Configuration of CTD water sampling system

The system consists of an underwater station that combines a CTD sensor and a water sampling device, an onboard station (a deck unit that receives data sent from the underwater station and a data recording PC that records and displays data received by the deck unit), and cables connecting them (Figure 2, 3, 4, 5). The underwater station is lifted above the sea surface using a crane, and then lowered into the sea by unrolling a special cable called an armored cable (coaxial cable covered with steel wire) wound on a winch. The values measured by the underwater station are immediately transmitted to the deck unit via the armored cable. The measurement data received by the deck unit is stored in a data recording PC and simultaneously monitored using dedicated software. In addition, the Niskin water sampler lid can be closed by emitting a water sampling signal from the onboard station to collect a seawater sample from any layer.

Fig 2 CTD water sampling system Configuration

_{・船上局　Onboard operation section
データ収録PC　Data recording PC
デッキユニット　Deck Unit
船内配線　Wiring on board}

_{CTDウィンチ　CTD Winch
アーマードケーブル　armored cable}

_{・水中局　In-water section
ニスキン採水器　Niskin water sampler
採水装置　Water sampling equipment
CTD
フレーム　Frame}

Fig 3 Configuration of CTD onboard station

デッキユニット　Deck Unit

水中局へ　To the In-water section

データ収録PC　Data recording PC

入出力機器（モニタ，キーボード，マウス）　Input/output devices (monitor, keyboard, mouse)

　Onboard stations consist of deck units, data recording PCs, monitors, and other input/output equipment. The photo shows the CTD operation room of the training ship Oshoro Maru (Hokkaido University), where two deck units and two data recording PCs are housed in a rack, and monitors and keyboards are installed right next to them.

Figure 4 Configuration of CTD underwater stations

アーマードケーブル　Armored cable

多筒採水装置　Multibarrel water sampler

ニスキン採水器　Niskin water sampler　

保護フレーム　Protective frame

採水器架台　Water sampler mounts

CTDセンサ　CTD sensor

Fig 5　Multibarrel water sampler

a) A latch that serves as a water sampling trigger is arranged in a radial pattern at the top of the water sampling device, and water samplers are placed around the latch. The latch is held open by hooking the tegus attached to the lid of the water sampler to the latch.　b) When the water sampling device receives the water sampling signal, the latch is released and the lid of the sampler closes.