Hargreaves, G. W.

English

NERC Open Research Archive

PROUDMAN OCEANOGRAPHIC LABORATORY   CRUISE REPORT NO.  31     VEINS: Inverted Echo Sounders in the Denmark Strait   As part of       FS METEOR CRUISE 39/5  AUGUST 13, 1997 - SEPTEMBER 10, 1997              G.W. Hargreaves       1999 DOCUMENT DATA SHEET   AUTHOR  G.W. HARGREAVES    PUBLICATION DATE    1999  TITLE VEINS: Inverted Echo Sounders in the Denmark Strait, as part of,  FS Meteor Cruise 39/5, August 13, 1997 – September 10, 1997    REFERENCE Proudman Oceanographic Laboratory, Cruise Report, No 31, 10pp   ABSTRACT  The overflow of cold dense water from the Denmark Strait is one of the key elements of the north Atlantic thermohaline circulation and has important consequences for global climate change.  It is important to measure the transport of this water and to understand it’s variability on seasonal and at longer time scales.  The European funded project "Variability of Exchanges in Northern Seas" (VEINS MAS3CT960070) is an attempt to measure variations in the Arctic circulation using modern oceanographic instrumentation.  A combined Inverted Echo Sounder and Bottom Pressure Recorder was successfully recovered and re-deployed.  An additional Inverted Echo Sounder and Bottom Pressure Recorder was deployed in the Denmark Strait to measure the thickness of this cold dense water and thus determine transport.          ISSUING ORGANISATION  Proudman Oceanographic Laboratory Bidston Observatory Birkenhead Merseyside L43 7RA UK  Acting Director: Dr J.M. Huthnance  TELEPHONE:  (0151) 653 8633    FAX:  (0151) 653 6269    TELEX: 628591 OCEAN BG  KEYWORDS Bottom Pressure Recorder     Denmark Strait    Inverted Echo Sounder VEINS    Sea Level     Bottom Water    North Atlantic     CONTRACT  PROJECT  3310 MLL-12-5  PRICE        £10.00   Copies of this report are available from: The Library, Proudman Oceanographic Laboratory.  CONTENTS   CRUISE PERSONNEL ....................................................................................................................... 1 ACKNOWLEDGEMENTS................................................................................................................. 1 OVERVIEW......................................................................................................................................... 1 POL CRUISE OBJECTIVES.............................................................................................................. 2 IES/BPR DEPLOYMENTS ................................................................................................................ 2 Ship Preparation....................................................................................................................... 2 RECOVERY OF IES/BPR (ICE1) 18/8/1997 ....................................................................... 2 IES/BPR Recovery Summary .................................................................................... 2 Modifications .............................................................................................................. 2 DEPLOYMENT OF IES/BPR (UK1/IES) 19/8/1997........................................................... 3 IES/BPR (UK1) Deployment Summary .................................................................... 3 DEPLOYMENT OF IES/BPR (G1/IES) 19/8/1997.............................................................. 3 IES/BPR (G1) Deployment Summary ....................................................................... 3 CONCLUSIONS ..................................................................................................................... 3 APPENDIX 1 – IES/BPR TECHNICAL INFORMATION.............................................................. 4 IES/BPR (ICE1) RECOVERY INFORMATION ................................................................. 4 Logger Information..................................................................................................... 4 Inverted Echo Sounder................................................................................................ 4 IES/BPR (UK1/IES) DEPLOYMENT INFORMATION..................................................... 5 Logger Information..................................................................................................... 5 Inverted Echo Sounder Information........................................................................... 6 IES/BPR (G1/IES) DEPLOYMENT INFORMATION........................................................ 7 Acoustic Servicing ...................................................................................................... 7 Logger Information..................................................................................................... 7 Inverted Echo Sounder Information........................................................................... 8 MAP OF IES/BPR DEPLOYMENT POSITIONS ............................................................................ 9 GLOSSARY......................................................................................................................................... 10     1 CRUISE PERSONNEL  POL Personnel  Scientific Officer  Geoff Hargreaves  Scientific Officer  Jon Ashley  MAFF Personnel  Senior Scientific Officer John Read   ACKNOWLEDGEMENTS  The author would like to thank the Captain, Officers and ship's company of FS Meteor for their help in the deployment of sea level equipment in the Denmark Strait.   OVERVIEW  The overflow of cold dense water from the Denmark Strait is one of the key elements of the north Atlantic thermohaline circulation and has important consequences for global climate change.  It is important to measure the transport of this water and to understand its variability on seasonal and longer time scales.  The European funded project "Variability of Exchanges in Northern Seas" (VEINS) is an attempt to measure the decadal variations in the Arctic circulation using modern oceanographic instrumentation. Part of this work is in the Denmark Strait where an array of current meters is in place to measure the strength of the Overflow Water (DSOW).  CTD surveys provide knowledge of the physical properties.  To measure the thickness of the DSOW, and hence get a value for transport, Inverted Echo Sounders (IES) were deployed at the core of the current with a view to detecting the echo from the interface between the cold bottom water and the overlying intermediate layer.        2 POL CRUISE OBJECTIVES  1) To recover an Inverted Echo Sounder in the Denmark Strait  2) To deploy two Inverted Echo Sounders in the Denmark Strait   IES/BPR DEPLOYMENTS  Ship Preparation  POL personnel joined FS Meteor at Reykjavik, Iceland on August 13, 1997. The equipment was loaded aboard the ship, unpacked and stowed safely. The Bottom Pressure Recorder was assembled, tested and set running. The Inverted Echo Sounder was opened, started and the re-sealed. The frame was prepared the ballast weight assembled and then the BPR and IES installed.     RECOVERY OF IES/BPR (ICE1) 18/8/1997  EVENTS  10.08 GMT  Arrive on station.  10.12 GMT  Released from the seabed.  11.07 GMT  On the surface.  Total time on station: 59 minutes.   IES/BPR Recovery Summary  Acoustic conditions were good, and the sea was calm. The IES/BPR was monitored to the surface using both sets of acoustics. Only one pyrolease was fired in order to allow the other to be reused.   Modifications  The recovered Inverted Echo Sounder needed modifying before it could be re-deployed. Modifications were carried out to the IES once the data had been successfully recovered. All of the equipment was fitted with new batteries and one of the acoustic release units was converted from a pyrolease release mechanism to a burnwire mechanism.        3  DEPLOYMENT OF IES/BPR (UK1/IES) 19/8/1997  EVENTS  09.15 GMT  Arrive on station.  09.29 GMT  Released into the water.  10.12 GMT  On the seabed.  Total time on station: 57 minutes   IES/BPR (UK1) Deployment Summary  Both acoustic units are fitted with burnwire release mechanisms and communicated well to the seabed. No radio beacon is fitted to this unit, however a flashing light is fitted.      DEPLOYMENT OF IES/BPR (G1/IES) 19/8/1997  EVENTS  11.30 GMT  Arrive on station.  11.46 GMT  Released into the water.  12.34 GMT  On the seabed.  Total time on station:  1 hour 4 minutes   IES/BPR (G1) Deployment Summary  One of the acoustic units is fitted with a pyrolease unit and the other unit is fitted with a burnwire mechanism. Both acoustics were successfully monitored to the seabed.   CONCLUSIONS  All of the cruise objectives were fully achieved despite the tight time schedule between the recovery and re-deployment of the Inverted Echo Sounder.        4 APPENDIX 1 – IES/BPR TECHNICAL INFORMATION  IES/BPR (ICE1) RECOVERY INFORMATION  Location details   - Latitude 63° 22.042' N       Longitude 036° 04.369' W       Depth  2180m  On station    - 10.08 GMT on 18/8/1997 Released from the seabed  - 10.12 GMT On the surface    - 11.07 GMT  Sea Temperature   - 10.4°C Air Temperature   - 9.5°C Barometric Pressure   - 1002.2 mbar  Acoustics fitted were 46428 (Rx 14.5 kHz, Tx 12.0 kHz, Release D) and 46457 (Rx 15.0 kHz, Tx 12.0 kHz, Release B). The release command was transmitted to acoustic 46428. The release command was not transmitted to the other unit since the pyrolease is to be re-used.   Logger Information Timebase scan Expected scan     Actual scan 21.30.00 GMT on 18/8/1997   21.29.00 GMT  Timebase is 60 seconds fast.  Data downloaded to Iceland.raw.  Data Arrangement The raw data are made up of six data columns.  Column  Data 1  Time 2  Date 3  Temperature (DQ36573) 4  Pressure       (DQ36753) 5  Temperature (DQ38175) 6  Pressure       (DQ38175)   Inverted Echo Sounder The IES was not pinging due to the hard disk being full of data.  IES Real Time Clock    Actual Time 17.03.07 17.12.15 GMT      5    IES/BPR (UK1/IES) DEPLOYMENT INFORMATION  Location details   - Latitude 63° 28.730' N       Longitude 036° 17.870' W       Depth  1991m  On station    - 09.15 GMT on 18/1/98 Released into the water  - 09.29 GMT On seabed    - 10.12 GMT  The deployment went very smoothly with a calm sea. The IES was monitored to the seabed using both sets of acoustics and communication was excellent.  Acoustic Information   - XT 6000 Acoustics, S/N 47166       Rx 13.5 kHz, Tx 12.0 kHz, Release B  - XT6000 Acoustics, S/N 58172 Rx 14.0 kHz, Tx 12.0 kHz, Release A  Radio Beacon    - N/A No radio beacon is fitted to this frame, however there is a Benthos flashing light.  Logger     - SSDL 4  Logger Information Sensors    - QT 119016       DQ 38173       DQ 46279  Timebase Channels  1    - Temperature QT 119016  2    - Pressure  3    - Temperature DQ 38173  4    - Pressure  5    - Temperature DQ 46279  6    - Pressure   Sensor Frequencies QT 119016    - Temperature - 45.096 kHz      - Pressure - 21.561 kHz DQ 38173    - Temperature - 169.961 kHz      - Pressure - 33.357 kHz DQ 46279    - Temperature - 172.430 kHz     6      - Pressure - 32.851 kHz  SSDL 4 timebase started at 16.15.00 GMT on 13/8/1997 First scan at 16.30.00 GMT on 13/8/1997  Battery Voltages Logger     - 13.54 V  Inverted Echo Sounder Information IES      - Chirp IES with POL ADC Board       Hard disk size 540Mb  The IES was powered up and the time set to 16.00.00 GMT on 14/8/1997  IES parameters   - Chirp Interval  240 minutes       Samples / Datafile 1       Sampling Rate  Fast       Lockout Time  0       Start File  1       Serial Number  5       Deployment Number 3   First Chirp at 20.00.00 GMT on 14/8/1997      7  IES/BPR (G1/IES) DEPLOYMENT INFORMATION  Location details   - Latitude 63° 21.970' N       Longitude 036° 03.880' W       Depth  2209m  On station    - 11.35 GMT on 18/1/98 Released into the water  - 11.46 GMT On seabed    - 12.34 GMT  The deployment went very smoothly with a calm sea. The IES was monitored to the seabed using both sets of acoustics and communication was excellent.  Acoustic Servicing  S/N 46457 was converted from a pyro release to a Burnwire release.  Old battery voltage   - Red 12.50V       Orange 12.53V New battery voltage   - Red 14.36V       Orange 14.36V Burnwire release voltage  - 28.60V   S/N 46428  Old battery voltage   - Red 12.35V       Orange 12.33V New battery voltage   - Red 14.29V       Orange 14.29V  Acoustic Information   - XT 6000 Acoustics, S/N 46457       Rx 15.0 kHz, Tx 12.0 kHz, Release B  - XT6000 Acoustics, S/N 46428 Rx 14.5kHz, Tx 12.0 kHz, Release D  Acoustic 46457 is fitted with a Burnwire release and 46428 is fitted with a pyrolease mechanism.   Radio Beacon    - Novatek 154.585 MHz  Logger     - SSDL 5  Logger Information Sensors    - DQ 36573       DQ 38175      8 Timebase Channels  1    - Temperature DQ 36573  2    - Pressure  3    - Temperature DQ 38175  4    - Pressure   Sensor Frequencies DQ 36573    - Temperature - 170.8 kHz      - Pressure - 32.7 kHz DQ 38175    - Temperature - 170.45 kHz      - Pressure - 33.3 kHz  SSDL 5 timebase started at 01.30.00 GMT on 19/8/1997 First scan at 01.45.00 GMT on 19/8/1997  Battery Voltages Logger     - 14.23 V  Inverted Echo Sounder Information IES      - Chirp IES with LDEO ADC Board       Hard disk size 540Mb  The IES was powered up and the time set to 00.00.00 GMT on 19/8/1997  IES parameters   - Chirp Interval  240 minutes       Samples / Datafile 1       Sampling Rate  Fast       Lockout Time  0       Start File  1       Serial Number  10       Deployment Number 3   First Chirp at 04.00.00 GMT on 19/8/1997          9 MAP OF IES/BPR DEPLOYMENT POSITIONS      10  GLOSSARY  ADC  - Analogue to Digital Converter BPR  - Bottom Pressure Recorder CTD  - Conductivity, Temperature and Depth Profiler DSOW  - Denmark Strait Overflow Water EPROM - Erasable Programmable Memory IES  - Inverted Echo Sounder LDEO  - Lamont Doherty Earth Observation Unit MAFF  - Ministry of Agriculture, Fisheries and Food POL  - Proudman Oceanographic Laboratory VEINS  - Variability of Exchanges in Northern Seas 

VEINS: Inverted Echo Sounders in the Denmark Strait, as part of , FS "Meteor" Cruise 39/5, August 13, 1997 - September 10, 1997

http://nora.nerc.ac.uk/6131/1/CRNo31-Meteor39-5-97.pdf

VEINS: Inverted Echo Sounders in the Denmark Strait, as part of , FS "Meteor" Cruise 39/5, August 13, 1997 - September 10, 1997

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