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1.
对表层海洋动力学及其调控机制的认识对准确认识海洋自然变化过程及其未来对气候变化的响应具有重要意义。志愿观测船作为自动观测系统的载体和样品采集平台的优势使其在提升人类对于表层海洋的观测能力方面具有极大优势。本文系统性地回顾了志愿观测船的概念、发展历史、现状和未来发展趋势。基于志愿观测船的诸多海洋观测项目的成功显示了,随着快速发展的传感器技术,志愿观测船能够以经济有效的方式显著地提升表层海洋现场观测的时间和空间分辨率。未来的海洋观测系统应该综合利用包括志愿观测船在内的多种海洋观测平台的优势。 相似文献
2.
Comparative Analysis of Chlorophyll-a Distribution from SeaWiFS,MODIS-Aqua,MODIS-Terra and MERIS in the Arabian Sea 总被引:1,自引:0,他引:1
The variability of Chlorophyll-a (Chl-a) distribution derived from MODIS (on Aqua and Terra platforms) and MERIS sensors have been compared with SeaWiFS data in the Arabian Sea. MODIS Aqua has overestimated the SeaWiFS Chl-a within 25–32% in the coastal turbid (eutrophic) waters and underestimated in open ocean waters with error within 20%. However, there is no significant bias (?0.1 on log-scale) observed as the slope is well within 0.97-1.1 (log transformed). MODIS-Terra has underestimated the Chl-a concentration in open ocean waters by about 29–31%, which is higher than MODIS-Aqua. MODIS-Terra is observed to be more accurate than MODIS-Aqua in the coastal waters. MERIS is overestimating the SeaWiFS Chl-a with log RMS error of ~0.15 and log bias of ~0.13–0.2. The differences in the Chl-a estimates between each sensor are possibly due to differences in the sensor design, bio-optical algorithms and also due to the time differences between the satellites over passes. We have examined that the MERIS is performing similar to SeaWiFS and the MODIS-Aqua (Terra) data are reliable in open ocean (coastal) waters. However, Chl-a retrieval algorithms need to be improved especially for coastal turbid waters to continue with SeaWiFS data for long-term studies. 相似文献
3.
Realistic representation of sea ice in ocean models involves the use of a non-linear free-surface, a real freshwater flux and observance of requisite conservation laws. We show here that these properties can be achieved in practice through use of a rescaled vertical coordinate “z*” in z-coordinate models that allows one to follow undulations in the free-surface under sea ice loading. In particular, the adoption of “z*” avoids the difficult issue of vanishing levels under thick ice.Details of the implementation within MITgcm are provided. A high resolution global ocean sea ice simulation illustrates the robustness of the z* formulation and reveals a source of oceanic variability associated with sea ice dynamics and ice-loading effects. The use of the z* coordinate allows one to achieve perfect conservation of fresh water, heat and salt, as shown in extended integration of coupled ocean sea ice atmospheric model. 相似文献
4.
It is generally accepted that a climate shift occurred about 1977 that affected the dynamics of North Pacific marine ecosystems. Agreement on the possibility of further climate shifts in 1989 and the late 1990s is yet to be achieved. However, there have been changes in the dynamics of key commercial fishes that indicate changes in their environment occurred in the early 1990s, and possibly around 1998. One method of measuring climate change is to observe the dynamics of species that could be affected.Several studies have described decadal-scale changes in North Pacific climate–ocean conditions. Generally, these studies focus on a single index. Using principal components analysis, we use a composite index based on three aspects of climate ocean conditions: the Aleutian Low Pressure Index, the Pacific Atmospheric Circulation Index and the Pacific Interdecadal Oscillation Index. We link this composite index (Atmospheric Forcing Index) to decadal-scale changes in British Columbia salmon and other fish populations. Around 1989 there was a change from intense Aleutian Lows (above average south-westerly and westerly circulation patterns and warming of coastal sea surface temperatures) to average Aleutian Lows (less frequent south-westerly and westerly circulation and slightly cooler coastal sea surface temperatures in winter). These climate–ocean changes were associated with changes in the abundance and ocean survival of salmon (Oncorhynchus spp.), distribution and spawning behaviour of hake (Merluccius productus) and sardines (Sardinops sagax) and in recruitment patterns of several groundfish species. 相似文献
5.
Nicholas R. Bates Liliane Merlivat Laurence Beaumont A. Christine Pequignet 《Marine Chemistry》2000,72(2-4)
The ocean is an important sink for carbon and heat, yet high-resolution measurements of biogeochemical properties relevant to global climate change are being made only sporadically in the ocean at present. There is a growing need for automated, real-time, long-term measurements of CO2 in the ocean using a network of sensors, strategically placed on ships, moorings, free-drifting buoys and autonomous remotely operated vehicles. The ground-truthing of new sensor technologies is a vital component of present and future efforts to monitor changes in the ocean carbon cycle and air–sea exchange of CO2.A comparison of a moored Carbon Interface Ocean Atmosphere (CARIOCA) buoy and shipboard fugacity of CO2 (fCO2) measurements was conducted in the western North Atlantic during two extended periods (>1 month) in 1997. The CARIOCA buoy was deployed on the Bermuda Testbed Mooring (BTM), which is located 5 km north of the site of the US Joint Global Ocean Flux Study (JGOFS) Bermuda Atlantic Time-series Study (BATS). The high frequency of sampling revealed that temperature and fCO2 responded to physical forcing by the atmosphere on timescales from diurnal to 4–8 days. Concurrent with the deployments of the CARIOCA buoy, frequent measurements of surface fCO2 were made from the R/V Weatherbird II during opportunistic visits to the BTM and BATS sites, providing a direct calibration of the CARIOCA buoy fCO2 data. Although, the in situ ground-truthing of the CARIOCA buoy was complicated by diurnal processes, sub-mesoscale and fine-scale variability, the CARIOCA buoy fCO2 data was accurate within 3±6 μatm of shipboard fCO2 data for periods up to 50 days. Longer-term assessments were not possible due to the CARIOCA buoy breaking free of the BTM and drifting into waters with different fCO2-temperature properties. Strategies are put forward for future calibration of other in situ sensors. 相似文献
6.
R.A. Saunders A. Ingvarsdttir J. Rasmussen S.J. Hay A.S. Brierley 《Progress in Oceanography》2007,72(4):313-342
Euphausiids are a key component of the northern North Atlantic marine ecosystem and Meganyctiphanes norvegica and Thysanoessa longicaudata are dominant both numerically and in terms of biomass. The Irminger Sea is remote and experiences often-hostile weather conditions. Consequently, few studies have been conducted there, and detailed information on the seasonal distribution, abundance and growth of euphausiids is limited. Here we explore patterns of abundance and spatial and temporal variation in length–frequency distribution in order to determine regional growth rates for both species in the Irminger Basin. Regional composite length–frequency distributions for spring, summer and winter were devised by aggregating discrete net haul data according to the results of a multivariate cluster analysis of length conducted on spring and summer net sample data. Three biologically distinct regions within the Irminger basin were apparent (Central Irminger Sea, Northern Irminger Sea and East of Greenland Shelf). These regions corresponded broadly with distinct physical zones within the basin. Modes in the composite length–frequency distributions were determined by fitting multiple normal distributions, and regional differences in growth were investigated by tracking modes between seasons. The results provide some evidence for regional variability in growth and population dynamics. The population structure and growth of M. norvegica was similar in the open ocean regions of the Northern and Central Irminger Basin, but different in the region around the East Greenland Shelf. There was a distinct absence of larger individuals (+I-group) in the open ocean regions compared to East Greenland Coast region, and growth rates were marginally higher. A similar pattern in population structure was also observed for T. longicaudata. Variability in growth and abundance are discussed in relation to prevailing environmental characteristics such as temperature and food availability. 相似文献
7.
Coastal ocean hydrodynamic models are subject to a number of stability constraints. The most important of these are the Courant–Friedrichs–Levy (CFL) constraint on gravity waves, a Courant (Cr) number constraint on advection, and a time step constraint on the vertical component of viscous stresses. The model described here removes these constraints using a semi-implicit approximation in time and a semi-Lagrangian approximation for advection. The accuracy and efficiency of semi-Lagrangian methods depends crucially on the methods used to calculate trajectories and interpolate at the foot of the trajectory. The focus of this paper is on evaluation of several new and old semi-Langrangian methods. In particular, we compare 3 methods to calculate trajectories (Runge–Kutta (RK2), analytical integration (AN), power-series expansion (PS)) and 3 methods to interpolate (local linear (LL), global linear (GL), global quadratic (GQ)) on unstructured grids. The AN and PS methods are both efficient and accurate, and the latter can be expanded in a straightforward manner to treat time-dependent velocity. The GQ interpolation method provides a major step in introducing efficient and accurate semi-Lagrangian methods to unstructured grids. 相似文献
8.
Oceanographic influences on the distribution and relative abundance of market squid paralarvae (Doryteuthis opalescens) off the Southern and Central California coast
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Market squid (Doryteuthis opalescens) are ecologically and economically important to the California Current Ecosystem, but populations undergo dramatic fluctuations that greatly affect food web dynamics and fishing communities. These population fluctuations are broadly attributed to 5–7‐years trends that can affect the oceanography across 1,000 km areas; however, monthly patterns over kilometer scales remain elusive. To investigate the population dynamics of market squid, we analysed the density and distribution of paralarvae in coastal waters from San Diego to Half Moon Bay, California, from 2011 to 2016. Warming local ocean conditions and a strong El Niño event drove a dramatic decline in relative paralarval abundance during the study period. Paralarval abundance was high during cool and productive La Niña conditions from 2011 to 2013, and extraordinarily low during warm and eutrophic El Niño conditions from 2015 to 2016 over the traditional spawning grounds in Southern and Central California. Market squid spawned earlier in the season and shifted northward during the transition from cool to warm ocean conditions. We used a general additive model to assess the variability in paralarval density and found that sea surface temperature (SST), zooplankton displacement volume, the log of surface chlorophyll‐a, and spatial and temporal predictor variables explained >40% of the deviance (adjusted r2 of .29). Greatest paralarval densities were associated with cool SST, moderate zooplankton concentrations and low chlorophyll‐a concentrations. In this paper we explore yearly and monthly trends in nearshore spawning for an economically important squid species and identify the major environmental influences that control their population variability. 相似文献
9.
Resulting from the rising levels of atmospheric carbon, ocean acidification has become a global problem. It has significant impacts on the development, survival, growth and physiology of marine organisms. Therefore, a highprecision sensor is urgently needed to measure the pH of sea-water. Iridium wire with a diameter of 0.25 mm is used as the substrate, and an Ir/Ir(OH)_x pH electrode is prepared by a one-step electrochemical method in a Li OH solution at the room temperature. A scanning electron microscope(SEM) observation reveals that it is coated with nanoscale particles. In laboratory tests, the electrode exhibits a very promising pH response, with an ideal Nernst slope(56.14–59.52), fast response, good stability and long life-span in tested pH buffer solutions. For a sea trial,four pH electrodes and one Ag/Ag Cl reference electrode are integrated with a self-made chemical sensor, and a profile detection of nearly 70 m is implemented near Newport Harbor, California on August 3, 2015. The results reflect that the pH value measured by the sensor is very close to the data given by Sea-Bird 911 plus CTD, with a difference value ranging from 0.000 075 to 0.064 719. And the sensor shows a better data matching degree in 0–40m water depth. In addition, the high precision and accuracy of the sensor make it possible to use in the ocean observation field. 相似文献
10.
《African Journal of Marine Science》2013,35(4):511-524
Two sets of high-resolution subsurface hydrographic and underway surface chlorophyll a (Chl a) measurements are used, in conjunction with satellite remotely sensed data, to investigate the upper layer oceanography (mesoscale features and mixed layer depth variability) and phytoplankton biomass at the GoodHope line south of Africa, during the 2010–2011 austral summer. The link between physical parameters of the upper ocean, specifically frontal activity, to the spatially varying in situ and satellite measurements of Chl a concentrations is investigated. The observations provide evidence to show that the fronts act to both enhance phytoplankton biomass as well as to delimit regions of similar chlorophyll concentrations, although the front–chlorophyll relationships become obscure towards the end of the growing season due to bloom advection and ‘patchy’ Chl a behaviour. Satellite ocean colour measurements are compared to in situ chlorophyll measurements to assess the disparity between the two sampling techniques. The scientific value of the time-series of oceanographic observations collected at the GoodHope line between 2004 to present is being realised. Continued efforts in this programme are essential to better understand both the physical and biogeochemical dynamics of the upper ocean in the Atlantic sector of the Southern Ocean. 相似文献
11.
Victoria J. Hill Richard C. Zimmerman 《Deep Sea Research Part I: Oceanographic Research Papers》2010,57(10):1243-1254
The Arctic Ocean, including its regional shelf seas, is assumed to play an important role in the global carbon cycle. However, the true magnitude of annual production is unknown, as in situ data are sparse in time and space. Remote sensing technology has the potential to provide large scale estimates of phytoplankton biomass at much higher frequency and spatial coverage than shipboard observations in this remote region. Subsurface peaks in both biomass and primary production (PP), which are the characteristics of the Arctic, are shown to limit the reliability of ocean color based integrated PP (IPP) models in the Chukchi Sea. Here we report that the retrievals of IPP from remotely sensed ocean color data were accurate only when limited to 1.2 optical depths, which severely constrains the utility of ocean color remote sensing for the assessment of Arctic Ocean dynamics.Active sensors such as LIDAR, can, in combination with passive ocean color, dramatically improve our ability to estimate IPP for the Arctic. IPP retrievals were improved to within a factor of 2–3 of the measured values, when the vertical distribution of Chl a was determined to a resolution of 1 m using modeled LIDAR retrievals of the beam attenuation coefficient. This was far better than models using only passive ocean color. The instrument specifications of the current NASA spaceborne LIDAR (CALIOP) allow for the retrieval of Kd at a depth resolution of 23 m. Even with this constraint, however, the accuracy of the modeled IPP was improved over passive ocean color retrievals to approximately a factor of 3. The Arctic is a perfect location to merge ocean color and LIDAR measurements as the polar orbit of CALIOP provides complete grid coverage of the area every 8 days, crossing the horizontal gradients in Chl a already known to exist from passive ocean color observations. 相似文献
12.
Louis C. St. Laurent Jonathan D. Nash 《Deep Sea Research Part II: Topical Studies in Oceanography》2004,51(25-26):3029
In this study, the energy flux and energy dissipation of deep ocean internal tides are examined. Properties of the internal tide from two distinct generation regions are contrasted: the Mid-Atlantic Ridge (MAR) and the Hawaiian Ridge. Considerable differences are noted for the baroclinic energy flux, u′p′, radiated from each site. Radiation from the MAR is relatively rich in high modes, with an energy flux spectral peak at mode 5 and modes 10 and greater accounting for 40% of the total flux. In contrast, Hawaiian Ridge radiation is dominantly composed of modes 1 and 2, with modes 10 and greater accounting for less than 5% of the total flux. Depth integrated energy flux levels are at the MAR site, and at the Hawaiian Ridge. Despite these differences, observed turbulent dissipation rates at these sites are similar in magnitude and depth dependence. Decay scales, estimated as , range from O(100)km to . The mean decay scale based on the MAR data is 230 km, a factor of 3 smaller than at the Hawaiian Ridge site. We demonstrate that the dissipation level scales with the energy flux available in the high modes, which is comparable at both sites, rather than the total energy flux. 相似文献
13.
Shigenao Maruyama Koutaro Tsubaki Keisuke Taira Seigo Sakai 《Journal of Oceanography》2004,60(3):563-568
Deep seawater in the ocean contains a great deal of nutrients. Stommel et al. have proposed the notion of a “perpetual salt fountain” (Stommel et al., 1956). They noted the possibility of a permanent upwelling of deep seawater with no additional external energy source. If
we can cause deep seawater to upwell extensively, we can achieve an ocean farm. We have succeeded in measuring the upwelling
velocity by an experiment in the Mariana Trench area using a special measurement system. A 0.3 m diameter, 280 m long soft
pipe made of PVC sheet was used in the experiment. The measured data, a verification experiment, and numerical simulation
results, gave an estimate of upwelling velocity of 212 m/day.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
14.
V. I. Kuzin G. A. Platov E. N. Golubeva V. V. Malakhova 《Izvestiya Atmospheric and Oceanic Physics》2012,48(1):102-119
Variations in hydrophysical parameters in the Arctic Ocean and the North Atlantic are studied on the basis of numerical simulation
with the use of an ocean circulation model (including ice formation and drift). The main circulation and ice-drift modes have
been ascertained depending on atmospheric cycles. The possibilities of the parameterization of intermediate and deep water
formation in numerical models of polar ocean dynamics are considered. The effect of the interannual variability of the discharge
of Siberian rivers on the distribution and propagation of fresh water in this region are estimated from numerical experiments.
The simulation results of the propagation of the dissolved methane from Siberian rivers are presented. 相似文献
15.
斜压海洋动力学的一种三维数值模式 Ⅰ.动力学方程数值格式 总被引:1,自引:0,他引:1
依据自由海面海洋动力学原始方程建立了一种三维有限差分数值模式,可用于潮波、风暴潮和海流的数值模拟和预报。运动方程和连续方程的数值格式采用内、外模态分离的技术。外模态采用交替方向隐格式,用于计算海面高度和垂直平均流速,时间步长不受Courant-Friderichs-Lewy条件限制;内模态采用半隐格式,用于计算海流的垂直2颁布,其时间步长可大于外模态时间步长。模式的计算程度比一般显式模式可快10倍 相似文献
16.
Ben J. Korgen 《Marine Geophysical Researches》1971,1(3):354-357
A versatile probe for simultaneous studies of heat flow and near-bottom water parameters has evolved through modifications of the Bullard heat probe frame. Suitable sensor arrays have been used with this instrument to study (1) heat flow through the ocean floor, (2) water column temperature structure, (3) near-bottom current speeds, and (4) the differential cooling of water-column temperature sensors placed in a current speed gradient.Some of the advantages of such a modified Bullard probe are: (1) several parameters, including heat flow, can be measured across the sediment-water interface simultaneously, (2) the instrument frame is rigidly pinned to the ocean floor during measurement, permitting true Eulerian measurement in the water column with no effects of ship movement, swaying moorings or cable oscillation, and (3) the device is inexpensive and simple. 相似文献
17.
Daisuke Inazu Tadahiro Sato Satoshi Miura Yusaku Ohta Kazuyuki Nakamura Hiromi Fujimoto Christopher F. Larsen Tomoyuki Higuchi 《Journal of Oceanography》2009,65(3):335-347
An accurate prediction of ocean tides in southeast Alaska is developed using a regional, barotropic ocean model with a finite
difference scheme. The model skill is verified by the observational tidal harmonics in southeast Alaska including Glacier
Bay. The result is particularly improved in Glacier Bay compared to the previous model described by Foreman et al. (2000). The model bathymetry dominates the model skill. We re-estimate tidal energy dissipation in the Alaska Panhandle
and suggest a value for tidal energy dissipation of 3.4 GW associated with the M2 constituent which is 1.5 times the estimation of Foreman et al. (2000). A large portion of the M2 energy budget entering through Chatham Strait is dissipated in the vicinity of Glacier Bay. Moreover, it is shown that the
developed model has the potential to correct the ocean tide loading effect in geodetic data more efficiently than the model
of Foreman et al. (2000), especially around Glacier Bay. 相似文献
18.
Toru Sato 《Journal of Oceanography》2004,60(4):807-816
The direct injection of CO2 in the deep ocean is a promising way to mitigate global warming. One of the uncertainties in this method, however, is its
impact on marine organisms in the near field before CO2 is diluted widely in the ocean. Since field experiments cost enormously, computational simulations are expected to show detailed
information on the dilution process near injection points and its impact on marine organisms. In general, the LC50 concept
is widely applied for testing the acute impact of a toxic agent on organisms. As a biological impact model we therefore consider
mortality, which reflects recent laboratory experiments on zooplankton at various concentrations of CO2. Here we regard the sigmoid-transformed mortality as a linear function of time in the logarithmic scale, and not just of
the concentration of CO2 in the logarithmic scale. This model was installed in a computational simulation code for the reconstruction of small-scale
ocean turbulence. The results suggest that the biological effect is not significant when the ship speed is 4 knots and CO2 is injected at 0.1 ton/sec in the form of a spray through 100 nozzles provided vertically on a pipe at 10 m intervals. It
is therefore considered that the moving-ship method is effective for direct CO2 injection.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Tidal data inversion: interpolation and inference 总被引:1,自引:0,他引:1
Gary D. Egbert 《Progress in Oceanography》1997,40(1-4)
Initial efforts in applying inverse methods to studies of ocean tides have focused on making the best use of a small number of observations to map tidal fields in a large area. As such, inversion can be viewed as an objective analysis scheme which uses a dynamically appropriate spatial covariance, derived from the shallow water equations, to interpolate and smooth a sparse data set. Data from recent altimetry missions are not sparsely distributed relative to tidal wavelengths in the open ocean, apparently reducing the need for complicated dynamically based interpolation schemes. Altimetric data sets are also quite large, making application of rigorous inversion methods to global tidal modeling a challenging computational problem. We describe here a new iterative solution scheme which allows us for the first time to fit the full set of TOPEX/Poseidon cross-over differences. The resulting solution (TPXO.3) fits validation tide gauges significantly better than previous inverse solutions. TPXO.3 also reduces residual cross-over variances relative to other recent inverse and empirical solutions, particularly in shallow water where improvements are dramatic. With the new solution approach very significant improvements in global tidal models should be possible in shallow areas and in the vicinity of complex bathymetry, where high-accuracy tidal modeling remains a challenging problem. With the recent improvements in the definition of tidal elevations in the open ocean it should now also be possible to resolve some long unanswered questions about tidal energetics and dynamics. Inverse methods provide a natural framework for addressing these issues, and making inferences about tidal dynamics. In particular, by bringing data and dynamics together in a single solution, we can rigorously test the consistency of the two. We present results of global and local inversions which suggest that over elongated bathymetric features oriented perpendicular to tidal flows, energy dissipation in the open ocean is significantly enhanced, presumably due to conversion of barotropic tidal motions into baroclinic modes. For the M2 tide our preliminary results suggest that perhaps as much as 0.5 TW of energy is dissipated in this manner. However, due to the simplified linear dynamics and limited spatial resolution used for our inversion, there are significant uncertainties associated with these results. A more careful application of inverse methods to make more rigorous inferences about tidal energetics, including use of more reasonable prior dynamics, and the highest possible spatial resolution, should allow for closure of the tidal energy budget within the next few years. 相似文献
20.
《Deep Sea Research Part I: Oceanographic Research Papers》2003,50(3):371-395
Dissipation rate statistics in the near-surface layer of the ocean were obtained during the month-long COARE Enhanced Monitoring cruise with a microstructure sensor system mounted on the bow of the research vessel. The vibration contamination was cancelled with the Wiener filter. The experimental technique provides an effective separation between surface waves and turbulence, using the difference in spatial scales of the energy-containing surface waves and small-scale turbulence. The data are interpreted in the coordinate system fixed to the ocean surface. Under moderate and high wind-speed conditions, we observed the average dissipation rate of the turbulent kinetic energy in the upper few meters of the ocean to be 3–20 times larger than the logarithmic layer prediction. The Craig and Banner (J. Phys. Oceanogr. 24 (1994) 2546) model of wave-enhanced turbulence with the surface roughness length from the water side z0 parameterized according to the Terray et al. (J. Phys. Oceanogr. 26 (1996) 792) formula z0=cHs provides a reasonable fit to the experimental dissipation profile, where z is the depth (defined here as the distance to the ocean surface), c≈0.6, and Hs is the significant wave height. In the wave-stirred layer, however, the average dissipation profile deviates from the model (supposedly because of extensive removing of the bubble-disturbed areas close to the ocean surface). Though the scatter of individual experimental dissipation rates (10-min averages) is significant, their statistics are consistent with the Kolmogorov's concept of intermittent turbulence and with previous studies of turbulence in the upper ocean mixed layer. 相似文献