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1.
Hydrographic data from eleven 1986–1991 cruises at zonal sections near 8°N from the Philippine coast to 130°E were used to examine thermohaline structures and water mass properties of the western boundary currents there, especially those of the Mindanao Undercurrent (MUC). The finding that the MUC consisted of two water masses with salinity of 34.6 at 26.9 σt and 34.52 at 27.2 σt which were remnants of the lower part of the Southern Pacific Subtropical Water (SPSW) and of the Antarctic Intermediate Water (AAIW) of South Pacific origin, respectively, showed that the MUC was not a local transient but originated elsewhere. As the MUC flowed from 7.5°N to 8°N, part of it carrying the SPSW turns anticyclonically and eastward. The Northern Pacific Intermediate Water (NPIW) often joins the MUC, which suggests that the NPIW carried by the MC partly returns northward as a result of the shear between the MC and the MUC or other processes. The shear instability provides the energy for the irregular fluctuation of the MUC. Contribution No. 3256 from the Institute of Oceanology, Chinese Academy of Sciences. Project 49176255 and 49706066 supported by NSFC, and also by Foundation of Post-doctoral Research.  相似文献   

2.
Vertical structure and evolution of the Luzon Warm Eddy   总被引：4，自引：0，他引：4  
Eddies are frequently observed in the northeastern South China Sea (SCS). However, there have been few studies on vertical structure and temporal-spatial evolution of these eddies. We analyzed the seasonal Luzon Warm Eddy (LWE) based on Argo float data and the merged data products of satellite altimeters of Topex/Poseidon, Jason-1 and European Research Satellites. The analysis shows that the LWE extends vertically to more than 500 m water depth, with a higher temperature anomaly of 5°C and lower salinity anomaly of 0.5 near the thermocline. The current speeds of the LWE are stronger in its uppermost 200 m, with a maximum speed of 0.6 m/s. Sometimes the LWE incorporates mixed waters from the Kuroshio Current and the SCS, and thus has higher thermohaline characteristics than local marine waters. Time series of eddy kinematic parameters show that the radii and shape of the LWE vary during propagation, and its eddy kinetic energy follows a normal distribution. In addition, we used the empirical orthogonal function (EOF) here to analyze seasonal characteristics of the LWE. The results suggest that the LWE generally forms in July, intensifies in August and September, separates from the coast of Luzon in October and propagates westward, and weakens in December and disappears in February. The LWE’s westward migration is approximately along 19°N latitude from northwest of Luzon to southeast of Hainan, with a mean speed of 6.6 cm/s.  相似文献   

3.
lwn0DorIONDuringthepastdeade,thestchdilyinewsingkn0wedgeonthewestemequatorialPadfic~ndrculation,espedallythel0w-latitudewesternboundaryimtsOLwnes)inthePadficdrin,wasrnarkedbytheimportantdiscoveryoftwowesternb0undaryundercurmtS,theNcwGuineaCoastalUndemirmt(NGCUC)Oindstrometal.,l987)andtheMindanaoUndemin-ent(MUC)peuandCui,l989),whichledtobeterdescrip-tionoftheverticalstruCture0fthePadficLLwncralth0ughunderstandingofthePadricLLWBChdynawhesisstillincomp1etC,bousetheinfluenceofthetwone…  相似文献   

4.
基于一个高分辨率准全球海洋模式HYCOM(HYbrid Coordinate Ocean Model),研究了热带西太平洋海域赤道潜流的起源。结果表明:赤道潜流在大约130°E处开始,流核位于225 m、2°N附近,最大流速超过15 cm/s,体积输运约1.6×106 m3/s,其水源来自棉兰老海流;在东部140°E断面,赤道潜流的北部主要是由棉兰老海流提供(9.7×106 m3/s),其南部主要是来自新几内亚沿岸潜流(9.1×106 m3/s)。  相似文献   

5.
We addressed the mesoscale structure variation of the central South China Sea (SCS) with the measurements by a long-lived Argo float and a high-resolution ATLAS buoy during 1998–2002. T-S diagram indicates cooling and freshening events in 2000 and 2001 with lower salinity (0.5–0.8) and lower temperature (1–1.7°C). Significant decrease in the net heat flux and increase in the precipitation suggest that the cooling and freshening is due to extra forcing by the atmosphere. Additional to large year-to-year changes, intraseasonal variability is moderate in the research area. The axis of the maximum intraseasonal temperature and salinity signals are mainly located on the thermocline. Typically, amplitude and period of intraseasonal temperature is about 2°C and 40–60 days, and that of salinity is 0.3–0.5 and 35–60 days. Rapidly-changing winds, heat flux, and precipitation are critical in controlling the intraseasonal fluctuations of the mixed layer of the area. Studies on heat and freshwater balance in the mixed-layer further suggest that horizontal advection plays an important role in intraseasonal fluctuation in the upper ocean. In addition, the energetic mesoscale propagation radiated from the east boundary is linked to the intraseasonal variability in winter.  相似文献   

6.
3-factor experiment was used to study the combined effects of temperature, irradiance and salinity on the growth of an HAB species diatomSkeletonema costatum (Grev.) Cleve. The results showed that temperature (12, 19, 25, 32 °C), irradiance (0.02, 0.08, 0.3, 1.6)×1016 quanta/(s·cm2)) and salinity (10, 18, 25, 30, 35) significantly influenced the growth of this species. There were interactive effects between any two of and among all three physical factors on the growth. In the experiment, the most optimal growth condition forS. costatum was temperature of 25°C, salinity of 18–35 and irradiance of 1.6×1016 quanta/(s·cm2). The results indicatedS. costatum could divide at higher rate and were more likely to bloom under high temperature and high illumination from spring to fall. It was able to distribute widely in ocean and estuary due to its adaptation to a wide range of salinities. This study was supported by the PREPP and National Key Basic Research Project (2001CB4097) NNSFC No. 39950001, 20177023, 49576301, 49906007 and KZCX2-206.  相似文献   

7.
Experiments on salimity tolerance of embryos and larvae of the southern bay scallopArgopecten irradians concentricus Say under controlled temperature of 28°C showed that although the eggs were fertilized and cleaved at salinity 18.1–37.4, they could further develop into normal D-shaped larvae only at salinity 23.4–36.1, while the trochophore larvae could develop into normal D—shaped larvae at salinity 22.1–39.9. For 72 hours, the larvae could tolerate salinity of 18.4–43.9, the salinity favoring growth was 19.8–42.4; the suitable range was 21–36, and the optimum at about 28. They metamorphosed at salinity 18.9–43.5, optimally at 24–32. Contribution No. 3301 from the Institute of Oceanology, Chinese Academy of Sciences. The research was supported by the National Climbing Project B(PDB6-3-2).  相似文献   

8.
The general features of the seasonal surface heat budget in the tropical western Pacific Ocean, 20° S–20°N, western boundary −160°E, were documented by Qu (1995) using a high-resolution general circulation model (GCM, Semtner & Chervin, 1992) and existing observations. Close inspection of the smaller areas, with the whole region further partitioned into six parts, showed different mechanisms balance the seasonal surface heat budget in different parts of the region. The results of study on five subregions are detailed in this article. In the equatorial (3°S–3°N) and North Equatorial Countercurrent (3°N–9°N) region, the surface heat flux does not change significantly throughout the year, so the surface heat content is determined largely by vertical motion near the equator and roughly half due to horizontal and half due to vertical circulation in the region of the North Equatorial Countercurrent (NECC). In the other subrigions (9°N–20°N, 20°S–11°S and 11°S–3°S), however, in addition to ocean dynamics, surface heat flux can also play a major role in the seasonal variation of sea surface temperature (SST). The remotely forced baroclinic waves and their effect on the surface heat storage in the model are also investigated. Comparison with observations indicates that the model wave activities are reasonably realistic. Contribution No. 2396 from the Institute of Oceanology, Chinese Academy of Sciences. This study was supported by the Australian CSIRO Division of Oceanography and the National Natural Science Foundation of China (No. 49176255)  相似文献   

9.
Effects of reduced salinity on the oxygen consumption rate (OCR) and the ammonia-N excretion rate (AER) of scallopChlamys farreri (3.2–5.9 cm in shell height, 0.147–1.635 g in soft tissue dry weight) were studied in laboratory from March 21, 1997 to April 16, 1997. Under the controlled conditions of reduced salinity from 31.5 to 15.0 and ambient temperature 17°C and 23°C, the concentrations of dissolved oxygen and ammonia-N were determined by the Winkle method and the hypobromite method, respectively. Results showed that with controlled reduced salinity, the mean values of the OCR were 2.17 mg/(g.h) at 17°C, and 2.86 mg/(g.h) at 23°C and that the mean values of the AER were 178.0 μg/(g.h) at 17°C and 147.0 μg/(g.h) at 23°C. The OCR and the AER decreased with reducing salinity from 31.5 to 15.0 both at 17°C and 23°C. The effects of reduced salinity on the OCR and the AER of scallopC. farreri could be represented by the allometric equation and the exponential equation, respectively. Contribution No. 3295 from the Institute of Oceanology, Chinese Academy of Sciences. Project supported by the National Ministry of Science and Technology of China and by the Chinese Academy of Sciences, Grant No. 96-922-02-04 and KZ951-A1-102-02.  相似文献   

10.
Results of numerical simulation of currents in the western North Tropical Pacific Ocean by using a barotropic primitive equation model with fine horizontal resolution agreed well with observations and showed that the Mindanao Cyclonic Eddy located north of the equator and east of Mindanao Island exists during most of the year with monthly (and large seasonal) variations in scope . strength and central location . In June , an anticyclonic eddy occurs northeast of Halmahera Island, strengthens to maximum in August , exists until October and then disappears . The observed large-scale circulation systems such as the North Equatorial Current . the Mindanao Current and the North Equatorial Countercurrent are all very well reproduced in the simulations.  相似文献   

11.
INTRODUCTIONTheSubeiShoalandtheChangjiangRiverestuarineareainthewestoftheHuanghaiandEastChinaSeasisoneofthemarginalseasintheworld ,wheresuspendedmatterisextremelyhigh .Here ,notonlyistheretheTaiwanWarmCurrentoneoftheKuroshio’sbranchesintheEastChinaSea,butalsotheHuanghaiCoastalCurrent,andChangjiangDilutedWater.Sothestrongmixingbetweenthecoastalandoffshorewaterscomplicatessuspendedmatterdistributioninthisarea.HowthesuspendedmatterdischargedfromtheChangjiangRiverandtheabandonedHuan…  相似文献   

12.
Based on a simple conceptual model of stratified ocean, the criterion of the geostrophic velocity inversion in and below the thermocline was derived ash′·ν′<0 and {ie1-1}, meaning that the slopes of the thermocline (h′) and the sea {ie1-2} must be opposite to each other, and thath′ must be strong enough to satisfy the latter inequality. The criterion was applied to discuss the features of the western boundary undercurrents, the counter undercurrents of the western boundary currents below the thermocline, and to discuss the dynamics of their formation finally resulting from the combination of the basin-scale circulation and local geostrophic balance. The formation mechanism, multicore structure, and transport variations of the Mindanao Undercurrent and those of other undercurrents, such as the North Equatorial Undercurrent and the Kuroshio undercurrent, can be satisfactorily explained by the above results. Research supported by the Postdoctoral Research Foundation and the NSFC (No. 49176255 and 49706066). Contribution No. 3405 from the Institute of Oceanology, Chinese Academy of Sciences.  相似文献   

13.
Effects of temperature on oxygen consumption rate (OCR) and ammonia—N excretion rate of scallopChlamys farreri (1.7–6.2 cm in shell height) were studied in laboratory from Dec. 30,1996 to Jan. 28,1997. Under the controlled conditions of ambient water temperature 10–31°C and salinity 32, the concentrations of dissolved oxygen and ammonia—N were determined by the Winkle method and the hypobromite method, respectively. Results showed that the OCR ranged from 1.20 mg/g (DW) · h to 5.76 mg/g (DW) · h. The OCR increased with temperature from 10°C to 23°C, but at 28°C the OCR of mature individuals decreased, and that of different size scallops reduced at 31°C. The ammonia—N excretion rate ranged from 113.03 μg NH4-N/g (DW) · h to 486.63 μg NH4-N/g (DW) · h, and increased with temperature from 10°C to 31°C. Contribution No.3180 from the Institute of Oceanology, Chinese Academy of Sciences. This work was supported by the National Commission of Science and Technology of China, Grant No.96-922-02-04.  相似文献   

14.
The regional observed temperature and precipitation changes and their abrupt jumps disturbed by large-scale reclamation in the Sanjiang Plain, Northeast China were studied. Mean annual temperature of the region was tending to go up and has increased by 1.2-2.2℃ over the past 50 years. A warming jump of mean annual temperature of the region occurred in the 1980s, which had an increase amplitude of 0.9℃. Linear tendency rates of annual precipitation were negative in most of the region. The maximum of annual precipitation decrease was 155.8mm over the past 50 years. An abrupt decrease of regional annual precipitation happened in the middle of the 1960s,which had a decrease of 102.1 mm. Based on the fact of climatic change of the Sanjiang plain over the past 50 years,it is held that the region had larger warming amplitude than that change of the Sanjiang Plain over the past 50 years,it is held that the region had larger warning amplitude than that of the surrounding areas in the recent years, which resulted from the large-scale reclamation of various kinds of wetlands.  相似文献   

15.
Eighy-one CTD profiles gathered in springtime were used for northem East China Sea tbermohalinefinestructure studies indicating that the finestructure properties vaned with region and depth, as shown infinesructure specra, distribution of Cox numbers etc..Some results closely wiated to distribution of watermasses and Analysis of two typical profiles revealed differenes in autospectra of temperature,salihity and potential density gradients, probobility distribution of temperature finestructure gradient,Cox numberc.etc. The probability density function of vertical temperature gradients, which varied withsample interval, is given. The variances of temperatare finestructare gradient are used to estimate the lat-eral diffusivity and lateral temperatare flux, which were 10.3 (m~2/s) and 5.5×10~(-4) (℃ m/s),respectivly.  相似文献   

16.
As it is well-known, the North Equatorial Current (NEC) bifurcates into the Kuroshio flowing northward and the equatorward Mindanao Current, which is well depicted by Munk’s theory in 1950 in terms of its climatology. However, Munk’s theory is unable to tell the NEC bifurcation variability with time. In the present paper, a time-dependent baroclinic model forced by wind, in which temporal and baroclinic terms are added to Munk’s equation, is proposed to examine the seasonal variability of the NEC bifurcation latitude. An analytical solution is obtained, with which the seasonal variability can be well described: NEC bifurcation reaches its northernmost position in December and its southernmost position in June with a range of about 1° in latitude, consistent with previous results with observations. The present solution will degenerate to Munk’s one in the case of steady and barotropic state.  相似文献   

17.
The Taiwan Warm Current Deep Water (or the East China Sea Upper Layer Water, or the East China Sea Subsurface Water) lying in the deep and bottom layers off the coast of Fujian-Zhejiang is one of the main watermasses in the continental shelf region of the western East China Sea. The hydrographical conditions and the fishery productions in this region are affected remarkably by the decline and growth of the Taiwan Warm Current Deep Water. Although the temperature, salinity and origin of the Taiwan Warm Current Deep Water have been investigated[3] by oceanographers the world over, there are up to now few papers published on its characteristics of ariations (seasonal and multiyear variations). Understanding of this problem will be helpful to further characterize this watermass. For this reason, in this paper, section 28°N representing the middle Taiwan Warm Current Deep Water and section 30°N representing the northern Taiwan Warm Current Deep Water are taken for examples, and the method of similar coefficient is used for analysis of this problem. Contribution No. 861 from the Institute of Oceanology, Academia Sinica. This paper was published in Chinese inOceanologia et Limnologia, Sinica 14 (4): 357–366.  相似文献   

18.
Heat center of the western Pacific warm pool   总被引：1，自引：0，他引：1  
A heat center (HC) of the western Pacific warm pool (WPWP) is defined, its variability is examined, and a possible mechanism is discussed. Analysis and calculation of a temperature dataset from 1945-2006 show that the mean position of the HC during this period was near 0.4°S/169.0°E, at 38.0 m depth. From a time series of the HC, remarkable seasonal variability was found, mainly in the meridional and vertical directions. Interannual variabilities were dominant in the zonal and vertical directions. In addition, semiannual variation in the HC depth was discovered. The longitude of the HC varies with ENSO events, and its latitude is weakly related to ENSO on time scales shorter than a decade. The variation of the HC longitude leads the Nio-3 index by about 3-4 months, and its depth lags the index for approximately 3 months. It is concluded that the HC depth results from a combination of its longitudinal and latitudinal variations. Low-pass-filtered time series reveal that the HC has moved eastward since the mid 1980s.  相似文献   

19.
Subtropical mode water in the northwestern pacific   总被引：1，自引：0，他引：1  
  相似文献   

20.
Based on the GDEM hydrographic data with a resolution of 0.5°×0.5°, the current system (Kuroshio south of Japan and Kuroshio Extension east of Japan) is determined by using the P-Vector Method, and its seasonal variability is investigated. The Kuroshio Meander south of Japan, the two lee-wave meanders in the Kuroshio Extension and the bifurcation of the Kuroshio Extension are properly presented. The path of the Kuroshio Meander, the position of the second (east) meander in the Kuroshio Extension and the bifurcation of the Kuroshio Extension display evident seasonal variation.  相似文献   

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