README for Shipboard ADCP Data 1. Overview The ADCP transmits acoustic pulses from a transducer assembly along four beams. The transducers receive backscattered sound from small particles floating ambiently with the water currents. Using the Doppler principle, the ADCP converts the backscattered sound into components of water-current velocity. The ADCP measures the speed and direction of the water currents at multiple depths in the water column. The ADCP makes a profile of these measurements for up to 128 depths called depth cells. 2. Specifications Manufacturer : RD Instruments System : VM75 Broadband Serial Number : Transducer S/N 02529 Frequency : 76.8kHz Configuration : 4 beam Beam angle : 30deg Output power : 1kW Echo Dynamic range : 80dB Echo Precision : +/-1.5dB CPU Firmware Version : 5.9 Transducer Depth : 6.5m beneath calm water line ADCP data logger : RDI VmDas 1.4 3. ADCP configuration depth range : 22.5 - 650m (bin centers) bin length : 16 m number of bins : 40 transmit pulse length : 8 m blanking interval : 8 m ensemble averaging interval : 5 min sound speed calculation : used transducer temperature during acquisition 4. About the revision of hull trembling Hull trembling was adjust using the tilt sensor for the Dopplar Radar. We used VMDAS ver.1.40 for adjustment. Tilt sensor make/model : IXSEA/PHINS Measuremant precision : Roll 0.01deg Pith 0.01deg Heading 0.01deg 5. ADCP Data Format Shipboard ADCP data are provided in two formats: 1) CODAS database(.blk files) processed from 5 minute average data. Details on CODAS data can be found at the University of Hawaii https://currents.soest.hawaii.edu/ 2) ODV (Ocean Data View) format as ASCII file. Details on ODV can be found at Alfred-Wegener-Institute https://odv.awi.de/ Data are stored as follows. Note that quality flag is "8", when percentgood is less than 30%. No. Parameter Unit Format Remarks 1 Cruise name a* The number of letters is different with each cruise 2 Station a* Ensemble Number (The number of letters changes) 3 Type a1 4 Date i2/i2/i4 mon/day/yr 5 Time i2:i2 hh:mm(UTC) 6 Longitude degree f9.4 positive: Eastern hemisphere negative: Western hemisphere 7 Latitude degree f8.4 positive: Northern hemisphere negative: Southtern hemisphere 8 Bottom Depth m f6.1 Only bottom track mode (missing:9999) 9 Measurement Depth m f6.1 10 U-component m/s f6.3 positive: Eastward, negative: Westward 11 Quality Flag i1 0 Fgood @8 Fno data or bad data 12 V-component m/s f6.3 positive: Northward, negative: Southward 13 Quality Flag i1 0 Fgood @8 Fno data or bad data 14 W-component m/s f6.3 positive: Upward, negative: Downward 15 Error Velocity m/s f6.3 16 Percent good % i* 6. Data acquisition and setting (UTC:YYYY/MM/DD,hh:mm) Leg-1 Data 1) Bottom track mode 2006/10/03 20:53 - 2006/10/04 02:42 2006/10/04 02:42 - 2006/10/04 06:48 (Ship in Hachinohe port) 2006/10/04 06:49 - 2006/10/04 23:54 2) Water track mode 2006/10/04 23:56 - 2006/10/11 02:22 2006/10/12 19:07 - 2006/10/13 19:27 2006/10/18 19:02 - 2006/10/23 11:07 2006/11/13 14:17 - 2006/11/26 04:35 Leg-2 Data 1) Bottom track mode 2006/12/11 22:08 - 2006/12/12 10:00 2) Water track mode 2006/11/29 05:40 - 2006/12/07 04:35 2006/12/07 04:43 - 2006/12/10 11:00 7. Remarks 1) During the following periods, sound speed was set to 1542m/sec due to the system trouble. 04:43 UTC 07 Dec. 2006 - 11:00 UTC 10 Dec. 2006 2) During the following periods, sound speed was set to 1541m/sec due to the system trouble. 22:08 UTC 11 Dec. 2006 - 10:00 UTC 12 Dec. 2006 3) During the following period, unusual sound speed data was mixed due to the system trouble. 23:25 UTC 05 Dec. 2006 - 04:35 UTC 07 Dec. 2006 ---------------------- end ----------------------