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Metadata Report for BODC Series Reference Number 1172783


Metadata Summary

Data Description

Data Category Towed STD/CTD
Instrument Type
NameCategories
Global Positioning Satellite System  NAVSTAR Global Positioning System receivers
Simrad EA500 echosounder  single-beam echosounders
Chelsea Technologies Group MINIpack CTD-F  fluorometers; CTD; water temperature sensor; salinity sensor
Instrument Mounting towed unmanned submersible
Originating Country United Kingdom
Originator Prof Jonathan Sharples
Originating Organization Proudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Seasonal Thermocline Production Control
 

Data Identifiers

Originator's Identifier SEASOAR_TOW5_CD173
BODC Series Reference 1172783
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2005-07-29 18:01
End Time (yyyy-mm-dd hh:mm) 2005-07-30 03:33
Nominal Cycle Interval 1.0 seconds
 

Spatial Co-ordinates

Southernmost Latitude 49.63410 N ( 49° 38.0' N )
Northernmost Latitude 50.18640 N ( 50° 11.2' N )
Westernmost Longitude 9.11100 W ( 9° 6.7' W )
Easternmost Longitude 8.47970 W ( 8° 28.8' W )
Positional Uncertainty Unspecified
Minimum Sensor or Sampling Depth 1.02 m
Maximum Sensor or Sampling Depth 86.49 m
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
Sea Floor Depth Source -
Sensor or Sampling Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor or Sampling Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum -
 

Parameters

BODC CODERankUnitsTitle
AADYAA011DaysDate (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ011DaysTime (time between 00:00 UT and timestamp)
ACYCAA011DimensionlessSequence number
ALATGP011DegreesLatitude north relative to WGS84 by unspecified GPS system
ALONGP011DegreesLongitude east relative to WGS84 by unspecified GPS system
CPHLPS011Milligrams per cubic metreConcentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer and calibration against sample data
DSRNCV011KilometresDistance travelled
MBANCT011MetresSea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder and correction using Carter's tables
POTMCV011Degrees CelsiusPotential temperature of the water body by computation using UNESCO 1983 algorithm
PRESPR011DecibarsPressure (spatial coordinate) exerted by the water body by profiling pressure sensor and correction to read zero at sea level
PSALST011DimensionlessPractical salinity of the water body by CTD and computation using UNESCO 1983 algorithm
SIGTPR011Kilograms per cubic metreSigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm
TEMPST011Degrees CelsiusTemperature of the water body by CTD or STD

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

CD173 SeaSoar Data quality report

Gaps

Problems were encountered with the logging of the SeaSoar data during this cruise, with communication issues requiring frequent re-boots of the software. This resulted in significant gaps in the data in several series, which last for up to one hour, however the data that is available are generally of a good quality. See the originator's quality report for more information

Salinity

The originator reported that poor flight control on this cruise resulted in fast dive and rise speeds which means that there were a limited number of values sampled within the sharp thermocline. This resulted in the sampled cycles showing "spiky" salinity profiles. In places this noise is amplified by missing data cycles as a result of the frequent re-boots of software. This compromises the salinity data for all tows and results in salinity values that are not real. As a result BODC have applied flags to the salinity channel and the derived density channel and these data should only be used with caution.

Prolonged periods at the surface

In places it is clear from the data that the SeaSoar spent some time at the surface (rather than undulating through the water column). The data at these times appear to be of a good quality and in all series the SeaSoar was undulating for the majority of the dataset.


Data Access Policy

Open Data

These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."


Narrative Documents

Kongsberg Simrad EA500 bathymetric echosounder

The EA500 is a bathymetric echosounder that can be used in water as deep as 10,000 m. It features triple frequency operation with a separate digitiser for each channel and high transmitted power with an instantaneous dynamic range of 160 dB. The instrument can operate with several pulses in the water simultaneously and has bottom tracking capabilities. A wide range of transducers (single beam, split beam or side-looking) is available and the ping rate is adjustable up to 10 pings per second. The split beam operation measures the athwartships inclination angle of the seabed.

This instrument was introduced in June 1989 and and replaced by the EA 600 in 2000.

Specifications

Operational range 1, 5, 10, 15, 25, 50, 100, 150, 250, 500, 750, 1000, 2500, 5000 and 10000 m
Phasing 0 to 10000 m in 1 m increments (manual or automatic)
Non saturated instantaneous input range -160 to 0 dB
Output power regulation 0 to 20 dB relative to full power
Noise figure 10 dB
Operating temperature 0 to 55°C
Ping rate max 10 pings per second (adjustable)

Further details can be found in the manufacturer's specification sheet.

Chelsea Technologies Minipack CTD-F

The Minipack CTD is a titanium/acetyl conductivity-temperature-depth system that can be used for discrete profiles, installed on a data buoy or on a towed undulator. The instrument includes conductivity, temperature, depth and fluorometer sensors, incorporating a high-performance 24-channel data logging and transmission system which allows for the acquisition of up to 16 external channels (e.g., dissolved oxygen, pH, PAR, fluorescence, turbidity, transmissance etc.).

Specifications

Sensor Type Range Accuracy Resolution
Temperature Pt resistance -2 to 35 °C 0.003 °C 0.0005 °C
Conductivity Induction cell 0 to 70 mmho cm-1 0.005 mmho cm-1 0.001 mmho cm-1
Pressure

Strain gauge with
temperature compensation

0 to 600 dbar 0.2 dbar 0.01 dbar

Optical sensor specifications

  Chlorophyll a Rhodamine Amido Rhodamine Fluorescein Nephelometer Phycoerythrin Phycocyanin
Excitation wavelengths 430/30 nm or 470/30 nm 470/30 nm 425/30 nm 480/80 nm *470/30 nm 530/30 nm 590/35 nm
Emission wavelengths 685/30 nm 590/45 nm 550/30 nm 530/30 nm *470/30 nm 580/30 nm 645/35 nm
Concentration range 0.03 - 100 µg L-1 0.03 - 100 µg L-1 0.04 - 200 µg L-1 0.03 - 100 µg L-1 *0.04 - 100 FTU 0.03 - 100 µg L-1 0.03 - 100 µg L-1
Resolution 0.01 µg L-1 0.01 µg L-1 0.025 µg L-1 0.01 µg L-1 *0.01 FTU 0.01 µg L-1 0.01 µg L-1

*the wavelengths for the turbidity filters are a customer option but must be in the range 400 to 700 nm. The same wavelength is used in both the excitation path and the emission path.

Further details can be found in the manufacturer's specification sheet.

Global Positioning Satellite System

A location system of unspecified make or model that determines location on the Earth's surface using the Global Positioning Satellite Network. Angular co-ordinates are given relative to WGS84 CRS. Other parameters such as platform velocity may be derived from this.

CD173 SeaSoar Originators processing document

Sampling strategy

The Penguin SeaSoar was deployed seven times from RRS Charles Darwin CD173 (15 July to 06 August 2005) in the Celtic Sea. A number of problems were encountered with the SeaSoar (described in more detail in the originators quality notes section below) which resulted in tows being cut short and some patchy data. Despite these problems data were collected for all seven runs and have been processed by the originator.

Tow Description Start time (UTC) Start position End time (UTC) End position Comments
1 Along Jones Bank 2005-07-16 06:10 50°2.334' N
7°37.566' W
2005-07-16 08:25 49°49.554' N
8°0.030' W
Collision with seabed led to early recovery.
2 Along Jones Bank 2005-07-20 05:31 49°55.392' N
7°49.314' W
2005-07-20 08:08 49°41.634' N
8°14.328' W
On recovery it was clear that the vehicle had again collided with the seabed.
3 Cross shelf to shelf edge 2005-07-20 22:35 49°57.804' N
7°31.260' W
2005-07-21 12:20 48°39.258' N
9°22.410' W
Patchy data return due to frequent need to re-boot Penguin.
4 25 hour box survey around Jones Bank Moorings 2005-07-27 20:52 49°59.802' N
7°43.482' W
2005-07-28 04:30 49°54.546' N
8°36.120' W
25 hour survey aborted due to poor vehicle behaviour in heavy seas
5 Small bank SW of Jones Bank and flat seabed. 2005-07-29 18:01 49°52.170' N
8°28.782' W
2005-07-30 03:33 50°11.184' N
8°52.452' W
 
6 Continuation of tow 5 over Labadie Bank. 2005-07-30 09:09 50°11.958' N
8°51.108' W
2005-07-30 18:17 50°47.652' N
7°36.384' W
 
7 Across Jones Bank and through station OB 2005-08-01 06:21 49°57.510' N
8°5.454' W
2005-08-01 11:27 49°48.954' N
7°32.784' W
 

Please note that the positions, start and end times are those for which data is available. The SeaSoar may have been in the water for a longer period than those reported here.

Correction of time data

The time stamp in the raw Minipack files has two origins: the Minipack internal clock and the DAS system associated with Penguin (recorded in Julian decimal days). After some work it was found that the DAS time was correct (UTC) for all of the runs except for tow 7 which was found to have an offset of 1.4598846 days (which needed to be added to the Julian days). The originator has applied this offset to raw data from this tow so that all data supplied to BODC are consistent and referenced to UTC.

Addition of navigation data

The Minipack data have been merged with corrected navigation data from the surface underway data files. The surface underway data were used to generate an interpolated series of positions with a 1 second resolution. The Minipack data were then stamped with the latitudes and longitudes corresponding to the sample times.

Calibrations

Calibration and processing of the SeaSoar data (depth, salinity, temperature, chlorophyll fluorescence) has been carried out by the originator. Calibration was done by comparing calibrated data from a CTD cast (cast CTD082 from cruise CD173) deployed at 06:04 UTC on 30 July 2005 which was followed by a vertical profile of the SeaSoar (tow 6).

Depth

On deck pressure data from CTD082 and the SeaSoar Minipack on 30 July 2005 showed that the SeaSoar Minipack pressure sensor was 0.09 dbar less than the CTD pressure sensor. For each SeaSoar tow Minipack pressure data were therefore calibrated by applying a pressure offset based on the average on-deck measurements from the nearest CTD casts before and after the SeaSoar tow, then corrected by the 0.09 dBar Minipack-CTD offset.

SeaSoar tow Mean CTD pressure offset (dbar) Total calibration applied to Minipack pressure data (dbar)
1 -0.374 +0.28
2 -0.286 +0.20
3 -0.375 +0.29
4 -0.524 +0.43
5 -0.404 +0.31
6 -0.405 +0.31
7 -0.059 -0.03

Salinity

SeaSoar Minipack salinity was calibrated by taking the surface and bottom mixed layer data from CTD082 and comparing with the corresponding Minipack data from the vertical haul of SeaSoar.

Calibrated salinity (dimensionless) = SeaSoar Minipack salinity + 0.03

The resulting error for this calibration was ±0.02.

Temperature

SeaSoar Minipack temperature was calibrated by taking the surface and bottom mixed layer data from CTD082 and comparing with the corresponding Minipack data from the vertical haul of SeaSoar.

Calibrated temperature (°C) = SeaSoar Minipack temperature - 0.006

The error for this calibration is ±0.007 °C

Chlorophyll.

SeaSoar Minipack chlorophyll was calibrated by taking data from CTD082 and comparing with the corresponding Minipack data from the vertical haul of SeaSoar. Comparisons used data collected through the subsurface chlorophyll maximum, as the surface and bottom layer data were excluded to achieve a reliable calibration. This method prevents the regression being driven by large numbers of low chlorophyll data points. A calibration equation was generated as:

Calibrated chlorophyll (mg m-3) = (0.09 x SeaSoar Minipack chlorophyll) + 0.02

The error for this calibration was ±0.06 mg m-3.

Originators quality notes

A number of significant problems were encountered using the SeaSoar during this cruise. These are summarised below:

  • poor flight control resulting in limited depth control (which caused two damaging seabed collisions)
  • fast dive and rise speeds (as a result of the poor flight control) which means limited numbers of values sampled within the sharp thermocline and sampled cycles showing "spiky" salinity profiles.
  • communication problems which required frequent re-boots resulting in significant data loss (particularly for tows 3 and 4).

More information about the problems faces can be found on page 56 of the cruise report.

CD173 SeaSoar Processing undertaken by BODC

Data were received by BODC in seven .dat files. The time channels in the data files for runs 3 and 4 were not consistent and were jumping backwards and forwards in time. The originator confirmed that this was a result of the original raw files being concatenated in the wrong order. BODC have corrected this by ordering the data in the files by time. The series were then reformatted by BODC to the internal format using established procedures. Where consecutive data cycles were assigned exactly the same time stamp the time stamp was changed so that there was an increasing time interval between the cycles and those immediately before and after them. The following table details mapping of variables to BODC parameter codes.

Originator' Variable Units BODC Parameter Code Description Units Comments
lat Degrees North ALATGP01 Latitude north (WGS84) by unspecified GPS system Degrees  
long Degrees East ALONGP01 Longitude east (WGS84) by unspecified GPS system Degrees  
depth Decibars PRESPR01 Pressure (measured variable) exerted by the water body by semi-fixed in-situ pressure sensor and corrected to read zero at sea level using independent measurements. Decibars Originator has confirmed that this parameter is pressure (and not depth as labelled). Converted by -1 so data are positive below sea surface
bottom Metres MBANCT01 Sea-floor depth (below instantaneous sea level) {bathymetric depth} in the water body by echo sounder and correction using Carter's tables. Metres Converted by -1 so data are positive below sea surface
temp Degrees Celsius TEMPST01 Temperature of the water body by CTD and verification against independent measurement Degrees Celsius Data calibrated by originator with data from CTD casts from this cruise.
salt Dimensionless PSALST01 Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements Dimensionless Data calibrated by originator with data from CTD casts from this cruise.
chl mg m-3 CPHLPS01 Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate phase] by in-situ chlorophyll fluorometer. mg m-3  
- - SIGTPR01 Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm. kg m-3 Density was re-derived by BODC to ensure a known and consistent methodology.
- - DSRNCV01 Distance travelled. Kilometres This parameter was re-derived by BODC from the latitude and longitude data as a problem was identified with some of the data supplied by the originator.
- - POTMCV01 Potential temperature of the water body by computation using UNESCO 1983 algorithm Degree Celsius This parameter was derived by BODC.

The reformatted data were visualised using BODC in-house software. Suspect data were marked by adding an appropriate quality control flag, and missing data marked by both setting the data to an appropriate absent data value and setting the quality control flag.


Project Information

Physical-Biological Control of New Production within the Seasonal Thermocline

This project was a NERC responsive-mode project which was co-funded by the Defence Science and Technology Laboratory and ran from 2003 to 2006. The key institutes and scientists involved were:

Institute Scientific personnel
Proudman Oceanographic Laboratory (POL) Jonathan Sharples
National Oceanography Centre, Southampton (NOCS) Patrick Holligan
Mark Moore
University of Wales, Bangor (UWB) John Simpson
Tom Rippeth

Research Aim

The main aim of this research was to investigate the generation and dissipation of turbulence in the thermocline, and to quantify how the resulting mixing (supplying nutrients and controlling the light experienced by the algae) affected the growth of phytoplankton within the sub-surface chlorophyll maximum (SCM).

Research Objectives

The objective of the research was to test the general hypothesis that, in seasonally-stratified shelf waters, temporal and spatial variability of the rate of 'new' production is determined by the degree of coupling between physical and biological processes within the seasonal thermocline. In particular it has been suggested that physiological adaptation by phytoplankton making up the subsurface chlorophyll maximum drives a biological pump for extracting nitrate from the bottom mixed layer that is sensitive to internal mixing and to external climatological factors.

Research Approach

The sampling and experimental strategy was based on established methods for obtaining compatible, high-resolution vertical profiles (alternate CTD and FLY) and sections (SeaSoar) of physical, chemical, and biological parameters, allowing quantification of vertical fluxes and primary production on tidal and internal wave time scales. The cruise schedule (with associated mooring deployments) for the project is below.

Cruise Schedule

Cruise ID Ship Sampling Region Cruise Dates Main measurements
JR98 RRS James Clark Ross St Georges Channel, Celtic Sea and shelf edge 25/07/03 - 14/08/03 CTD casts, SeaSoar transects (CTD, chlorophyll, fluorescence), FRRF, ship ADCP, primary productivity, nutrients, trace metals, phytoplankton uptake rates, algal photophysiology, oxygen concentration, particle size, optics, mooring deployments
PD32_03 RV Prince Madog Celtic Sea and shelf edge 27/07/03 - 13/08/03 5 x FLY 25 hour tidal cycle stations, particle size analysis, particle settling velocity, CTD casts, mooring deployments
CD173 RRS Charles Darwin Celtic Sea and shelf edge 15/07/05 - 06/08/05 CTD casts, chlorophyll, oxygen concentration, FLY profiles, SeaSoar tows (CTD, chlorophyll, FRRF), phytoplankton pigments, nutrients, primary productivity, phytoplankton uptake rates, FRRF profiles, optics, particle size analysis, mooring deployments
PD27_05 RV Prince Madog Celtic Sea and shelf edge 22/07/05 - 06/08/05 FLY profiles, mooring deployments

Moorings

Station ID Latitude Longitude Depth (m) Mooring Deployment date Recovery date Deployment vessel
CS3 51.471 -6.428 95 Seabed frame 300 kHz ADCP 01/08/03 11/08/03 RV Prince Madog
CS3 51.471 -6.428 95 Seabed frame 1200 kHz ADCP 01/08/03 11/08/03 RV Prince Madog
CS3 51.474 -6.437 95 Mid-water subsurface 300 kHz ADCP 01/08/03 11/08/03 RV Prince Madog
CS3 51.469 -6.437 95 Thermistor chain from 5 - 45 m depth 01/08/03 11/08/03 RV Prince Madog
ACW 51.266 -5.741 85 Seabed frame 300 kHz ADCP 06/08/03 08/08/03 RV Prince Madog
CS2 48.532 -9.463 200 Surface temperature toroid 28/07/03 12/08/03 RRS James Clark Ross
CS2 48.532 -9.463 200 Thermistor chain throughout water column 28/07/03 12/08/03 RRS James Clark Ross
CS2 48.532 -9.463 200 Sub-suface 600 kHz ADCP (90 m) 28/07/03 12/08/03 RRS James Clark Ross
CS2 48.532 -9.463 200 Aanderaa RCM7 current meter/CTD (12 mab)* 28/07/03 12/08/03 RRS James Clark Ross
CS2 48.532 -9.463 200 Seabed frame 150 kHz ADCP 28/07/03 12/08/03 RRS James Clark Ross
CS2 48.532 -9.463 200 Seabed frame 300 kHz ADCP 28/07/03 12/08/03 RRS James Clark Ross
U2 49.236 -6.166 121 Sub-suface 300 kHz ADCP (5 mab)* 15/07/05 03/08/05 RRS Charles Darwin
U2 49.233 -6.167 120 Thermistor chain throughout water column 19/07/05 Mooring lost RRS Charles Darwin
CS2 48.571 -9.509 200 Thermistor chain throughout water column 17/07/05 24/07/05 RRS Charles Darwin
CS2 48.573 -9.51 194 Sub-suface 300 kHz ADCP (100 m) 17/07/05 24/07/05 RRS Charles Darwin
CS2 48.572 -9.508 196 Seabed frame 300 kHz ADCP 17/07/05 24/07/05 RRS Charles Darwin
CS2 48.571 -9.507 202 Seabed frame 150 kHz ADCP 17/07/05 24/07/05 RRS Charles Darwin
Bank 1 49.938 -7.792 118 Thermistor chain throughout water column 26/07/05 Mooring lost RRS Charles Darwin
Bank 1 49.936 -7.792 118 Seabed frame 300 kHz ADCP 27/07/05 Recovered by trawler 29/07/05 RRS Charles Darwin
Bank 2 49.895 -7.872 114 Thermistor chain throughout water column 20/07/05 04/08/05 RRS Charles Darwin
Bank 2 49.876 -7.897 112 Sub-surface 600 kHz ADCP (56 m) 26/07/05 04/08/05 RRS Charles Darwin
Bank 2 49.894 -7.873 110 Seabed frame 300 kHz ADCP 26/07/05 04/08/05 RRS Charles Darwin
Bank 3 49.851 -7.952 78 Thermistor chain throughout water column 26/07/05 03/08/05 RV Prince Madog
Bank 3 49.854 -7.948 78 Seabed frame 300 kHz ADCP 26/07/05 Mooring lost RV Prince Madog

* = metres above seabed

Project Outcomes

The main products of the research were:

  • The first large scale interdisciplinary study of the dynamic processes that determine the properties of the SCM in NW European shelf waters.
  • Substantive advances in quantifying internal mixing in NW European shelf seas, and in understanding how primary production is controlled by this small-scale turbulence.
  • New parameterisations for internal vertical mixing, and the response of primary production, for use in coupled numerical models.
  • Improved capability for estimating primary productivity in stratified waters by satellite remote sensing (ocean colour, sea surface temperature, wind mixing etc.)
  • An overall development of our understanding of the dynamics of ecosystems that support important fisheries, and of our abilities in predicting ecological and biogeochemical responses to variations and changes in the climate of the marine environment.

Data Activity or Cruise Information

Cruise

Cruise Name CD173
Departure Date 2005-07-15
Arrival Date 2005-08-06
Principal Scientist(s)Jonathan Sharples (Proudman Oceanographic Laboratory)
Ship RRS Charles Darwin

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
B nominal value
Q value below limit of quantification