The past decade has seen a growing interest in ocean sensor networks because of their wide applications in marine research,oceanography,ocean monitoring,offshore exploration,and defense or homeland security.Ocean sens...The past decade has seen a growing interest in ocean sensor networks because of their wide applications in marine research,oceanography,ocean monitoring,offshore exploration,and defense or homeland security.Ocean sensor networks are generally formed with various ocean sensors,autonomous underwater vehicles,surface stations,and research vessels.To make ocean sensor network applications viable,efficient communication among all devices and components is crucial.Due to the unique characteristics of underwater acoustic channels and the complex deployment environment in three dimensional(3D) ocean spaces,new efficient and reliable communication and networking protocols are needed in design of ocean sensor networks.In this paper,we aim to provide an overview of the most recent advances in network design principles for 3D ocean sensor networks,with focuses on deployment,localization,topology design,and position-based routing in 3D ocean spaces.展开更多
This paper reports high-resolution biomarker records of the last 260 ka for core MD05-2904 from the northern South China Sea (SCS). The sea surface temperature (SST) record using the U k3’7 index re-veals a minimum o...This paper reports high-resolution biomarker records of the last 260 ka for core MD05-2904 from the northern South China Sea (SCS). The sea surface temperature (SST) record using the U k3’7 index re-veals a minimum of 21.5℃ (MIS 2) and a maximum of 28.3℃ (MIS 5.5), for a temperature difference of almost 7℃, and provides the longest high-resolution U k3’7 SST record in northern SCS. The content of odd-number long chain n-alkanes and several n-alkanes indexes such as the CPI, ACL and the C31/C27 ratio, all reveal generally higher values during the glacials and lower values during the interglacials. Terrestrial input as indicated by n-alkane content was mostly controlled by sea-level changes: During the glacials, lower sea-level exposed the continental shelf to enable rivers to transport more terrestrial materials to the slope; and the situation reverses during the interglacials. The n-alkane indexes changes reveal more n-alkanes from contemporary vegetation during glacials as a result of the prox-imity of the core site to the source region, while the increases in ACL and C31/C27 ratio during glacials indicate a change to more grassy vegetation. However, the highest values for CPI, ACL and the C31/C27 ratio all occurred during late MIS 3, and it was suggested that this period was characterized by a strong summer monsoon-dominated humid climate which resulted in a denser vegetation for the exposed continental shelf region.展开更多
Deep sea circulation is important for world climate and has been a substantial research area in ocean science, leading to various breakthroughs and discoveries. With the rapid advance in research on ocean science, the...Deep sea circulation is important for world climate and has been a substantial research area in ocean science, leading to various breakthroughs and discoveries. With the rapid advance in research on ocean science, these matters have received increasing attention from the oceanography community. In this article, we attempt to convey the progress made in recent years. We first provide an overview of existing observations, theories, and simulations of deep South China Sea circulation. Finally, we discuss remaining issues.展开更多
Sea level variations(SLVs) can be divided into two major components:the steric SLV and the mass-induced SLV.These two components of SLV in the South China Sea(SCS) are studied by using satellite altimetry,GRACE(Gravit...Sea level variations(SLVs) can be divided into two major components:the steric SLV and the mass-induced SLV.These two components of SLV in the South China Sea(SCS) are studied by using satellite altimetry,GRACE(Gravity Recovery and Climate Experiment) satellite gravity,and oceanographic data on annual and inter-annual timescales.On the annual timescale,the geographic distribution of mass-induced SLV's amplitude jointly estimated from altimetry and the ECCO(Estimation of the Circulation and Climate of the Ocean) model agrees very well with that from GRACE.GRACE observes obvious seasonal mass-induced SLV in the SCS with annual amplitude of 2.7±0.4 cm,which is consistent with the annual amplitude of 2.7±0.3 cm estimated from the steric-corrected altimetry.On the inter-annual timescales,the mean SLV in the SCS shows a large oscillation,which is mainly caused by the steric effect.The trend of mean SLV inferred from altimetry in the SCS is 5.5±0.7 mm/yr for the period of 1993-2009,which is significantly higher than the global sea level rise rate of 3.3±0.4 mm/yr in the same period.There is no obvious trend signal in the mass-induced SLV detected from GRACE that indicates the water exchange between the SCS and its adjacent seas and land is in balance within the study period.展开更多
The area of the southwestern Nansha Trough is one of the most productive areas of the southern South China Sea.It is a typical semi-deep sea area of transition from shoal to abyssal zone.To understand distributions an...The area of the southwestern Nansha Trough is one of the most productive areas of the southern South China Sea.It is a typical semi-deep sea area of transition from shoal to abyssal zone.To understand distributions and roles of nitrogen forms involved in biogeochemical cycling in this area,contents of nitrogen in four extractable forms:nitrogen in ion exchangeable form(IEF-N),nitrogen in weak acid extractable form(WAEF-N),nitrogen in strong alkali extractable form(SAEF-N) and nitrogen in strong oxidation extractable form(SOEF-N),as well as in total nitrogen content(TN) in surface sediments were determined from samples collected from the cruise in April-May 1999.The study area was divided into three regions(A,B and C) in terms of clay sediment(<4 μm) content at <40%,40%-60% and >60%,respectively.Generally,region C was the richest in the nitrogen of all forms and region A the poorest,indicating that the finer the grain size is,the richer the contents of various nitrogen are.The burial efficiency of total nitrogen in surface sediments was 28.79%,indicating that more than 70% of nitrogen had been released and participated in biogeochemical recycling through sediment-water interface.展开更多
This study examined wintertime (November-April) cold wave frequency (CWF) in northern China during the last 42 years and its association with Arctic Oscillation (AO) through analysis of daily mean surface temperature ...This study examined wintertime (November-April) cold wave frequency (CWF) in northern China during the last 42 years and its association with Arctic Oscillation (AO) through analysis of daily mean surface temperature from 280 stations across northern China and European Centre for Medium-Range Weather Forecasts (ECMWF) 40-Year Re-analysis ERA-40 data. The leading empirical orthogonal function EOF mode of wintertime CWF (CWF-EOF1) indicates an identical signal over most northern China, with the characteristic trend of linear decline for the leading principal component (CWF-PC1). After the linear trend is removed, remarkable inter-annual variability is found to be the dominant feature of the CWF-PC1. The regression map for sea level pressure based on CWF-PC1 corresponds to the negative phase of AO. Correlation analysis further proves that CWF-PC1 has a significant negative correlation with AO at the inter-annual time scale. The relationship between AO and global surface air temperature is also investigated in order to understand its association with cold air activity over East Asia, and it is suggested that the anomalies of atmospheric circulation in Siberia may serve as a bridge for interaction between AO and CWF in northern China during wintertime.展开更多
基金Y. Wang was supported in part by the US National Science Foundation (NSF) under Grant Nos.CNS-0721666,CNS-0915331,and CNS-1050398Y. Liu was partially supported by the National Natural Science Foundation of China (NSFC) under Grant No. 61074092+1 种基金by the Shandong Provincial Natural Science Foundation,China under Grant No.Q2008E01Z. Guo was partially supported by the NSFC under Grant Nos. 61170258 and 6093301
文摘The past decade has seen a growing interest in ocean sensor networks because of their wide applications in marine research,oceanography,ocean monitoring,offshore exploration,and defense or homeland security.Ocean sensor networks are generally formed with various ocean sensors,autonomous underwater vehicles,surface stations,and research vessels.To make ocean sensor network applications viable,efficient communication among all devices and components is crucial.Due to the unique characteristics of underwater acoustic channels and the complex deployment environment in three dimensional(3D) ocean spaces,new efficient and reliable communication and networking protocols are needed in design of ocean sensor networks.In this paper,we aim to provide an overview of the most recent advances in network design principles for 3D ocean sensor networks,with focuses on deployment,localization,topology design,and position-based routing in 3D ocean spaces.
基金the National Natural Science Foundation of China (Grant Nos. 40676032, 40776029 and 40403012) the Innovation Research Group of the National Natural Science Foundation of China (Grant No. 40621063)
文摘This paper reports high-resolution biomarker records of the last 260 ka for core MD05-2904 from the northern South China Sea (SCS). The sea surface temperature (SST) record using the U k3’7 index re-veals a minimum of 21.5℃ (MIS 2) and a maximum of 28.3℃ (MIS 5.5), for a temperature difference of almost 7℃, and provides the longest high-resolution U k3’7 SST record in northern SCS. The content of odd-number long chain n-alkanes and several n-alkanes indexes such as the CPI, ACL and the C31/C27 ratio, all reveal generally higher values during the glacials and lower values during the interglacials. Terrestrial input as indicated by n-alkane content was mostly controlled by sea-level changes: During the glacials, lower sea-level exposed the continental shelf to enable rivers to transport more terrestrial materials to the slope; and the situation reverses during the interglacials. The n-alkane indexes changes reveal more n-alkanes from contemporary vegetation during glacials as a result of the prox-imity of the core site to the source region, while the increases in ACL and C31/C27 ratio during glacials indicate a change to more grassy vegetation. However, the highest values for CPI, ACL and the C31/C27 ratio all occurred during late MIS 3, and it was suggested that this period was characterized by a strong summer monsoon-dominated humid climate which resulted in a denser vegetation for the exposed continental shelf region.
基金supported by the National Natural Science Foundation of China (40890153)the National High-tech R&D Program of China (2008AA09A402)the National Key Scientific Research Project "the South China Sea Deep" (91028008)
文摘Deep sea circulation is important for world climate and has been a substantial research area in ocean science, leading to various breakthroughs and discoveries. With the rapid advance in research on ocean science, these matters have received increasing attention from the oceanography community. In this article, we attempt to convey the progress made in recent years. We first provide an overview of existing observations, theories, and simulations of deep South China Sea circulation. Finally, we discuss remaining issues.
基金supported by the Chinese Academy of Sciences (Grant No. KZCX2-YW-143)National Natural Science Foundation of China (Grant Nos. 40974045,41021003)Open Fund in KLDG/IGG (Grant No. L09-18)
文摘Sea level variations(SLVs) can be divided into two major components:the steric SLV and the mass-induced SLV.These two components of SLV in the South China Sea(SCS) are studied by using satellite altimetry,GRACE(Gravity Recovery and Climate Experiment) satellite gravity,and oceanographic data on annual and inter-annual timescales.On the annual timescale,the geographic distribution of mass-induced SLV's amplitude jointly estimated from altimetry and the ECCO(Estimation of the Circulation and Climate of the Ocean) model agrees very well with that from GRACE.GRACE observes obvious seasonal mass-induced SLV in the SCS with annual amplitude of 2.7±0.4 cm,which is consistent with the annual amplitude of 2.7±0.3 cm estimated from the steric-corrected altimetry.On the inter-annual timescales,the mean SLV in the SCS shows a large oscillation,which is mainly caused by the steric effect.The trend of mean SLV inferred from altimetry in the SCS is 5.5±0.7 mm/yr for the period of 1993-2009,which is significantly higher than the global sea level rise rate of 3.3±0.4 mm/yr in the same period.There is no obvious trend signal in the mass-induced SLV detected from GRACE that indicates the water exchange between the SCS and its adjacent seas and land is in balance within the study period.
基金Supported by the National Basic Research Program of China (973 Program, No. 2007CB407305)Qingdao Special Project for Outstanding Scientists (No.05-2-JC-90)the 100 Talents Project of Chinese Academy of Sciences (No.2003-202)
文摘The area of the southwestern Nansha Trough is one of the most productive areas of the southern South China Sea.It is a typical semi-deep sea area of transition from shoal to abyssal zone.To understand distributions and roles of nitrogen forms involved in biogeochemical cycling in this area,contents of nitrogen in four extractable forms:nitrogen in ion exchangeable form(IEF-N),nitrogen in weak acid extractable form(WAEF-N),nitrogen in strong alkali extractable form(SAEF-N) and nitrogen in strong oxidation extractable form(SOEF-N),as well as in total nitrogen content(TN) in surface sediments were determined from samples collected from the cruise in April-May 1999.The study area was divided into three regions(A,B and C) in terms of clay sediment(<4 μm) content at <40%,40%-60% and >60%,respectively.Generally,region C was the richest in the nitrogen of all forms and region A the poorest,indicating that the finer the grain size is,the richer the contents of various nitrogen are.The burial efficiency of total nitrogen in surface sediments was 28.79%,indicating that more than 70% of nitrogen had been released and participated in biogeochemical recycling through sediment-water interface.
基金supported by the National Basic Research Program of China (973 Program) (Grant No.2009CB421406)the National Key Technologies R&D Program of China (Grant No.2007BAC29B03)the The National Natural Science Foundation of China Project (Grant No.40821092)
文摘This study examined wintertime (November-April) cold wave frequency (CWF) in northern China during the last 42 years and its association with Arctic Oscillation (AO) through analysis of daily mean surface temperature from 280 stations across northern China and European Centre for Medium-Range Weather Forecasts (ECMWF) 40-Year Re-analysis ERA-40 data. The leading empirical orthogonal function EOF mode of wintertime CWF (CWF-EOF1) indicates an identical signal over most northern China, with the characteristic trend of linear decline for the leading principal component (CWF-PC1). After the linear trend is removed, remarkable inter-annual variability is found to be the dominant feature of the CWF-PC1. The regression map for sea level pressure based on CWF-PC1 corresponds to the negative phase of AO. Correlation analysis further proves that CWF-PC1 has a significant negative correlation with AO at the inter-annual time scale. The relationship between AO and global surface air temperature is also investigated in order to understand its association with cold air activity over East Asia, and it is suggested that the anomalies of atmospheric circulation in Siberia may serve as a bridge for interaction between AO and CWF in northern China during wintertime.
