Metadata Report for BODC Series Reference Number 1644714


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 Kingdom
Originator Dr Peggy Courtois
Originating Organization University of Southampton School of Ocean and Earth Science
Processing Status banked
Project(s) DIMES
 

Data Identifiers

Originator's Identifier SOC110019_J003_02_DOWNCAST
BODC Series Reference 1644714
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2009-12-09 22:55
End Time (yyyy-mm-dd hh:mm) 2009-12-10 01:48
Nominal Cycle Interval 1.0 decibars
 

Spatial Co-ordinates

Latitude 56.01240 S ( 56° 0.7' S )
Longitude 57.82275 W ( 57° 49.4' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 20.0 m
Maximum Sensor Depth 3680.0 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
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 -
 

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
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)
LRZALW01 1 Centimetres per second UpVelLADCP Upward current velocity in the water body by lowered acoustic doppler current profiler (ADCP)
NLADCPBN 1 Dimensionless Num_LADCP_bin Number (per bin) of measurements by lowered acoustic doppler current profiler (ADCP)
SDEWLW01 1 Centimetres per second Std_dev_EW_LADCP Eastward current velocity standard deviation (Eulerian) in the water body by lowered acoustic doppler current profiler (ADCP)
SDNSLW01 1 Centimetres per second Std_dev_NS_LADCP Northward current velocity standard deviation (Eulerian) in the water body by lowered acoustic doppler current profiler (ADCP)
SDZALW01 1 Centimetres per second UpVelStdDevLADCP Upward current velocity standard deviation 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 RDI WorkHorse Monitor 300 KHz 12920 - Down-looking master configuration
LADCP RDI WorkHorse Monitor 300 KHz 4275 - Up-looking slave configuration

The LADCP package consisted of two RDI 300 kHz Workhorse ADCPs mounted on a Sea-Bird 9 11 plus CTD frame. The downward looking RDI was mounted off centre at the bottom of the rosette frame and the upward looking RDI was mounted outside the main frame. The battery packs for both LADCPs were mounted horizontally at the level of the CTD.

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

The data were received in six Matlab formatted files, one per downward-looking LADCP profile. Each LADCP profile contains velocity components for the downcast, upcast and the mean of these. The upcast and downcast data were transferred separately into BODC internal format following standard BODC procedures. The data for the meancast (variables with names ending in #_mn_i) were not transferred as these have been derived and can be recalculated.

The following tables shows how the variables within the Matlab files were mapped to appropriate BODC parameter codes:

Downcast data with originator's identifier of the format j[station number]_02_DOWNCAST

Originator's Parameter Name Units Description BODC Parameter Code BODC Units Comments
d_samp m ADCP bin depth DBINAA01 m -
pxy - Location of the cast (longitude, latitude) - - -
sm_dn_i - Flag mask for the downward cast - - Used to identify nulled cycles for applying BODC flags.
sn_dn_i Dimensionless Number points points per 20 m bin for the downward cast NLADCPBN Dimensionless Used to identify nulled cycles for applying BODC flags.
su_dn_i m s -1 East-west velocity component for the downward cast LCEWLW01 cm s -1 Units converted from m s -1 to cm s -1 by *100.
su_var_dn_i m s -1 Variance of east-west velocity component for the downward cast directly from instrument SDEWLW01 cm s -1 Units converted from variance m s -1 to standard deviation cm s -1 by ^0.5*100.
sv_dn_i m s -1 North-south velocity component for the downward cast LCNSLW01 cm s -1 Units converted from m s-1 to cm s-1 by *100.
sv_var_dn_i m s -1 Variance of north-south velocity component for the downward cast directly from instrument SDNSLW01 cm s -1 Units converted from variance m s -1 to standard deviation cm s -1 by ^0.5*100.
sw_dn_i m s -1 Up-down velocity component for the downward cast LRZALW01 cm s -1 Units converted from m s-1 to cm s-1 by *100.
sw_var_dn_i m s -1 Variance of up-down velocity component for the downward cast directly from instrument SDZALW01 cm s -1 Units converted from variance m s-1 to standard deviation cm s-1 by ^0.5*100.
txy_start_end - Decimal_day, longitude and latitude at start and end of cast - - -

Upcast data with originator's identifier of the format j[station number]_02_UPCAST

Originator's Parameter Name Units Description BODC Parameter Code BODC Units Comments
d_samp m ADCP bin depth DBINAA01 m -
pxy - Location of the cast (longitude, latitude) - - -
sm_up_i - Flag mask for the upward cast - - Used to identify nulled cycles for applying BODC flags.
sn_up_i Dimensionless Number points points per 20 m bin for the upward cast NLADCPBN Dimensionless Used to identify nulled cycles for applying BODC flags.
su_up_i m s -1 East-west velocity component for the upward cast LCEWLW01 cm s -1 Units converted from m s -1 to cm s -1 by *100.
su_var_up_i m s -1 Variance of east-west velocity component for the upward cast directly from instrument SDEWLW01 cm s -1 Units converted from variance m s -1 to standard deviation cm s -1 by ^0.5*100.
sv_up_i m s -1 North-south velocity component for the upward cast LCNSLW01 cm s -1 Units converted from m s-1 to cm s-1 by *100.
sv_var_up_i m s -1 Variance of north-south velocity component for the upward cast directly from instrument SDNSLW01 cm s -1 Units converted from variance m s -1 to standard deviation cm s -1 by ^0.5*100.
sw_up_i m s -1 Up-down velocity component for the upward cast LRZALW01 cm s -1 Units converted from m s-1 to cm s-1 by *100.
sw_var_up_i m s -1 Variance of up-down velocity component for the upward cast directly from instrument SDZALW01 cm s -1 Units converted from variance m s-1 to standard deviation cm s-1 by ^0.5*100.
txy_start_end - Decimal_day, longitude and latitude at start and end of cast - - -

Originator's Data Processing

Sampling Strategy

One LADCP profile was obtained from each of the CTD casts. A total of 10 CTD stations were carried out, this included six CTD casts (CTD001 to CTD006) and four tow-yo casts (CTD007 to CTD010). LADCP data from the six CTD casts only were processed.

Initial Processing

The data supplied to BODC were processed using the UH (University of Hawaii) method using the software package originally from Eric Firing's group. CTD calibration was applied.

For further details on the scripts used see the cruise report.


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 JC041 (UKD-1)
Departure Date 2009-12-05
Arrival Date 2009-12-21
Principal Scientist(s)Alberto C Naveira Garabato (University of Southampton School of Ocean and Earth Science)
Ship RRS James Cook

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