal upwelling on the inner shelf are discussed by using cross-shelf transect profiles and horizontal distributions of chemical and hydrographic variables. Results show that the coastal upwelling was year-round, but the areas and intensities of the upwelling were quite different in season. The coastal upwelling occurred in all of the coastal areas of the region in spring and summer, but in autumn only in the area off Zhejiang Province, and in winter in the area off Fujian Prov- ince. It was the strongest in summer and the weakest in winter. Geographically, it was the strongest in the area off Zhejiang Province and the weakest in the southmost or northmost parts of the East China Sea. The estimated nutrient fluxes upward into euphotic zone through coastal upwelling were quite large, es- pecially for phosphate, which contributed significantly to primary production and improved the nutrient structure of the coastal ecosystem in the East China Sea.展开更多
According to the cross coupling theorem of atmospheric turbulence, latent heat flux comprises two components, a vertical humidity gradient flux and a coupling flux of vertical velocity. In this paper, observational da...According to the cross coupling theorem of atmospheric turbulence, latent heat flux comprises two components, a vertical humidity gradient flux and a coupling flux of vertical velocity. In this paper, observational data are employed to demonstrate and analyze the coupling effect of vertical velocity on latent heat flux. The results highlight the presence of a coupling zero-effect height. When the observational level exceeds or underlies the coupling zero-effect height, the coupling effect suppresses or enhances the latent heat flux, respectively. Above the heterogeneous terrain in the experimental region, the overall difference between the estimated and the observed latent heat fluxes decreases from 27% to 2% (for ascending flow) and from 47% to 28% (for descending flow), after compensating for gradient flux. The coupling theorem of atmospheric turbulence is well validated by our analysis, supporting a role for experimental datasets in unraveling the mysteries of atmospheric turbulence.展开更多
This study represents the first quantitative evaluation of pollution transport budget within the boundary layer of typical cities in the Beijing-Tianjin-Hebei (BTH) region from the perspective of horizontal and vertic...This study represents the first quantitative evaluation of pollution transport budget within the boundary layer of typical cities in the Beijing-Tianjin-Hebei (BTH) region from the perspective of horizontal and vertical exchanges and further discusses the impact of the atmospheric boundary layer (ABL)-free troposphere (FT) exchange on concentration of fine particulate matter (PM_(2.5)) within the ABL during heavy pollution.From the perspective of the transport flux balance relationship,differences in pollution transport characteristics between the two cities is mainly reflected in the ABL-FT exchange effect.The FT mainly flowed into the ABL in BJ,while in SJZ,the outflow from the ABL to the FT was more intense.Combined with an analysis of vertical wind profile distribution,BJ was found to be more susceptible to the influence of northwest cold high prevailing in winter,while sinking of strong cold air allowed the FT flowing into the ABL influence the vertical exchange over BJ.In addition,we selected a typical pollution event for targeted analysis to understand mechanistic details of the influence of ABL-FT exchange on the pollution event.These results showed that ABL-FT interaction played an important role in PM_(2.5)concentration within the ABL during heavy pollution.Especially in the early stage of heavy pollution,FT transport contributed as much as 82.74% of PM_(2.5)within the ABL.These findings are significant for improving our understanding of pollution transport characteristics within the boundary layer and the effect of ABL-FT exchange on air quality.展开更多
文摘Based on the data obtained from oceanographic surveys at the central and northern parts of the TaiwanStrait during the period from 1983 to 1988, it is showed that the nutrient content in the coastal and bottom waters isrelatively high with an upward and offward decrease, and that the upwelling in the Fujian coastal area controls the distribution of nutrients in summer.The upwelling water is characterized by 2. 29 μmol/dm ̄3 of nitrate; 2. 83 μmol/dm ̄3of silicate; 0. 20 μmol/dm ̄3 of dissolved inorganic phosphate,respectively. Significant correlation between nutrientsand dissolved oxygen content and its degree of saturation, temperature, and salinity, respectively are found in the upweiling area. Average of N/P ratio in the area(15. 9) approaches to Redfield ratio. Their vertical flux is estimated tobe 23. 6 mg/(m ̄2·d) for - P, 223 mg/(m ̄2·d) for NO-N, 302 mg/(m ̄2·d) for SiO-Si, respectively,which is the main source Of nutients in the areas in summer. The mean of the flux of P and NO-N is about86 % and 73% necessary for phytoplankton in the euphotic zone.
基金The National Natural Science Foundation of China under contract Nos 41676022,41630970 and 41521005the National Programme on Global Change and Air-Sea Interaction under contract No.GASI-IPOVAI-04+1 种基金the Open Project Program of State Key Laboratory of Tropical Oceanography under contract No.LTOZZ1801the Instrument Developing Project of the Chinese Academy of Sciences under contract No.YZ201432
文摘An integrated analysis of internal solitary wave(ISW) observations obtained from two moorings over the continental slope in the northern South China Sea(SCS) leads to an assessment of the vertical heat transport of the ISWs. The clusters of ISW packets are phase-locked to the fortnightly cycle of the semidiurnal tide. The ISWs appear during large semidiurnal tides, and there is a period of 5–6 d when no ISWs are observed. The effect of the ISWs on the continental slope heat budget is observed. The ISWs can modify a local temperature field in which the temperature in the upper layer can be changed by O(100) °C after the ISWs passed the mooring. Both ISWinduced diffusion and ISW-induced advection contribute to the temperature variation. The estimates imply an average vertical heat flux of 0.01 to 0.1 MW/m^2 in the ISWs in the upper 500 m of the water column. The vertical heat transport ranges from 0.56 to 2.83 GJ/m^2 with a mean value of 1.63 GJ/m^2. The observations suggest that the vertical heat transport is proportional to the maximum vertical displacement.
基金The Scientific Research Foundation of the Third Institute of Oceanography,Ministry of Natural Resources under contract Nos 2023007 and 2020017the Natural Science Foundation of Fujian Province under contract No.2020J05010+1 种基金the Foundation of Xiamen Institute of Marine Development under contract No.KFY202204the Asian Cooperation Fund Project-Study on Typical Bay Ecological Protection and Management Demonstration.
文摘The transport and diffusion of substances in seawater are limited by the mixing motion of water bodies,while the main forms of mixing in offshore water bodies are advection and eddy diffusion.The eddy diffusion process of water indicates the possible transport direction of dissolved substances.However,the complex environment in the coastal zone makes it difficult to quantitatively assess the water diffusion process.^(222)Rn is a useful tool to trace the diffusion process of water bodies.However,studies on the^(222)Rn distribution and its behavior in the Beibu Gulf are scarce.In this study,the activity distribution characteristics of^(222)Rn in surface seawater of the Guangxi shelf area of the Beibu Gulf were measured.Based on the one-dimensional,steady-state model,the vorticity diffusion coefficient of^(222)Rn in the horizontal direction was calculated as(0.42−2.13)×10^(8) m^(2)/d,and the offshore fluxes of^(222)Rn under the influence of water mixing were calculated as 2.00×10^(12) Bq/d.Correspondingly,the horizontal transport fluxes of silicate,phosphate,nitrite and nitrate were 6.28×10^(−3)mol/(m^(2)·d),0.10×10^(−3)mol/(m^(2)·d),0.20×10^(−3)mol/(m^(2)·d)and 4.15×10^(−3)mol/(m^(2)·d),respectively.These results indicate that the study of eddy current diffusion in offshore marine water facilitates a deeper understanding of the water mixing process and nutrient transport and migration.
基金Supported by the National Basic Research Program of China (973 Pro-gram), No. 2001CB4097
文摘Based on the field data obtained during cruises on the shelf of the East China Sea from 1997 to 1999, seasonal variations of coastal upwelling on the inner shelf are discussed by using cross-shelf transect profiles and horizontal distributions of chemical and hydrographic variables. Results show that the coastal upwelling was year-round, but the areas and intensities of the upwelling were quite different in season. The coastal upwelling occurred in all of the coastal areas of the region in spring and summer, but in autumn only in the area off Zhejiang Province, and in winter in the area off Fujian Prov- ince. It was the strongest in summer and the weakest in winter. Geographically, it was the strongest in the area off Zhejiang Province and the weakest in the southmost or northmost parts of the East China Sea. The estimated nutrient fluxes upward into euphotic zone through coastal upwelling were quite large, es- pecially for phosphate, which contributed significantly to primary production and improved the nutrient structure of the coastal ecosystem in the East China Sea.
基金supported by National Natural Science Foundation of China(Grant Nos. 40705007, 1141130961 & 91025011)the Hundred-Talent Project of Chinese Academy of Sciences granted to Dr. YU.
文摘According to the cross coupling theorem of atmospheric turbulence, latent heat flux comprises two components, a vertical humidity gradient flux and a coupling flux of vertical velocity. In this paper, observational data are employed to demonstrate and analyze the coupling effect of vertical velocity on latent heat flux. The results highlight the presence of a coupling zero-effect height. When the observational level exceeds or underlies the coupling zero-effect height, the coupling effect suppresses or enhances the latent heat flux, respectively. Above the heterogeneous terrain in the experimental region, the overall difference between the estimated and the observed latent heat fluxes decreases from 27% to 2% (for ascending flow) and from 47% to 28% (for descending flow), after compensating for gradient flux. The coupling theorem of atmospheric turbulence is well validated by our analysis, supporting a role for experimental datasets in unraveling the mysteries of atmospheric turbulence.
基金supported by the National Key Research and Development Program of China (No.2018YFC0213206)the National Natural Science Foundation of China (Nos. 52000005, 51638001)。
文摘This study represents the first quantitative evaluation of pollution transport budget within the boundary layer of typical cities in the Beijing-Tianjin-Hebei (BTH) region from the perspective of horizontal and vertical exchanges and further discusses the impact of the atmospheric boundary layer (ABL)-free troposphere (FT) exchange on concentration of fine particulate matter (PM_(2.5)) within the ABL during heavy pollution.From the perspective of the transport flux balance relationship,differences in pollution transport characteristics between the two cities is mainly reflected in the ABL-FT exchange effect.The FT mainly flowed into the ABL in BJ,while in SJZ,the outflow from the ABL to the FT was more intense.Combined with an analysis of vertical wind profile distribution,BJ was found to be more susceptible to the influence of northwest cold high prevailing in winter,while sinking of strong cold air allowed the FT flowing into the ABL influence the vertical exchange over BJ.In addition,we selected a typical pollution event for targeted analysis to understand mechanistic details of the influence of ABL-FT exchange on the pollution event.These results showed that ABL-FT interaction played an important role in PM_(2.5)concentration within the ABL during heavy pollution.Especially in the early stage of heavy pollution,FT transport contributed as much as 82.74% of PM_(2.5)within the ABL.These findings are significant for improving our understanding of pollution transport characteristics within the boundary layer and the effect of ABL-FT exchange on air quality.