Metadata Report for BODC Series Reference Number 1219534


Metadata Summary

Data Description

Data Category Currents -subsurface Eulerian
Instrument Type
NameCategories
Teledyne RDI Ocean Surveyor 75kHz vessel-mounted ADCP  current profilers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Dr Stuart Cunningham
Originating Organization National Oceanography Centre, Southampton
Processing Status banked
Project(s) Rapid Climate Change Programme
RAPIDMOC
 

Data Identifiers

Originator's Identifier SUR304I1_8
BODC Series Reference 1219534
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2006-05-19 00:01
End Time (yyyy-mm-dd hh:mm) 2006-05-19 18:41
Nominal Cycle Interval 120.0 seconds
 

Spatial Co-ordinates

Start Latitude 23.81650 N ( 23° 49.0' N )
End Latitude 24.08650 N ( 24° 5.2' N )
Start Longitude 24.12917 W ( 24° 7.8' W )
End Longitude 27.85383 W ( 27° 51.2' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 16.0 m
Maximum Sensor Depth 960.0 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
Sensor Distribution Sensor fixed, measurements made at fixed depths - 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 Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum -
 

Parameters

BODC CODE Rank Units Short Title Title
DBINAA01 0 Metres BinDep Depth below sea surface (ADCP bin)
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
ACYCAA01 1 Dimensionless Record_No Sequence number
ALATGP01 1 Degrees Lat_GPS Latitude north (WGS84) by unspecified GPS system
ALONGP01 1 Degrees Lon_GPS Longitude east (WGS84) by unspecified GPS system
APEWAS01 1 Centimetres per second PlatformVelE_GPS Eastward velocity (over ground) of measurement platform by Ashtech GPS
APNSAS01 1 Centimetres per second PlatformVelN_GPS Northward velocity (over ground) of measurement platform by Ashtech GPS
DSRNCV01 1 Kilometres Cmpval Distance travelled
ASAMSP00 2 Decibels SB_ADCP_SA Signal return amplitude from the water body by shipborne acoustic doppler current profiler (ADCP) beam 1
ASAMSP02 2 Decibels SB_ADCP_SA2 Signal return amplitude from the water body by shipborne acoustic doppler current profiler (ADCP) beam 2
ASAMSP03 2 Decibels SB_ADCP_SA3 Signal return amplitude from the water body by shipborne acoustic doppler current profiler (ADCP) beam 3
ASAMSP04 2 Decibels SB_ADCP_SA4 Signal return amplitude from the water body by shipborne acoustic doppler current profiler (ADCP) beam 4
LCEWAS01 2 Centimetres per second CurrVelE_ADCP Eastward current velocity (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP)
LCNSAS01 2 Centimetres per second CurrVelN_ADCP Northward current velocity (Eulerian) in the water body by shipborne acoustic doppler current profiler (ADCP)
LERRAS01 2 Centimetres per second ADCPER Current velocity error in the water body by shipborne acoustic doppler current profiler (ADCP)
LRZAAS01 2 Centimetres per second ADCPVC Upward current velocity in the water body by shipborne 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- Ocean Surveyor 75kHz Vessel mounted ADCP.

Long-Range Mode
Vertical Resolution Cell Size 3 Max. Range (m) 1 Precision (cm/s) 2
8m 520 - 650 30
16m 560 - 700 17
High-Precision Mode
Vertical Resolution Cell Size 3 Max. Range (m) 1 Precision (cm/s) 2
8m 310 - 430 12
16m 350 - 450 9

1 Ranges at 1 to 5 knots ship speed are typical and vary with situation.
2 Single-ping standard deviation.
3 User's choice of depth cell size is not limited to the typical values specified.

Profile Parameters

Bottom Track

Maximum altitude (precision <2cm/s): 950m

Echo Intensity Profile

Dynamic range: 80dB
Precision: ±1.5dB

Transducer and Hardware

Beam angle: 30°
Configuration: 4-beam phased array
Communications: RS-232 or RS-422 hex-ASCII or binary output at 1200 - 115,200 baud
Output power: 1000W

Standard Sensors

Temperature (mounted on transducer)

Environmental

Operating temperature: -5° to 40°C (-5° to 45°C)*
Storage temperature: -30° to 50°C (-30° to 60°C)*

*later instruments have greater range.

Web Page

Further details can be found on the manufacturer's website or in the specification sheet

RAPID cruise D304 75kHz Shipboard ADCP data processing

Originator's processing

The following was taken from the D304 cruise report. For more detailed information please refer to Rayner (2007).

The 75kHz ADCP is a narrow band phased array with a 30-degree beam angle. Data were acquired using the RDI data acquisition software version 1.3.

ADCP setup

The instrument was configured as follows

Variable Setting
Number of Bins 60
Bin size 16m
Blank distance 8m
Sample interval 120 seconds
Processing mode Short term averaging

Calibration

The software logs the PC clock time and its offset from GPS time. This offset was applied to the data during processing, before merging with navigation. Gyro heading and GPS Ashtech heading, location and time were fed as NMEA messages into the software, which was configured to use the gyro heading for coordinate transformation. Calibration of the instrument was not performed due to the unavailability of a bottom track record before julian day 155. Instead calibration values of phi and A were used from a previous cruise, D279. On day 155, at 15:55 GMT, the configuration file was changed to bottom track mode. The BX maximum tracking depth was set to 1200m. The logging was stopped on day 155. A final calibration using bottom track data has not been worked up.

Screening

Data were edited to flag data based on the percent good variable. Only ship's velocities and absolute velocities in the range -1000cm/s to 1000 cm/s were kept, due to the huge and unrealistic velocities obtained when the gps did not receive the correction term to apply to the data from the differential.

References

Rayner, D. et al. RV Ronald H. Brown Cruise RB0602 and RRS Discovery Cruise D304 . RAPID mooring cruise report March and May 2006. Southampton, UK: National Oceanography Centre, Southampton, 165pp, National Oceanography Centre Cruise Report, No 16.'

BODC processing

The data were converted from Pstar format into BODC internal format, a netCDF subset, to allow use of in-house visualisation tools. The table below shows the mapping of originator variables to BODC Parameter codes.

Originator's variable Units Description BODC Parameter Code Units Comments
bindepth m Depth of ADCP bin DBINAA01 m -
evelcal cm s -1 Relative Eastward current velocity LCEWAS01 cm s -1 Not in final file as absolute velocities are present
nvelcal cm s -1 Relative Northward current velocity LCNSAS01 cm s -1 Not in final file as absolute velocities are present
velvert cm s -1 Vertical current velocity LRZAAS01 cm s -1 -
velerr cm s -1 Velocity error LERRAS01 cm s -1 -
intense1 db Beam 1 intensity ASAMSP00 db -
intense2 db Beam 2 intensity ASAMSP02 db -
intense3 db Beam 3 intensity ASAMSP03 db -
intense4 db Beam 4 intensity ASAMSP04 db -
ve cm s -1 Ship's Eastward velocity APEWGP01 cm s -1 -
vn cm s -1 Ship's Northward velocity APNSGP01 cm s -1 -
absve cm s -1 Absolute Eastward current velocity LCEWAS01 cm s -1 -
absvn cm s -1 Absolute Northward current velocity LCNSAS01 cm s -1 -
lat Degrees Latitude ALATGP01 Degrees -
lon Degrees Longitude ALONGP01 Degrees -
distrun km Distance run DSRNCV01 km -

Reformatted data were visually checked using the in-house editor EDSERPLO. No data values were edited or deleted. Flagging was achieved by modification of the associated quality control flag to 'M' for suspect values and 'N' for nulls.

Once quality control screening was complete, the data were archived in the BODC National Oceanographic Database and the associated metadata were loaded into an ORACLE Relational Database Management System.


Project Information

Rapid Climate Change (RAPID) Programme

Rapid Climate Change (RAPID) is a £20 million, six-year (2001-2007) programme of the Natural Environment Research Council (NERC). The programme aims to improve our ability to quantify the probability and magnitude of future rapid change in climate, with a main (but not exclusive) focus on the role of the Atlantic Ocean's Thermohaline Circulation.

Scientific Objectives

Projects

Overall 38 projects have been funded by the RAPID programme. These include 4 which focus on Monitoring the Meridional Overturning Circulation (MOC), and 5 international projects jointly funded by the Netherlands Organisation for Scientific Research, the Research Council of Norway and NERC.

The RAPID effort to design a system to continuously monitor the strength and structure of the North Atlantic Meridional Overturning Circulation is being matched by comparative funding from the US National Science Foundation (NSF) for collaborative projects reviewed jointly with the NERC proposals. Three projects were funded by NSF.

A proportion of RAPID funding as been made available for Small and Medium Sized Enterprises (SMEs) as part of NERC's Small Business Research Initiative (SBRI). The SBRI aims to stimulate innovation in the economy by encouraging more high-tech small firms to start up or to develop new research capacities. As a result 4 projects have been funded.


Monitoring the Meridional Overturning Circulation at 26.5N (RAPIDMOC)

Scientific Rationale

There is a northward transport of heat throughout the Atlantic, reaching a maximum of 1.3PW (25% of the global heat flux) around 24.5°N. The heat transport is a balance of the northward flux of a warm Gulf Stream, and a southward flux of cooler thermocline and cold North Atlantic Deep Water that is known as the meridional overturning circulation (MOC). As a consequence of the MOC northwest Europe enjoys a mild climate for its latitude: however abrupt rearrangement of the Atlantic Circulation has been shown in climate models and in palaeoclimate records to be responsible for a cooling of European climate of between 5-10°C. A principal objective of the RAPID programme is the development of a pre-operational prototype system that will continuously observe the strength and structure of the MOC. An initiative has been formed to fulfill this objective and consists of three interlinked projects:

The entire monitoring array system created by the three projects will be recovered and redeployed annually until 2008 under RAPID funding. From 2008 until 2014 the array will continue to be serviced annually under RAPID-WATCH funding.

The array will be focussed on three regions, the Eastern Boundary (EB), the Mid Atlantic Ridge (MAR) and the Western Boundary (WB). The geographical extent of these regions are as follows:

References

Baehr, J., Hirschi, J., Beismann, J.O. and Marotzke, J. (2004) Monitoring the meridional overturning circulation in the North Atlantic: A model-based array design study. Journal of Marine Research, Volume 62, No 3, pp 283-312.

Baringer, M.O'N. and Larsen, J.C. (2001) Sixteen years of Florida Current transport at 27N Geophysical Research Letters, Volume 28, No 16, pp3179-3182

Bryden, H.L., Johns, W.E. and Saunders, P.M. (2005) Deep Western Boundary Current East of Abaco: Mean structure and transport. Journal of Marine Research, Volume 63, No 1, pp 35-57.

Hirschi, J., Baehr, J., Marotzke J., Stark J., Cunningham S.A. and Beismann J.O. (2003) A monitoring design for the Atlantic meridional overturning circulation. Geophysical Research Letters, Volume 30, No 7, article number 1413 (DOI 10.1029/2002GL016776)


Data Activity or Cruise Information

Cruise

Cruise Name D304
Departure Date 2006-05-12
Arrival Date 2006-06-06
Principal Scientist(s)Torsten Kanzow (National Oceanography Centre, Southampton)
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