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平成17年度 海洋音響学会 第1回講演会 (2005/12)

平成17年度 特定非営利活動法人 海洋音響学会

--- 第1回講演会---

日時: 平成17年12月7日(水) 15:30-16:45

場所: 東京海洋大学楽水会館 大会議室

   東京都港区港南4-5-7

地図:http://www.kaiyodai.ac.jp/Japanese/info/campus-map_01.html

交通機関: JR線,京浜急行線「品川」駅下車 徒歩15分 

演題: Acoustic Current Measurements with Moored Instruments: Possibilities and Limitations of Single Point and Profiling Instruments

(係留式の音響流速計測:ポイント計測とプロファイル計測の可能性と限界)

講演者: Dr. Anders Tengberg

Goteborg University (Sweden) and Aanderaa Data Instruments A/S (Norway)

参加費: 名誉会員・通常会員 無料, 賛助会員・学生 1,000円, 一般 2,000円

懇親会: 17:00~18:30 東京海洋大学生協 会費:1,000円

講演要旨:

Acoustic Current Measurements with Moored Instruments: Possibilities and Limitations of Single Point and Profiling Instruments

Suggested presentation with simultaneous translation into Japanese

(60minutes + 15 minutes questions) for Marine Acoustic Society of Japan, November/December, 2005

Dr. Anders Tengberg Goteborg University (Sweden) and Aanderaa Data Instruments A/S (Norway)

For more than forty years oceanographers have used moored equipment to measure physical parameters in the sea. The "classical" way to obtain current information is to use rotor/propeller equipped mechanical instruments.

A more recent generation of current meters collect current speed and direction data without moving parts. Mainly three different measuring principles exist and those are: Electromagnetic, Acoustic Time Travel and Acoustic Doppler. The main focus of this presentation is on Acoustic Doppler current meters but to start with the different measuring principles will be briefly described and compared by giving field and tow tank data examples.

The Acoustic Doppler principle has proven well suited to accurately measure currents in oceans and lakes. Some of the advantages of this technology include no need for calibrations, no drift over time and low sensitivity to fouling. In addition to being used for single point measurements this technology can also serve to obtain current information in multiple layers, so called Acoustic Doppler Current Profiling (ADCP).

The advantages and limitations of Acoustic Doppler instruments will be discussed and exemplified with field data. Different profiling instruments will be compared with each other and with single point instruments.

Finally a new type of Acoustic Doppler Current Profiler (RDCP-600) with unique measuring capabilities will be presented. One of the new and useful features of this instrument is that it is the first ADCP that can measure the true surface current. This has proven useful when monitoring transport and dispersion of for example oil and other chemical spills. Also for navigational safety in most harbor installations information on surface currents is essential. Another unique feature with the instruments is the ability to supply "multiple column data". Examples will be given from harbor installations in which the RDCP-600 is used to output on-line current speed and direction data for navigational use which is limited to eight layers. At the same time a high resolution (seventy 0.5 m bins) current profile (including horizontal and vertical currents) and information on signal strength, waves etc. is stored on-board the instrument for weekly download by scientific users. Other user applications that will be demonstrated include environmental investigations looking at the correlation of surface currents and waves with the bottom currents and the resuspension of bottom sediments (using turbidity sensors) as well as the close to bottom changes in salinity, temperature and oxygen conditions.