Metadata Report for BODC Series Reference Number 1208493

• 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

AMT17 Data Quality Report

Fluorescence (Chelsea MkIII Aquatracka)

For some casts, the calibrated fluorometer channel (CPHLPS01) contains values that 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.

Light sensors (Chelsea PAR sensor)

The data from the light sensors are only available as raw voltages. No serial numbers were recorded in the cruise report. The UKORS technician notes or Seabird configuration files were provided to BODC. The onboard processing did not convert light sensor voltages to irradiance units, so there were no calibration coefficients present in the configuration files to be used. These channels were not transferred to the database files.

Attenuance (Chelsea MkII Alphatracka)

The Chelsea transmissometers were not converted from voltages as there were contradictory evidence as to which instrument was on which rig.

The Chelsea transmissometers appeared to suffer from pressure hysteresis at depth for most casts. The pattern showed a voltage maxima in the range 200-300 db and then a slight decrease in value as the profile went deeper. This pattern was not observed for profiles from the Wet Labs transmissometer. In addition the Chelsea instruments appeared to suffer with temperature hysteresis for casts from 24 to 37 and for cast 46 at depth. The pattern showed a rapid increase to an attenaunce maximum and then tailed off. This pattern coincided with the base of the thermocline. The Chelsea transmissometer voltages were not transferred to the database files.

The Wet Labs transmissometer has 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. The attenuance data 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 should be used with caution but the relative profiles at each station should be reliable. Where present the Wet Labs transmissometer attenuance profiles were included in the database files.

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.

Discovery Cruise AMT17 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.

Chelsea MkII Alphatracka serial number not definitively recorded. Some contradictions as to which sensor was on which rig.

Change of sensors during cruise: A Wetlabs C-star transmissometer (serial number 113) was added to the rig from cast 36 onwards.

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.

Chelsea MkII Alphatracka serial number not definitively recorded. Some contradictions as to which sensor was on which rig.

Change of sensors during cruise: A Wetlabs C-star transmissometer (serial number 113) was added to the rig for casts 27-35.

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.

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.

Discovery Cruise AMT17 CTD Processing

Sampling strategy

A total of 60 successful CTD casts were made during the cruise of which 29 used a stainless steel frame and 31 a titanium frame. Two casts (CTD005t and CTD016t) were abandoned due to technical problems. Test casts were made with both frames on 17th October 2005 between 12:00 and 13:30 GMT but data were not supplied to BODC. 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. There were 2 unsuccessful casts which did not generate profiles (5 and 16).

Originator's processing

Only a subset of files had been partially processed on board during the cruise. The raw data were therefore reprocessed at BODC to produce a homogeneous set of CTD data files for this cruise.

BODC post-processing and screening

BODC used the latest version of the SeaBird Processing software available at the time to process the raw binary data files (DAT files) based on information held in the sensor configuration files (CON files), and bottle firing files (BL).

• Sea-Bird processing

  The CON files were first checked for any changes which may have occurred during the cruise, none were made. The information was also cross checked against information held in the sensors' calibration reports.

  The following SeaBird routines were then carried out using SBE Data Processing software version 5.30a: DATCNV, CELLTM, FILTER, LOOPEDIT, DERIVE, BINAVG, STRIP. After CELLTM was run, tests were carried out to check whether an alignment of the conductivity sensor was necessary. It was decided that no lag need to be applied to conductivity. A lag of 3 s was applied to the oxygen channel. Details of the routines and settings used were as follows:

  DATCNV converts the raw data into engineering units. Both down and upcasts were selected. All channels were selected for transfer.

  The manufacturer's calibration for the fluorometer was applied during Sea-Bird processing as follows:

  Stainless steel	Nominal chl-a conc (µg/l) = (0.0125 * 10voltage) - 0.026
  Titanium	Nominal chl-a conc (µg/l) = (0.0109 * 10voltage) - 0.0229

  CELLTM was run on the DATCNV output using SeaBird's recommended settings of alpha= 0.03 and Tau=7.

  FILTER was run on pressure using a low pass time constant of 0.15 seconds.

  LOOPEDIT was run in order to minimise the marked wake effect linked to ship rolling observed on recent cruises.

  DERIVE, BINAVG and STRIP were then run to derive the salinity and oxygen concentration, reduce the data to 2Hz and strip redundant channels from the final sets of ASCII files.

  Conversion of transmissometer voltages to beam attenuation

  The transmissometer raw voltages have not been converted to attenuance values, since the serial numbers of the deployed instruments were not recorded and calibration details cannot be matched to the sensors on each rig.

  Conversion of PAR sensor voltages to irradiance

  The PAR sensor raw voltages have not been converted to PAR values since the serial numbers of the deployed instruments were not recorded and calibration details cannot be matched to the sensors on each rig.

• Reformatting

  The data were converted from Sea-Bird ASCII format into BODC internal format (PXF) using BODC transfer function 357. The following table shows how the variables within the Sea-Bird files were mapped to appropriate BODC parameter codes:

  Sea-Bird Parameter Name	Units	Description	BODC Parameter Code	Units	Comments
  Pressure, Digiquartz	dbar	CTD pressure	PRESPR01	dbar	-
  Temperature [ITS-90]	°C	Temperature of water column by CTD sensor 1	TEMPCU01	°C	-
  Temperature, 2 [ITS-90]	°C	Temperature of water column by CTD sensor 2	TEMPCU02	°C	-
  Salinity	-	Practical salinity of the water body by CTD sensor 1	PSALCU01	-	-
  Salinity, 2	-	Practical salinity of the water body by CTD sensor 2	PSALCU02	-	-
  Oxygen	µmol kg-1	Dissolved oxygen concentration	DOXYSU01	µmol l-1	Converted from µmol kg-1 to µmol l-1 using sigma-T during transfer
  Fluorescence	mg m-3	Nominal chl-a concentration	CPHLPM01	mg m-3	Manufacturer's calibration applied during processing
  Voltage 4	V	Downwelling sub-surface PAR irradiance	LVLTPD01	V	Only for titanium rig casts shallower than 500m
  Voltage 5	V	Upwelling sub-surface PAR irradiance	LVLTPU01	V	Only for titanium rig casts shallower than 500m
  Voltage 6	V	Transmissometer voltage	TVLTZZ01	V	Titanium rig casts 27 - 35 Stainless steel rig casts 36 - 62
  Voltage 7	V	Transmissometer voltage	TVLTDR01	V	25cm pathlength
  -	-	Practical salinity of the water body by CTD sensor 1 - sample calibrated	PSALCC01	-	PSALCU01 calibrated against bench salinometer data
  -	-	Practical salinity of the water body by CTD sensor 2 - sample calibrated	PSALCC02	-	PSALCU02 calibrated against bench salinometer data
  -	-	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
  -	-	Attenuance	ATTNZZ01	m-1	Wet Labs instrument
  -	-	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 PXF 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.

  Salinity and temperature The secondary temperature and salinity channels were used to aid screening of the primary channels only. The primary channels should be used in preference to the secondary channel as they have been quality controlled.

  Dissolved oxygen Profiles for this sensor looked fine overall. No particular spikes were observed along the profiles. There were possibly features related to water entrainments but they were judged as not very conspicuous and therefore they were not flagged. Specific Casts CTD47: two large spikes present on both sensors, not flagged.

  Attenuance

  CTD Frame Deployment Notes (extracted from the UKORS report) stated there was the usual warm-water hysteresis problem encountered with the Chelsea transmissometers (ATTNDR01) on the cruise. Visual analysis of the profile by BODC confirmed UKORS suspicions: the up- and down-cast profiles often appear very different. The down-cast, however, appears to be more reliable than the up-cast and its profile is often similar to that of the auxiliary Wet Labs transmissometer (ATTNZZ01). For a number of casts (24 to 37 and 46) the Chelsea instrument profiles presents a strange maximum which does not match the more reliable Wet Labs instrument profiles when deployed on the same rig.

  Up and downwelling PAR sensor voltages The UKORS report mentions that the PAR sensors were mounted on the titanium casts. The UKORS notes/data files, however, did not specify the units and data types for a number of the voltage channels for the sensors present on the titanium casts. Therefore the irradiance parameters were attributed to these channels provisionally. Analysis of PAR profiles shows that in numerous casts the channel attributed to up-welling irradiance are larger than down-welling irradiance below the euphotic zone. Therefore the validity of these data are unclear. The sensors were removed for casts deeper than 500m. Specific Cast details CTD10: down-welling very noisy at top. CTD14: up-welling some large spikes flagged below euphotic zone. Down-welling noisy on bottom and flagged. CTD17: upwelling with large spikes in lower part causing shift in signal flagged. Data in down-welling channel are all zero. CTD19 downwelling strange large spikes between 150-180 m not flagged CTD21 downwelling strange large spikes between 220-270 m not flagged CTD33, 35, 37 and 39: suspicious upwelling profile. CTD45 and 46: channels are both zero. CTD48, 50, 52 and 56: downwelling very noisy at the bottom, not flagged.

• Banking

  Once quality control screening was complete, the data were binned against pressure at 1 dbar increments. The intermediate channels, voltages and secondary channels were dropped to produce the final parameter set. Finally, the CTD downcasts were banked following BODC procedures.

Voltage conversions

• PAR sub-surface irradiance

  The PAR sensor calibration coefficients are not available and raw voltages have not been converted to PAR irradiance values.

• Attenuance

  The Chelsea transmissometer raw voltages have been not been converted to attenuance values because the serial number for each sensor could not be confirmed to match to a calibation certificate and calibration coefficients.

  The Wet Lab tranmissometer voltages were converted following the calibration sheet method:

  Attenuance = - 1 / 0.25 * ln (( voltage - 0.061) / (4.718 - 0.061))

  Sensor s/n	Calibration	BODC cal ref
  113R	ATTNDR01 = -1 / 0.25 * ln (TVLTDR01 * 0.2147 - 0.0131)	6273

Field Calibrations

• Temperature

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

• Salinity

  Bench salinometer data were provided by UKORS. The salinometer data was compared with CTD values from the primary and secondary sensor of the stainless steel and titanium casts on the up-cast at the time of bottle firing.

  Casts	Calibration	N	R2	BODC cal ref
  Stainless steel	PSALCC01 = PSALCU01 + 0.0030 (± 0.0052)	40	-	6168
  Stainless steel	PSALCC02 = PSALCU02 + 0.0008 (± 0.0063)	37	-	6169
  Titanium	PSALCC01 = PSALCU01 + 0.0170 (± 0.0212)	46	-	6185
  Titanium	PSALCC02 = PSALCU02 + 0.0160 (± 0.0209)	46	-	6186

• Dissolved oxygen

  The oxygen sensors from each rig were calibrated using dissolved oxygen data measured with Winkler titration from discrete bottle samples compared to the measurements from the sensor on each rig from the up cast at the time of bottle firing. Analysis showed a linear relationship with the offset for each CTD rig type and the calibration equations were applied through the BODC calibration form.

  Casts	Calibration	N	R2	BODC cal ref
  Stainless steel	DOXYSC01 = 1.0661 * DOXYSU01 + 1.8543	211	0.9957	6166
  Titanium	DOXYSC01 = 1.0132 * DOXYSU01 + 6.6963	133	0.9940	6167

• Fluorescence

  The fluorometer was calibrated using extracted chlorophyll-a data from CTD bottle samples and the nominal chlorophyll-a values derived from the fluorometer voltages from the up cast at the point when the bottle was fired. Water samples (300-500 ml) from CTD bottles were filtered on 25 mm GFF filters. Filters were extracted in 90% acetone for 24 hrs and total chlorophyll-a measured with a TD-700 Turner Designs fluorometer following the procedure of Welschmeyer (1994), which minimises interference by chlorophyll-b. The fluorometer was calibrated with dilutions of a solution of pure chlorophyll-a (Sigma, UK) in 90% acetone, the concentration of which was determined spectrophotometrically after the cruise. The casts were split into 3 regions for calibration.

  Stainless steel rig

  Casts	Calibration	N	R2	BODC cal ref
  1 - 21	CPHLPS01 = 1.6909 * CPHLPM01 - 0.0061	66	0.7753	6176
  22 - 37	CPHLPS01 = 2.1441 * CPHLPM01 + 0.0054	40	0.7453	6177
  38 - 62	CPHLPS01 = 1.3033 * CPHLPM01 + 0.0001	75	0.8844	6178

  Titanium rig

  Casts	Calibration	N	R2	BODC cal ref
  1 - 21	CPHLPS01 = 2.7755 * CPHLPM01 + 0.0214	29	0.8388	6179
  22 - 37	CPHLPS01 = 2.8629 * CPHLPM01 + 0.0487	34	0.8173	6180
  38 - 62	CPHLPS01 = 1.5451 * CPHLPM01 + 0.0368	49	0.9037	6181

Project Information

The Atlantic Meridional Transect - Phase 2 (2002-2006)

Who was involved in the project?

The Atlantic Meridional Transect Phase 2 was designed by and implemented by a number of UK research centres and universities. The programme was hosted by Plymouth Marine Laboratory in collaboration with the National Oceanography Centre, Southampton. The universities involved were:

• University of Liverpool
• University of Newcastle
• University of Plymouth
• University of Southampton
• University of East Anglia

What was the project about?

AMT began in 1995, with scientific aims to assess mesoscale to basin scale phytoplankton processes, the functional interpretation of bio-optical signatures and the seasonal, regional and latitudinal variations in mesozooplankton dynamics. In 2002, when the programme restarted, the scientific aims were broadened to address a suite of cross-disciplinary questions concerning ocean plankton ecology and biogeochemistry and the links to atmospheric processes.

The objectives included the determination of:

• how the structure, functional properties and trophic status of the major planktonic ecosystems vary in space and time
• how physical processes control the rates of nutrient supply to the planktonic ecosystem
• how atmosphere-ocean exchange and photo-degradation influence the formation and fate of organic matter

The data were collected with the aim of being distributed for use in the development of models to describe the interactions between the global climate system and ocean biogeochemistry.

When was the project active?

The second phase of funding allowed the project to continue for the period 2002 to 2006 and consisted of six research cruises. The first phase of the AMT programme ran from 1995 to 2000.

Brief summary of the project fieldwork/data

The fieldwork on the first three cruises was carried out along transects from the UK to the Falkland Islands in September and from the Falkland Islands to the UK in April. The last three cruises followed a cruise track between the UK and South Africa, only deviating from the traditional transect in the southern hemisphere. During this phase the research cruises sampled further into the centre of the North and South Atlantic Ocean and also along the north-west coast of Africa where upwelled nutrient rich water is known to provide a significant source of climatically important gases.

Who funded the project?

Natural Environment Research Council (NERC)

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: