Metadata Report for BODC Series Reference Number 1650535


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Teledyne RDI 300kHz Workhorse Monitor direct-reading ADCP  current profilers
Instrument Mounting lowered unmanned submersible
Originating Country United States
Originator Dr Andreas Thurnherr
Originating Organization Lamont-Doherty Earth Observatory
Processing Status banked
Project(s) DIMES
 

Data Identifiers

Originator's Identifier LADCP_037
BODC Series Reference 1650535
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2010-12-28 10:22
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 7.9 decibars
 

Spatial Co-ordinates

Latitude 59.38896 S ( 59° 23.3' S )
Longitude 68.07878 W ( 68° 4.7' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 7.8 m
Maximum Sensor Depth 3646.4 m
Minimum Sensor Height 52.6 m
Maximum Sensor Height 3691.2 m
Sea Floor Depth 3699.0 m
Sensor Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor Depth Datum Approximate - Depth is only approximate
Sea Floor Depth Datum Approximate - Depth is only approximate
 

Parameters

BODC CODE Rank Units Short Title Title
ACYCAA01 1 Dimensionless Record_No Sequence number
ADEPZZ01 1 Metres DepBelowSurf Depth below surface of the water body
ERRVLDCP 1 Centimetres per second LADCPErrVel Current velocity error in the water body by lowered acoustic doppler current profiler (ADCP)
LCEWLW01 1 Centimetres per second CurrVelE_ADCP Eastward current velocity (Eulerian) in the water body by lowered acoustic doppler current profiler (ADCP)
LCNSLW01 1 Centimetres per second CurrVelN_ADCP Northward current velocity (Eulerian) in the water body by lowered 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

Instrument Description

The LADCP data were collected using the instrumentation detailed below:

Sensor Model Serial Number Calibration (UT) Comments
LADCP Teledyne RDI high-power Workhorse 300kHz 12736 - LDEO unit, downward looking
LADCP Teledyne RDI standard Workhorse 300kHz 150 - LDEO unit, upward looking for stations 1-3
LADCP Teledyne RDI standard Workhorse 300kHz 4275 - NOC unit, upward looking for stations 4-53
LADCP Teledyne RDI standard titanium Workhorse 300kHz 13400 - NOC unit, upward looking for station 54
LADCP Teledyne RDI standard Workhorse 300kHz 4275 - NOC unit, upward looking for station 55

Two Teledyne RDI Workhorse 300kHz ADCPs were mounted on the Sea-Bird 9 11 plus CTD frame at a time, one pointing downward (downlooker) and one upward (uplooker).

The first three stations were carried out with the standard instrument configurations supplied with the LDEO data acquisitions software 25 x 8 m bins, beam coordinates, zero blanking distance, narrow bandwidth, 2.5 m s -1 ambiguity velocity, 1.5/2.0 s staggered ping rate.

There were large velocity warnings during processing therefore the ambiguity velocity was increased on station 4 to 3 m s -1 , on station 11 to 3.5 m s -1 and on station 20 to 4.0 m s -1 .

In an attempt to increase sampling the pinging interval was decreased to 1.0/1.3 s on station 20. Inspection of the raw ensemble times indicated that the instruments were not capable of such a high pinging rate and the rate was therefore decreased to 1.2/1.4 s on station 23 and, finally, to 1.3/1.5 s on station 33.

Due to a problem with the star cable, station 41 was carried out with asynchronous pinging, with a staggered rate of 1.3/1.5 s in the master and 1.0 s in the slave.

There are no uplooker data for station 39 because of cable problems, and no valid uplooker data for station 54 due to hardware problems.

Teledyne RDI's Workhorse Monitor ADCP

The Workhorse Monitor acoustic doppler current profler (Teledyne RD Instruments) is a long-range and long-term self contained ADCP. It has a patented four beam signal (300, 600 or 1200 kHz) and a standard depth rating of 200m or 600m. It operates effectively between temperatures of -5°C and 45°C and has a velocity accuracy of ±1% ±5mm/s.

BODC Processing

LDEO processed data were provided by the originator in Matlab and ASCII formats. The LDEO processed data in ASCII format were converted into BODC internal format after discussion with the originator. All data provided were from the downward looking RDI 300 kHz Workhorse ADCP which was in operation at the time. The following table shows how the variables within the ASCII files were mapped to appropriate BODC parameter codes:

Originator's Parameter Name Units Description BODC Parameter Code Units Comments
z m Depth of LADCP bin ADEPZZ01 m -
u m s -1 Eastward velocity LCEWLW01 cm s -1 Units converted from m s -1 to cm s -1 by multiplying by 100.
v m s -1 Northward velocity LCNSLW01 cm s -1 Units converted from m s -1 to cm s -1 by multiplying by 100.
ev m s -1 Uncertainty estimates of LADCP velocity profile ERRVLDCP cm s -1 Units converted from m s -1 to cm s -1 by multiplying by 100.

All reformatted data were visualised using the in-house Edserplo software. Suspect and missing data were marked by adding an appropriate quality control flag.

Note that the more complex LDEO processed data are available on request in Matlab format as well as the unprocessed raw LADCP files.

Originator's Data Processing

Sampling Strategy

A total of 55 LADCP profiles were collected at all CTD stations in order to derive full-depth profiles of ocean velocity, as well as profiles of finestructure vertical shear.

Data processing

Preliminary shipboard processing of the LADCP data was carried out with the LDEO IX.6 LADCP processing software using one second averaged uncalibrated CTD data in order to correct the LADCP data for depth and sound speed. The CTD data were minimally processed using 'AlignCTD' which applies temporal shifts to align the sensor readings and 'CellTM' which corrects for the thermal mass. Velocity referencing was accomplished with post-processed (i.e. non-RDI) bottom-track data, 75kHz VMADCP data, and GPS information in the CTD time series files. The first bin of each instrument was discarded during processing. Note that the profiles 2, 23, 26, 35, 45, 47, 50, 52, 53 and 55 were not processed with bottom tracking and profile 7 did not have bottom tracking or VMADCP data.

Please refer to Thurnherr (2014) and cruise report for a more detailed processing methodology. However, please be aware that this processing guide is for software versions IX.7 to IX.10 only, and changes have been made between versions which have the potential for significantly changing the solutions.

References

Thurnherr, A. M., 2014. How To Process LADCP Data With the LDEO Software, Versions IX.7 - IX.10.


Project Information

Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES) project document

DIMES is a US/UK field program aimed at measuring diapycnal and isopycnal mixing in the Southern Ocean, along the tilting isopycnals of the Antarctic Circumpolar Current.

The Meridional Overturning Circulation (MOC) of the ocean is a critical regulator of the Earth's climate processes. Climate models are highly sensitive to the representation of mixing processes in the southern limb of the MOC, within the Southern Ocean, although the lack of extensive in situ observations of Southern Ocean mixing processes has made evaluation of mixing somewhat difficult. Theories and models of the Southern Ocean circulation have been built on the premise of adiabatic flow in the ocean interior, with diabatic processes confined to the upper-ocean mixed layer. Interior diapycnal mixing has often been assumed to be small, but a few recent studies have suggested that diapycnal mixing might be large in some locations, particularly over rough bathymetry. Depending on its extent, this interior diapycnal mixing could significantly affect the overall energetics and property balances for the Southern Ocean and in turn for the global ocean. The goals of DIMES are to obtain measurements that will help us quantify both along-isopycnal eddy-driven mixing and cross-isopycnal interior mixing.

DIMES includes tracer release, isopycnal following RAFOS floats, microstructure measurements, shearmeter floats, EM-APEX floats, a mooring array in Drake Passage, hydrographic observations, inverse modeling, and analysis of altimetry and numerical model output.

DIMES is sponsored by the National Science Foundation (U.S.), Natural Environment Research Council (U.K) and British Antarctic Survey (U.K.)

For more information please see the official project website at DIMES


Data Activity or Cruise Information

Cruise

Cruise Name JC054 (UKD-2)
Departure Date 2010-12-04
Arrival Date 2011-01-08
Principal Scientist(s)Mike Meredith (British Antarctic Survey)
Ship RRS James Cook

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameDrake Passage - WOCE SR1
CategoryOffshore route/traverse

World Ocean Circulation Experiment (WOCE) Southern Repeat Section 1 - South America to West Antarctic Peninsula

WOCE established a repeat hydrographic section across Drake Passage and designated it SR1 (also known as A21). The section is located between the Southern tip of South America and the West Antarctic Peninsula within a bounding box of 55° 19.40' S, 68° 15.80' W (North-Western corner) and 64° 8.52' S, 63° 4.80' W (South-Eastern corner).

A table of cruises which occupied SR1 is presented below with links to the relevant cruise reports (where available).

Cruise Country Start Date End Date
R/V Meteor 11/5 Germany 23-01-1990 08-03-1990
Polarstern ANT 10-5 Germany 08-08-1992 26-09-1992
R/V Vidal Gormaz 20VDSR0193_1 Chile 02-11-1993 25-12-1993
R/V Vidal Gormaz 20VDSR0194_1 Chile 08-11-1994 08-12-1994
R/V Vidal Gormaz 20VDSR0195_1 Chile 04-12-1995 15-12-1995
R/V Vidal Gormaz 20VDSR0196_1 Chile 28-11-1996 13-12-1996
R/V Vidal Gormaz 20VDSR0198_1 Chile 26-11-1998 15-12-1998
RRS James Clark Ross JR40 United Kingdom 15-03-1999 22-04-1999
RRS James Cook JC031 United Kingdom 03-02-2009 03-03-2009
RRS James Cook JC054 United Kingdom 28-11-2010 08-01-2011
RRS James Cook JC069 United Kingdom 31-01-2012 22-03-2012

Other Series linked to this Fixed Station for this cruise - 1088422 1088434 1088446 1088471 1088483 1088495 1088502 1088514 1088526 1088538 1088551 1088563 1088575 1088599 1088606 1088618 1088631 1088643 1649927 1649939 1649940 1649952 1649964 1649976 1649988 1650001 1650013 1650418 1650431 1650443 1650455 1650467 1650479 1650480 1650492 1650511 1650523 1650547 1650559 1650560 1650572 1650584 1650596 1650603

Other Cruises linked to this Fixed Station (with the number of series) - JC031 (142) JC069 (UKD-3) (8) JR19950320 (JR10) (128) JR20110409 (JR276, UKD-2.5) (13)


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