Metadata Report for BODC Series Reference Number 969448

• 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

Originator's Data Quality Comments

Relative uncertainty in the flux, accounting for error in the DMS atmospheric concentration, is likely to be in the order of 30-40% for an integration time of about an hour, and is likely higher with shorter integration times. The few slightly negative flux values are results of noise when the ambient flux was near zero.

The data were inspected visually at BODC and no further action was taken

Data Access Policy

Public domain 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.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

BODC Data Processing

The data were provided to BODC in tab delimited text file format representing the roughly one hour resolution sea-to-air flux of dimethyl sulphide derived from measurements collected during the UK SOLAS DOGEE-II cruise D320. These were reformatted to the BODC internal QXF (NetCDF) format with start time as the single dimension using BODC transfer function 410. The following table shows how the DMS variables were mapped to the appropriate BODC parameter codes:

The reformatted data were visualised using the in-house EDSERPLO screening software.

Originator's Data Processing

Methodology

The sea-to-air flux of dimethyl sulphide (DMS) was determined by eddy correlation and atmospheric pressure ionisation mass spectrometry (APIMS) (Bandy et al., 2002; Huebert et al., 2004). Instantaneous relative wind speeds, acceleration and rotation in three axes were recorded at the same frequency as the atmospheric DMS concentration (see data series 907291) by a Gill Sonic anemometer and a Systron-Donner Motionpak accelerometer, respectively. Ship's motion was removed from relative winds to get true winds following Edson et al (1998). To obtain the sea-to-air flux via eddy covariance, atmospheric DMS concentration was correlated with the notion-corrected vertical wind velocity.

Data processing

Fluxes were computed in ten-minute segments that overlap by 50% (11 segments per hour) and reduced to hourly averages. Only segments with relative wind directions within 60 degrees from the bow and a maximum of 10 degrees range for the ship's heading were included in the hourly averages. Every valid hourly value contains at least three ten-minute segments that passed the aforementioned criteria (minimum of 20 minutes). The wind direction and gyro filtering criteria were necessary because turbulent eddies were more likely to be distorted by the ship's superstructure when the winds were coming from the stern or when the ship was turning sharply; either can result in an inadequate motion correction on the relative winds and a lack of correlation between DMS and the wind velocity.

References cited

Bandy, A.R., Thornton, D.C., Tu, F.H., Blomquist, B.W., Nadler, W., Mitchell, G.M., and Lenchow, D.H. 2002. Determination of the vertical flux of dimethylsulfide by eddy correlation and atmospheric pressure ionization mass spectrometry (APIMS). Journal of Geophysical Research, 107(D24), 4743, doi:10.1029/2002JD002472

Edson, J. B., Hinton, A. A., Prada, K. E., Hare, J. E., and Fairall, C. W. 1998. Direct covariance flux estimates from mobile platforms at sea. Journal of Atmospheric and Oceanic Technology, 15, 547-562.

Huebert, B.J., Blomquist, B.W., Hare, J.E., Fairall, C.W., Johnson, J.E., and Bates, T.S. 2004. Measurement of the sea-air DMS flux and transfer velocity using eddy correlation. Geophysical Research Letters. 31, L23113, doi:10.1029/2004GL021567

Project Information

UK SOLAS, Deep Ocean Gas Exchange Experiment (DOGEE)

This project was led by Newcastle University, in collaboration with: University of Southampton; Plymouth Marine Laboratory; National Oceanography Centre, Southampton; University of East Anglia. The multidisciplinary team aimed to provide a holistic study of the exchange rates of gases important in biogeochemical cycles.

Fieldwork comprised of two dedicated open ocean research cruises in the North Atlantic Ocean: D313 and D320. During D320 an artifical surfactant patch was successfully deployed and sampled. The observational data include:

• sea state, whitecapping and wave breaking
• bubble properties
• surfactants
• air-sea gas fluxes

Complimentary measurements were made by US-based research groups who participated in both cruises.

More detailed information on this project may be found in the official cruise reports for the DOGEE cruises, D313 andD320.

Weblink: http://www.nerc.ac.uk/research/programmes/solas/

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: