Using long term observation data in the main part of East China Sea Kuroshio, variations of Kuroshio upper layer temperature and salinity, their relationships with surface temperature and precipitation in east China a...Using long term observation data in the main part of East China Sea Kuroshio, variations of Kuroshio upper layer temperature and salinity, their relationships with surface temperature and precipitation in east China are studied. Results reveal that the Kuroshio upper layer temperature experienced slight rise while salinity decreased in the past 50 years. In winter, Kuroshio upper layer temperature is closely related to the surface temperature in east China, and large area in east China shows positive correlation to the Kuroshio upper layer temperature, which might be related to the mass temperature reduction as a result of the cold air activities in winter. In summer, the increase of the precipitation causes the increase of diluted Yangtze River water into the shelf sea, thereby results in the salinity decrease of Kuroshio in the upper layer.展开更多
Mangrove-derived dissolved organic matter (DOM) has an important effect on estuarine and coastal area on a large scale. In order to improve the understanding of origin, composition, and fate of DOM in mangrove-fring...Mangrove-derived dissolved organic matter (DOM) has an important effect on estuarine and coastal area on a large scale. In order to improve the understanding of origin, composition, and fate of DOM in mangrove-fringed estuarine and coastal areas, dissolved humic substances (DHS) were isolated from one mangrove pore-water sample and one near-shore seawater sample downstream the mangrove pore-water site in the eastern coast of Hainan Island, South China. Fulvic acids, humic acids and XAD-4 fractions were obtained from the two water samples by using a two-column array of XAD-g and XAD-4 resins. Chemica~ and spectroscopic methods were used to analyze the features of these DHS. Compared to the mangrove pore-water DHS, the near-shore seawater DHS were found rich in 13C with lower C/N ratios and more aliphatic compounds and carbohydrates, but less aromatic structures and carboxyl groups. As for the three fractions of the two DHS, XAD-4 fractions contain more aliphatics, carbohydrates, carboxyl groups, and enrich in 13C with respect to both fulvic and humic acids. Photo-oxidation transformation and contribution from marine-derived DOM were considered as the main reasons resulted in the difference in compositional features for these DHS in this study.展开更多
The Okinawa Trough is a natural laboratory for the study of air-sea interaction and paleoenvironmental change. It has been demonstrated that present offshore export of particles in the bottom nepheloid layer occur pri...The Okinawa Trough is a natural laboratory for the study of air-sea interaction and paleoenvironmental change. It has been demonstrated that present offshore export of particles in the bottom nepheloid layer occur primarily with downwelling from the northeast winter monsoon, which is inhibited by a transverse circulation pattern in summer. This current system was very different during the Last Glacial Maximum owing to low sea level (-120 m) and exposure of a large shelf area. We collected sediment core Oki01 from the middle Okinawa Trough during 2012 using R/V Kexue No. 1 to elucidate the timing and cause of the current system transition in the East China Sea. Clay mineral, dry density, and elemental (Ti, Ca) composition of core Oki01 was analyzed. The results indicate that clay minerals derived mainly from the Huanghe (Yellow) and the Changjiang (Yangtze) Rivers during 16.0-11.6 ka, and the modem current system in the East China Sea formed beginning in the early Holocene. Therefore, mixing of East China Sea continental shelf, Changjiang River and partially Taiwan Island sediment are the major contributors. The decrease of log(Ti/Ca) and alternating provenance since the early Holocene indicate less sediment from the East China in summer because of resistance of the modern current system, i.e., a "water barrier" and upwelling. Conversely, sediment delivery persists in winter and log(Ti/Ca) indicates the winter monsoon signal since the early Holocene. Our evidence also suggests that sediment from Taiwan Island could be transported by the Kuroshio Current to the middle Okinawa Trough, where it mingles with winter monsoon- induced export of sediment from the Changjiang River and East China Sea continental shelf. Although the present research advances understanding of the evolutionary history of paleoenvironmental change in the Okinawa Trough, more sediment cores should be retrieved over wide areas to construct a larger scenario.展开更多
Rainwater samples were collected in series in Qianliyan Island (southern Yellow Sea) and Shengsi Archipelago (East China Sea) between May 2000 and May 2002, chemical analysis for pH values, concentrations of heavy met...Rainwater samples were collected in series in Qianliyan Island (southern Yellow Sea) and Shengsi Archipelago (East China Sea) between May 2000 and May 2002, chemical analysis for pH values, concentrations of heavy metals (Cu, Pb, Zn and Cd) and nutrients (NH4+, NO3-, PO43-, SiO32-) were performed. Results indicate that concentrations of most of the heavy metals and nutrients in rainwater show clear seasonal variation, i.e. high level in winter and low level in summer. Regionally, concentrations are higher in the southern Yellow Sea than in the East China Sea, but the annual input of heavy metals into oceans by wet deposition is similar in both stations. However, the input of nutrients by wet deposition in the East China Sea is 2–3 times higher than that in the southern Yellow Sea. In individual, Pb and PO43- are input to the sea mainly by dry deposition; whereas Cu, Zn, Cd and N compounds are input dominantly by wet deposition, the N/P ratios in the rainwater from two stations are much higher than those in seawater, showing a significant impact of atmospheric wet deposition on marine production and biogeochemical circulation of nutrients in these sea regions.展开更多
The DPSIR assessment method, which implies the relationships among driving force (D), pressure (P), status (S), impact (I), and response (R), is widely applied by scholars. This paper aims to establish a com...The DPSIR assessment method, which implies the relationships among driving force (D), pressure (P), status (S), impact (I), and response (R), is widely applied by scholars. This paper aims to establish a comprehensive assessment system for regional energy security in eastern coastal China based on the above model using different indicators. Factor analysis and the SPSS statistical analysis software were used to carry out scientific and quantitative assessments. The results indicated that con- tradictions of energy supply and demand as well as environmental pollution are the critical factors that present great challenges to regional energy security in this area. The authors argued that a sustainable, stable, and safe supply energy supply is crucial in solving the aforesaid dilemma, and improving the energy use efficiency is one of the best choices. Some countermeasures and suggestions regarding regional energy supply stability and utilization security were pointed out.展开更多
An MOM2 based 3-dimentional prognostic baroclinic Z-ordinate model was established to study the circulation in eastern China seas, considering the topography, inflow and outflow on the open boundary, wind stress, temp...An MOM2 based 3-dimentional prognostic baroclinic Z-ordinate model was established to study the circulation in eastern China seas, considering the topography, inflow and outflow on the open boundary, wind stress, temperature and salinity exchange on the sea surface. The results were consistent with observation and showed that the Kuroshio intrudes in large scale into the East China Sea continental shelf East China, during which its water is exchanged ceaselessly with outer sea water along Ryukyu Island. The Tsushima Warm Current is derived from several sources, a branch of the Kuroshio, part of the Taiwan Warm Current, and Yellow Sea mixed water coming from the west of Cheju Island. The water from the west of Cheju Island contributes ap-proximately 13% of the Isushima Warm Current total transport through the Korea Strait. The circulation in the Bohai Sea and Yellow Sea is basically cyclonic circulation, and is comprised of coastal currents and the Yellow Sea Warm Current. Besides simulation of the real circulation, numerical experiments were conducted to study the dynamic mechanism. The numerical experiments indicated that wind directly drives the East China Sea and Yellow Sea Coastal Currents, and strengthens the Korea Coastal Current and Yellow Sea Warm Current. In the no wind case, the kinetic energy of the coastal current area and main YSWC area is only 1% of that of the wind case. Numerical experiments also showed that the Tsushima Warm Current is of great importance to the formation of the Korea Coastal Current and Yellow Sea Warm Current.展开更多
To discuss the intrusion of the Kuroshio into the SCS,we examined the mixing between the North Pacific and South China Sea(SCS) waters based on in-situ CTD data collected in August and September 2008 and the moored AD...To discuss the intrusion of the Kuroshio into the SCS,we examined the mixing between the North Pacific and South China Sea(SCS) waters based on in-situ CTD data collected in August and September 2008 and the moored ADCP data taken from mid September 2008 to early July 2009.The CTD survey included four meridional sections from 119°E to 122°E around the Luzon Strait,during which pressure,temperature,and salinity were measured.The CTD data show that the isopycnal surface tilted from the SCS to the North Pacific;and it was steeper in the lower layers than in the upper ones.Meanwhile,we found strong vertical mixing taken place in the areas near 121°E.The Kuroshio in high temperature and salinity intruded westward through Luzon Strait.The frequency of buoyancy was one order of magnitude greater than that of the common ones in the ocean,suggesting stronger stratification in the northeastern SCS.On the other hand,the long-term ADCP data show that before late October 2008,the direction of water flow in the SCS was eastward,and from November 2008 to late February 2009,it turned northwestward in the layers shallower than 150 m,while remained unchanged in deep layers from 200 to 450 m.From March to June 2009,the direction shifted with increasing depth from northward to southward,akin to the Ekman spiral.EOF analysis of the current time series revealed dominant empirical modes:the first mode corresponded to the mean current and showed that the Kuroshio intrusion occurred in the upper layers only from late December to early March.The temporal coefficient of the first and the second mode indicated clearly a dominant signal in a quasi-seasonal cycle.展开更多
A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19-25 March, 2002. The modeling result well reproduced PM10 con...A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19-25 March, 2002. The modeling result well reproduced PM10 concentrations in various distances from the dust sources and the transport pathway of the dust strom. The results showed that both the concentrations and the dry deposition fluxes of PM10 increased over the China seas during the dust event following the passage of a cold front system. The maximum fluxes of PM10 in the Yellow Sea and the East China Sea during the dust event were 5.5 and 8.4 times of those before the event, respectively. However, the temporal variations of the dry deposition fluxes of particulate inorganic nitrogen differed over the Yellow Sea from those over the East China Sea. Nitrate and ammonium in the whole northern China rapidly decreased because of the intrusion of dust-loaded air on 19 March. The dust plume arrived in the Yellow Sea on 20 March, decreasing the particulate inorganic nitrogen in mass concentration accordingly. The minimum dry deposition fluxes of nitrate and ammonium in the Yellow Sea were about 3/5 and 1/6 of those before the dust arrival, respectively. In contrast, when the dust plume crossed over the Yangtze Delta area, it became abundant in nitrate and ammonium and increased the concentrations and dry deposition fluxes of particulate inorganic nitrogen over the East China Sea, where the maximum dry deposition fluxes of nitrate and ammonium increased approximately by 4.1 and 2.6 times of those prior to the dust arrival.展开更多
Sea surface temperature (SST) variation in the Subei coastal waters, East China, which is important for the ecological environment of the Yellow Sea where Enteromorphaprolifera blooms frequently, is affected by the ...Sea surface temperature (SST) variation in the Subei coastal waters, East China, which is important for the ecological environment of the Yellow Sea where Enteromorphaprolifera blooms frequently, is affected by the East Asian winter monsoon (EAWM), El Nifio-Southem Oscillation (ENSO), and Pacific Decadal Oscillation (PDO). In this study, correlations between climatic events and SST anomalies (SSTA) around the Subei (North Jiangsu Province, East China) Coast from 1981-2012 are analyzed, using empirical orthogonal function (EOF) and correlation analyses. First, a key region was determined by EOF analysis to represent the Subei coastal waters. Then, coherency analyses were performed on this key region. According to the correlation analysis, the EAWM index has a positive correlation with the spring and summer SSTA of the key region. Furthermore, the Nifio3.4 index is negatively correlated with the spring and summer SSTA of the key region 1 year ahead, and the PDO has significant negative coherency with spring SSTA and negative coherency with summer SSTA in the key region 1 year ahead. Overall, PDO exhibits the most significant impact on SSTA of the key region. In the key region, all these factors are correlated more significantly with SSTA in spring than in summer. This suggests that outbreaks ofEnteromorpha prolifera in the Yellow Sea are affected by global climatic changes, especially the PDO.展开更多
To investigate the influence of root system architectural properties of three indigenous (cold- adapted) shrubs on the hillslope stability of loess deposits in the Xining Basin, northeast part of Qinghai-Tibet Plate...To investigate the influence of root system architectural properties of three indigenous (cold- adapted) shrubs on the hillslope stability of loess deposits in the Xining Basin, northeast part of Qinghai-Tibet Plateau (QTP), indoor direct shear tests have been conducted on the remolded rooted soil of three shrubs. Test results show that root system architectural indices (root area ratio (RAR), root length density (RLD) and root density (RD)) of the shrubs decline with depth and the relationship between RAR, RD and depth is exponential, while a power relationship describes the relationship between RLD and depth. The cohesion force of remolded rooted soil for the shrubs initially increases with depth, but it then demonstrates a slightly decreasing trend, which can be described with a power relationship. Power relationships also describe relationships between cohesion force and RAR, RLD and RD for the shrubs. As the growth period increases from lO to 17 months, the incremental increase in RAR is 48.32% ~ 21o.25% for Caragana korshinskii Kom and 0.56% ~ 166.85% for ZygophyUum xanthoxylon (Bunge) Maxim. This proportional increase is notably larger than that for RLD and RD. The increment in RAR is marginally greater for C. korshinskff than it is for Z. xanthoxylon. Correspondingly, the cohesion force incremental rates of remolded rooted soil for C. korshinskii and Z. xanthoxylon are 12.41% ~ 25.22% and 3.45% ~ 17.33% respectively. Meanwhile, as root content increases, the contribution by roots to cohesion force increases markedly until a threshold condition is reached.展开更多
This study investigates the wind energy input, an important source of mechanical energy, in the coastal seas east of China. Using the wind field from the high-resolution sea surface meteorology dataset in the Bohai Se...This study investigates the wind energy input, an important source of mechanical energy, in the coastal seas east of China. Using the wind field from the high-resolution sea surface meteorology dataset in the Bohai Sea, Yellow Sea, and East China Sea, we studied the wind energy input through surface ageostrophic currents and surface waves. Using a simple analytical formula for the Ekman Spiral with time- dependent wind, the wind energy input through ageostrophic currents was estimated at -22 GW averaged from 1960 to 2007, and through use of an empirical formula, the wind energy input through surface waves was estimated at -169 GW. We also examined the seasonal variation and long-term tendency of mechanical energy from wind stress, and found that the wind energy input to the East China Sea decreased before the 1980s, and then subsequently increased, which is contrary to what has been found for the Bohai Sea and Yellow Sea. More complicated physical processes and varying diffusivity need to be taken into account in future studies.展开更多
Heterotrophic bacterial production (BP) in the East China Sea was measured using tritiated thymidine incorporation (TTI) method in winter 1997 and in summer 1998. The results showed BP in summer (1998, 3.50-15.70 μgC...Heterotrophic bacterial production (BP) in the East China Sea was measured using tritiated thymidine incorporation (TTI) method in winter 1997 and in summer 1998. The results showed BP in summer (1998, 3.50-15.70 μgC/(L·h) was higher than that in winter(1997, 0.46-2.62 μgC/(L·h). The high values of BP occurred around the Changjiang River estuary and around Station 410. The results at two anchor stations showed that vertical variation of BP was bottom>middle>surface in winter and middle>bottom>surface in summer. Compared with primary production (BP:PP), the average ratio of BP:PP was 0.17(0.04-0.30) in winter and 0.32(0.21-0.43) in summer. There were high ratios around the Changjiang River estuary in winter and around Station 111 in summer.展开更多
To reconstruct the productivity changes for the last 10 500 a in the northeastern East China Sea (ECS), biogenic compounds (such as carbonate, organic carbon and opal), marine micropaleontological fossils (plankt...To reconstruct the productivity changes for the last 10 500 a in the northeastern East China Sea (ECS), biogenic compounds (such as carbonate, organic carbon and opal), marine micropaleontological fossils (planktonic foraminifera, benthic foraminifera, radiolarian and silicoflagellate) and the compositional characters of benthic foraminifera fauna analyses were carried out on a sediment core DOC082 obtained from the western slope of Okinawa Trough (29°13.93′N, 128°08.53′E; 1 128 m water depth). The long-term changes of biogenic and micropaleontological proxies display some similarities through the last 10 500 a, which show three different phases: lower values are recorded during the early and middle ttolocene (before about 4 000 a BP), followed by an abrupt and remarkable increase at about 4 000 a BP, the late Holocene (after about 3 000 a BP) is characterized by continuously high values. The multi-proxy data of paleoproductivity and percents of benthic foraminifera genera (Uvigerina and Bulimina) show that during the early and middle Holocene (10 500-4 000 a BP) productivity was relatively low with a sudden and distinct increase at about 4 000 a BP, and the late Holocene (3 400-0 a BP) is marked by significantly higher productivity. Also, the radiolarian-based sea surface temperature (SST) records reveal a distinct decline in SST in the late Holocene after 3 200 a BP, very different from the early and middle Holocene. For the last 3 000 a, the enhanced biological productivity and distinctly lower SST indicate a major change of oceanographic conditions in the northeastern ECS. These marine environmental anomalies are consistent with other paleoclimatic records for the late Holocene in the Chinese continent and its surrounding regions. After analyzing the mechanisms of modern productivity and SST changes in the northeastern ECS, and based on the climatic anomalies in the Chinese continent and variations in the Kuroshio Current during modern El Nino periods, we suggest that the anomalous environmental conditions in the northeastern ECS may imply intensified El Nino activity during the late Holocene.展开更多
We used a set of 75-day long ADCP data from the northeastern South China Sea(SCS) to investigate nonlinear interactions among freely propagating internal tidal waves.The kinetic energy spectra displayed significant pe...We used a set of 75-day long ADCP data from the northeastern South China Sea(SCS) to investigate nonlinear interactions among freely propagating internal tidal waves.The kinetic energy spectra displayed significant peaks at some higher tidal frequencies,such as O1M2(O1+M2),and M4(M2 +M2),where O1 is the lunar diurnal internal tide,M2 is the lunar semidiurnal internal tide,and M4 is the first higher harmonic frequency of M2.These higher tidal harmonic frequency peaks,as well as the fundamental tidal harmonic peaks,show a σ-2.3 spectral falloff rate with frequency.In addition,we explored the possible generation mechanism of higher tidal harmonics.Analysis on the rotary and bicoherence spectra suggests that strong forced non-resonant interaction induced by nonlinear advections was the dominant physical mechanism that induced these higher tidal harmonics.Moreover,the energetic,freely propagating semidiurnal(M2) internal tidal wave played the most crucial role in these interactions.These results indicate that strong nonlinear forced non-resonant interactions among internal tides can be one of the processes responsible for the redistribution of energy in the internal wave spectrum.展开更多
In a study of surface monsoon winds over the China marginal seas, Sun et al. (2012) use singular value decomposition method to identify regional dominant modes and analyze their interdecadal variability. This paper ...In a study of surface monsoon winds over the China marginal seas, Sun et al. (2012) use singular value decomposition method to identify regional dominant modes and analyze their interdecadal variability. This paper continues to evaluate the interannual variability of each dominant mode and its relation to various atmospheric, oceanic and land factors. The findings include: 1) The intensity of the winter monsoon over the East China Sea is highly correlated with the Siberian High intensity and anti-correlated with the latitudinal position of the Aleutian Low as well as the rainfall in eastern China, Korean Peninsula and Japan; 2) The western Pacific subtropical high is significantly correlated with the summer monsoon intensity over the East China Sea and anti-correlated with the summer monsoon over the South China Sea; 3) The winter monsoon in a broad zonal belt through the Luzon Strait is dominated by the ENSO signal, strengthening in the La Nifia phase and weakening in the E1 Nifio phase. This inverse relation exhibits interdecadal shift with a period of weak correlation in the 1980s; 4) Analysis of tidal records validates the interdecadal weakening of the East Asian summer monsoon and reveals an atmospheric bridge that conveys the ENSO signal into the South China Sea via the winter monsoon.展开更多
Hyperspectral data are an important source for monitoring soil salt content on a large scale. However, in previous studies, barriers such as interference due to the presence of vegetation restricted the precision of m...Hyperspectral data are an important source for monitoring soil salt content on a large scale. However, in previous studies, barriers such as interference due to the presence of vegetation restricted the precision of mapping soil salt content. This study tested a new method for predicting soil salt content with improved precision by using Chinese hyperspectral data, Huan Jing-Hyper Spectral Imager(HJ-HSI), in the coastal area of Rudong County, Eastern China. The vegetation-covered area and coastal bare flat area were distinguished by using the normalized differential vegetation index at the band length of 705 nm(NDVI705). The soil salt content of each area was predicted by various algorithms. A Normal Soil Salt Content Response Index(NSSRI) was constructed from continuum-removed reflectance(CR-reflectance) at wavelengths of 908.95 nm and 687.41 nm to predict the soil salt content in the coastal bare flat area(NDVI705 < 0.2). The soil adjusted salinity index(SAVI) was applied to predict the soil salt content in the vegetation-covered area(NDVI705 ≥ 0.2). The results demonstrate that 1) the new method significantly improves the accuracy of soil salt content mapping(R2 = 0.6396, RMSE = 0.3591), and 2) HJ-HSI data can be used to map soil salt content precisely and are suitable for monitoring soil salt content on a large scale.展开更多
The world today is .faced with the critical challenge of developing industries .for both high technological efficiency and possibly less impact on resources and the environment. This paper employs the Slacks-based mea...The world today is .faced with the critical challenge of developing industries .for both high technological efficiency and possibly less impact on resources and the environment. This paper employs the Slacks-based measure (SBM) to conduct an empirical analysis of China's industrial environmental efficiency between 1998 and 2008. We.found a slight decline in SBM nationwide due to the combined effects of resource^environmental constraint as well as technological progress. From a static perspective, there is a clear disparity in coordination among regions, particularly between western regions and eastern coastal regions. From a dynamic perspective, there is limited change in the coordination of industries with natural resources and the environment in coastal and central regions, but a marked decline in the northeast and western regions. This contrast can be traced to the .following reasons: the capital-intensive structure of the economy and the high proportion of large industrial enterprises that restrict the improvement of SBM environmental efficiency. Higher living standards, indigenous innovation, acquisition of new technologies, and foreign direct investment will be conducive to industries'synchronous development with natural resources and the environment.展开更多
A statistical regression downscaling method was used to project future changes in precipitation over eastern China based on Phase 5 of the Coupled Model Intercomparison Project (CMIPS) the Representative Concentrati...A statistical regression downscaling method was used to project future changes in precipitation over eastern China based on Phase 5 of the Coupled Model Intercomparison Project (CMIPS) the Representative Concentration Pathway (RCP) scenarios simulated by the second spectral version of the Flexible Global Ocean- Atmosphere-Land System (FGOALS-s2) model. Our val- idation results show that the downscaled time series agree well with the present observed precipitation in terms of both the annual mean and the seasonal cycle. The regres- sion models built from the historical data are then used to generate future projections. The results show that the en- hanced land-sea thermal contrast strengthens both the subtropical anticyclone over the western Pacific and the east Asian summer monsoon flow under both RCPs. However, the trend of precipitation in response to warming over the 21 st century are different across eastern Chi- na under different RCPs. The area to the north of 32°N is likely to experience an increase in annual mean precipitation, while for the area between 23°N and 32°N mean precipitation is projected to decrease slightly over this century under RCP8.5. The change difference between scenarios mainly exists in the middle and late century. The land-sea thermal contrast and the associated east Asian summer monsoon flow are stronger, such that precipitation increases more, at higher latitudes under RCP8.5 compared to under RCP4.5. For the region south of 32°N, rainfall is projected to increase slightly under RCP4.5 but decrease under RCP8.5 in the late century. At the high resolution of 5 km, our statistically downscaled results for projected precipitation can be used to force hydrological models to project hydrological processes, which will be of great benefit to regional water planning and management.展开更多
Based on a data base of multi-channel seismic profiles covered over Dongsha plateau of the northern South China Sea margin, we found that the sea bed morphology of northern South China Sea margin had been changed dram...Based on a data base of multi-channel seismic profiles covered over Dongsha plateau of the northern South China Sea margin, we found that the sea bed morphology of northern South China Sea margin had been changed dramatically after Dongsha uplifting, that sedimentary layer since Miocene age had been eroded with maximum eroded thickness more than 1000 m, and that an erosive channel had been formed of 20 km in width and 200 km in length and several hundreds meters in depth on the outer shelf of northern South China Sea. The erosive channel is parallel to the 600 m isobath line, stretching from northeast to the southwest north of Dongsha uplift. The Kuroshio intrudes the South China Sea through Luzon Strait both in winter time and summer time, and in the northern South China Sea margin area, the intruded Kuroshio Branch takes the form of Pacific-Indian Ocean Through Flow (PITH) in winter time, while the Luzon Strait Subsurface Inflow (LSSIF) in summer time, the routes of both PITH and LSSIF coincide well with the distribution of the erosive channel. After climbing from the northern slope up to the northern shelf, and after joined by the southward flow from the middle northern shelf of South China Sea, the Kuroshio Branch is strengthened and thus is able to erode the sea floor, and the shape of the erosive channel is a result of the long-term interaction between the Kuroshio South China Sea Branch and the Dongsha outer shelf sea floor.展开更多
During Mesozoic to Cenozoic time, the large-scale tectono-magmatism had strongly modified the lithosphere beneath the southeastern continent of China, leaving the present-day lithosphere as a new one evolving from the...During Mesozoic to Cenozoic time, the large-scale tectono-magmatism had strongly modified the lithosphere beneath the southeastern continent of China, leaving the present-day lithosphere as a new one evolving from the ancient lithosphere that was largely removed and replaced. But this model proposed from geochemical and petrological research is urgently in need of support from seismic observational evidence. In this paper, based on the dataset recorded by the dense stations of two NE ori- ented broadband seismic profiles deployed in the coastal area of southeastern China (SE China), both P-wave (P-RF) and S-wave (S-RF) receiver functions were isolated. We identified Pls phase converted from the Lithosphere-Asthenosphere Boundary (LAB) in P-RFs of individual stations. Migrated Pls phase indicated a depth of 60-70 km for LAB. Inver- sions/comparisons of P-RF (Pls phase) and S-RF (Sip phase) waveforms together with Ps and Sp imaging for the crust and up- per mantle structure further confirmed this result. P-RF and S-RF migrated images exhibit that a flat LAB is positioned at the depth of 60-70 km spreading along the profile, whereas a distinct structural change of lithospheric base appears at the Min River estuary. Both Ps and PpPs migrated images of P-RFs present an abrupt Moho drop across the Min River fault from south to north, which is consistent with previous result obtained from deep seismic sounding. By taking into consideration other ge- ological and geophysical features such as locally high anomalies of crustal Poisson's ratios and heat flow at the Min River es- tuary, we infer that the Min River fault penetrates down to the Moho and may, furthermore, interfere in the deeper lithospheric structure.展开更多
基金supported by National Natural Science Foundation Project ‘Multi-core Structure of Antarctic Circumpolar Current and a Dynamic View of Its Spatial-temporal Variation’ (No. 40506011)The key project of the National Natural Science Foundation of China ‘Diagnostic Analysis and Numerical Simulation of the Inter-decadal Variations of East Asian Summer Monsoon and Summer Precipitation in East of China’ (No. 40331010)The key project of the Major Natural Fundamental Researches of Universities in Jiangsu Province ‘Research of development and prediction theory of Drought and Flood in the mid-lower reaches of Yangtze River’ (No. 05KJA17002)
文摘Using long term observation data in the main part of East China Sea Kuroshio, variations of Kuroshio upper layer temperature and salinity, their relationships with surface temperature and precipitation in east China are studied. Results reveal that the Kuroshio upper layer temperature experienced slight rise while salinity decreased in the past 50 years. In winter, Kuroshio upper layer temperature is closely related to the surface temperature in east China, and large area in east China shows positive correlation to the Kuroshio upper layer temperature, which might be related to the mass temperature reduction as a result of the cold air activities in winter. In summer, the increase of the precipitation causes the increase of diluted Yangtze River water into the shelf sea, thereby results in the salinity decrease of Kuroshio in the upper layer.
基金Supported by the National Natural Science Foundation of China(Nos.40906041,41021064)the State Key Laboratory of Estuarine and Coastal Research (SKLEC) of East China Normal University(Nos.2012KYYW05,201202)
文摘Mangrove-derived dissolved organic matter (DOM) has an important effect on estuarine and coastal area on a large scale. In order to improve the understanding of origin, composition, and fate of DOM in mangrove-fringed estuarine and coastal areas, dissolved humic substances (DHS) were isolated from one mangrove pore-water sample and one near-shore seawater sample downstream the mangrove pore-water site in the eastern coast of Hainan Island, South China. Fulvic acids, humic acids and XAD-4 fractions were obtained from the two water samples by using a two-column array of XAD-g and XAD-4 resins. Chemica~ and spectroscopic methods were used to analyze the features of these DHS. Compared to the mangrove pore-water DHS, the near-shore seawater DHS were found rich in 13C with lower C/N ratios and more aliphatic compounds and carbohydrates, but less aromatic structures and carboxyl groups. As for the three fractions of the two DHS, XAD-4 fractions contain more aliphatics, carbohydrates, carboxyl groups, and enrich in 13C with respect to both fulvic and humic acids. Photo-oxidation transformation and contribution from marine-derived DOM were considered as the main reasons resulted in the difference in compositional features for these DHS in this study.
基金Supported by the National Natural Science Foundation of China(Nos.41430965,41376057)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA11030302)
文摘The Okinawa Trough is a natural laboratory for the study of air-sea interaction and paleoenvironmental change. It has been demonstrated that present offshore export of particles in the bottom nepheloid layer occur primarily with downwelling from the northeast winter monsoon, which is inhibited by a transverse circulation pattern in summer. This current system was very different during the Last Glacial Maximum owing to low sea level (-120 m) and exposure of a large shelf area. We collected sediment core Oki01 from the middle Okinawa Trough during 2012 using R/V Kexue No. 1 to elucidate the timing and cause of the current system transition in the East China Sea. Clay mineral, dry density, and elemental (Ti, Ca) composition of core Oki01 was analyzed. The results indicate that clay minerals derived mainly from the Huanghe (Yellow) and the Changjiang (Yangtze) Rivers during 16.0-11.6 ka, and the modem current system in the East China Sea formed beginning in the early Holocene. Therefore, mixing of East China Sea continental shelf, Changjiang River and partially Taiwan Island sediment are the major contributors. The decrease of log(Ti/Ca) and alternating provenance since the early Holocene indicate less sediment from the East China in summer because of resistance of the modern current system, i.e., a "water barrier" and upwelling. Conversely, sediment delivery persists in winter and log(Ti/Ca) indicates the winter monsoon signal since the early Holocene. Our evidence also suggests that sediment from Taiwan Island could be transported by the Kuroshio Current to the middle Okinawa Trough, where it mingles with winter monsoon- induced export of sediment from the Changjiang River and East China Sea continental shelf. Although the present research advances understanding of the evolutionary history of paleoenvironmental change in the Okinawa Trough, more sediment cores should be retrieved over wide areas to construct a larger scenario.
基金Supported by the National "973" Program (No. G1999043705), and the Natural Sciences Foundation of Shandong Province (No. Y2000E02).
文摘Rainwater samples were collected in series in Qianliyan Island (southern Yellow Sea) and Shengsi Archipelago (East China Sea) between May 2000 and May 2002, chemical analysis for pH values, concentrations of heavy metals (Cu, Pb, Zn and Cd) and nutrients (NH4+, NO3-, PO43-, SiO32-) were performed. Results indicate that concentrations of most of the heavy metals and nutrients in rainwater show clear seasonal variation, i.e. high level in winter and low level in summer. Regionally, concentrations are higher in the southern Yellow Sea than in the East China Sea, but the annual input of heavy metals into oceans by wet deposition is similar in both stations. However, the input of nutrients by wet deposition in the East China Sea is 2–3 times higher than that in the southern Yellow Sea. In individual, Pb and PO43- are input to the sea mainly by dry deposition; whereas Cu, Zn, Cd and N compounds are input dominantly by wet deposition, the N/P ratios in the rainwater from two stations are much higher than those in seawater, showing a significant impact of atmospheric wet deposition on marine production and biogeochemical circulation of nutrients in these sea regions.
基金Supported by the State Nature Science Foundation (40771085) the National Science & Technology Support Program (2006BZC 18B01-05)
文摘The DPSIR assessment method, which implies the relationships among driving force (D), pressure (P), status (S), impact (I), and response (R), is widely applied by scholars. This paper aims to establish a comprehensive assessment system for regional energy security in eastern coastal China based on the above model using different indicators. Factor analysis and the SPSS statistical analysis software were used to carry out scientific and quantitative assessments. The results indicated that con- tradictions of energy supply and demand as well as environmental pollution are the critical factors that present great challenges to regional energy security in this area. The authors argued that a sustainable, stable, and safe supply energy supply is crucial in solving the aforesaid dilemma, and improving the energy use efficiency is one of the best choices. Some countermeasures and suggestions regarding regional energy supply stability and utilization security were pointed out.
基金This study was supported by the Major State Basi(No.G1999043808) Youth Fund of the National 863 Project(No.G2002AA639350) and the Scientific Foundation of the Chinese
文摘An MOM2 based 3-dimentional prognostic baroclinic Z-ordinate model was established to study the circulation in eastern China seas, considering the topography, inflow and outflow on the open boundary, wind stress, temperature and salinity exchange on the sea surface. The results were consistent with observation and showed that the Kuroshio intrudes in large scale into the East China Sea continental shelf East China, during which its water is exchanged ceaselessly with outer sea water along Ryukyu Island. The Tsushima Warm Current is derived from several sources, a branch of the Kuroshio, part of the Taiwan Warm Current, and Yellow Sea mixed water coming from the west of Cheju Island. The water from the west of Cheju Island contributes ap-proximately 13% of the Isushima Warm Current total transport through the Korea Strait. The circulation in the Bohai Sea and Yellow Sea is basically cyclonic circulation, and is comprised of coastal currents and the Yellow Sea Warm Current. Besides simulation of the real circulation, numerical experiments were conducted to study the dynamic mechanism. The numerical experiments indicated that wind directly drives the East China Sea and Yellow Sea Coastal Currents, and strengthens the Korea Coastal Current and Yellow Sea Warm Current. In the no wind case, the kinetic energy of the coastal current area and main YSWC area is only 1% of that of the wind case. Numerical experiments also showed that the Tsushima Warm Current is of great importance to the formation of the Korea Coastal Current and Yellow Sea Warm Current.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (Nos.KZCX1-YW-12,KZCX2-YW-201)the National High Technology Research and Development Program of China (863 Program) (No.2007AA092201)
文摘To discuss the intrusion of the Kuroshio into the SCS,we examined the mixing between the North Pacific and South China Sea(SCS) waters based on in-situ CTD data collected in August and September 2008 and the moored ADCP data taken from mid September 2008 to early July 2009.The CTD survey included four meridional sections from 119°E to 122°E around the Luzon Strait,during which pressure,temperature,and salinity were measured.The CTD data show that the isopycnal surface tilted from the SCS to the North Pacific;and it was steeper in the lower layers than in the upper ones.Meanwhile,we found strong vertical mixing taken place in the areas near 121°E.The Kuroshio in high temperature and salinity intruded westward through Luzon Strait.The frequency of buoyancy was one order of magnitude greater than that of the common ones in the ocean,suggesting stronger stratification in the northeastern SCS.On the other hand,the long-term ADCP data show that before late October 2008,the direction of water flow in the SCS was eastward,and from November 2008 to late February 2009,it turned northwestward in the layers shallower than 150 m,while remained unchanged in deep layers from 200 to 450 m.From March to June 2009,the direction shifted with increasing depth from northward to southward,akin to the Ekman spiral.EOF analysis of the current time series revealed dominant empirical modes:the first mode corresponded to the mean current and showed that the Kuroshio intrusion occurred in the upper layers only from late December to early March.The temporal coefficient of the first and the second mode indicated clearly a dominant signal in a quasi-seasonal cycle.
基金supported by the National Science Foundation of China (No.40976063)International Cooperative Projects of MOST (No.2010DFA91350)
文摘A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19-25 March, 2002. The modeling result well reproduced PM10 concentrations in various distances from the dust sources and the transport pathway of the dust strom. The results showed that both the concentrations and the dry deposition fluxes of PM10 increased over the China seas during the dust event following the passage of a cold front system. The maximum fluxes of PM10 in the Yellow Sea and the East China Sea during the dust event were 5.5 and 8.4 times of those before the event, respectively. However, the temporal variations of the dry deposition fluxes of particulate inorganic nitrogen differed over the Yellow Sea from those over the East China Sea. Nitrate and ammonium in the whole northern China rapidly decreased because of the intrusion of dust-loaded air on 19 March. The dust plume arrived in the Yellow Sea on 20 March, decreasing the particulate inorganic nitrogen in mass concentration accordingly. The minimum dry deposition fluxes of nitrate and ammonium in the Yellow Sea were about 3/5 and 1/6 of those before the dust arrival, respectively. In contrast, when the dust plume crossed over the Yangtze Delta area, it became abundant in nitrate and ammonium and increased the concentrations and dry deposition fluxes of particulate inorganic nitrogen over the East China Sea, where the maximum dry deposition fluxes of nitrate and ammonium increased approximately by 4.1 and 2.6 times of those prior to the dust arrival.
基金Supported by the National Basic Research Program of China(973 Program)(No.2010CB950403)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA11020301)+1 种基金the National Natural Science Foundation of China(No.41176018)the Special Fund for Marine Research in the Public Interest(No.201005006)
文摘Sea surface temperature (SST) variation in the Subei coastal waters, East China, which is important for the ecological environment of the Yellow Sea where Enteromorphaprolifera blooms frequently, is affected by the East Asian winter monsoon (EAWM), El Nifio-Southem Oscillation (ENSO), and Pacific Decadal Oscillation (PDO). In this study, correlations between climatic events and SST anomalies (SSTA) around the Subei (North Jiangsu Province, East China) Coast from 1981-2012 are analyzed, using empirical orthogonal function (EOF) and correlation analyses. First, a key region was determined by EOF analysis to represent the Subei coastal waters. Then, coherency analyses were performed on this key region. According to the correlation analysis, the EAWM index has a positive correlation with the spring and summer SSTA of the key region. Furthermore, the Nifio3.4 index is negatively correlated with the spring and summer SSTA of the key region 1 year ahead, and the PDO has significant negative coherency with spring SSTA and negative coherency with summer SSTA in the key region 1 year ahead. Overall, PDO exhibits the most significant impact on SSTA of the key region. In the key region, all these factors are correlated more significantly with SSTA in spring than in summer. This suggests that outbreaks ofEnteromorpha prolifera in the Yellow Sea are affected by global climatic changes, especially the PDO.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.41162010,41572306)provincial key project in science and technologies of Qinghai(Grant No.2003-N-134)+1 种基金Excellent Talents in University of New Century by Ministry of Education of the People’s Republic of China(Grant No.NCET–04–G983)International Science&Technology Cooperation Program of China(Grant No.2011DFG93160)
文摘To investigate the influence of root system architectural properties of three indigenous (cold- adapted) shrubs on the hillslope stability of loess deposits in the Xining Basin, northeast part of Qinghai-Tibet Plateau (QTP), indoor direct shear tests have been conducted on the remolded rooted soil of three shrubs. Test results show that root system architectural indices (root area ratio (RAR), root length density (RLD) and root density (RD)) of the shrubs decline with depth and the relationship between RAR, RD and depth is exponential, while a power relationship describes the relationship between RLD and depth. The cohesion force of remolded rooted soil for the shrubs initially increases with depth, but it then demonstrates a slightly decreasing trend, which can be described with a power relationship. Power relationships also describe relationships between cohesion force and RAR, RLD and RD for the shrubs. As the growth period increases from lO to 17 months, the incremental increase in RAR is 48.32% ~ 21o.25% for Caragana korshinskii Kom and 0.56% ~ 166.85% for ZygophyUum xanthoxylon (Bunge) Maxim. This proportional increase is notably larger than that for RLD and RD. The increment in RAR is marginally greater for C. korshinskff than it is for Z. xanthoxylon. Correspondingly, the cohesion force incremental rates of remolded rooted soil for C. korshinskii and Z. xanthoxylon are 12.41% ~ 25.22% and 3.45% ~ 17.33% respectively. Meanwhile, as root content increases, the contribution by roots to cohesion force increases markedly until a threshold condition is reached.
基金Supported by the National 111 Project of China(No.B07036)the National Natural Science Foundation of China(Nos.40930844,40976004)the Research Fund for the Doctoral Program of Higher Education of China(No.20110132130001)
文摘This study investigates the wind energy input, an important source of mechanical energy, in the coastal seas east of China. Using the wind field from the high-resolution sea surface meteorology dataset in the Bohai Sea, Yellow Sea, and East China Sea, we studied the wind energy input through surface ageostrophic currents and surface waves. Using a simple analytical formula for the Ekman Spiral with time- dependent wind, the wind energy input through ageostrophic currents was estimated at -22 GW averaged from 1960 to 2007, and through use of an empirical formula, the wind energy input through surface waves was estimated at -169 GW. We also examined the seasonal variation and long-term tendency of mechanical energy from wind stress, and found that the wind energy input to the East China Sea decreased before the 1980s, and then subsequently increased, which is contrary to what has been found for the Bohai Sea and Yellow Sea. More complicated physical processes and varying diffusivity need to be taken into account in future studies.
文摘Heterotrophic bacterial production (BP) in the East China Sea was measured using tritiated thymidine incorporation (TTI) method in winter 1997 and in summer 1998. The results showed BP in summer (1998, 3.50-15.70 μgC/(L·h) was higher than that in winter(1997, 0.46-2.62 μgC/(L·h). The high values of BP occurred around the Changjiang River estuary and around Station 410. The results at two anchor stations showed that vertical variation of BP was bottom>middle>surface in winter and middle>bottom>surface in summer. Compared with primary production (BP:PP), the average ratio of BP:PP was 0.17(0.04-0.30) in winter and 0.32(0.21-0.43) in summer. There were high ratios around the Changjiang River estuary in winter and around Station 111 in summer.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (Project No. KZCX2-YW-221)the State Key Basic Research and Development Plan of China (Project No2007CB815903)the National Natural Science Foundation of China (Project No. 40506015)
文摘To reconstruct the productivity changes for the last 10 500 a in the northeastern East China Sea (ECS), biogenic compounds (such as carbonate, organic carbon and opal), marine micropaleontological fossils (planktonic foraminifera, benthic foraminifera, radiolarian and silicoflagellate) and the compositional characters of benthic foraminifera fauna analyses were carried out on a sediment core DOC082 obtained from the western slope of Okinawa Trough (29°13.93′N, 128°08.53′E; 1 128 m water depth). The long-term changes of biogenic and micropaleontological proxies display some similarities through the last 10 500 a, which show three different phases: lower values are recorded during the early and middle ttolocene (before about 4 000 a BP), followed by an abrupt and remarkable increase at about 4 000 a BP, the late Holocene (after about 3 000 a BP) is characterized by continuously high values. The multi-proxy data of paleoproductivity and percents of benthic foraminifera genera (Uvigerina and Bulimina) show that during the early and middle Holocene (10 500-4 000 a BP) productivity was relatively low with a sudden and distinct increase at about 4 000 a BP, and the late Holocene (3 400-0 a BP) is marked by significantly higher productivity. Also, the radiolarian-based sea surface temperature (SST) records reveal a distinct decline in SST in the late Holocene after 3 200 a BP, very different from the early and middle Holocene. For the last 3 000 a, the enhanced biological productivity and distinctly lower SST indicate a major change of oceanographic conditions in the northeastern ECS. These marine environmental anomalies are consistent with other paleoclimatic records for the late Holocene in the Chinese continent and its surrounding regions. After analyzing the mechanisms of modern productivity and SST changes in the northeastern ECS, and based on the climatic anomalies in the Chinese continent and variations in the Kuroshio Current during modern El Nino periods, we suggest that the anomalous environmental conditions in the northeastern ECS may imply intensified El Nino activity during the late Holocene.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences (Nos.KZCX1-YW-12-02 and YZ200745)the National Natural Science Foundation of China (Nos.40776008,40976010)
文摘We used a set of 75-day long ADCP data from the northeastern South China Sea(SCS) to investigate nonlinear interactions among freely propagating internal tidal waves.The kinetic energy spectra displayed significant peaks at some higher tidal frequencies,such as O1M2(O1+M2),and M4(M2 +M2),where O1 is the lunar diurnal internal tide,M2 is the lunar semidiurnal internal tide,and M4 is the first higher harmonic frequency of M2.These higher tidal harmonic frequency peaks,as well as the fundamental tidal harmonic peaks,show a σ-2.3 spectral falloff rate with frequency.In addition,we explored the possible generation mechanism of higher tidal harmonics.Analysis on the rotary and bicoherence spectra suggests that strong forced non-resonant interaction induced by nonlinear advections was the dominant physical mechanism that induced these higher tidal harmonics.Moreover,the energetic,freely propagating semidiurnal(M2) internal tidal wave played the most crucial role in these interactions.These results indicate that strong nonlinear forced non-resonant interactions among internal tides can be one of the processes responsible for the redistribution of energy in the internal wave spectrum.
基金Supported by the National Basic Research Program of China (973Program) (No. 2012CB417400)the Knowledge Innovation Program of Chinese Academy of Sciences (No. KZCX2-YW-Q11-02)
文摘In a study of surface monsoon winds over the China marginal seas, Sun et al. (2012) use singular value decomposition method to identify regional dominant modes and analyze their interdecadal variability. This paper continues to evaluate the interannual variability of each dominant mode and its relation to various atmospheric, oceanic and land factors. The findings include: 1) The intensity of the winter monsoon over the East China Sea is highly correlated with the Siberian High intensity and anti-correlated with the latitudinal position of the Aleutian Low as well as the rainfall in eastern China, Korean Peninsula and Japan; 2) The western Pacific subtropical high is significantly correlated with the summer monsoon intensity over the East China Sea and anti-correlated with the summer monsoon over the South China Sea; 3) The winter monsoon in a broad zonal belt through the Luzon Strait is dominated by the ENSO signal, strengthening in the La Nifia phase and weakening in the E1 Nifio phase. This inverse relation exhibits interdecadal shift with a period of weak correlation in the 1980s; 4) Analysis of tidal records validates the interdecadal weakening of the East Asian summer monsoon and reveals an atmospheric bridge that conveys the ENSO signal into the South China Sea via the winter monsoon.
基金Under the auspices of National Natural Science Foundation of China(No.41230751,41101547)Scientific Research Foundation of Graduate School of Nanjing University(No.2012CL14)
文摘Hyperspectral data are an important source for monitoring soil salt content on a large scale. However, in previous studies, barriers such as interference due to the presence of vegetation restricted the precision of mapping soil salt content. This study tested a new method for predicting soil salt content with improved precision by using Chinese hyperspectral data, Huan Jing-Hyper Spectral Imager(HJ-HSI), in the coastal area of Rudong County, Eastern China. The vegetation-covered area and coastal bare flat area were distinguished by using the normalized differential vegetation index at the band length of 705 nm(NDVI705). The soil salt content of each area was predicted by various algorithms. A Normal Soil Salt Content Response Index(NSSRI) was constructed from continuum-removed reflectance(CR-reflectance) at wavelengths of 908.95 nm and 687.41 nm to predict the soil salt content in the coastal bare flat area(NDVI705 < 0.2). The soil adjusted salinity index(SAVI) was applied to predict the soil salt content in the vegetation-covered area(NDVI705 ≥ 0.2). The results demonstrate that 1) the new method significantly improves the accuracy of soil salt content mapping(R2 = 0.6396, RMSE = 0.3591), and 2) HJ-HSI data can be used to map soil salt content precisely and are suitable for monitoring soil salt content on a large scale.
文摘The world today is .faced with the critical challenge of developing industries .for both high technological efficiency and possibly less impact on resources and the environment. This paper employs the Slacks-based measure (SBM) to conduct an empirical analysis of China's industrial environmental efficiency between 1998 and 2008. We.found a slight decline in SBM nationwide due to the combined effects of resource^environmental constraint as well as technological progress. From a static perspective, there is a clear disparity in coordination among regions, particularly between western regions and eastern coastal regions. From a dynamic perspective, there is limited change in the coordination of industries with natural resources and the environment in coastal and central regions, but a marked decline in the northeast and western regions. This contrast can be traced to the .following reasons: the capital-intensive structure of the economy and the high proportion of large industrial enterprises that restrict the improvement of SBM environmental efficiency. Higher living standards, indigenous innovation, acquisition of new technologies, and foreign direct investment will be conducive to industries'synchronous development with natural resources and the environment.
基金financed by the National Basic Research Program of China (Grant No. 2010CB428502)the National Natural Science Foundation of China (Grant No. 40925015)
文摘A statistical regression downscaling method was used to project future changes in precipitation over eastern China based on Phase 5 of the Coupled Model Intercomparison Project (CMIPS) the Representative Concentration Pathway (RCP) scenarios simulated by the second spectral version of the Flexible Global Ocean- Atmosphere-Land System (FGOALS-s2) model. Our val- idation results show that the downscaled time series agree well with the present observed precipitation in terms of both the annual mean and the seasonal cycle. The regres- sion models built from the historical data are then used to generate future projections. The results show that the en- hanced land-sea thermal contrast strengthens both the subtropical anticyclone over the western Pacific and the east Asian summer monsoon flow under both RCPs. However, the trend of precipitation in response to warming over the 21 st century are different across eastern Chi- na under different RCPs. The area to the north of 32°N is likely to experience an increase in annual mean precipitation, while for the area between 23°N and 32°N mean precipitation is projected to decrease slightly over this century under RCP8.5. The change difference between scenarios mainly exists in the middle and late century. The land-sea thermal contrast and the associated east Asian summer monsoon flow are stronger, such that precipitation increases more, at higher latitudes under RCP8.5 compared to under RCP4.5. For the region south of 32°N, rainfall is projected to increase slightly under RCP4.5 but decrease under RCP8.5 in the late century. At the high resolution of 5 km, our statistically downscaled results for projected precipitation can be used to force hydrological models to project hydrological processes, which will be of great benefit to regional water planning and management.
基金supported by National Basic Research Program of China (Grant No. 2007CB411702)
文摘Based on a data base of multi-channel seismic profiles covered over Dongsha plateau of the northern South China Sea margin, we found that the sea bed morphology of northern South China Sea margin had been changed dramatically after Dongsha uplifting, that sedimentary layer since Miocene age had been eroded with maximum eroded thickness more than 1000 m, and that an erosive channel had been formed of 20 km in width and 200 km in length and several hundreds meters in depth on the outer shelf of northern South China Sea. The erosive channel is parallel to the 600 m isobath line, stretching from northeast to the southwest north of Dongsha uplift. The Kuroshio intrudes the South China Sea through Luzon Strait both in winter time and summer time, and in the northern South China Sea margin area, the intruded Kuroshio Branch takes the form of Pacific-Indian Ocean Through Flow (PITH) in winter time, while the Luzon Strait Subsurface Inflow (LSSIF) in summer time, the routes of both PITH and LSSIF coincide well with the distribution of the erosive channel. After climbing from the northern slope up to the northern shelf, and after joined by the southward flow from the middle northern shelf of South China Sea, the Kuroshio Branch is strengthened and thus is able to erode the sea floor, and the shape of the erosive channel is a result of the long-term interaction between the Kuroshio South China Sea Branch and the Dongsha outer shelf sea floor.
基金supported by Sinoprobe02-03(Grant No.201011042)the National Natural Science Foundation of China(Grant No.41174081)
文摘During Mesozoic to Cenozoic time, the large-scale tectono-magmatism had strongly modified the lithosphere beneath the southeastern continent of China, leaving the present-day lithosphere as a new one evolving from the ancient lithosphere that was largely removed and replaced. But this model proposed from geochemical and petrological research is urgently in need of support from seismic observational evidence. In this paper, based on the dataset recorded by the dense stations of two NE ori- ented broadband seismic profiles deployed in the coastal area of southeastern China (SE China), both P-wave (P-RF) and S-wave (S-RF) receiver functions were isolated. We identified Pls phase converted from the Lithosphere-Asthenosphere Boundary (LAB) in P-RFs of individual stations. Migrated Pls phase indicated a depth of 60-70 km for LAB. Inver- sions/comparisons of P-RF (Pls phase) and S-RF (Sip phase) waveforms together with Ps and Sp imaging for the crust and up- per mantle structure further confirmed this result. P-RF and S-RF migrated images exhibit that a flat LAB is positioned at the depth of 60-70 km spreading along the profile, whereas a distinct structural change of lithospheric base appears at the Min River estuary. Both Ps and PpPs migrated images of P-RFs present an abrupt Moho drop across the Min River fault from south to north, which is consistent with previous result obtained from deep seismic sounding. By taking into consideration other ge- ological and geophysical features such as locally high anomalies of crustal Poisson's ratios and heat flow at the Min River es- tuary, we infer that the Min River fault penetrates down to the Moho and may, furthermore, interfere in the deeper lithospheric structure.