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Metadata Report for BODC Series Reference Number 1085067

Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags

Metadata Summary

Data Description

Data Category

CTD or STD cast

Instrument Type

Name	Categories
Sea-Bird SBE 19plus SEACAT CTD	CTD; water temperature sensor; salinity sensor
Chelsea Instruments MINITracka II fluorometer	fluorometers

Instrument Mounting

lowered unmanned submersible

Originating Country

United Kingdom

Originator

Dr James Fishwick

Originating Organization

Plymouth Marine Laboratory

Processing Status

banked

Project(s)

L4 time-series

Data Identifiers

Originator's Identifier	020422_L4
BODC Series Reference	1085067

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm)	2002-04-22 09:08
End Time (yyyy-mm-dd hh:mm)	-
Nominal Cycle Interval	0.5 metres

Spatial Co-ordinates

Latitude	50.25000 N ( 50° 15.0' N )
Longitude	4.21700 W ( 4° 13.0' W )
Positional Uncertainty	0.5 to 1.0 n.miles
Minimum Sensor Depth	2.0 m
Maximum Sensor Depth	53.5 m
Minimum Sensor Height	1.5 m
Maximum Sensor Height	53.0 m
Sea Floor Depth	55.0 m
Sensor Distribution	Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor Depth Datum	Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum	Chart reference - Depth extracted from available chart

Parameters

BODC CODE	Rank	Units	Title
ACYCAA01	1	Dimensionless	Sequence number
DEPHPR01	1	Metres	Depth below surface of the water body by profiling pressure sensor and converted to seawater depth using UNESCO algorithm
FVLTZZ01	1	Volts	Instrument output (voltage) by in-situ chlorophyll fluorometer
PRESPR01	1	Decibars	Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level
PSALST01	1	Dimensionless	Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm
SIGTPR01	1	Kilograms per cubic metre	Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm
TEMPST01	1	Degrees Celsius	Temperature 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

Data Quality Document

Temperature, salinity and sigma-theta:

On the whole the trends appear reasonable for the location and time of year that the casts were made. Casts which displayed unrealistic values for the location and time of the year have been flagged accordingly. Once in 2002, 2003 and 2008, entire profiles had to be flagged. A specific problem report has been created for these casts to highlight the problem. Users should be aware that the salinity channel was sometimes noisy, particularly close to the surface or in the vicinity of strong gradients. This was particularly strong in casts collected in 2005.

Fluorometer voltage:

The fluorometer output which was labelled as a voltage channel in the originators' files was sometimes in excess of the maximum voltage of 4 volts specified in the manufacturer's specification sheet. Nevertheless the overall trends including occasional strong vertical variability appear reasonable given the location and time of year. However on four occasions in April and May 2002 the fluorescence vertical profiles showed very low values and unrealistically low variability with depth for the time or year and hydrographic conditions. These were deemed suspect and flagged accordingly by BODC.

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

Instrument description

Make	Model	Serial number	Comments
Sea-Bird	SBE19plus	4180	-
Chelsea Technologies	MiniTracka II	07-6310-003	-

Sea-Bird SBE 19 and SBE 19plus SEACAT Profiler CTDs

The SBE 19 SEACAT Profiler is a self-contained, battery powered, pumped CTD system designed to measure conductivity, temperature, and pressure in marine or fresh water environments to depths of 10,500 meters. It was replaced by the SBE 19plus model in 2001. An updated version of this instrument is the SBE 19plus V2, which incorporates an electronics upgrade and additional features, with six differentially amplified A/D input channels, one RS-232 data input channel, and 64 MB FLASH memory.

The standard CTD unit comes with a plastic housing (rated to 600 m), although this can be replaced by titanium housing for depths up to 7000 m. It is typically used for CTD profiling although a conversion kit is available for mooring deployments. The CTD can also be attached to an SBE 36 CTD Deck Unit and Power/Data Interface Module (PDIM) for real-time operation on single-core armored cable up to 10,000 m.

Specifications

Parameter	SBE 19	SBE 19plus
Temperature	Range: -5 to +35 °C Accuracy: 0.01 °C Resolution: 0.001 °C Calibration: +1 to +32 °C*	Range: -5 to +35 °C Accuracy: 0.005 °C Resolution: 0.0001 °C Calibration: +1 to +32 °C*
Conductivity	Range: 0 to 7 S m^-1 (0 to 70 mmho cm^-1) Accuracy: 0.001 S m^-1 Resolution: 0.0001 S m^-1 Calibration: 0 to 7 S m^-1. Physical calibration over the range 1.4 - 6 S m^-1*	Range: 0 to 9 Sm^-1 Accuracy: 0.0005 Resolution: 0.00005 (most oceanic waters, resolves 0.4 ppm in salinity); 0.00007 (high salinity waters, resolves 0.4 ppm in salinity); 0.00001 (fresh waters, resolves 0.1 ppm in salinity) Calibration: 0 to 9 S m^-1. Physical calibration over the range 1.4 - 6 S m^-1*
Strain gauge pressure sensor	Range: 0 to100, 150, 300, 500, 1000, 1500, 3000, 5000, 10000 or 15000 psia Accuracy: 0.25% of full scale range (100 - 1500 psia); 0.15% of full scale range (3000 - 15000 psia) Resolution: 0.015% of full scale Calibration: 0 to full scale in 20% steps	Range: 0 to 20, 100, 350, 1000, 2000, 3500 or 7000 m Accuracy: 0.1% of full scale range Resolution: 0.002% of full scale range Calibration: ambient pressure to full scale range in 5 steps

Parameter

SBE 19

SBE 19plus

Temperature

Range: -5 to +35 °C

Accuracy: 0.01 °C

Resolution: 0.001 °C

Calibration: +1 to +32 °C*

Range: -5 to +35 °C

Accuracy: 0.005 °C

Resolution: 0.0001 °C

Calibration: +1 to +32 °C*

Conductivity

Range: 0 to 7 S m^-1 (0 to 70 mmho cm^-1)

Accuracy: 0.001 S m^-1

Resolution: 0.0001 S m^-1

Calibration: 0 to 7 S m^-1. Physical calibration over the range 1.4 - 6 S m^-1*

Range: 0 to 9 Sm^-1

Accuracy: 0.0005

Resolution: 0.00005 (most oceanic waters, resolves 0.4 ppm in salinity); 0.00007 (high salinity waters, resolves 0.4 ppm in salinity); 0.00001 (fresh waters, resolves 0.1 ppm in salinity)

Calibration: 0 to 9 S m^-1. Physical calibration over the range 1.4 - 6 S m^-1*

Strain gauge pressure sensor

Range: 0 to100, 150, 300, 500, 1000, 1500, 3000, 5000, 10000 or 15000 psia

Accuracy: 0.25% of full scale range (100 - 1500 psia); 0.15% of full scale range (3000 - 15000 psia)

Resolution: 0.015% of full scale

Calibration: 0 to full scale in 20% steps

Range: 0 to 20, 100, 350, 1000, 2000, 3500 or 7000 m

Accuracy: 0.1% of full scale range

Resolution: 0.002% of full scale range

Calibration: ambient pressure to full scale range in 5 steps

*Measurements outside this range may be at slightly reduced accuracy due to extrapolation errors.

Options and accessories

Additional sensors can be attached to the CTD, including:

high accuracy Paroscientific Digiquartz pressure sensor (depth range 0 to 20, 60, 130, 200, 270, 680, 1400, 2000, 4200, 7000 or 10500 m; accuracy 0.02% of full scale; resolution 0.0025% of full scale)
Dissolved Oxygen (SBE 43 DO Sensor)
pH* (SBE 18 pH Sensor or SBE 27 pH/ORP Sensor)
fluorescence
radiance (PAR)
light transmission
optical backscatter (turbidity)

The standard SBE 5M pump may be replaced by an SBE 5P (plastic housing) or 5T (titanium housing) pump for use with dissolved oxygen and/or other pumped sensors. Further details can be found in the manufacturer's SBE 19plus V2 instrument specification or theSBE 19 andSBE 19 plus user guides.

Chelsea Instruments MINI^tracka Fluorometer

The MINI^tracka Fluorometer is an in-situ optical sensor that uses a single high intensity LED light source and, according to the manufacturer, is designed to enhance rejection of ambient daylight. The fluorometer provides a linear response between chlorophyll concentration and fluorometer voltage.

Sensor specifications, current at August 2006, are given in the table below. More information can be found at the manufacturer's specification sheet.

Sensor Specifications

	Chlorophyll-a	Chlorophyll-a	Rhodamine	Amido Rhodamine	Fluorescein
Excitation wavelengths	430/30 nm	470/30 nm	470/30 nm	425/30 nm	480/80 nm
Emission wavelength	685/30 nm	685/30 nm	590/45 nm	550/30 nm	530/30 nm
Concentration range	0.03-100 µg l^-1	0.03-100 µg l^-1	0.03-100 µg l^-1	0.04-200 µg l^-1	0.03-100 µg l^-1
Resolution	0.01 µg l^-1	0.01 µg l^-1	0.01 µg l^-1	0.025 µg l^-1	0.01 µg l^-1
Calibration standard	Chlorophyll-a in acetone	Chlorophyll-a in acetone

	Nephelometer	Phycoerythrin	Phycocyanin
Excitation wavelengths	470/30 nm	530/30 nm	590/35nm
Emission wavelength	470/30 nm	580/30 nm	645/35 nm
Concentration range	0.04-100 FTU	0.03-100 µg l^-1	0.03-100 µg l^-1
Resolution	0.01 FTU	0.01 µg l^-1	0.01 µg l^-1

Mechanical		Electrical
Body Size	149 mm long x 70 mm dia	Input Voltage	7 to 40 VDC
Weight in Air	0.7 Kg	Output Voltage	0 to 4 VDC (linear)
Weight in Water	0.15 Kg	Power requirements	0.7 W typical
Depth Rating	600 m	Signal : Noise	10,000 : 1 @ full scale

Data Processing

Originator's Sampling Strategy

These data were collected using a CTD rig deployed from PML research vessels.

Originator's Processing

The raw CTD data were processed using the Sea-Bird software. The data were provided in tab delimited format.

BODC post-processing and screening

Reformatting

The data were converted from tab delimited format into BODC internal format using BODC transfer function 401. During transfer the depth variable was converted to pressure using the routine 'sw_pres', a part of the Seawater toolbox, this used the method of Fofonoff and Millard Jr. (1983) using inputs of depth and latitude. The density parameter was not transferred by BODC as this is generated to a standard algorithm during BODC transfer.

The measured variables were mapped to BODC parameter codes shown in the table below:

Originator's Parameter Name	Units	Description	BODC parameter code	Units	Comments
Tv290v	Deg C	Temperature of the water column	TEMPST01	Deg C	-
FlCM	volts	Raw fluorometer voltage	FVLTZZ01	volts	-
DepSM	m	Depth of the water column	DEPHPR01	m	-
Density00	kg m^-3	Density of the water column by unknown algorithm	-	-	Channel not transferred as generated during BODC transfer
Sal00	-	Salinity of the water column	PSALST01	-	-
-	-	Pressure	PRESPR01	dbar	Calculated by BODC from depth and latitude
-	-	Sigma-theta	SIGTPR01	kg m^-3	Generated by BODC using Fofonoff and Millard (1983) algorithm with parameters PRESPR01, TEMPST01 and PSALST01.

Screening

Reformatted CTD data were transferred onto a graphics work station for visualisation using the in-house editor EDSERPLO. No data values were edited or deleted. Flagging was achieved by modification of the associated BODC quality control flag for suspect or null values.

Banking

The profiles were banked to the National Oceanographic Database (NODB) following BODC procedures.

References

Fofonoff, N.P. and Millard, R.C., 1983. Algorithms for computations of fundamental properties of seawater. UNESCO Technical Papers in Marine Science No. 44, 53pp.

Project Information

L4 time-series (1998-2002)

Who funded the programme?

The Natural Environment Research Council (NERC) through PML core funding.

Who was involved in the programme?

Plymouth Marine Laboratory (PML).

What was the programme about?

Beginning in 1988, through the work of the Plymouth Marine Laboratory Zooplankton Group, a programme of weekly observations began at L4 (50^o 15' N, 4^o 13' W). Station L4 is one of a series of hydrographic stations in the Western English Channel. These stations have been the basis of a series of hydrographic surveys carried out during the 20th Century by scientists at the Marine Biological Association in Plymouth. No formal research programme was proposed, so the time-series exploited the activities of the PML small boats, "Sepia" and "Squilla" in a opportunistic way as by-product of their other sampling activities (e.g., collection of live plankton, sea-water, trawling for fish and squid). It is important to recognise, when using these data, the nature of the data-set. The programme was not initially designed as a long-term time series, with standardised methods, and long-term funding. Rather the approach has been to build a time-series from other on-going research activities. Every attempt has been made to standardise methodology and achieve data consistency, but the varied personnel and research objectives which have contributed to the dataset should be borne in mind.

When was the programme active?

The time-series began in 1988 and in 2002 was expanded to include sampling at neighbouring stations with a history of marine measurements. This formed basis of the Western Channel Observatory from 2002.

Brief summary of the programme fieldwork/data

At the L4 station weekly samples were taken (weather conditions permitting) for zooplankton biomass, identification and abundance. In 1992 phytoplankton identification and abundance was added to the data obtained from the weekly samples. The measurements taken were further expanded in 2000 to include hydrography, optics, nutrients (opportunitistically) and pigments in the water column at L4.

Weblink: http://www.westernchannelobservatory.org.uk/l4/

Data Activity or Cruise Information

Cruise

Cruise Name	SQ020422
Departure Date	2002-04-22
Arrival Date	2002-04-22
Principal Scientist(s)	Roger Harris (Plymouth Marine Laboratory)
Ship	RV Squilla

Complete Cruise Metadata Report is available here

Fixed Station Information

Station Name	Western Channel Observatory L4
Category	Coastal location
Latitude	50° 15.00' N
Longitude	4° 13.02' W
Water depth below MSL	55.0 m

Western Channel Observatory station L4

The Western Channel Observatory (WCO) is situated in the Western English Channel and comprises of long-term sustained observations at a number of stations.

Station L4 is located south-west of Plymouth at 50° 15.00 N, 4° 13.02 W.

More information can be found on the Western Channel Observatory website.

Other Cruises linked to this Fixed Station (with the number of series) - MS070903 (1) MS070910 (1) MS070917 (1) MS070928 (1) MS071002 (1) MS071008 (1) MS071025 (1) MS071030 (1) MS071105 (1) MS071112 (1) MS071122 (1) MS071126 (1) MS071211 (1) MS080213 (1) MS080220 (1) MS080227 (1) MS081208 (1) MS081215 (1) MS090105 (1) MS090316 (1) MS090421 (1) PML011212 (1) PML011219 (1) PML020715 (1) PML020807 (1) PML030311 (1) PML030321 (1) PML030327 (1) PML030402 (1) PML030409 (1) PML030507 (1) PML030513 (1) PML030605 (1) PML030612 (1) PML030620 (1) PML030701 (1) PML030703 (1) PML030730 (1) PML030801 (1) PML030829 (1) PML030917 (1) PML031027 (1) PML031110 (1) PML031124 (1) PML031210 (1) PML031215 (1) PML040121 (1) PML040216 (1) PML040301 (1) PML040308 (1) PML040317 (1) PML040329 (1) PML040413 (1) PML040422 (1) PML040426 (1) PML040510 (1) PML040517 (1) PML040524 (1) PML040602 (1) PML040607 (1) PML040614 (1) PML040621 (1) PML040630 (1) PML040706 (1) PML040721 (1) PML040802 (1) PML040816 (1) PML040825 (1) PML040831 (1) PML040906 (1) PML041018 (1) PML041026 (1) PML041101 (1) PML041109 (1) PML041116 (1) PML041123 (1) PML041129 (1) PML041206 (1) PML041213 (1) PML041220 (1) PML050106 (1) PML050124 (1) PML050131 (1) PML050215 (1) PML050222 (1) PML050228 (1) PML050307 (1) PML050315 (1) PML050321 (1) PML050329 (1) PML050401 (1) PML050411 (1) PML050426 (1) PML050504 (1) PML050509 (1) PML050516 (1) PML050525 (1) PML050601 (1) PML050606 (1) PML050613 (1) PML050620 (1) PML050627 (1) PML050704 (1) PML050711 (1) PML050725 (1) PML050801 (1) PML050808 (1) PML050815 (1) PML050830 (1) PML050905 (1) PML050912 (1) PML050919 (1) PML050926 (1) PML051003 (1) PML051010 (1) PML051017 (1) PML051115 (1) PML051122 (1) PML051128 (1) PML051205 (1) PML051212 (1) PML051219 (1) PML060103 (1) PML060109 (1) PML060116 (1) PML060123 (1) PML060202 (1) PML060206 (1) PML060213 (1) PML060227 (1) PML060306 (1) PML060315 (1) PML060320 (1) PML060329 (1) PML060403 (1) PML060504 (1) PML060508 (1) PML060523 (1) PML060606 (1) PML060612 (1) PML060620 (1) PML060627 (1) PML060703 (1) PML060710 (1) PML060807 (1) PML060814 (1) PML060829 (1) PML060904 (1) PML060912 (1) PML060925 (1) PML061003 (1) PML061030 (1) PML061106 (1) PML061218 (1) PML070122 (1) PML070129 (1) PML070205 (1) PML070320 (1) PML070326 (1) PQ070410 (1) PQ070416 (1) PQ070423 (1) PQ070430 (1) PQ070508 (1) PQ070521 (1) PQ070604 (1) PQ070611 (1) PQ070625 (1) PQ070703 (1) PQ070709 (1) PQ070716 (1) PQ070723 (1) PQ070730 (1) PQ070806 (1) PQ070813 (1) PQ070820 (1) PQ070828 (1) PQ080305 (1) PQ080317 (1) PQ080407 (1) PQ080414 (1) PQ080421 (1) PQ080428 (1) PQ080506 (1) PQ080512 (1) PQ080519 (1) PQ080528 (1) PQ080602 (1) PQ080609 (1) PQ080616 (1) PQ080623 (1) PQ080630 (1) PQ080714 (1) PQ080721 (1) PQ080728 (1) PQ080820 (1) PQ080826 (1) PQ080902 (1) PQ080915 (1) PQ080922 (1) PQ080929 (1) PQ081006 (1) PQ081013 (1) PQ081021 (1) PQ081103 (1) PQ090113 (1) PQ090121 (1) PQ090211 (1) PQ090216 (1) PQ090223 (1) PQ090302 (1) PQ090309 (1) PQ090323 (1) PQ090330 (1) PQ090406 (1) PQ090414 (1) PQ090514 (1) PQ090521 (1) PQ090602 (1) PQ090615 (1) PQ090622 (1) PQ090629 (1) PQ090707 (1) PQ090713 (1) PQ090720 (1) PQ090727 (1) PQ090811 (1) PQ090901 (1) PQ090907 (1) PQ090914 (1) PQ090922 (1) PQ090930 (1) PQ091007 (1) PQ091012 (1) PQ091019 (1) PQ091026 (1) PQ091109 (1) PQ091201 (1) PQ091209 (1) PQ091215 (1) PQ091221 (1) PQ100104 (1) PQ100111 (1) PQ100118 (1) PQ100126 (1) PQ100201 (1) PQ100215 (1) PQ100225 (1) PQ100301 (1) PQ100308 (1) PQ100315 (1) PQ100407 (1) PQ100412 (1) PQ100419 (1) PQ100426 (1) PQ100504 (1) PQ100510 (1) PQ100517 (1) PQ100524 (1) PQ100602 (1) PQ100607 (1) PQ100614 (1) PQ100621 (1) PQ100629 (1) PQ100706 (1) PQ100712 (1) PQ100719 (1) PQ100726 (1) PQ100803 (1) PQ100811 (1) PQ100816 (1) PQ100831 (1) PQ100906 (1) PQ100913 (1) PQ100920 (1) PQ100927 (1) PQ101004 (1) PQ101013 (1) PQ101018 (1) PQ101025 (1) PQ101101 (1) PQ101110 (1) PQ101116 (1) PQ101122 (1) PQ101130 (1) PQ101206 (1) PQ101213 (1) PQ101221 (1) PQ110106 (1) PQ110117 (1) PQ110125 (1) PQ110131 (1) PQ110208 (1) PQ110222 (1) PQ110228 (1) PQ110307 (1) PQ110314 (1) PQ110322 (1) PQ110328 (1) PQ110406 (1) PQ110411 (1) PQ110418 (1) PQ110426 (1) PQ110511 (1) PQ110516 (1) PQ110524 (1) PQ110601 (1) PQ110606 (1) PQ110614 (1) PQ110620 (1) PQ110627 (1) PQ110704 (1) PQ110711 (1) PQ110719 (1) PQ110725 (1) PQ110801 (1) PQ110808 (1) PQ110815 (1) PQ110822 (1) PQ110830 (1) PQ110915 (1) PQ110919 (1) PQ110926 (1) PQ111003 (1) PQ111012 (1) PQ111017 (1) PQ111025 (1) PQ111101 (1) PQ111108 (1) PQ111116 (1) PQ111121 (1) PQ111219 (1) PQ120109 (1) PQ120116 (1) PQ120123 (1) PQ120130 (1) PQ120207 (1) PQ120213 (1) PQ120220 (1) PQ120227 (1) PQ120306 (1) PQ120313 (1) PQ120319 (1) PQ120326 (1) PQ120402 (1) PQ120411 (1) PQ120416 (1) PQ120424 (1) PQ120501 (1) PQ120508 (1) PQ120514 (1) PQ120521 (1) PQ120523 (1) PQ120528 (1) PQ120611 (1) PQ120618 (1) PQ120625 (1) PQ120702 (1) PQ120709 (1) PQ120719 (1) PQ120723 (1) PQ120730 (1) PQ120806 (1) PQ120814 (1) PQ120820 (1) PQ120903 (1) PQ120910 (1) PQ120917 (1) PQ120926 (1) PQ121008 (1) PQ121015 (1) PQ121022 (1) PQ121030 (1) PQ121107 (1) PQ121114 (1) PQ121128 (1) PQ121205 (1) PQ121210 (1) PQ121218 (1) SEP020618 (1) SEP020624 (1) SEP020709 (1) SEP021203 (1) SEP030325 (1) SEP030331 (1) SEP030407 (1) SEP030422 (1) SEP030623 (1) SEP030811 (1) SEP030911 (1) SEP030915 (1) SEP030924 (1) SEP030929 (1) SEP031021 (1) SEP031106 (1) SQ020212 (1) SQ020304 (1) SQ020402 (1) SQ020415 (1) SQ020501 (1) SQ020507 (1) SQ020516 (1) SQ020527 (1) SQ020611 (1) SQ020701 (1) SQ020722 (1) SQ020729 (1) SQ020805 (1) SQ020812 (1) SQ020828 (1) SQ020902 (1) SQ020909 (1) SQ020916 (1) SQ020930 (1) SQ021007 (1) SQ021014 (1) SQ021028 (1) SQ021104 (1) SQ021118 (1) SQ021125 (1) SQ030106 (1) SQ030113 (1) SQ030122 (1) SQ030127 (1) SQ030203 (1) SQ030210 (1) SQ030217 (1) SQ030317 (1) SQ030414 (1) SQ030512 (1) SQ030519 (1) SQ030528 (1) SQ030602 (1) SQ030609 (1) SQ030616 (1) SQ030630 (1) SQ030707 (1) SQ030714 (1) SQ030721 (1) SQ030728 (1) SQ030804 (1) SQ030820 (1) SQ030827 (1)

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