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
Data Description |
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Time Co-ordinates(UT) |
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Parameters |
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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:
Originator's Variable | Units | Description | BODC Parameter Code | Units | Comments |
---|---|---|---|---|---|
- | - | Sample duration | AZDRZZ01 | seconds | BODC derived from the start and end times of the sampling period |
DMS_flux_umoles_m2_day | micromoles per metre squared per day | Steady-state flux of dimethyl sulphide {DMS} per unit time per unit area of the water body to atmosphere by calculation from atmospheric DMS concentration and 3-D wind velocity | FLUXDMS1 | micromoles per metre squared per day | n/a |
Lat_Ashtech | degrees | Latitude (positive north) by Ashtech GPS | ALATAS01 | degrees | n/a |
Lon_Ashtech | degrees | Longitude (positive east) by Ashtech GPS | ALONAS01 | degrees | n/a |
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
Cruise Name | D320 |
Departure Date | 2007-06-16 |
Arrival Date | 2007-07-18 |
Principal Scientist(s) | Robert Upstill-Goddard (Newcastle University School of Marine Science and Technology) |
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 |
B | nominal value |
Q | value below limit of quantification |