鉛直多層式プlランクトン採集器(ORI-VMPS)はアーマードケーブルに接続し,船上からの指令で2,000m 以浅の所定深度語ネットを開閉できる装置である。1m×1mの正方形型軽合金製枠には4組のプランク トンネットが取り付けられる。ORI-VMPSの開口比は5.9,漉水効率は95.3%(GG54ネット使用時）で， 総重量は約50kg:である。曳網時のネットの深度は船上の記録計に表示される。深度2,000mまでの曳網に 要する時間は約'90分であるので1日に10回以上の深海採集を行うことが可能である。鉛直曳のため破損 の少ない層別試料を得ることができる。

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Using Landsat TM Image of the Kimhae Delta Plain, Korea, this study clarifies the reason why paddy fields make different tones after harvest. In order to examine the brightness difference, the study collected soil samples from areas and analyzed a soil grain size and chemical contents. According to the analyses, the brightness difference could not be explain by the soil moisture, grain size composition and the quantity of organic matters. However, two sample areas showed a clear difference in their saline contents, and the distribution pattern of saline soil and non-saline soil corresponded with the landform development of delta. Therefore, the study concluded that the saline difference is the cause of the bright difference.

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ADEOS/NSCATで観測された海上風ベクトルの精度評価を目的として,初期データの全球海洋における 風速･風向の統計分布を調べ，ヨーロッパ中期気象予報センター(ECMWF)の客観解析データとの比較を 行った。その結果，風速については，低風速域でNSCATのデータはECMWFに比べて風速を過小評価す る傾向が明らかになった｡風速のヒストグラムを見ると,低風速域のデータが極端に多く，風速分布のピー クの低風速側に膨らみのある形を持つことが示された。この風速分布の歪みは，入射角によって系統的に 菰を変える性質を持つことから,現在NSCATの風速ベクトルの算出に暫定的に用いられているモデル関数 SASS-2の低風速域における誤差によるものと考えられる。風向については,衛星の軌道に相対的な風向方 位角に対する頻度分布を求めたところ，アンテナビームの方向と相対的に，鋭いスパイクやギャップなど の系統的な偏りを持つことが明らかになった。全球海洋上の風速場が衛星軌道やアンテナの方向と相対的 に分布を持つことは考えられないので，このような風速場の指向性もモデル関数の風向特性の誤差による ものと考えられる。

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ERS-1/AMI散乱計で観測されたC一バンドの散乱断面積とECMWF客観解析データの風速，風向，表 面気温,海面水温のデータを用いて散乱断面積の水温依存性を調べた。入射角が大きく，風向に直交して 入射し，風速が中程度の時に，散乱断面種と海面水温が負の相関を持つことが示された。最小2乗法で求 めた回帰曲線の傾きは最大で-0.07dB/Cに達し，この散乱断面積の海面水温依存性が散乱計による風速 ベクトルの観測に対して無視できない影響を持つことが示唆された。入射角が小さいとき，および風上・ 風下入射の場合には有意な相関は見られなかった｡本論文で示された散乱断面種の海面水温依存性の物理 機構について，粘性係数の水温依存性との関連について考察を行った結果,本論文の結果は粘性係数の水 温依存性では説明できないことが示された。

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It is becoming well known that alias effects associated with ocean tides could be a major source of systematic error in altimeter sea level measurements, as a result of asynoptic sampling and imperfect tide models. However, it has been pointed out that signals of non-tidal origin may also contribute a significant part to the observed aliasing (Chen and Ezraty, 1996). In this paper, numerical simulations are performed to demonstrate the full aliasing potential associated with altimeter observations of sea sonal sea level variability and annual Rossby waves. Our results indicate that ignorance of non-tidal aliasing may lead to the possibilities of underestimating the total alias effects and misinterpreting or overlooking existing geophysical phenomena. Therefore, it is argued that an entire aliasing picture should be kept in mind when satellite altimeter data are analyzed.

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Surface layer(0-17 °C isotherm depth) heat balance of a closed rectangular system (the Kuroshio system) in the North-West Pacifichas been examined for a period of 10 days (from 16th to 25th October, 1991), by considering the residual of net surface heat flux and heat divergence of the systemdue to horizontaladvection. The Kuroshio system has been formulated by taking hydrographic sections (CTD) across the lateral boundaries. Net surface heat flux for the system has been obtained exclusively from satellite observations of surface meteorological parameters using bulk method. Heat divergence in the systemis deducedby consideringthe residual heat advection into/out of the system due to geostrophic currents across the lateral boundaries, derived using method of Wunsch (1978). Synoptic flux estimates using satellite observations are compared with earlier estimates for this region (in the same season) from in situ data and are found to be reasonable. While the Kuroshio regime shows large net heat loss, towards the south it decreases and have heat surplus. An evaluation of the satellite derived heat fluxes by comparing with flux estimates from in situ observations at ocean weather station-Tango are also found to be comparable. For net satellite derived heat flux varying from 0 to 300w/m^2 the uncertainties are found to be of the order of 50- 80w/m^2. For the same range of flux values the possible uncertainties in ground based climatological estimates are from 40 to 60w/m^-2. This increase in uncertainties for satellite derived fluxes are found to be due to remote sensing error. For the Kuroshio system, the net heat flux varies from 0-300w/m2 with uncertainties varying from 50 to 80w/m^2. Regarding the heat balance of the Kuroshio box model, the net surface heat flux for the box is -1.4x10^14watt. Though there is a general view that Kuroshio act as an effective feeder for the surface heat loss for this region in the present case it is found that for 10-days mean period this is not hapening. Instead of that the system is also losing heat in terms of advection. The horizontal heat divergence due to advection is -0.6x10^14watt. During the observation period it is seen that the surface layer (nearly 100m) temperature falls down considerably (of the order of 1°C). It is found that the observed surface heat loss alone is not sufficient to cause the fall in the surface layer temperature of such a large system. The observed horizontal heat divergence is largely caused by the mass imbalance rather than the flow temperature difference at the boundaries.

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This paper proposes a new method in sonar signal processing using ”Overlappingsectional synthetic aperture.” This method is developed to provide high azimuth resolution in a synthetic aperture operation evenwhena ship cannotkeepmoving on a straightbaseline.Theaperture direc tion is at first detected with a gyroscope and made parallel to the base line using mechanical feed back system. Signals from the overlapping part of two successive apertures overlapping in the base line direction with the lateral deviation in position are compared and the phase difference between two signals is detected. Signal of non-overlapping part of the second aperture is corrected using thisphase difference. It is possible to obtain much higher azimuth resolution thana realaperture by repeating this procedure. This method does not require to change most of conventional sonar sys tem and the signal processing is performed mostly using Fourier transform. Results of computer simulation prove the effectiveness of this method.

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海洋理工学会誌 Vol.3, No.2 (1997)掲載の以下の論文で, 一部誤りがありました。 ここのお詫びして訂正いたします。

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