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Metadata Report for BODC Series Reference Number 684522


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Teledyne RDI 150kHz Narrowband Vessel-Mounted ADCP  current profilers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator -
Originating Organization Southampton Oceanography Centre (now National Oceanography Centre, Southampton)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) CROZEX
 

Data Identifiers

Originator's Identifier ADP28519
BODC Series Reference 684522
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2004-11-21 04:00
End Time (yyyy-mm-dd hh:mm) 2004-11-22 03:58
Nominal Cycle Interval 120.0 seconds
 

Spatial Co-ordinates

Start Latitude 48.92833 S ( 48° 55.7' S )
End Latitude 48.98933 S ( 48° 59.4' S )
Start Longitude 51.58083 E ( 51° 34.8' E )
End Longitude 51.30217 E ( 51° 18.1' E )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 11.0 m
Maximum Sensor or Sampling Depth 391.0 m
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
Sea Floor Depth Source -
Sensor or Sampling Distribution Sensor fixed with measurements made at multiple depths within a fixed range (e.g. ADCP) - The sensor is at a fixed depth, but measurements are made remotely from the sensor over a range of depths (e.g. ADCP measurements)
Sensor or Sampling Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum -
 

Parameters

BODC CODERankUnitsTitle
DBINAA010MetresDepth (spatial coordinate) of ADCP bin relative to water surface {bin depth} in the water body
AADYAA011DaysDate (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ011DaysTime (time between 00:00 UT and timestamp)
ALATZZ011DegreesLatitude north
ALONZZ011DegreesLongitude east
DSRNGR011KilometresDistance travelled by ADCP bottom tracking refined using GPS fixes
APEWGP012Centimetres per secondEastward velocity of measurement platform relative to ground surface by unspecified GPS system
APNSGP012Centimetres per secondNorthward velocity of measurement platform relative to ground surface by unspecified GPS system
ASAMAS012DecibelsSignal return amplitude from the water body by shipborne acoustic doppler current profiler (ADCP)
LCEWAS012Centimetres per secondEastward velocity of water current (Eulerian measurement) in the water body by shipborne acoustic doppler current profiler (ADCP)
LCNSAS012Centimetres per secondNorthward velocity of water current (Eulerian measurement) in the water body by shipborne acoustic doppler current profiler (ADCP)
LERRAS012Centimetres per secondError velocity of water current in the water body by shipborne acoustic doppler current profiler (ADCP)
LREWAS012Centimetres per secondEastward velocity of water current relative to moving platform in the water body by shipborne acoustic doppler current profiler (ADCP)
LRNSAS012Centimetres per secondNorthward velocity of water current relative to moving platform in the water body by shipborne acoustic doppler current profiler (ADCP)
LRZAAS012Centimetres per secondUpward velocity of water current in the water body by shipborne acoustic doppler current profiler (ADCP)
PCGDAP012PercentAcceptable proportion of acoustic signal returns from the water body by acoustic doppler current profiler (ADCP)

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

Problem Reports

No Problem Report Found in the Database


Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."


Narrative Documents

RD Instruments 150kHz Narrow Band Acoustic Doppler Current Profiler

Specifications

Water velocity measurements relative to the ADCP
Accuracy (long term) 0.5 % of measured velocity ± 0.5 cm/s
Statistical uncertainty for one ping (cm/s) Depth cell length of 4, 8, 16 m = 26, 13, 6.5 respectively (for horizontal velocities using the standard transducer)
Ping rate (pings per second) 2 (100 pings averaged in ADCP)
Maximum profiling range (meters) 290
Minimum range to start of first depth cell (meters) 4
Number of depth cells 8 to 128
Velocity range ± 0.01 to 9.5 m/s (horizontal)
Velocity resolution (cm/s) 0.25 or 0.125
Velocity measurements relative to the bottom and measurement of bottom depth
Accuracy 0.5% of measured velocity ± 0.5 cm/s
Statistical uncertainty of one ping (percent of measured velocity) 3.5 (for horizontal velocities using the standard transducer)
Ping rate (pings per second) 0.9 (100 pings averaged in ADCP)
Depth range 290 (the maximum depth range can be up to 1.5 times greater than specified)
Bottom depth resolution (meters) 4
Velocity range ± 0.01 to 9.5 m/s (horizontal)
Velocity resolution (cm/s) 0.25 or 0.125
Measurement of echo intensity
Accuracy (with temperature correction) Before calibration : ± 8 dB, After calibration: ± 3 dB
Statistical uncertainty for one ping Approximately ± 5 dB
Ping rate (pings per second) 2 (100 pings averaged in ADCP)
Profiling range (meters less than for water velocity measurement) 64
Number of depth cells 8 to 128
Dynamic range 80 dB
Resolution 0.45 dB typical (temperature/system dependent)
Data communication
Interface Modified RS-232/422 serial at baud rates of 300-19,200
Data format Binary (8-bit) or ASCII (76-character) lines separated by a carriage return/line feed.
Data storage capacity 2 MB (standard); expandable to 40 MB in 1 and/or 2 MB increments
Power requirements
ADCP electronics Voltage range (VDC) 6-12; Standby current (amps) 0.0002; Operate current (amps) 0.24; Peak current (amps) 0.5
transmit and EPROM recorder Voltage range (VDC) 20-40; Standby current (amps) 0.0001; Operate current (amps) 0.10; Peak current (amps) 2.0
CTD sensors Voltage range (VDC) 12-20; Standby current (amps) 0.0001; Operate current (amps) 0.022; Peak current (amps) 0.05
Temperature sensor
Accuracy ± 0.2°C
Time constant Approximately 2 minutes
Range -5° to 45°C
Resolution 0.012°C
Environmental
Operating temperature -5°C to 40°C
Humidity Must be non-condensing
Depth capability 35 meters (transducer only)
Physical characteristics
Weight in air 67.6 kg
Weight in water 25.0
Diameter 45.9 cm
Length 141.4 cm

RRS Discovery 285 150kHz VMADCP

Deployment and originator's processing

Two RDI Vessel-Mounted Acoustic Doppler Current Profilers (VM-ADCPs) were operated on Discovery 285; the 150kHz VM-ADCP and the 75 kHz Phased Array instrument (Ocean Surveyor) that had been fitted immediately prior to FISHES (Discovery 253, May-June 2001). The 150 kHz ADCP is mounted in the hull 1.75 m to port of the keel, 33 m aft of the bow at the waterline and at an approximate depth of 5 m. The 75 kHz ADCP is mounted in a second well in the hull, but 4.15 m forward and 2.5 m to starboard of the 150 kHz well. The 150kHz RDI ADCP was logged using RDI Data Acquisition Software (DAS) version 2.48 with profiler firmware 17.20. The instrument was configured to sample over 120 second intervals with 96 bins of 4 m thickness, pulse length 4 m and a blank beyond transmit of 4m. The high vertical resolution was chosen to support the remote detection of zooplankton patchiness. Early in the cruise the ADCP was switched to bottom and water track mode over shallow ground to enable calibration. After closely inspecting the data from the two ADCPs without configuring them to synchronise their pings over the ensemble period, it was decided to leave them in this mode as little evidence of interference could be seen. To synchronise the instruments, the 150 kHz instrument has to be set as the master and the 75 as the slave, as recommended by RDI and discussed by Penny Holliday in the D253 cruise report. The result is that each ADCP has only 40 water track pings in the 2 minute period. With no obvious evidence of interference this seemed an unacceptable compromise. Spot gyro heading data were fed into the transducer deck unit where they were incorporated into the individual ping profiles to correct the velocities to earth co-ordinates before being reduced to a 2 minute ensemble. Following advice from RDI, the 150 KHz ADCP on RRS Discovery had been refitted in dry dock, several years ago, to a heading offset of ~45°. This offset was accounted for in the DAS software configuration on D285.The following table describes the setup of the 150kHz ADCP.

Frequency dependent constant 4.17e5
Power into water (W) 183.15
Dimensionless noise factor 8.95
Bin length (m) 4
Blanking distance (m) 4

A calibration of the 150 kHz ADCP was achieved using bottom tracking data available from our departure across the Agulhas Bank. Using long, straight, steady speed sections of standard two minute ensemble profiles we obtained a calibration of tanØ= -0.0039 (±s.d.= 0.0080), Ø= -0.22° and A =1.0034 (±s.d.= 0.0064)

BODC processing

A total of 37 files were submitted to BODC. The data were supplied in P* binary format. The following variables were transferred to BODC QXF format (a BODC-defined subset of NetCDF and BODC's format for 2 dimensionsal datacycle storage) using transfer process tr339.

BODC Code Description Units Originator's variable
ALATZZ01 Latitude degrees lat
ALONZZ01 Longitude degrees lon
AADYAA01 Date (time from 00:00 01/01/1760 to 00:00 UT on day) days time
AAFDZZ01 Time (time between 00:00 UT and timestamp) days time
APEWGP01 Eastward platform velocity ve cm/s
APNSGP01 Northward platform velocity vn cm/s
DBINAA01 Bin depth metres bindepth
DSRNGR01 Distance Run distrun km
ASAMAS01 Signal return amplitude decibels ampl
LCEWAS01 Eastward current velocity (Eulerian) cm/s absve
LCNSAS01 Northward current velocity (Eulerian) cm/s absvn
LERRAS01 Current velocity error cm/s velerr
LREWAS01 Relative eastward current velocity cm/s evelcal
LRNSAS01 Relative northward current velocity cm/s nvelcal
LRZAAS01 Upward current velocity cm/s velvert
PCGDAP01 Percentage good return signal % good

Screening and Data quality

The data have been visually screened for obvious problems using the BODC EDSERPLO software. No significant problems were detected.


Project Information

CROZet natural iron bloom EXport experiment (CROZEX)

The multidisciplinary CROZet natural iron bloom EXport experiment (CROZEX) was a major component of the Natural Environment Research Council (NERC) funded core strategic project Biophysical Interactions and Controls over Export Production (BICEP). The project is the first planned natural iron fertilisation experiment to have been conducted in the Southern Ocean.

The overall objective of CROZEX was to examine, from surface to sediment, the structure, causes and consequences of a naturally occurring phytoplankton bloom in the Southern Ocean. The Crozet Plateau was chosen as the study area. This area typically exhibits two phytoplankton blooms a year, a primary bloom in that peaks in October and a secondary bloom in December or January. Specific aims with respect to these were to:

  • Determine what limits the primary bloom
  • Determine the cause of the secondary bloom

The project was run by the George Deacon Division (GDD), now Ocean Biogeochemistry and Ecosystems (OBE) at the National Oceanography Centre Southampton (NOCS). Participants from five other university departments also contributed to the project.

The project ran from November 2004 to January 2008 with marine data collection between 3rd November 2004 and 21st January 2005. There were 2 cruises to the Crozet Islands Plateau, which are summarised in Table 1.

Table 1: Details of the RRS Discovery CROZEX cruises.

Cruise No. Dates
D285 3rd November 2004 - 10th December 2004
D286 13th December 2004 - 21st January 2005

The two cruises aimed to survey two areas at different phases of the bloom cycle described above. A control area to the south of the Crozet Islands, which is classified as High Nutrient Low Chorophyll (HNLC), where the blooms do not occur and a second area in the region of the blooms to the north of the Crozet Islands.

Sampling was undertaken at ten major stations (see Pollard et al., 2007) numbered M1 to M10. The following observations/sampling were conducted at each station where possible:

  • Several CTD casts sampling:
    • Iron (using a titanium rig)
    • 234Th
    • Physical parameters (temperature, salinity etc)
    • Oxygen
    • CO2
    • Nutrients using a stainless steel rig including a Lowered Acoustic Doppler Current Profiller (LADCP)
  • At each thorium cast there was an associated Stand Alone Pump System (SAPS) deployment
  • At some stations, a drifting PELAGRA trap was deployed for the duration of the work
  • Megacoring was undertaken at M5 and M6
  • Gravity coring was undertaken at M5, M6 and M10
  • Longhurst Hardy Plankton Recorder (LPHR) tows were undertaken at a few major stations

For each of the major stations (M1 to M10), the following were determined:

  • Primary productivity
  • New Production
  • Phytoplankton community composition
  • Bacterial activity
  • Iron
  • Nutrient drawdown
  • Thorium export

Sampling between major stations included:

  • SeaSoar runs instrumented with:
    • CTD
    • Optical Plankton Counter (OPC)
    • Fast Repetition Rate fluorimeter (FRRf)
  • Physics CTD casts on several lines
  • Argo float deployments
  • Zooplankton nets at nearly every CTD and major station
  • Underway and on-station CO2 measurements
  • Underway nutrients and radium sampling
  • 5 to 6 day ship-board iron-addition incubation experiments
  • Checks against near-real-time satellite and model data
  • Mooring deployments based on the satellite imagery in support of the CROZET (Benthic CROZEX) project.

The CROZEX cruises included 6 extra days in support of the CROZET (Benthic CROZEX) project, whose main cruise took place one year after the CROZEX cruises. The CROZET work undertaken during the CROZEX cruises was primarily the moored sediment trap deployments, although some of the coring work is applicable to both projects.

CROZEX produced significant findings in several disciplines, including confirmation that iron from Crozet fertilised the bloom and that phytoplankton production rates and most export flux estimates were much larger in the bloom area than the HNLC area (Pollard et al. 2007). Many of the project results are presented in a special CROZEX issue of Deep-Sea Research II (volume 54, 2007).

References

Pollard R., Sanders R., Lucas M. and Statham P., 2007. The Crozet natural iron bloom and export experiment (CROZEX). Deep-Sea Research II, 54, 1905-1914.


Data Activity or Cruise Information

Cruise

Cruise Name D285
Departure Date 2004-11-03
Arrival Date 2004-12-10
Principal Scientist(s)Raymond T Pollard (Southampton Oceanography Centre)
Ship RRS Discovery

Complete Cruise Metadata Report is available here


Fixed Station Information


No Fixed Station Information held for the Series


BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
Blank Unqualified
< Below detection limit
> In excess of quoted value
A Taxonomic flag for affinis (aff.)
B Beginning of CTD Down/Up Cast
C Taxonomic flag for confer (cf.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
I Taxonomic flag for single species (sp.)
K Improbable value - unknown quality control source
L Improbable value - originator's quality control
M Improbable value - BODC quality control
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain
Q value below limit of quantification