横穿黑潮锋断面的流场结构

基于一组简化了的运动方程组，在充分考虑底Ekman层作用的情况下，提出一种横穿锋面的断面上流场结构的计算方法。应用该方法对东海横穿黑潮锋的不同断面上的流场（1989－1990年资料）进行计算。结果表明，黑潮锋左侧（向岸侧）存在较强的上升流，而锋区右侧（离岸侧）表现为海水的下降运动。垂直流速为（1－20）×10－3cm／s的量级，而横穿锋面方向的水平流速为1－3cm／s，其中以夏、秋季跃层附近最强。在陆架坡折处，上升流转向陆架。同时，还分析了正压场和斜压场对这种流场的不同贡献，认为在黑潮区，正压场起主要作用;而在内陆架区，斜压场则变得重要。将计算的流场与硝酸盐的分布比较表明，两者有较好的对应关系。     

Surface boundary-layer variability off Northern California, USA, during upwelling

A five-element mooring array is used to study surface boundary-layer transport over the Northern California shelf from May to August 2001. In this region, upwelling favorable winds increase in strength offshore, leading to a strong positive wind stress curl. We examine the cross-shelf variation in surface Ekman transport calculated from the wind stress and the actual surface boundary-layer transport estimated from oceanic observations. The two quantities are highly correlated with a regression slope near one. Both the Ekman transport and surface boundary layer transport imply curl-driven upwelling rates of about 3×10⁻⁴ m s⁻¹ between the 40 and 90 m isobaths (1.5 and 11.0 km from the coast, respectively) and curl-driven upwelling rates about 1.5×10⁻⁴m s⁻¹ between the 90 and 130 m isobaths (11.0 and 28.4 km from the coast, respectively). Thus curl-driven upwelling extends to at least 25 km from the coast. In contrast, upwelling driven by the adjustment to the coastal boundary condition occurs primarily inshore of the 40-m isobath. The upwelling rates implied by the differentiating the 40-m transport observations with the coastal boundary condition are up to 8×10⁻⁴ m s⁻¹. The estimated upwelling rates and the temperature–nitrate relationship imply curl-driven vertical nitrate flux divergences are about half of those driven by coastal boundary upwelling.     

Inferring upwelling rates in the equatorial Atlantic using Be measurements in the upper ocean

Ocean upwelling rates are difficult to measure because of the relatively small velocities involved, and therefore are typically inferred from indirect methods such as heat budget estimates or tracer observations. Here we present the first results using a novel technique, based on the isotope ⁷Be, to infer rates of upwelling along the equator. Beryllium-7 (half-life=53.3 d) is a cosmic-ray produced radioactive nuclide that is deposited by rainfall upon the ocean surface and subsequently enriched and homogenized within the mixed layer. Previous investigations have utilized the penetration of characteristically high mixed layer concentrations into the upper thermocline to trace ocean ventilation and subduction over seasonal timescales. Here, the tracer is used in a reverse sense; that is, the ⁷Be concentration in the usually ⁷Be-rich surface mixed layer will be diluted from penetration of ⁷Be “dead” water upwelled from below. This dilution provides a means to infer upwelling rates. Furthermore, with knowledge of upwelling rates, ⁷Be profiles can be used to constrain vertical diffusivity within the upper thermocline. These ideas were tested with samples collected during the Tropical Atlantic Climate Experiment (TACE) cruise (May 22-June 27, 2009). The observations indicated a nearly linear relationship between ⁷Be inventory and mixed layer temperature, as with increased upwelling, lower mixed layer temperatures correspond to greater ⁷Be dilution from depth. With this data, upwelling rates were estimated at a number of stations near the equator between 0°E and 30°W within and adjacent to the equatorial cold tongue. The derived upwelling rates ranged from 0 to 2.2 m/d, with maximum values found between the equator and 2°S. The corresponding K_z values derived for the upper thermocline were in the range 1-4×10⁻⁴ m²/s.     

Organic carbon accumulation and sulfate reduction rates in slope and basin sediments of the Ulleung Basin,East/Japan Sea

This study investigated the organic carbon accumulation rates (OCARs) and sulfate reduction rates (SRRs) in slope and basin sediments of the Ulleung Basin, East/Japan Sea. These sediments have high organic contents at depths greater than 2,000 m; this is rare for deep-sea sediments, except for those of the Black Sea and Chilean upwelling regions. The mean organic carbon to total nitrogen molar ratio was estimated to be 6.98 in the Ulleung Basin sediments, indicating that the organic matter is predominantly of marine origin. Strong organic carbon enrichment in the Ulleung Basin appears to result from high export production, and low dilution by inputs of terrestrial materials and calcium carbonate. Apparent sedimentation rates, calculated primarily from excess ²¹⁰Pb distribution below the zone of sediment mixing, varied from 0.033 to 0.116 cm year⁻¹, agreeing well with previous results for the basin. OCARs fluctuated strongly in the range of 2.06–12.5 g C m⁻² year⁻¹, these rates being four times higher at the slope sites than at the basin sites. Within the top 15 cm of the sediment, the integrated SRRs ranged from 0.72 to 1.89 mmol m⁻² day⁻¹, with rates approximately twice as high in the slope areas as in the basin areas. SRR values were consistently higher in areas of high sedimentation and of high organic carbon accumulation, correlating well with apparent sedimentation rates and OCARs. The sulfate reduction rates recorded in the basin and slope sediments of the Ulleung Basin are higher than those reported for other parts of the world, with the exception of the Peruvian and Chilean upwelling regions. This is consistent with the high organic carbon contents of surface sediments of the Ulleung Basin, suggesting enhanced organic matter fluxes.     

Seasonal dynamics of inorganic nutrients and phytoplankton biomass in the NW Alboran Sea

The seasonal dynamics of inorganic nutrients and phytoplankton biomass (chlorophyll a), and its relation with hydrological features, was studied in the NW Alboran Sea during four cruises conducted in February, April, July and October 2002. In the upper layers, the seasonal pattern of nutrient concentrations and their molar ratios (N:Si:P) was greatly influenced by hydrological conditions. The higher nutrient concentrations were observed during the spring cruise (2.54 μM NO₃⁻, 0.21 μM PO₄³⁻ and 1.55 μM Si(OH)₄, on average), coinciding with the increase of salinity due to upwelling induced by westerlies. The lowest nutrient concentrations were observed during summer (<0.54 μM NO₃⁻, 0.13 μM PO₄³⁻ and 0.75 μM Si(OH)₄, on average), when the lower salinities were detected. Nutrient molar ratios (N:Si:P) followed the same seasonal pattern as nutrient distribution. During all the cruises, the ratio N:P in the top 20 m was lower than 16:1, indicating a NO₃⁻ deficiency relative to PO₄³⁻. The N:P ratio increased with depth, reaching values higher than 16:1 in the deeper layers (200–300 m). The N:Si ratio in the top 20 m was lower than 1:1, excepting during spring when N:Si ratios higher than 1:1 were observed in some stations due to the upwelling event. The N:Si ratio increased with depth, showing a maximum at 50–100 m (>1.5:1), which indicates a shift towards Si-deficiency in these layers. The Si:P ratio was much lower than 16:1 throughout the water column during the four cruises. In general, the spatial and seasonal variation of phytoplankton biomass showed a strong coupling with hydrological and chemical fields. The higher chlorophyll a concentrations at the depth of the chlorophyll maximum were found in April (2.57 mg m⁻³ on average), while the lowest phytoplankton biomass corresponded to the winter cruise (0.74 mg m⁻³ on average). The low nitrate concentrations together with the low N:P ratios found in the upper layers (top 20 m) during the winter, summer and autumn cruises suggest that N-limitation could occur in these layers during great part of the year. However, N-limitation during the spring cruise was temporally overcome by nutrient enrichment caused by an intense wind-driven upwelling event.     

Coastal upwelling and downwelling events in the Seto Inland Sea

Prominent coastal upwelling and downwelling events due to Ekman transport were observed during the period from 14 to 18 August 1983 along the Misaki Peninsula in the Seto Inland Sea, Japan. The coastline of the Misaki Peninsula is aligned approximately in an ENE-WSW direction. When an ENE wind continued blowing for about two days, the warm water in the upper layer was pushed offshore and cold water in the lower layer upwelled along the peninsula. The estimated upwelling speed 3 m below the sea surface was 0.032 cm sec^–1. On the other hand, when a WSW wind continued blowing for about two days the warm water in the upper layer sank into the lower layer along the peninsula. The estimated downwelling speed 3 m below the sea surface was 0.080 cm sec^–1. The time lag between the variations of the alongshore wind and offshore current was about 0.5 days.     

Age and growth of the pufferfish Uranostoma richei (Plectognathi: Lagocephalidae) from Lyttelton Harbour

Abstract

The age of pufferfish Uranostoma richei (Freminville) in Lyttelton Harbour, South Island, New Zealand is described from analyses of length‐frequency distributions and growth zones in otoliths. Length‐frequency analysis is adequate only for aging smaller fish. The validity of using growth zones in otoliths is checked by examining the pattern and time of zone formation. Length‐weight relationships are established and growth rates calculated. Compared with males, females grow faster (2.4cm·y^?1; 2.1 for males), attain a larger size (to 18 cm and 120 g; 12 cm and 40 g for males) and live longer (to 7 y; 5 for males).     

Structure of potential upwelling areas in the Philippines

The three-dimensional structure of two potential mesoscale upwelling areas that are located in the external waters of the Philippine archipelago (i.e. northwest of Luzon and east of Mindanao) were constructed by analysis of historical data. A unique characteristic of both upwelling sites is that they can be identified by their anomalously cold subsurface temperatures rather than sea surface temperature distributions. As such, they cannot be observed in sea surface temperature fields derived by satellite imagery. The data used in the analysis were obtained from the National Oceanographic Data Center hydrographic database. Objective analysis was performed to produce monthly temperature fields at several standard depths within the upper 500 m of the region 0–30°N and 100–140°E with a horizontal grid resolution of 0.5°. The extent and timing of these upwelling areas are described. A review of existing hypothesis on the mechanisms for their evolution and seasonal modulation are presented. The change in heat content during the upwelling season is greater than 300 W m⁻² in both areas. Based on the excursion of isotherms, vertical velocities of 83 cm day⁻¹ and 26 cm day⁻¹ were obtained for upwelling northwest of Luzon and east of Mindanao, respectively.     

Air–sea carbon dioxide fluxes in the coastal southeastern tropical Pacific

Comprehensive sea surface surveys of the partial pressure of carbon dioxide (pCO₂) have been made in the upwelling system of the coastal (0–200 km from shore) southeastern tropical Pacific since 2004. The shipboard data have been supplemented by mooring and drifter based observations. Air–sea flux estimates were made by combining satellite derived wind fields with the direct sea surface pCO₂ measurements. While there was considerable spatial heterogeneity, there was a significant flux of CO₂ from the ocean to the atmosphere during all survey periods in the region between 4° and 20° south latitude. During periods of strong upwelling the average flux out of the ocean exceeded 10 moles of CO₂ per square meter per year. During periods of weaker upwelling and high productivity the CO₂ evasion rate was near 2.5 mol/m²/yr. The average annual fluxes exceed 5 mol/m²/yr. These findings are in sharp contrast to results obtained in mid-latitude upwelling systems along the west coast of North America where the average air–sea CO₂ flux is low and can often be from the atmosphere into the ocean. In the Peruvian upwelling system there are several likely factors that contribute to sea surface pCO₂ levels that are well above those of the atmosphere in spite of elevated primary productivity: (1) the upwelling source waters contain little pre-formed nitrate and are affected by denitrification, (2) iron limitation of primary production enhanced by offshore upwelling driven by the curl of the wind stress and (3) rapid sea surface warming. The combined carbon, nutrient and oxygen dynamics of this region make it a candidate site for studies of global change.     

The herbivorous impact of microzooplankton during two short-term Lagrangian experiments off the NW coast of Galicia in summer 1998

Microzooplankton (heterotrophic microplankton and heterotrophic nanoflagellates) and their herbivorous activity were estimated from dilution experiments in August 1998 during two Lagrangian drift experiments that sampled contrasting conditions—an upwelling/relaxation event along the shelf edge and an oligotrophic offshore filament. During upwelling/relaxation, heterotrophic microplankton were present at mean surface concentrations between 15,000 and 48,000 cells l⁻¹. Heterotrophic nanoflagellate concentrations were between 200 and 700 cells ml⁻¹ and the most abundant component of the heterotrophic microplankton was the aloricate choreotrich ciliates which increased dramatically in concentration from 6,000 to 24,000 cells l⁻¹ during the first 4 days of the study. Total microzooplankton biomass reached a maximum of 39mgC.m⁻³. In the filament, which developed from the upwelling, cell concentrations were lower and averaged 4,500 cells l⁻¹ for heterotrophic microplankton and 250 cells ml⁻¹ for heterotrophic nanoflagellates. Total microzooplankton biomass was about 10–12mgC.m⁻³. Microzooplankton turned over between 40 and 85% of the phytoplankton standing stock, thereby consuming between 5 and 78mg phytoplankton carbon.m⁻³.d⁻¹. The magnitude of this activity was highest during upwelling/relaxation and was positively correlated to heterotrophic nanoflagellate biomass and chlorophyll-a concentration but not heterotrophic microplankton biomass. The proportion of primary production grazed decreased from 160 to 59% d⁻¹ during upwelling/relaxation and ranged between 60 and 90% d⁻¹ in the filament. Microzooplankton herbivory within the euphotic zone increased from 684 to >2000mgC.m⁻².d⁻¹ during upwelling/relaxation and was between 327 and 802mgC.m⁻².d⁻¹ in the filament. Although microzooplankton herbivory was lower and less variable during the filament study, microzooplankton consumed on average 60% of the phytoplankton standing stocks which was higher than found during upwelling/relaxation. Microzooplankton assimilation efficiency ranged between 3 and 33% during upwelling/relaxation and between 0 and 13% in the filament. Our data demonstrate a close coupling between phytoplankton growth and microzooplankton herbivory in surface waters off the Galician Coast and suggest that microzooplankton may have been a significant sink for phytogenic carbon during August 1998.     

Determining spatial changes in the diet of nearshore suspension-feeders along the South African coastline: Stable isotope and fatty acid signatures

Mesoscale oceanographic features, such as upwellings, are known to play an important role in regulating the structure and productivity of nearshore marine communities. Stable isotope (δ¹³C and δ¹⁵N) and fatty acid analyses were employed to assess the influence of an upwelling cell along the south-eastern coastline of southern Africa on the diet of the mussel, Perna perna. Eight sites were sampled: two upstream, three in the vicinity and three downstream of the upwelling cell. Stable isotope and fatty acid signatures indicated that the mussels consumed a diet of detritus derived mainly from macroalgae, diatoms and dinoflagellates. One-way ANOVA on the δ¹³C and δ¹⁵N signatures and the principal component analysis of the fatty acid profiles of the mussels identified distinct groups corresponding to the above mentioned regions. The proportion of diatom biomarkers in the fatty acid profiles decreased downstream of the upwelling region while the proportion of dinoflagellate biomarkers increased. Upwelling regions are typically associated with elevated levels of productivity; however, these systems usually become silicon depleted and result in the replacement of diatoms with dinoflagellates. The highest proportions of the dinoflagellate markers were recorded in the two furthest sites downstream of the upwelling cell. The spatial variation in the diet of the mussels, therefore, appears to reflect the presence of the upwelling cell in the nearshore biology of the region.     

Distribution and transport of organic matter along a filament-eddy system in the Canaries – NW Africa coastal transition zone region

The distribution and transport of chlorophyll a (Chla), particulate (POC) and dissolved (DOC) organic carbon, and the respiratory ETS activity of the microplankton community were studied along a filament-eddy system located in the transition zone between the NW Africa upwelling and Canary Islands waters. Two independent filaments (F1 and F2) stemming from the coastal jet, between Cape Juby and Cape Bojador, merged about 100 km offshore, turning southward and onshore forced by the circulation of a recurrent oceanic cyclonic eddy. In general, the coastal upwelling waters presented higher Chla, but lower POC, DOC and ETS activity than filament waters. However, differences in organic carbon distribution and respiratory activity were observed among stations from the two filaments. The bio-chemical fields were strongly influenced by a complex sub-mesoscale hydrography resulting from the interaction of cyclonic and anticyclonic island eddies with the filaments. The combined F1 + F2 filament system transported 97.1 kg s⁻¹ of excess (non-refractory) total organic carbon (e-TOC), a value comparable to other published estimates from upwelling filaments in the NE Atlantic. About 90% of e-TOC was exported as DOC, since eddy re-circulation precluded the offshore transport of POC. Assuming that the calculated transport of e-TOC is representative of the annual average, the yearly offshore transport (3.1 x 10⁹ kg C) would represent about 25% of the upwelling primary production of the region of study.     

Numerical studies of upwelling in coastalareas of the East China Sea——Ⅰ The tide-induced upwelling

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Growth of red gurnard (Teleostei: Triglidae) from Pegasus bay,Canterbury, New Zealand

Growth of the red gurnard, Chelidonichthys kumu (Lesson and Garnot), from Pegasus Bay, Canterbury, was measured during 1966–67. Otoliths were used as an indicator of fish growth; mean length‐at‐age data were obtained from back‐calculated fish lengths at the time of formation of successive annual rings in the otoliths. Growth in length was found to be adequately expressed by the von Bertalanffy growth equation :

l_t = 52.0 [1 ‐ e‐^{0.406 (t‐o.291)}]

(where l_t is the fork length in cm at age t). The length: weight relationship was:

w = 78.56 × 10^‐4 l ^3.072

(where w is the weight in grams). From this relationship, growth in weight was described by the equation:

w_t = 1469 [1 ‐ e‐0.406 (t‐0.291)]³.     

Estimation of the upwelling rate of deep waters in the Black Sea from the H2S vertical distribution

The expression for the bottom convection intensity is derived from the equality of the advective vertical flux of H₂S within 1000–2000 m to the diffusion turbulent flow close to the H₂S zone upper boundary. The upwelling rate, which is expressed via the H₂S concentration in deep waters and the gradient of the H₂S concentration near the upper boundary, is 10^–4 cm/s. It is shown that the H₂S diffusion flux in deep waters is an order less than the advective one. The conclusion that below 1000 m the age of H₂S does not exceed 30 years and H₂S reaches the upper boundary in approximately 150 years is derived.Translated by Mikhail M. Trufanov.     

南海浅层经向翻转环流及相关的内部水体流动

The structure of the annual-mean shallow meridional overturning circulation(SMOC) in the South China Sea(SCS) and the related water movement are investigated,using simple ocean data assimilation(SODA) outputs.The distinct clockwise SMOC is present above 400 m in the SCS on the climatologically annual-mean scale,which consists of downwelling in the northern SCS,a southward subsurface branch supplying upwelling at around 10°N and a northward surface flow,with a strength of about 1×10~6 m~3/s.The formation mechanisms of its branches are studied separately.The zonal component of the annual-mean wind stress is predominantly westward and causes northward Ekman transport above 50 m.The annual-mean Ekman transport across 18°N is about 1.2×10~6 m~3/s.An annual-mean subduction rate is calculated by estimating the net volume flux entering the thermocline from the mixed layer in a Lagrangian framework.An annual subduction rate of about 0.66×10~6m~3/s is obtained between 17° and 20°N,of which 87% is due to vertical pumping and 13% is due to lateral induction.The subduction rate implies that the subdution contributes significantly to the downwelling branch.The pathways of traced parcels released at the base of the February mixed layer show that after subduction water moves southward to as far as 11°N within the western boundary current before returning northward.The velocity field at the base of mixed layer and a meridional velocity section in winter also confirm that the southward flow in the subsurface layer is mainly by strong western boundary currents.Significant upwelling mainly occurs off the Vietnam coast in the southern SCS.An upper bound for the annual-mean net upwelling rate between 10° and 15°N is 0.7×10~6m~3/s,of which a large portion is contributed by summer upwelling,with both the alongshore component of the southwest wind and its offshore increase causing great upwelling.     

南海东北部春季海表pCO_2分布及海-气CO_2通量

2013年南海东北部春季共享航次采用走航观测方式,现场测定了表层海水和大气的二氧化碳分压(pCO2)及相应参数。结合水文、化学等同步观测要素资料,对该海域pCO2的分布变化进行了探讨。结果表明,陆架区受珠江冲淡水、沿岸上升流及生物活动的影响,呈现CO2的强汇特征;吕宋海峡附近及吕宋岛西北附近海域受海表高温、黑潮分支"西伸"、吕宋岛西北海域上升流等因素影响,呈现强源特征。根据Wanninkhof的通量模式,春季整个南海东北部海域共向大气释放约4.25×104 t碳。     

Three-dimensional circulation in the NW Africa coastal transition zone

High-resolution data collected southeast of the Canary Islands during late winter 2006 are analyzed to describe the hydrography and three-dimensional circulation in the coastal transition zone off NW Africa. The data are optimally interpolated over a regular grid, the geostrophic velocity field is calculated and the Q-vector formulation of the omega equation is used to compute the quasi-geostrophic (QG) mesoscale vertical velocity. The coastal transition zone is divided into upwelling, frontal and offshore regions with distinct physical and dynamic characteristics. The upwelling region is characterized by cold and weakly stratified waters flowing towards the equator, with a poleward undercurrent of approximately 0.05 m s⁻¹ over the continental slope. The frontal region exhibits a southwestward baroclinic jet associated with cross-shore raising isopycnals; the jet transport is close to 1 Sv, with maximum velocities of 0.18 m s⁻¹ at surface decreasing to 0.05 m s⁻¹ at 300 db. Vertical sections across the frontal region show the presence of deep eddies probably generated by the topographic blocking of the islands to the southward current, as well as much shallower eddies that likely have arisen as instabilities of the baroclinic upwelling jet. The QG mesoscale vertical velocity field is patchy, estimated to range from −18 to 12 m day⁻¹, with the largest absolute values corresponding to an anticyclonic eddy located south of Fuerteventura Island. These values are significantly larger than estimates for other vertical velocities: diapycnal vertical velocities associated with mixing in the frontal region (a few meters per day), and wind-induced vertical velocities (non-linear Ekman pumping arising from the interaction between the wind stress and the background vorticity, maximum values of a few meters per day; linear Ekman pumping due to the divergence of Ekman transport, a fraction of a meter per day; or the coastal constraint in the upwelling region, about 0.7 m day⁻¹). However, the patchiness in both the QG mesoscale vertical velocity and the non-linear Ekman pumping velocity cause their integrated vertical transports to be one order of magnitude smaller than either coastal Ekman transport (0.08 Sv), integrated linear Ekman pumping (−0.05 Sv) or diapycnal transfer (about 0.1–0.2 Sv). The pattern of the near-surface fluorescence field is a good indicator of these different contributions, with large homogeneous values in the coastal upwelling region and a patchy structure associated with the offshore mesoscale structures.     

Currents along the Tsitsikamma coast,South Africa,and potential transport of squid paralarvae and ichthyoplankton

In July 1998, a bottom-mounted Acoustic Doppler Current Profiler was deployed at 36m depth in the centre of the Tsitsikamma National Park on the eastern Agulhas Bank, South Africa. The purpose was to investigate transport of chokka squid Loligo vulgaris reynaudii paralarvae hatched on the inshore spawning grounds (<60m) and ichthyoplankton spawned within the park. Analysis of the first 12 months of data (July 1998–June 1999) shows that surface flow was mainly eastward (alongshore), with a maximum velocity (u-component) of +115cm s^?1 and an average of +24cm s^?1. Generally, velocity decreased with depth, with a maximum bottom velocity (u-component) of +65cm s^?1 and an average of +10cm s^?1. Data from a nearby thermistor array show that the water column was usually isothermal during winter (July–September), with bottom flow in the same direction as the surface layer. In summer (December–March), vertical stratification was most intense, and surface and bottom flows differed in velocity and direction. Potential net monthly displacements calculated for three depths (5m, 23m and 31m) indicate that passive, neutrally buoyant biological material (e.g. squid paralarvae, fish eggs and larvae) would likely be transported eastwards in the surface layer for eight of the 12 months, and would generally exceed distances of 220km month–1. Displacement in the bottom layer was more evenly distributed between east and west, with net monthly (potential) transport typically 70–100km, but reaching a maximum of 200km. Wind-driven coastal upwelling, prevalent during the summer, causes the surface layer of the coastal counter-current to flow offshore for several days, resulting in potential displacement distances of 40km from the coast. These results suggest that squid paralarvae hatched on the inshore spawning grounds are not generally transported towards the 'cold ridge', a prominent semi-permanent oceanographic feature of cold, nutrient-rich upwelled water, where food is abundant, and that fish larvae, whether from the surface or bottom layer, are exported beyond the boundaries of the Tsitsikamma National Park.     

Quantitative evaluation of turbulent mixing in the Central Equatorial Pacific

Turbulent mixing in the central equatorial Pacific has been quantitatively evaluated by analyzing data from microstructure measurements and conductivity temperature depth profiler (CTD) observations in a meridionally and vertically large region. The result that strong turbulent mixing with dissipation rate ε (>O(10^?7) W kg^?1), continuing from sea-surface mixed layer to low Richardson number region below, in the area within 1° of the equator, shows that turbulent mixing has a close relationship to shear instability. ε > O(10^?7) W kg^?1 and turbulent diffusivity K _ρ  > O(10^?3) m² s^?1 were obtained from near-surface to 85 db at stations even southwardly beyond 3°S, where it is already far from the southern boundary (~2°S) of the Equatorial Undercurrent. Turbulence-induced heat flux and salinity flux were calculated, and both had their maxima in the equatorial upwelling region, though the former was downward and the latter was upward. Accordingly, vertical velocity in the upwelling region was estimated to be similar to the results derived by other methods. These fluxes and the vertical velocity suggest the critical importance of turbulent mixing in maintaining the well-mixed upper layer. Secondly, in the intermediate region (>500 db), turbulent eddies were investigated by applying Thorpe’s method to the CTD data. A large number of overturns were detected, with spatial-averaged K _ρ (700–1,000 db) being 3.3 × 10^?6 m² s^?1, and the corresponding K _ρ-max reaching to O(10^?4) m² s^?1 in the north (3°–13°N). The results suggest that, in the intermediate region, considerable turbulent mixing occurs and moderates the properties of the water masses.