海洋理工学会誌
Online ISSN : 2188-3262
Print ISSN : 1341-2752
ISSN-L : 1341-2752
4 巻 , 2 号
選択された号の論文の24件中1~24を表示しています
序文
論文
  • William G. Pichel, Pablo Clemente-Colon, Karen Friedman, Arleen C. Lun ...
    1998 年 4 巻 2 号 p. 147-154
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    NOAA in partnership with the National Ice Center has constructed a near real-time data deliv ery system for SAR imagery. One of the principal applications of this imagery is to support the mission of the NOAA CoastWatch program; i.e., to provide near real-time satellite data to envi ronmental resource managers, fishery scientists, and environmental analysts. There are two CoastWatch applications of SAR imagery that are approaching operational status: (1) remote sensing of ice on the Great Lakes and in Alaska coastal waters, and (2) monitoring of the spring ice break-up on Alaskan rivers. The status of these applications will be presented. Also, the devel opment status of other potential applications of SAR data will be summarized, including: (1) high-resolution wind measurement, (2) mapping of oil spills, and (3) fisheries management.
  • Paul A. Hwang, William J. Teague, Gregg A. Jacobs
    1998 年 4 巻 2 号 p. 155-164
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Spaceborne altimeters provide accurate measurements of significant wave heights and wind speeds. In the Yellowand East China Seas region, there are 17TOPEX/POSEIDON groundtracks that provide long-term coverage of the area. These data can be used to study the seasonal and regional variation of winds and waves. The results indicate that the spatial and temporal varia tions of winds and waves in the region are strongly influenced by major current features such as the Kuroshio. This implies that the wind and wave parameters derived from the spaceborne altim eters can be used as tracers to study the air-sea and wave-current interactions on a regional scale the size of the Yellow and East China Seas.
  • J. F. R. Gower
    1998 年 4 巻 2 号 p. 165-174
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Since 1992, a local receiver for NOAA weather satellite (AVHRR) images has been used at IOS, Sidney, BC to map the sporadic bright patches in western North American (Canadian and adjacent US) coastal waters, which indicate the occurrence of intense plankton blooms. These events represent high concentrations of bloom organisms over wide areas, but have gone largely unobserved and unreported before the start of this program. A test of the software developed for this work using imagery collected in Korea and Taiwan, detected a similar event in the Yellow Sea in the fall of 1996. In September 1997, data from Seawifs became available, and are also being received at the IOS station. This imagery shows the existence of blooms over a wider range of seasons and in the central Gulf of Alaska. Nature of events is being confirmed by water samples and in-water observations.
  • Chao Fang Zhao, 秋山 , 杉森 , 諏訪 , Ming Xia He
    1998 年 4 巻 2 号 p. 175-184
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    The carbon dioxide (CO2) flux estimation between the atmosphere and the ocean is very im portant in carbon cycling and climate change research. Generally the carbon dioxide flux is pro portional to the difference of gas concentration (or partial pressure) and to the gas exchange coefficient. In this research, theCO2 exchange coefficient is investigated basedon whitecapmodel assuming thatCO2transfer velocity is proportional to whitecap coverage, which is related to wind friction velocity.Weestimate the gas exchange coefficient using the relationship between wind friction velocity and wave age. The gas exchange coefficient and its distribution, seasonal and annual variation in the North Pacific were estimated based on the modified whitecap model by using the observations of the scatterometer on the European Remote Sensing (ERS) satellites, the Special Sensor Microwave / Imager (SSM/I) on the operational spacecraft of the Defense Meteo rological Space Program (DMSP) and the Advanced Very High Resolution Radiometer (AVHRR) on the National Oceanic andAtmospheric Administration satellites. The global meanCO2 ex change coefficient is close to the result derived from ,4C data and the global mean value has shown an increase trend during the period 1991 - 1992.
  • Alexander S. Kazmin
    1998 年 4 巻 2 号 p. 185-190
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    A global approach to investigation of the large-scale oceanic frontal zones (OFZ), i.e. consider ation of OFZ as a part of single interconnected global ocean-atmosphere system and coherent analysis of the variability and frontogenesis over the whole World ocean, is presented. Global satellite sea surface temperature (SST) data for the period of 1982-97, global satellite phytoplankton pigment concentration measurements for 1978-86 and estimates of the surface forcing due to wind stress and net heat flux are used to investigate a global monthly climatology of large-scale oceanic frontal zones, the variability of SST gradient in several frontal zones, the large-scale me ridional frontogenesis in the North Pacific and some features of spatio-temporal variability of pigment concentration.
  • J. P. Angell, S. P. Lawrence, D. Llewellyn-Jones
    1998 年 4 巻 2 号 p. 191-196
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Data from the first five years of the TOPEX/Poseidon mission are used to investigate the reflec tion of Kelvin waves from the eastern boundary of the Pacific Ocean. Sea level anomaly data from TOPEX/Poseidon are projected onto long equatorial waves. If Kelvin waves are reflecting at the eastern boundary, then their wave coefficients should exhibit high correlation with the Rossby wave coefficients at the appropriate lag. Correlations are performed with the full Rossby coeffi cients, and also with Rossby coefficients that have had their annual signal removed. It is demon strated that certain apparent reflections of Kelvin waves may be due to coincidental timing of the Kelvin wave with the normal annual Rossby signal, and not due to the production of intraseasonal waves. The analysis indicates only two examples of intraseasonal Rossby waves produced by re flection of a Kelvin wave at the eastern boundary. The hypothesis is put forward that some Kelvin waves do not reflect due to interactions with easterly winds, which modify their strength and shape.
  • Ian J. Barton
    1998 年 4 巻 2 号 p. 197-204
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    It is now becoming widely accepted that satellite infrared instruments actually measure the skin temperature of the ocean surface rather than the bulk temperature as measured by in-situ devices mounted on ships and buoys. Traditional fields of satellite-derived SST have been supplied through the long-term series of AVHRR instruments either as MCSST or as a product of the joint NASANOAA Pathfinder Project. Algorithm coefficients have been derived using regression analyses with coincident satellite and in-situ measurements of bulk-SST. Thus the difference between the skin (as measured by the AVHRR) and the bulk (in-situ) temperatures has been inherently included in the AVHRR SST algorithms. In contrast data from the ATSR instruments on the ERS-1 and ERS-2 satellites have been analysed using theoretically derived SST algorithms and thus provide a direct measure of the skin temperature. Precise validation of the ATSR SST product has only been possiblewith the use of surface-or airborne-based infraredradiometers. Before numerical modellers will be convinced of the need to use skin (radiative) temperatures rather than bulk temperatures in air-sea interaction processes it is crucial that a globally robust relation or parameterisation between the two ”sea surface temperatures” is obtained. This paper will suggest and explore the future directions of investigations that are needed to provide such a relation.
  • Kevin B. Smith, Jose G. Rojas, James H. Miller, Gopu Potty
    1998 年 4 巻 2 号 p. 205-216
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    During the summer of 1996, the first of two ONR-sponsored shelf break acoustic experiments was conducted near the Mid-Atlantic Bight off the coast of New Jersey. Vertical line arrays of receivers placed near the edge of the shelf were used to record the acoustic transmissions of several sources including air-deployed SUS explosive charges. In between such scheduled transmissions, the ambient noise field was also recorded. From the vertical coherence of the ambient noise field and wavelet scalograms of the SUS transmissions, attempts are made to estimate the bottom sound speed, density, and attenuation. The results from these calculations are then compared to those values obtained from a genetic algorithm technique in which a numerical propagation model is employed to produce replicas of the predicted transmission. The results indicate a bottom sound speed near the surface of the interface of roughly 1565 m/s. However, the SUS data were found to produce inconclusive density and attenuation results.
  • 鈴木 , Naoto Ebuchi, Masatoshi Akiyama, Jun Suwa, Yasuhiro Sugimori
    1998 年 4 巻 2 号 p. 217-224
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Wind and wave data observed at a coastal tower are analyzed to investigate wave dependence of the sea-surface wind stress. The eddy correlation method is utilized to derive the wind stress from wind velocity components measured by a sonic anemometer. Only the data which satisfied criteria for the near-neutral stratification, the local equilibrium between wind and waves, and the aerodynamically rough flow, were selected. In a composite data set collected from previous studies, there has existed lack of data at a range of wave age between laboratory and open ocean waves. It is shown that the present data set fill the gap and make it possible for us to discuss continuity from laboratory to open ocean. Distribution of the data points shows consistent trend with the composite data set including data from labora tory experiments to open sea observations, and also with proposed formula indicating positive dependence of the wind stress on the wave age. Systematic differences from the formula indicat ing negative dependence deduced from field data sets by previous studies are discernible.
  • Taerim Kim, Masatoshi Akiyama, Yasuhiro Sugimori
    1998 年 4 巻 2 号 p. 225-230
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    A directional wave spectrum obtained from SAR image data is compared with a directly ob served directional wavespectrumfrom buoydata.TheSAR image was taken during winter storms in 1994, coincidently with the buoy measurement near Marado island which is the southernmost island of Korea. In order to get a directional wave spectrum, the linear modulation transfer function is applied to the image intensityspectrumfrom SAR imagery and maximum entropy method to the buoy data, respectively. The directional wavespectrum from the SAR imagery shows very similar patterns in main wave system to the directional spectrum from buoy data.
  • M. L. Heron, A. Prytz, P. Kalangi
    1998 年 4 巻 2 号 p. 231-241
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    HF ocean surface radars routinely map ocean currents at a spatial resolution of the order of 1 km over a coastal area of some 1000 square kilometres with a repeat period of the order of 30 minutes and have become a routine oceanographic and engineering tool. The availability of such spatial and temporal data allows us to calculate psuedo-Lagrangian tracks for surface particles. It is now shown that this technology can be used to monitor the spreading of surface particles which one would encounter in pollution events or dispersion of biological eggs and larvae. This calcula tion is applied to HF radar data from Port Phillip Bay in Victoria, Australia, using the COSRAD system. Two case studies are given: one is in an area with a high degree of bathymetric structure, and the other is in an area with uniform shallow water. We find that the spreading cannot be explained by eddy diffusion alone but requires the introduction of shears in the tidal flow.
  • Leonid Mitnik, Ming-Kuang Hsu
    1998 年 4 巻 2 号 p. 241-248
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    The surface imprints of atmospheric and oceanic vortex streets in the vicinity of islands of the northwestern Pacific Ocean were found in fields of sea surface roughness on radar images. The images were obtained by an X-band side-looking real aperture radar (RAR) from the Okean se ries satellites and an S-band synthetic aperture radar (SAR) from ERS-1/2. The broad swath width (460 km) and a spatial resolution of 1-2 km of the RAR allow estimation of the characteristic parameters of atmospheric vortices and vortex street evolution downstream. A comparison of visible/IR images with radar images has shown that sharp gradients of surface winds were ob served near boundaries of cloud vortices. The detailed structure of the oceanic vortices and vortex streets formed by the Kuroshio east of Taiwan and tidal currents west of Taiwan was revealed with ERS SAR images.
  • Pablo Clemente-Colon, Donald R. Montgomery, William G. Pichel, Karen S ...
    1998 年 4 巻 2 号 p. 249-258
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    The North Pacific Ocean supports one of the most productive fisheries in the world. For ex ample, the highly managed walleye pollock fishery in the Eastern Bering Sea and the Aleutian Islands region is the most valuable fishery in the U.S. Exclusive Economic Zone (EEZ). Rou tinely available RADARSAT synthetic aperture radar(SAR)images of the BeringSea are provid ing indications of ongoinglarge scale fishing activities in the region. Due to the stronghard target radar return produced by ships, the location of fishing fleets is being frequently determined using SAR imagery. SAR data also provide additional simultaneous information on oceanographic, meteorological, and biological processes relevant to local fisheries. Slick patterns resulting from fishing operations are also detectable by SAR. Extensiveslick patterns are found to be ubiquitous over trawl fishing areas in both the U.S. EEZ and the Russian EEZ in the Bering Sea. These slicks are thought to be mainly the result of fish processing residue and bycatch discharged into the water during trawl fishing and processing operations. Persistence of these features for several days is observed. Spaceborne SAR is a promising tool for fisheries management and surveillance as it can provide information on fishing fleet location, ongoing fishing operations, and in some cases, the location of previous fishing activities inside and outside the U.S. EEZ.
  • Yoshiaki Toba
    1998 年 4 巻 2 号 p. 259-264
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Although the Advanced Earth Observing Satellite (ADEOS) was operated for only a rather short period, from November 1996 to the end of June 1997, a revolution has been initiated in oceanography using data from ADEOS sensors, such as the Ocean Color and Temperature Scan ner (OCTS), NASA Scatterometer (NSCAT), and Advanced Visible and Near-Infrared Radiom eter (AVNIR). This paper presents highlights of the new research, citing published references.
  • Hui Feng, Janet W. Campbell, Timothy S. Moore
    1998 年 4 巻 2 号 p. 265-274
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    A general approach is presented to quantify retrieval errors in in-water constituent concentra tions induced by uncertainty in inherent optical property (IOP) submodel parameterization. Chlo rophyll concentrations are retrieved by inverting a radiance model with nonlinear IOP submodels. We demonstrate quantitatively how uncertainty in the IOP submodel parameterization influences the accuracy of the chlorophyll concentration retrieval at different chlorophyll concentration lev els. Two complete sets of simulations were designed and conducted, representing two extreme cases between which ”real” cases are expected to occur. The simulations show that precise knowl edge of spectral shapes of IOP submodels is important in chlorophyll retrieval.
  • Y. S. Sun, S. D. Hahn, Y. Q. Kang, B. G. Mitchell
    1998 年 4 巻 2 号 p. 275-280
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Spring and autumn satellite sea surface temperature observations have identified a recurring eddy at the terminal end of the East Korean Warm Current (e.g. Huh 1982). During late April, 1997 thermal infrared imagery from the NOAA AVHRR sensor and ocean color data from the Japanese OCTS sensor, revealed this feature. The cold core had elevated chlorophyll concentra tions, based on OCTS estimates, of greater than 3 mg/m1 while the warmer surrounding waters had chlorophyll concentrations of 1 mg/m1 or less. The elevated chlorophyll associated with this eddy has not been previously described. The eddy is also evident in SST images from autumn, but the SST in the core is warmer than in spring, and the warmjet flowing to the west of the eddy is also warmer in autumn compared to spring. The eddy forms at the northern extent of the East Korean Warm Current as those waters collide with the cold, south-flowing Liman Current over a topographic shelf about 1500m deep. This region of the eddy formation appears to have a strong connection with the dynamics of the western part of the polar front eddy field that dominates surface mesoscale structure in the central East (Japan) Sea. Interaction of the eddy with ARGOS tracked drifters, and evidence for its persistence are discussed.
  • Andrei Yu. Ivanov, Konstantin Ts. Litovchenko, Stanislav A. Ermakov
    1998 年 4 巻 2 号 p. 281-288
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    This paper presents the results of oil spill observations using the Almaz-1 SAR collected in the Norwegian Sea during the Dedicated Oil Spill Experiment in 1991. Three artificial slicks were released from a vessel on August 1991 and data on the sea and weather conditions near the test area were collected. The test area was imaged by the Almaz-1 SAR. The analysis of acquired Almaz-1 SAR images shows that the reduction of the backscatter from oil-covered sea surface ranged between 4.4 and 6.5 dB. For the first time an effect of an intensification of wind waves both in the area of the slick and at the windward edge of the oil spill expressed as a magnification of the SAR image brightness has been detected. The increase of relative backscatter power was up to 2.0 dB. It is concluded that Almaz-1 was a valuable tool for oil spill detection and localization but the detectability essentially depended on wind speed, sea state and age of spills.
  • Xiao -Hai Yan, Yun He, R. Dwi Susanto, W. Timothy Liu, Hui Lin
    1998 年 4 巻 2 号 p. 289-300
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    The variabilities of the western Pacific warm pool, including areas of the warm pool, positions of the gravitational center, sea surface temperature anomalies, and sea surface height anomalies are studied using Florida State University wind data. ERS -1,2, and NSCATscatterometer wind data. Reynolds optimum interpolation and historical reconstructed sea surface temperature data, and TOPEX/Poseidon sea surface height data.The relationship between the westerly wind forc ing and corresponding sea surface height and sea surface temperature responses in the tropical PacificOcean duringEl Ninoand other years are analyzed. Acommoncharacteristic for typical El Nino events is found and explainedby the westerly wind pattern.Time-frequency analysis of the Topex/Poseidon sea level deviation time series along the equator using the Empirical Mode Decomposition-Hilbert Spectrum method is also performed.
  • K. S. Prasad, R. L. Bernstein, M. Kahru, B. G. Mitchell
    1998 年 4 巻 2 号 p. 301-306
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Relationships between water-leaving radiances (Lwn) in the blue:Green region of electromag netic spectrum, Secchi disk depth and the diffuse attenuation coefficient at 490 nm (K490) were examined using data from several CalCOFI cruises (1993-1997). We were able to explain ap proximately 90% of the variance in Secchi depth and K490 using band ratios of Lwn490/Lwn555. We present results that support the view that a ratio of Lwns at 490:555 perform better than the 443:550 in explaining the variance of K490 and Secchi depth. We also performed a neural net (NN) analyses to predict Secchi depth using a combination of Lwn ratios and information from a series of channels corresponding to SeaWiFS (Lwns at 412,443,490, 512,555 and Lwn ratios at 443/510, 443/555,490/555). The best training set from the NN analyses resulted in an r of 0.91. A sensitivity analysis using the neural network methodology allowed us to specify the variables that are most useful in predicting Secchi depth. We present results of predicted Secchi depth and K490 using SeaWiFS data from Southern California and other locations where water turbidity is of great interest to recreational and commercial fishing and diving.
  • A. M. Zapolsky, V. P. Dzyuba, G. I. Dolgikh, F. A. Zapolsky
    1998 年 4 巻 2 号 p. 307-312
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    In this paper one of the kinds of the interaction between hydrophysical and seismoacoustic fields on the ocean floor is considered. Done in natural conditions, experiments on generation of hydroacoustic signals in the shelf region and registration seismoacoustic waves, which are exited in the result of the interaction mentioned above by the laser strainmeters located on shore are described. For a theoretical study of these pro-cesses method of elastodynamic Green's function is proposed. Some results of numerical modeling are given. They show agreement with experi ments. Thus the theory and modeling method, described in this paper, may be useful for investiga tions of interaction in the sea-land system.
  • Yunhe Zhao, Antony Liu, Cathleen A. Geiger
    1998 年 4 巻 2 号 p. 313-322
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Wavelet analysis of DMSP (Defense Meteorological Satellite Program) SSM/I (Special Sensor Microwave/Imager) 85GHz data from October of 1992 to March of 1993 is used to obtain daily sea ice drift information for the Arctic region. The derived maps of sea ice drift provide both improved spatial coverage over the existing array of Arctic Ocean buoys and better temporal resolution over techniques utilizing satellite data from SAR (Synthetic Aperture Radar). Com parisons of the derived ice velocities from SSM/I with ice velocities derived from buoys show good quantitative agreement. Therefore, the ice velocities derived from the wavelet analysis of SSM/I are suitable for validation of the ice velocities derived from an ice-ocean interaction model and for data assimilation input to a model. For demonstration purposes, the ice velocities from SSM/I are compared with the ice velocities derived from a coupled Arctic ice-ocean system with the comparison revealing the similarities of the general circulation patterns and significant ice velocity differences between the two. These results indicate where the model results need to be improved; with the expectation that the data assimilation of the model with ice velocities derived from SSM/I data would improve the model results. This wavelet analysis procedure is robust and can make a major contribution to the understanding of ice motion over large areas at relatively high temporal resolutions and would help to improve our current knowledge of sea ice drift and related processes through the data assimilation of ice-ocean numerical modeling.
  • Yoshiyuki Kawata, Toshiaki Izumiya, Yuichi Takano, Akihiro Yamazaki
    1998 年 4 巻 2 号 p. 323-328
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Wemade a cross calibration analysis between the POLDER and OCTS sensors on board ADEOS satellite in terms of the space reflectance. Space reflectances in the samesea target area were computed from the POLDER and OCTS data, acquired simultaneously on April 26, 1997. We found that they are in good agreement with relative differences of less than 10 % in all bands, when the latest in-flight calibration gain factors for each sensor were used. Then, the aerosol optical parameter retrieval was made using ADEOS/POLDER's directional reflectance and polar ization data in 760 and 865[nm] bands. Retrieved results for aerosol's optical parameters were presented in the form of distribution map in the case of aerosol refractive index of m=l .40-i0.0.
  • Bingquan Chen, Knut Stamnes, Banghua Yan, Oyvind Frette, Jakob J. Stam ...
    1998 年 4 巻 2 号 p. 329-338
    発行日: 1998年
    公開日: 2019/02/16
    ジャーナル フリー
    Atmospheric correction of ocean color imagery is commonly based on the assumption that water-leaving radiances (Lw) at near-infrared (NIR) wavelengths are negligible.To investigate the validity of this assumption, we carry out radiative transfer simulations using a model appro priate for the coupled atmosphere-ocean system. In this model both reflection (including total reflection) and refraction at the atmosphere-ocean interface as well as light scattering both in the atmosphere and the ocean are taken into account.Weassume that the atmosphere-ocean system is vertically stratified, and that the effects of wave-slopeshave been removed so as to leave behind a flat atmosphere-ocean interface. Simulated results show that for common open-ocean aerosol loadings (aerosol optical depths in the range 0.08-0.11) water-leaving radiances at NIR wave lengths (e.g., 865 nm) are usually not negligible. The impact of the non-negligible values of water-leaving radiances at NIR wavelengths on atmospheric correction depends on (i) the ocean particle concentration; (ii) the scattering charac teristics of particles in the near-surface ocean water, described by their shape, size, and refractiveindex distributions, which in turn determine the scattering phase function; (iii) the aerosol optical depth; and (iv) the sun-satellite geometry. Our simulations demonstrate that a new approach to atmospheric correction of ocean color imagery is needed to obtain reliable and accurate results for open-ocean waters when particle concentrations are high. This is particularly important when the aerosol loading is low because then the contribution from the water-leaving radiance to the total radiance received by the satellite sensor is relatively larger, and will if ignored introduce significant errors in atmospheric correction.
feedback
Top