Observation work flow

　Observations with the CTD water sampling system are made while the vessel is stationary. Once the ship arrives at the observation site and enters the observation mode, the ship proceeds in the order shown in Figure 9: in CTD observation, "Down Cast" is defined as lowering the underwater station into the sea by uncoiling the wire, while "Up Cast" is defined as raising the underwater station in the sea by coiling the wire.

Fig.9　CTD observation work flow

採水器のセッティング　Setting up water sampling equipment

水中への投入作業　Loading operation into the water

ダウンキャスト　Down Casting

アップキャスト，採水　Up Casting and collecting water

船上への揚収作業　Unloading to ship

配水作業　Water distribution

① Setting up water sampling equipment

Before feeding the underwater station, open the top and bottom lids of the water sampler to prepare the water sampling device for feeding. Also, make sure that the water sampler intake and air vent are closed (Figure 10).

Fig.10　Setting up water sampling equipment

採水装置トリガー部拡大図　Enlarged view of water sampling device trigger section

スナップフック拡大図　Enlarged view of snap hook

エアベント拡大図　Enlarged view of air vent

ペットコック拡大図　Enlarged view of Petcock

a) Hook the end of the tegus connected to the upper lid onto the trigger of the water sampling device to secure the upper lid in the open position.　
b) Secure the lower lid in the open position by hooking the snap hook on the lower end of the lower lid's ring-shaped texus, which is branched off from the upper lid's texus and extended downward.
c) Make sure that the air vent (air hole) and PETCOCK (water sampling port) are closed. The air vent is closed by turning clockwise and screwing it in. The PET cock is closed by pulling it out toward you.

② Loading operation into the water

　After the underwater station is lifted above the sea surface by crane, the cable is unloaded and placed in the water. During this operation, the underwater station is secured by ropes or other means to prevent it from swinging around due to hull movement. If the underwater station swings around, it may collide with the port side, damaging sensors and water sampling equipment, or injuring the operator.

③Down casting

After placing the cable into the sea, the operator operates the on-board station to begin data acquisition. The cable is unloaded to the desired depth and the vertical profile is continuously measured. The operator stops the cable ejection at the desired depth based on the output value of the CTD's pressure sensor.

④ Up casting

　Water sampling is performed at an arbitrary depth before the cable is wound up and the submersible station is retrieved on board. While monitoring the value of the CTD sensor, the operator stops winding the wire at the pre-determined water sampling depth, then sends a water sampling signal from the onboard station to the submersible station and closes the lid of the water sampler.

⑤ Unloading to ship

　Once the water sampling is completed, the underwater station is lifted on board.

⑥ Water distribution

　Once the underwater station is pumped on board, the seawater sample is sorted from the water sampler into sample bottles (water distribution).