日本リモートセンシング学会誌
Online ISSN : 1883-1184
Print ISSN : 0289-7911
ISSN-L : 0289-7911
2 巻 , 3 号
選択された号の論文の8件中1~8を表示しています
  • 愛甲 敬, 高橋 正征
    1982 年 2 巻 3 号 p. 3-9_1
    発行日: 1982/08/20
    公開日: 2009/12/11
    ジャーナル フリー
    海洋の沿岸域において,海流や吹送流が海底・海岸地形と作用しあって,湧昇(局地性湧昇)を発生させることは,海洋物理学的に古くから予測されてきた。船舶による狭い範囲内での精密な測点観測や,表層水の航走連続観測法の普及によって,日本近海でも最近湧昇水塊が観察されている。その結果,湧昇水塊は海面で1~数10kmの巾の空間的広がりをもち,周辺水に比べて水温が1~5℃程度低いことが明らかになってきた。航空機MSSは,水温差から海面での湧昇水塊の分布様式を見事に把え,海流場内の島陰に後背渦性の湧昇水塊を検出した。加えて,湧昇水塊がしばしば数時間のスケールで変形したり,移動しているらしいこともわかってきた。
    そのために航空機よりさらに広域をカバーでき,しかも頻繁に観測情報の入手可能な手法の利用が急務になってきた。そこで人工衛星の利用を考えることにし,対象としてNOAA-6に塔載されている高解像度放射計(AVHRR)をとりあげた。1980年11月19日午前8時のAVHRR/NOAA-6の観測資料を入手し,伊豆大島周辺水域の第4チャンネルの情報を分析した。海面での水温分布が明瞭に把えられ,船舶による水温実測からほぼ3℃ほど低温側にズレていることが明らかになった。補正した水温パターンは,海面での水温実測とかなり良い一致を示した。観測当時伊豆大島周辺には黒潮の枝流が流れており,島の裏側に,以前に航空機MSSで把えられたと同様の後背渦が観察された。渦は島の北側沖では時計回り,南側沖では反時計回りを示し,渦の一部分に湧昇性の低水温域が検出された。
    AVHRR/NOAA-6は約0.1℃の温度分解能および約1kmの空間分解能をもち,さらに測定空間巾が約3,000kmの広大さである。これは広域での湧昇水塊の分布把握に極めて有効である。また,NOAA-6は日本近海に1日2回飛来し,少なくとも4~5日周期でほぼ同一水域上を通過するので,1~数日より長い時間間隔での湧昇水塊の移動・変形あるいは出現頻度などの時系列研究も可能である。
  • 田中 總太郎, 杉村 俊郎, 西村 司, 二宮 泰, 畠山 祐二
    1982 年 2 巻 3 号 p. 11-30_2
    発行日: 1982/08/20
    公開日: 2009/05/22
    ジャーナル フリー
    This paper describes a method of compiling the Kuroshio Current vector map from NOAA-6/AVHRR data, and aims at obtaining knowledge of the dynamics of oceanic currents and eddies. Through the compilation of the map, the following results were obtained. (1) A projection method of NOAA-6/AVHRR data to the 1:3, 000, 000 scaled map entiled "Japan and Its Surroundings" produced by Geometrical Survey Institute was worked out. This method allows for keeping a geometrical accuracy of 1% or less distortion at any portion in the mapping range of about 2, 000 x 3, 000 km2. (2) Continuous colour display from B&W imagery was developed. Oceanic currents and eddies can be recognized more effectively in this display than in conventional displays such as colour sliced ones. (3) The Kuroshio current vector map gives us the differences in the sea surface temperature over wide area, patterns of oceanic currents, and also sea bottom topography. All of this information is given on one photo. (4) A method of measuring current velocities using corresponding sea marks on time serial scenes was developed. With this method a measuring accuracy of 0.1 knots or less can be obtained. This method can be used to measure the angular velocity of oceanic eddies (this is attained by measuring twin current velocities on the sea surface at the eddy's center).
    Next, the following items of oceanic currents and eddies are discussed using some hydrodynamical model tests. (1) To strengthen the oceanic current chart provided by the Maritime Safety Board. (2) Oceanic eddies distributed in the surroundings of Japan Islands and their hydrodynamical features. (3) Observation of meandering in a very short period along the Kuroshio and its characteristics.
  • 岡本 謙一, 尾嶋 武之, 増子 治信, 吉門 信, 猪股 英行, 畚野 信義
    1982 年 2 巻 3 号 p. 31-49_1
    発行日: 1982/08/20
    公開日: 2009/05/22
    ジャーナル フリー
    The airborne microwave rain-scatterometer/radiometer system operated at X-band and Ka-band was developed for the remote sensing of precipitation, especially rain from the airplane. This sensor system is the combination of the active microwave remote sensors, (i.e. the rain-scatterometers of X-band and Ka-band) and the passive microwave remote sensors, (i.e. the microwave radiometers of X-band and Ka-band). Airborne rain-scatterometers were developed as a first step for the development of the future space-borne rain-scatterometer.
    The total system is installed in the Cessna 404 and the remote sensing of precipitation is performed from the top of raining area through clouds. Flight experiments of more than 80 hours were perfomed in June, July and October, 1980 and in June, 1981. Date recorded in magnetic tapes are analyzed by the ground-based computer.
    An outline of airborne microwave rain-scatterometer/radiometer system is introduced. The sensor system in the flight experiment is shown with the example of measurement result. Some examples of preliminary data analyses are also discussed.
  • 安岡 善文, 宮崎 忠国
    1982 年 2 巻 3 号 p. 51-62
    発行日: 1982/08/20
    公開日: 2009/05/22
    ジャーナル フリー
    Remote sensing is regarded as a potentially effective data source for the measurement of water quality and for the environmental evaluation of water .bodies. In this paper, the water quality measurement by LANDASAT multispectral scanner data is described. Discussion emphasizes the estimation of the model for water quality measurement as well as the evaluation of path radiance and transmittance in the atmosphere. First, the path radiance and the transmittance were evaluated based on the linear regression analysis between the LANDSAT MSS data and the radiance data measured above the water surface. Next, the model for estimating water quality was derived based onthe linear regression analysis between the water quality parameters monitored on the lake and the LANDSAT MSS data after the atmospheric correction utilizing the evaluated path radiance and transmittance. The transparency and the suspended sediment concentration were mapped from the LANDSAT MSS images by the estimated model.
  • 石井 吉徳, 六川 修一
    1982 年 2 巻 3 号 p. 63-77
    発行日: 1982/08/20
    公開日: 2009/05/22
    ジャーナル フリー
    This paper firstly describes the principles of SAR(Synthetic Aperture Radar) imaging, i.e. resolution concept, frequency pulse modulation, pulse compression and Doppler effects. In the real aperture radar systems, the azimuth resolution depends on slant-range, wave length and antenna length, therefore it is greatly limited by the sensor itself. On the contrary SAR can achieve much higher resolution by storing observed signals and processing afterward.
    Secondly the analytical expression of transmitted and received signals is studied, and the digital processing of them to reconstruct SAR images is also theretically treated in detail, in terms of both range and azimuth directions, as one of compression problems of two-dimensional impulse response which is reflected from a point target. In this paper, matched filters in frequency domain are described along with some detailed evaluation of them. This processing is mainly consists of 4 steps, (1) holographic data generation, (2) real-complex data conversion, (3) range compression and (4) azimuth compression. In addition to the azimuth compression, multilook images are stacked to reduce the speckle noises which appear in reconstructed images because of the coherency of microwaves used.
    As an actual example, a two-dimensional impulse response generated by computer with SEASATSAR parameters was successfully compressed to a sharp single impulse.
    Finally a SEASAT-SAR image around LOSANGELS is reconstructed to show the validity of the digital processing presented by the authors.
  • 石井 吉徳
    1982 年 2 巻 3 号 p. 79-83
    発行日: 1982/08/20
    公開日: 2009/05/22
    ジャーナル フリー
  • 1982 年 2 巻 3 号 p. 87
    発行日: 1982年
    公開日: 2009/05/22
    ジャーナル フリー
  • 1982 年 2 巻 3 号 p. 92
    発行日: 1982年
    公開日: 2009/05/22
    ジャーナル フリー
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