Metadata Report for BODC Series Reference Number 1208604

• 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

JC039 Data Quality Report

Salinity and Temperature

The fin mounted sensors were used as the primary channels for loading to the database.

Oxygen (SBE 43)

CTD109 shows a step increase at 410 db on the down-cast of 20 µmol per litre and data below these depths have been flagged suspect. The step remains during the up-cast and is likely explained as this was the cast where the conductivity sensor was found to be faulty and replaced before the next cast.

Attenuance and transmittance (Chelsea MkII Alphatracka)

The transmittance and Attenuance channels (POPTDR01 and ATTNMR01) for many of the casts in this dataset have possible issues with the calibrations that have been applied. This is highlighted by series which have many values that are outside of the expected parameter ranges. For transmittance, a large amount of the values are over 100% and have been flagged by BODC as suspect. For Attenuance, there are a lot of negative values which have also been flagged suspect as they are not within the expected parameter range. This does not necessarily mean that the data are not useful scientifically, just that the calibration coefficients may be slightly out. Where previous flags indicating interpolated data were overwritten, the original flagged data are available on request.

The Chelsea transmissometers have been calibrated with pure water as the reference for 100% transmission and therefore beam attenuation values in clear water should be close to 0 m^-1. Chelsea Instruments advise that ALPHAtracka is calibrated at the factory at 20°C in distilled water with an electrical conductivity less than one µS cm^-1and filtered to better than 5 µm and that it is possible that the user will encounter water which is purer than that used during the calibration. Indeed the minimum attenuance values for the profiles from the stainless steel rig mounted tranmissometer were lower then 0 m^-1 for many casts, suggesting that the calibration procedure recommended by Sea-Bird and Chelsea Instruments may need adjusting to use deep clear oceanic water as the reference for 100% transmission. The attenuance data from the transmissometers will need further offset correction to bring them in line with recognised values. Whether this should be done for the dataset as a whole or on a cast by cast basis is for the user to decide based on their requirements. The absolute attenuation values are therefore questionable but the relative profile should be reliable except for profiles where hysteresis was a problem at depth.

Fluorescence (Chelsea MkIII Aquatracka)

The calibrated fluorometer channel (CPHLPS01) contains some casts where values are negative and therefore outside of the expected parameter range (0 to 999 mg m-3). All these values have been flagged by BODC as suspect and should be used with caution. This is likely due to an issue with the fluorometer calibration, however this does not necessarily mean that the data are not useful scientifically, just that the calibration coefficients may be slightly out. Where previous flags indicating interpolated data were overwritten, the original flagged data are available on request.

Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."

Narrative Documents

Sea-Bird Dissolved Oxygen Sensor SBE 43 and SBE 43F

The SBE 43 is a dissolved oxygen sensor designed for marine applications. It incorporates a high-performance Clark polarographic membrane with a pump that continuously plumbs water through it, preventing algal growth and the development of anoxic conditions when the sensor is taking measurements.

Two configurations are available: SBE 43 produces a voltage output and can be incorporated with any Sea-Bird CTD that accepts input from a 0-5 volt auxiliary sensor, while the SBE 43F produces a frequency output and can be integrated with an SBE 52-MP (Moored Profiler CTD) or used for OEM applications. The specifications below are common to both.

Specifications

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

James Cook Cruise JC039 AMT19 CTD Instrumentation

Two different CTD frames were used - a stainless steel frame and a titanium frame used for trace metal sampling.

Stainless Steel

The CTD unit was a Sea-Bird Electronics 911plus system, with dissolved oxygen sensor. The CTD was fitted with a transmissometer and a fluorometer. All instruments were attached to a Sea-Bird SBE 32 carousel. The table below lists more detailed information about the various sensors.

Change of sensors during cruise: Three different fluorometers were deployed on this rig during the cruise.

Sampling device

Rosette sampling system equipped with 24 x 20 l sampling bottles (manufactured by Ocean Test Equipment Inc.).

Titanium

The CTD unit was a Sea-Bird Electronics 911plus system, with dissolved oxygen sensor. The CTD was fitted with a transmissometer and a fluorometer. All instruments were attached to a Sea-Bird SBE 32 carousel (titanium). The table below lists more detailed information about the various sensors.

Change of sensors during cruise: Two different fluorometers were used on this rig during the cruise.

Sampling device

Rosette sampling system equipped with 24 x 10 l trace metal free sampling bottles (manufactured by Ocean Test Equipment Inc.).

Sea-Bird Electronics SBE 911 and SBE 917 series CTD profilers

The SBE 911 and SBE 917 series of conductivity-temperature-depth (CTD) units are used to collect hydrographic profiles, including temperature, conductivity and pressure as standard. Each profiler consists of an underwater unit and deck unit or SEARAM. Auxiliary sensors, such as fluorometers, dissolved oxygen sensors and transmissometers, and carousel water samplers are commonly added to the underwater unit.

Underwater unit

The CTD underwater unit (SBE 9 or SBE 9 plus) comprises a protective cage (usually with a carousel water sampler), including a main pressure housing containing power supplies, acquisition electronics, telemetry circuitry, and a suite of modular sensors. The original SBE 9 incorporated Sea-Bird's standard modular SBE 3 temperature sensor and SBE 4 conductivity sensor, and a Paroscientific Digiquartz pressure sensor. The conductivity cell was connected to a pump-fed plastic tubing circuit that could include auxiliary sensors. Each SBE 9 unit was custom built to individual specification. The SBE 9 was replaced in 1997 by an off-the-shelf version, termed the SBE 9 plus, that incorporated the SBE 3 plus (or SBE 3P) temperature sensor, SBE 4C conductivity sensor and a Paroscientific Digiquartz pressure sensor. Sensors could be connected to a pump-fed plastic tubing circuit or stand-alone.

Temperature, conductivity and pressure sensors

The conductivity, temperature, and pressure sensors supplied with Sea-Bird CTD systems have outputs in the form of variable frequencies, which are measured using high-speed parallel counters. The resulting count totals are converted to numeric representations of the original frequencies, which bear a direct relationship to temperature, conductivity or pressure. Sampling frequencies for these sensors are typically set at 24 Hz.

The temperature sensing element is a glass-coated thermistor bead, pressure-protected inside a stainless steel tube, while the conductivity sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Thermistor resistance or conductivity cell resistance, respectively, is the controlling element in an optimized Wien Bridge oscillator circuit, which produces a frequency output that can be converted to a temperature or conductivity reading. These sensors are available with depth ratings of 6800 m (aluminium housing) or 10500 m (titanium housing). The Paroscientific Digiquartz pressure sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.

Additional sensors

Optional sensors for dissolved oxygen, pH, light transmission, fluorescence and others do not require the very high levels of resolution needed in the primary CTD channels, nor do these sensors generally offer variable frequency outputs. Accordingly, signals from the auxiliary sensors are acquired using a conventional voltage-input multiplexed A/D converter (optional). Some Sea-Bird CTDs use a strain gauge pressure sensor (Senso-Metrics) in which case their pressure output data is in the same form as that from the auxiliary sensors as described above.

Deck unit or SEARAM

Each underwater unit is connected to a power supply and data logging system: the SBE 11 (or SBE 11 plus) deck unit allows real-time interfacing between the deck and the underwater unit via a conductive wire, while the submersible SBE 17 (or SBE 17 plus) SEARAM plugs directly into the underwater unit and data are downloaded on recovery of the CTD. The combination of SBE 9 and SBE 17 or SBE 11 are termed SBE 917 or SBE 911, respectively, while the combinations of SBE 9 plus and SBE 17 plus or SBE 11 plus are termed SBE 917 plus or SBE 911 plus.

Specifications

Specifications for the SBE 9 plus underwater unit are listed below:

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

Chelsea Technologies Group Aquatracka MKIII fluorometer

The Chelsea Technologies Group Aquatracka MKIII is a logarithmic response fluorometer. Filters are available to enable the instrument to measure chlorophyll, rhodamine, fluorescein and turbidity.

It uses a pulsed (5.5 Hz) xenon light source discharging along two signal paths to eliminate variations in the flashlamp intensity. The reference path measures the intensity of the light source whilst the signal path measures the intensity of the light emitted from the specimen under test. The reference signal and the emitted light signals are then applied to a ratiometric circuit. In this circuit, the ratio of returned signal to reference signal is computed and scaled logarithmically to achieve a wide dynamic range. The logarithmic conversion accuracy is maintained at better than one percent of the reading over the full output range of the instrument.

Two variants of the instrument are available, both manufactured in titanium, capable of operating in depths from shallow water down to 2000 m and 6000 m respectively. The optical characteristics of the instrument in its different detection modes are visible below:

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

The instrument measures chlorophyll a, rhodamine and fluorescein with a concentration range of 0.01 µg l^-1 to 100 µg l^-1. The concentration range for turbidity is 0.01 to 100 FTU (other wavelengths are available on request).

The instrument accuracy is ± 0.02 µg l^-1 (or ± 3% of the reading, whichever is greater) for chlorophyll a, rhodamine and fluorescein. The accuracy for turbidity, over a 0 - 10 FTU range, is ± 0.02 FTU (or ± 3% of the reading, whichever is greater).

Further details are available from the Aquatracka MKIII specification sheet.

Chelsea Technologies Group ALPHAtracka and ALPHAtracka II transmissometers

The Chelsea Technologies Group ALPHAtracka (the Mark I) and its successor, the ALPHAtracka II (the Mark II), are both accurate (< 0.3 % fullscale) transmissometers that measure the beam attenuation coefficient at 660 nm. Green (565 nm), yellow (590 nm) and blue (470 nm) wavelength variants are available on special order.

The instrument consists of a Transmitter/Reference Assembly and a Detector Assembly aligned and spaced apart by an open support frame. The housing and frame are both manufactured in titanium and are pressure rated to 6000 m depth.

The Transmitter/Reference housing is sealed by an end cap. Inside the housing an LED light source emits a collimated beam through a sealed window. The Detector housing is also sealed by an end cap. A signal photodiode is placed behind a sealed window to receive the collimated beam from the Transmitter.

The primary difference between the ALPHAtracka and ALPHAtracka II is that the Alphatracka II is implemented with surface-mount technology; this has enabled a much smaller diameter pressure housing to be used while retaining exactly the same optical train as in the Mark I. Data from the Mark II version are thus fully compatible with that already obtained with the Mark I. The performance of the Mark II is further enhanced by two electronic developments from Chelsea Technologies Group - firstly, all items are locked in a signal nulling loop of near infinite gain and, secondly, the signal output linearity is inherently defined by digital circuitry only.

Among other advantages noted above, these features ensure that the optical intensity of the Mark II, indicated by the output voltage, is accurately represented by a straight line interpolation between a reading near full-scale under known conditions and a zero reading when blanked off.

For optimum measurements in a wide range of environmental conditions, the Mark I and Mark II are available in 5 cm, 10 cm and 25 cm path length versions. Output is default factory set to 2.5 volts but can be adjusted to 5 volts on request.

Further details about the Mark II instrument are available from the Chelsea Technologies Group ALPHAtrackaII specification sheet.

Chelsea Technologies Photosynthetically Active Radiation (PAR) Irradiance Sensor

This sensor was originally designed to assist the study of marine photosynthesis. With the use of logarithmic amplication, the sensor covers a range of 6 orders of magnitude, which avoids setting up the sensor range for the expected signal level for different ambient conditions.

The sensor consists of a hollow PTFE 2-pi collector supported by a clear acetal dome diverting light to a filter and photodiode from which a cosine response is obtained. The sensor can be used in moorings, profiling or deployed in towed vehicles and can measure both upwelling and downwelling light.

Specifications

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

Paroscientific Absolute Pressure Transducers Series 3000 and 4000

Paroscientific Series 3000 and 4000 pressure transducers use a Digiquartz pressure sensor to provide high accuracy and precision data. The sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.

The 3000 series of transducers includes one model, the 31K-101, whereas the 4000 series includes several models, listed in the table below. All transducers exhibit repeatability of better than ±0.01% full pressure scale, hysteresis of better than ±0.02% full scale and acceleration sensitivity of ±0.008% full scale /g (three axis average). Pressure resolution is better than 0.0001% and accuracy is typically 0.01% over a broad range of temperatures.

Differences between the models lie in their pressure and operating temperature ranges, as detailed below:

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

James Cook Cruise JC039 AMT19 CTD Processing

Sampling strategy

A total of 120 successful CTD casts were made during the cruise, 38 casts used the stainless steel rig and 82 used the titanium rig. Rosette bottles were fired throughout the water column on the upcast of most profiles. Data were measured at 24 Hz by a PC running SEASAVE, Sea-Bird's data acquisition software. The raw data files were supplied to BODC after the cruise. A further 48 casts were used for surface sampling at ~5 m during three 30 hour diel stations. No data were acquired for these surface casts.

Originator's processing

CTD casts were recorded using the SeaBird data collection software Seasave-Win32. The software outputs were then processed using SBE Data Processing-Win32 v7.18; the processing routines are named after each stage in brackets. The software applied the calibrations as appropriate through the instrument configuration file to the data in engineering units output by the CTD hardware. Due to an oversight in post cruise processing only one PAR channel was transferred for each profile. As the voltage channels were inverted for the PAR sensors on the stainless steel rig compared with the titanium rig, the transferred data were the data from the down-welling PAR sensor for the stainless steel rig and data for the up-welling PAR sensor for the titanium rig. The Altimeter and Wetlabs BBRTD backscatter data streams were not transferred during processing.

A binary file including the 24 Hz data for up and down casts was generated along with a bottle file containing all the information from the instant the bottle was fired for each cast (DatCnv). The oxygen sensor was then shifted relative to the pressure by 5 seconds, to compensate for the lag in the sensor response time (AlignCTD). Pressure spikes were removed (WildEdit), the effect of thermal 'inertia' on the conductivity cells was removed (CellTM) and then the binary files were converted to ascii so they could be read in PSTAR format (translate).

The CTD files produced from SeaBird processing were converted from 24 Hz ascii files into PSTAR format. The data were than averaged into a 1 Hz file. A file was created for each cast containing the mean values of all the variables at the bottle firing locations. Bench salinometer data were collected during the cruise from a range of depths from each CTD cast. The salinometer data was compared with CTD values from the frame and fin mounted sensors during processing and a calibration applied. Details of these calibrations are given in the Cruise Report.

More details of the processing routines can be found in the Cruise Report.

BODC post-processing and screening

• Reformatting

  The data files were sent to BODC in the NOCS PSTAR format. The *.CTU PSTAR format files containing 1 Hz downcast and up-cast data were converted to a BODC internal format. The PSTAR data channels were mapped to BODC parameter codes and units were converted where applicable as part of the transfer. The oxygen concentration was converted from millilitres per litre to micromoles per litre using a conversion factor of 44.66 and the conductivity from milliSiemens per cm to Siemens per metre using a conversion factor of 0.1. The PSTAR header details reported the PAR data as %, after checking with the data originator and the PAR sensor calibration sheets the units were confirmed to be Wm^-2.The following table shows how the variables within the PSTAR files were mapped to appropriate BODC parameter codes:

  Sea-Bird Parameter Name	Units	Description	BODC Parameter Code	Units	Comments
  press	dbar	CTD pressure	PRESPR01	dbar	-
  temp	°C	Temperature of water column by CTD sensor 1	TEMPCU01	°C	-
  temp2	°C	Temperature of water column by CTD sensor 2	TEMPCU02	°C	-
  salin	-	Practical salinity of the water body by CTD sensor 1	PSALCC01	-	Calibrated against bench salinometer data
  salin2	-	Practical salinity of the water body by CTD sensor 2	PSALCC02	-	Calibrated against bench salinometer data
  oxygen	ml l-1	Dissolved oxygen concentration	DOXYSU01	µmol l-1	Converted from ml l-1 to µmol l-1 during transfer
  fluor	mg m-3	Nominal chl-a concentration	CPHLPM01	mg m-3	Manufacturer's calibration applied during processing
  PAR	W m-2	Downwelling sub-surface PAR irradiance	DWIRPP01	W m-2	Only for stainless steel rig casts shallower than 500m
  PAR	W m-2	Upwelling sub-surface PAR irradiance	UWIRPP01	W m-2	Only for titanium rig casts shallower than 500m
  Trans	%	Beam attenuance	POPTDR01	%	-
  Atten	m-1	Beam attenuance	ATTNDR01	m-1	-
  -	-	Dissolved oxygen concentration - sample calibrated	DOXYSC01	µmol l-1	DOXYSU01 calibrated against Winkler titration data
  -	-	Fluorometer - sample calibrated	CPHLPS01	mg m-3	CPHLPM01 calibrated against fluorometric chlorophyll-a data
  -	-	Oxygen saturation	OXYSSC01	%	Generated by BODC using the Benson and Krause (1984) algorithm wioth parameters DOXYSC01, PSALCC01 and TEMPCU01
  -	-	Potential temperature	POTMCV01	°C	Generated by BODC using UNESCO Report 38 (1981) algorithm with parameters PRESPR01, PSALCC01 and TEMPCU01
  -	-	Sigma-theta	SIGTPR01	kg m-3	Generated by BODC using the Fofonoff and Millard (1982) algorithm with parameters PSALCC01 and POTMCV01

• References

  Benson, B.B. and Krause, D., 1984. The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnol. Oceanogr., 29(3), 620-632

  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.

  UNESCO, 1981. Background papers and supporting data on the International Equation of State of Seawater 1980. UNESCO Technical Papers in Marine Science No. 38, 192pp

• Screening

  The transferred data were compared with the original data files to ensure that no errors had been introduced during the conversion process. Reformatted CTD data were transferred onto a graphics work station for visualisation using the in-house editor EDSERPLO. Downcasts and upcasts were differentiated and the limits manually flagged. No data values were edited or deleted. Flagging was achieved by modification of the associated BODC quality control flag for suspect or null values.

  From visual screening of the 1Hz data profiles, it was clear that on occasion the profiles suffered from the problem of ship's heave/entrainment, which has now become conspicuous on most cruises. The frame mounted temperature and conductivity sensors were located within the rig and the fin mounted temperature and conductivity sensors were deployed on an external fin and the entrainment features were greatly reduced in the data from the fin mounted sensors. Therefore the data from the fin mounted sensor channels were considered more reliable and anomalies on the fin mounted sensor channels were flagged systematically whenever it was believed that they would affect the quality of the final 1 dbar-binned data. The frame mounted sensor data has been left unflagged (except in cases of obviously bad data) and can be used as a reference for what the profile, once averaged into 1 or 2 dbar bins, would be like had the anomalies not been flagged and sensors not been placed on a fin external to the main rig.

  Temperature and salinity: CTD001 profiles were noisy in the surface 10 db and flagged suspect for both sensors. CTD060-64 had low surface salinities. CTD109 the frame sensor failed and this can be seen in the profile at 480m. The sensor on the fin continued to return reasonable data.

  Oxygen sensors: The channel showed variation for the majority of casts, whether that reflected natural variability or entrainment was not always clear. For some casts where the variation is minimal the entrainment problem where obvious has been flagged, however the variability on most casts makes it difficult to distinguish. CTD109 shows a step increase at 410 db on the down-cast of 20 µmol per litre and data below these depths have been flagged suspect. The step remains during the up-cast and are likely explained as this was the cast where the conductivity sensor was found to be faulty and replaced before the next cast.

  Fluorometers: No obvious problem with entrainment for the fluorometer channels. Cruise documentation indicates a problem with the SS fluorometer during the up-cast of CTD026s which was also apparent on cast CTD029, so a connecting cable was changed. The problem returned as soon as the CTD was submerged for CTD038s. The cable was changed prior to cast CTD050s and while the signal was good on-deck, data dropped to 0v once in the water. The fluorometer was changed prior to CTD053s and instrument S/N 09-7117-001 replaced instrument S/N 088224. The same problem appeared on the TT rig for the deeper casts from CTD92t and CTD093s swapping the fluorometers between rigs solved this problem.

  Transmissometers: The transmissometer data are not correctly calibrated and the attenuance and transmission values should not be used as absolute values. Casts 007, 017 and 049 have had spikes and anomalous data flagged suspect in the mid-water column. From cast 56 to 80 the transmissometer starts behaving suspiciously, see the problem report for more details.

  Irradiance sensors: For the down- and up-welling PAR profiles, spiky data were generally associated with movement when the package was going down too slowly and "bouncing" in the surface layer. However the majority of casts were not flagged given that the variation can be the result of variation in surface conditions (e.g. changing cloud cover).

• Field Calibrations

  Temperature

  Temperature readings from the two temperature sensors were almost identical outside of entrainment features and no other independent measurements of better quality were available. No further correction was therefore applied to the data.

  Salinity

  The salinity channels have been calibrated by the originators and no further correction was applied to the data. 281 salinity samples were taken during the cruise from a range of CTD casts and depths.

  Dissolved oxygen

  The oxygen sensors were calibrated using the sensor readings from the up-cast at the point when the bottles were fired and the dissolved oxygen data measured using the Winkler titration methodology on water samples collected from bottles. The samples collected were from a range of depths on a number of casts throughout the cruise. The data from CTD109 were removed from the calibration dataset due to the problem with the conductivity sensor on the up-cast. The reduction in the RMS residual indicates the improved match to the Winkler titration dataset after calibration for deployments of both the stainless steel (uncalibrated RMS = 9.319; calibrated RMS = 2.469) and titanium rigs (uncalibrated RMS = 16.860; calibrated RMS = 3.448).

  Casts	Calibration	N	R2	p	BODC cal ref
  Stainless steel	DOXYSC01 = 1.0274 * DOXYSU01 + 3.3505	142	0.994	<0.001	6434
  Titanium	DOXYSC01 = 1.0896 * DOXYSU01 - 0.9260	99	0.989	<0.001	6435

  Fluorescence

  The fluorometer profiles were calibrated using the sensor readings from the up-casts at the point when the bottles were fired and the HPLC chl-a data measured from water samples collected from bottles. The samples collected were from a range of depths on a number of casts throughout the cruise.

  The up-cast data that were considered suspect were removed from the calibration dataset due to the problem with the fluorometer (sn 088244) on the up-cast. The regression for this fluorometer deployed on the stainless steel rig from casts 2 to 50 was not significant and a mean offset was applied to the data. The data from casts 17, 29, 38, 41 and 50 were considered suspect and these casts have not been calibrated. The casts showed consistent regressions when the calibration datasets were grouped by fluorometer and rig. All remaining regressions were significant (p<0.001). The reduction in the RMS residual (uncalibrated RMS = 0.192; calibrated RMS = 0.098) for the calibration dataset indicates the improved match to the HPLC chl-a dataset after calibration.

  Stainless steel rig

  Casts	Calibration	N	R2	p	BODC cal ref
  2 - 50	CPHLPS01 = CPHLPM01 + 0.0050	38	0.034	0.139	6529
  53 - 90	CPHLPS01 = 0.8000 * CPHLPM01 + 0.0069	64	0.356	<0.001	6534
  93 - 118	CPHLPS01 = 2.2236 * CPHLPM01 - 0.0189	43	0.980	<0.001	6541

  * Calibration not applied to casts 17 and 29 as the down and up-cast profiles appeared inconsistent. As the fluorometer was behaving inconsistently between up and down-casts from cast to cast for this period the calibration (and fluorometer data in general) should be used with caution for all stainless steel casts 14-35.

  Titanium rig

  Casts	Calibration	N	R2	p	BODC cal ref
  12 - 87	CPHLPS01 = 1.7732 * CPHLPM01 - 0.0966	58	0.647	<0.001	6542
  91 - 120	CPHLPS01 = 1.7337 * CPHLPM01 - 0.0004	110	0.532	<0.001	6544

• Banking

  Once quality control screening was complete, the data were binned against pressure at 1 dbar increments. Finally, the CTD downcasts were banked in the National Oceanographic Database (NODB).

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: