Metadata Report for BODC Series Reference Number 2207205

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

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

AMT19 RRS James Cook (JC039) Inherent optical properties - Instrumentation

Optical measurements were conducted on water passing through the ship's non-toxic flow-through system during the RRS James Cook Cruise JC039 (AMT19).

For further information on these instruments please see the JC039 cruise report.

WET Labs {Sea-Bird WETLabs} ECO triplet BB3SLO scattering sensor

A variant of the ECO Puck Triplet (http://vocab.nerc.ac.uk/collection/L22/current/TOOL0673/). It is a three-optical-sensor, user-defined instrument that carries 3 scattering meters. ECO Pucks are real�time only sensors as they are integrated onto the OEM platform that provides power and data handling. The SLO designation signifies this is a 1st generation model that is specific for integration into Slocum gliders. The fluorometers and scattering meter are single wavelength sensors. The model is depth-rated to 600 m.

For more information, please see this document: https://www.bodc.ac.uk/data/documents/nodb/pdf/datasheet_ECOtriplet.pdf

WETLabs ac-9 and ac-s Spectral Absorption and Attenuation Meters

The WETLabs ac-9 and ac-s meters measure the spectral transmittance and spectral absorption of water, allowing determination of absorption and beam attenuation coefficients. The instruments incorporate a flow-through system and a dual path configuration that permits concurrent measurement of both coefficients along a 25 cm path. The ac-9 provides measurements at nine wavelengths in the range 412-715 nm, whereas the ac-s provides measurements at >80 wavelengths from 400-730 nm.

Specifications

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

WETLabs ac-s in-situ spectrophotometer

The WETLabs ac-s in-situ spectrophotometer is based on the ac-9 flow through sensor offering increased spectral resolution of in-situ absorption and beam attenuation. The ac-s can have 80 (+/- 5) wavelength outputs with a range of 400-730 nm. The ac-s consists of a 10 or 25 cm pathlength, a 4nm resolution, an accuracy of 0.001 - 10 m^-1, an operational temperature range of 0 - 30 °C and an operational depth rating of 500 m.

Specification

Mechanical

Electrical

Environmental

Optical

For more information see the manufacturer's brochure or user guide.

WETLabs C-Star transmissometer

This instrument is designed to measure beam transmittance by submersion or with an optional flow tube for pumped applications. It can be used in profiles, moorings or as part of an underway system.

Two models are available, a 25 cm pathlength, which can be built in aluminum or co-polymer, and a 10 cm pathlength with a plastic housing. Both have an analog output, but a digital model is also available.

This instrument has been updated to provide a high resolution RS232 data output, while maintaining the same design and characteristics.

Specifications

Further details are available in the manufacturer's specification sheet or user guide.

AMT19 RRS James Cook (JC039) Inherent optical properties - Data Processing Documentation

Originator's Processing

Measurements and Methods

Optical measurements were conducted on water passing through the ship's non-toxic flow-through system during the RRS James Cook Cruise JC039 (AMT19).

• Beam attenuation co-efficients were measured at 526 and 651 nm by WET Labs C-star transmissometers.
• Hyperspectral beam attenuation and absorption coefficients were also measured between 400 and 750 nm by a WET Labs ac-s and a WET Labs AC-9.
• The volume scattering function at a central angle of about (117°) was measured by a WET Labs ECO-BB3 at 470 nm and 526 nm.

The data were processed as described by Dall'Olmo (Dall'Olmo et al. 2009, Dall'Olmo et al., 2012) with the use of a 0.2 µm cartridge filter in order to provide a baseline for the absorption and attenuation measurements. The C-star, ac-s and AC-9 optical measurements were averaged into 1-min time intervals before further processing. To compute particulate beam attenuation and absorption coefficients (c_p and a_p respectively), the median values of the beam attenuation and absorption coefficients measured during each of the 0.2 µm filtration times were linearly and piecewise interpolated between hours and subtracted from the bulk measurements. This procedure allowed the determination of calibration-independent particulate beam-attenuation and absorption coefficients, with the uncertainties determined mostly by the instrument precision (Boss et al., 2007).

For further information please see the JC039 cruise report.

Originator's Quality Control

ac-s c_p and a_p spectra were further processed to:

• Remove a spurious spectral step that was at times observed in the green spectral region.
• Remove the scattering error from the a_p data.
• Account for variations in sample temperature between consecutive 0.2 µm filtered data points.

Calibrations

No calibration files were provided for these ac-s, AC-9 and Cstar data, because these data were derived using the filter-no-filter technique (Dall'Olmo et al., 2009, 2012; Slade et al., 2010). The following scaling factors and uncertainties are given below:

Wall effects (bb_{wall}, see Dall'Olmo et al., 2009) were derived from two measurements of 0.2 µm filtered MilliQ water during the cruise. These wall effects were:

Dark counts were also determined during the cruise:

BODC Processing

The data were received by email and archived under BODC accession number PML110038. The data were then transferred to the BODC format and loaded to the database.

Parameter codes defined in the BODC parameter dictionary were assigned to the variable as shown in the table below:

N.B. The same parameter was used for the C-Star (cp526 and cp651) attenuation co-efficients as the ac-s and AC-9 attenuation co-efficients.

Screening

Once transferred the reformatted data were imported into the BODC in-house visualisation software, Edserplo. Data were appropriately flagged and double checked for any anomalous results. Further details are given in the data quality report.

References

Boss G., Malladi P., Quan D., Legregni L. and Hall H. (2007). Cloud computing IBM Technical Report: High Performance On Demand Solutions (HiPODS). IBM white paper, 2007-10-08, Version 1.0.

Dall'Olmo G., Westberry T. K., Behrenfeld M. J., Boss E. and Slade, W. H. (2009). Significant contribution of large particles to optical backscattering in the open ocean. Biogeosciences, 6, pp. 947-967.

Dall'Olmo G., Boss E., Behrenfeld M. J., and Westberry T. K. (2012). Particulate optical scattering coefficients along an Atlantic Meridional Transect. Optics Express, 20, pp. 21532-21551.

Slade W. H., Boss E., Dall'Olmo G., Langner M. R., Loftin J., Behrenfeld M. J., Roesler C., and Westberry T. K. (2010). Underway and moored methods for improving accuracy in measurement of spectral particulate absorption and attenuation. Journal of Atmospheric and Oceanic Technology, 27(10), pp. 1733-1746.

AMT19 RRS James Cook (JC039) Inherent optical properties Data Quality Report

Negative (non-null) values that occurred throughout the dataset were flagged 'M' by BODC. Values for inherent optical properties within this dataset (ATTNXAC9, ABSPXAC9 and BSXXXVSF) below 0 are outside of BODC parameter limits, indicating there may be a problem with the data. Approximately 0.8% of data across these parameters have the flag 'M' applied.

Null values were flagged 'N' by BODC. The first 56 cycles were null across all bins (82) of optical property data, with the first non-null values being recorded at 09:20 (14/10/2009). Throughout the dataset, null periods occur at regular intervals, where an approximately 15 minute period of null values occur after approximately 45 minutes of readings. There are also instances where longer durations of null values, that cover over 24 hours, are present. Further to this, there are cases where a bin does not follow this regular pattern, and instead remains null. Constant null bin numbers for ABSPXAC9 were 17, 31 and 60, while only bin number 17 was constantly null for ATTNXAC9. The majority of data for BB117XXX were null, with only bin numbers 17 and 31 having non-null values. Overall, approximately 75% of data across these parameters have the flag 'N' applied.

Project Information

Oceans 2025 Theme 10, Sustained Observation Activity 1: The Atlantic Meridional Transect (AMT)

The Atlantic Meridional Transect has been operational since 1995 and through the Oceans 2025 programme secures funding for a further five cruises during the period 2007-2012. The AMT programme began in 1995 utilising the passage of the RRS James Clark Ross between the UK and the Falkland Islands southwards in September and northwards in April each year. Prior to Oceans 2025 the AMT programme has completed 18 cruises following this transect in the Atlantic Ocean. This sustained observing system aims to provide basin-scale understanding of the distribution of planktonic communities, their nutrient turnover and biogenic export in the context of hydrographic and biogeochemical provinces of the North and South Atlantic Oceans.

The Atlantic Meridional Transect Programme is an open ocean in situ observing system that will:

• give early warning of any fundamental change in Atlantic ecosystem functionng
• improve forecasts of the future ocean state and associated socio-economic impacts
• provide a "contextual" logistical and scientific infrastructure for independently-funded national and international open ocean biogeochemical and ecological research.

The specific objectives are:

• To collect hydrographic, chemical, ecological and optical data on transects between the UK and the Falkland Islands
• To quantify the nature and causes of ecological and biogeochemical variability in planktonic ecosystems
• To assess the effects of variability in planktonic ecosystems on biogenic export and on air-sea exchange of radiatively active gases

The measurements taken and experiments carried out on the AMT cruises will be closely linked to Themes 2 and 5. The planned cruise track also allows for the AMT data to be used in providing spatial context to the Sustained Observation Activities at the Porcupine Abyssal Plain Ocean Observatory (SO2) and the Western Channel Observatory (SO10).

More detailed information on this Work Package is available at pages 6 - 9 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10

Weblink: http://www.oceans2025.org/

Data Activity or Cruise Information

Cruise

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:

SeaDataNet Quality Control Flags

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