Metadata Report for BODC Series Reference Number 541914


Metadata Summary

Data Description

Data Category Water column chemistry
Instrument Type
NameCategories
EnviroTech LLC NAS-2E Nutrient Analyser  nutrient analysers
Instrument Mounting subsurface mooring
Originating Country United Kingdom
Originator -
Originating Organization Dunstaffnage Marine Laboratory (now Scottish Association for Marine Science)
Processing Status banked
Project(s) Provess
 

Data Identifiers

Originator's Identifier nas1714_798
BODC Series Reference 541914
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1998-09-09 10:08
End Time (yyyy-mm-dd hh:mm) 1998-10-26 14:08
Nominal Cycle Interval 7200.0 seconds
 

Spatial Co-ordinates

Latitude 59.32280 N ( 59° 19.4' N )
Longitude 1.01080 E ( 1° 0.6' E )
Positional Uncertainty 0.1 to 0.5 n.miles
Minimum Sensor Depth 1.0 m
Maximum Sensor Depth 1.0 m
Minimum Sensor Height 110.0 m
Maximum Sensor Height 110.0 m
Sea Floor Depth 111.0 m
Sensor Distribution Sensor fixed, measurements made at fixed depths - The sensor is at a fixed depth, but measurements are made remotely from the sensor over a range of depths (e.g. ADCP measurements)
Sensor Depth Datum Sea floor reference - Depth measured as a height above sea floor but converted into a depth relative to the sea surface according to the same datum as used for sea floor depth (applicable to instrument depths not bathymetric depths)
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
 

Parameters

BODC CODE Rank Units Short Title Title
AADYAA01 1 Days Date(Loch_Day) Date (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ01 1 Days Time(Day_Fract) Time (time between 00:00 UT and timestamp)
NTRZNS01 1 Micromoles per litre NO3+NO2_Unfilt_Colin-Situ Concentration of nitrate+nitrite {NO3+NO2} per unit volume of the water body [dissolved plus reactive particulate phase] by in-situ nutrient analysis system
 

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 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

NAS-2E in situ Nutrient Analyser

The NAS-2E in situ Nutrient Analyser is a submersible instrument for the automated measurement of dissolved nutrient concentrations in marine and fresh waters. It employs colorimetric wet-chemistry to determine nutrient concentrations by measuring the light absorbance of a coloured dye produced by a chemical reaction. The instrument, manufactured by WS Ocean Systems Ltd., Hans, UK, is designed for deployment on moorings. Versions have been developed for nitrate+nitrite, phosphate and silicate. The use of standard wet-chemistry techniques ensure comparability with laboratory results.

References for manufacturer's standard chemical methods are:

although these may be altered by the user.

The system utilizes a syringe pump and rotary valve to acquire and react discrete water samples. For nitrate+nitrite analysis, the samples is first passed over a copper-cadmium column to reduce nitrate to nitrite before reacting with the reagents to form the dye. Once the reaction takes place the sample is injected into the colorimeter where optical beam attenuation is measured. An integral system controller drives the syringe and valve via stepper motors and records the colorimeter readings.

The analysis routines include blank measurements for turbidity and optical fouling. An on-board calibration standard is periodically analysed to ensure the continuous integrity of the results. Programmable controls allows the operator to develop and program alternative chemical routines. All raw data are recorded as voltages representing beam transmission through the sample within the colorimeter pathlength. Following recovery of the instrument, raw data are downloaded to a PC and converted to absorbance units and nutrient concentration using manufacturer's calibration and on- board blank and standard readings.

Manufacturer's specification:

Wavelength 560 nm 880 nm
Accuracy 2% of range 5% of range
Sensitivity 0.5% of range 2.5% of range

Level of detection (PL = colorimeter path length):

Nitrate (µM) 0-300 with 5 mm PL
  0-60 with 10 mm PL
  0-10 with 20 mm PL
  0-5 with 40 mm PL
Silicate (µM) 0-60 with 10 mm PL
  0-10 with 20 mm PL
Phosphate (µM) 0-3 with 20 mm PL
  0-1 with 40 mm PL

Data Processing Notes

Data processing was carried out at the Dunstaffnage Marine Laboratory, Oban, UK. The instrument voltages were corrected for blank readings and converted to absorption according to the formula:

[Absorbance] = log 10 ([blank voltage]/[sample voltage])

Absorption readings were then converted to concentrations by calibration against calibration samples from an on-board standard taken every 6 samples during the deployment according to the formula:

[Concentration, µM] = [sample absorbance]/([standard absorbance]*[standard concentration, µM])

The on-board standard concentration was 10 µM of nitrite.

General Data Screening carried out by BODC

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

Documents are written by BODC highlighting irregularities which cannot be resolved.

Data cycles are inspected using time or depth series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value; the data values will not be altered.

The following types of irregularity, each relying on visual detection in the plot, are amongst those which may be flagged as suspect:

If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as the following:

This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.


Project Information

PROcesses of Vertical Exchange in Shelf Seas (PROVESS)

Introduction

PROVESS was an interdisciplinary study of the vertical fluxes of properties through the water column and the surface and bottom boundary layers. The project was funded by the European Community MAST-III programme (MAS3-CT97- 0159) and ran from March 1998 to May 2001.

Scientific Rationale

PROVESS was based on the integration of experimental, theoretical and modelling studies with the aim of improving understanding and quantification of vertical exchange processes in the water column, in particular in the surface and benthic boundary layers and across the> pycnocline. PROVESS also explored mechanisms of physical-biological coupling in which vertical exchanges and turbulence significantly affect the environmental conditions experienced by the biota with particular reference to aggregation, flocculation, sedimentation and trophic interactions.

Fieldwork

The experimental phase of the project was carried out at two contrasting sites in the North Sea: the northern North Sea site (NNS) and the southern North Sea site (SNS).

The two sites had the following characteristics:

SNS NNS
Position 52° 15.0' N, 4° 17.0' E 59° 20.0' E, 1° 00.0' E
Time of year April-May September-November
Water depth (m) 16 100
M2 max amplitude (m s-1) 0.75 0.15
Max current (m s-1) 1.0 0.6
Delta T (deg C) mixed 7-1
Thermocline depth (m) mixed 35-100
Delta S 1 small
Halocline depth (m) 5-10 cf. thermocline depth
Max wind speed (m s-1) 20 25
Max wave height (m) 5 10
Max wave period (s) 8 10
Internal motion No Yes
Sediment muddy-sand muddy-sand
Biology eutrophic oligotrophic

At both locations measurements were concentrated at a central position with additional measurements being made to estimate horizontal gradients. Moored instruments (including current meters, temperature and pressure sensors, fluorometers, transmissometers, nutrient analysers and meteorological sensors) were deployed between 7 September and 5 November 1998 at the NNS and between 29 March and 25 May 1999 at the SNS. Each experiment was supported by intensive measurement series made from oceanographic ships and involving turbulence dissipation profiler CTD, particle size profilers, optical profilers, benthic sampling and water bottle sampling.

Details of the cruises were as follows:

Site Ship
(nationality)
Cruise
Mnemonic
Date
NNS Valdivia (GER) VA174 5 - 17 Sep 1998
  Dana (DK) D1198 14 - 26 Oct 1998
  Pelagia (NL) PE125 19 - 30 Oct 1998
  Challenger (UK) CH140 22 Oct - 9 Nov 1998
SNS Pelagia (NL) PE135 29 Mar - 9 Apr 1999
  Mitra (NL) MT0499 19 - 30 Apr 1999
  Belgica (BE) BG9912 17 - 21 May 1999

Data Activity or Cruise Information

Data Activity

Start Date (yyyy-mm-dd) 1998-09-09
End Date (yyyy-mm-dd) 1998-10-26
Organization Undertaking ActivityProudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Country of OrganizationUnited Kingdom
Originator's Data Activity IdentifierPOLRIG#798
Platform Categorysubsurface mooring

PROVESS Project POLRIG#798

This mooring was also known within PROVESS as 'Rig I'. It was one of a cluster of moorings deployed at the main focus of the Northern North Sea Site in the autumn of 1998. The rig was deployed by FS Valdivia (cruise #174) in September 1998 and recovered by RRS Challenger (cruise #140) in October/November 1998.

Mooring type Surface environmental mooring with 1.9 m toroid
Instruments TRB2 transmissometer 1 m below surface
DML fluorometer 1 m below surface
NAS nitrate analyser 1 m below surface
NIOZ fluorometer 15 m below surface

Other Series linked to this Data Activity - 541963 524204 541951

Cruise

Cruise Name VLD174 (PROVESS N-1)
Departure Date 1998-09-05
Arrival Date 1998-09-17
Principal Scientist(s)Gunther Krause (Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research)
Ship FS Valdivia

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NamePROVESS Northern North Sea Site
CategoryOffshore area
Latitude59° 18.00' N
Longitude1° 0.00' E
Water depth below MSL110.0 m

PROVESS Northern North Sea Site

Nineteen mooring packages were deployed at PROVESS Northern North Sea site during the cruise Valdivia VA174 in September 1998. The layout of the mooring assemblage was L-shaped. It consisted of an heavily-instrumented site centred close to 59° 20' N, 1° 00'E (Site A with rigs A, B, Ca/b, D, E, Fa/b, G, H, I, J1, J2 and L) and secondary single-rig sites extending up to 40 km north (V and Y) and east (U and X). An addition mooring package, NIOZ or Rig M, was also deployed at Site A during the RV Pelagia PE125 cruise in October 1998.

Rigs Ca/b and Fa/b were two short-term rigs which were recovered at the end of the cruise VA174 and redeployed during the cruise Challenger CH140 in October. All the other rigs were recovered during the cruise CH140 in October-November 1998 apart from rigs H and L which could not be found and rig Cb which was trawled and recovered from Peterhead (Scotland).

The layout of the mooring array was:

BODC image

Mooring data

The data returned from each rig were as follows:

Rig identifier Data
A POLRIG#790 ADCP currents
Water level
Near-bed temperature
B POLRIG#791 ADCP currents
Near-bed temperature
Ca POLRIG#792 Near-bed temperature
Cb POLRIG#808 Rig trawled, no data returned
D POLRIG#793 Currents
Temperature, salinity and attenuance
E POLRIG#794 Currents
Fa POLRIG#795 Currents
Fb POLRIG#809
NIOZ Unknown Thermistor chain
G POLRIG#796 Meteorology
H POLRIG#797 Mooring lost, no data returned
I POLRIG#798 Surface attenuance, nutrients and chlorophyll
J1 POLRIG#799 Mid-water attenuance, nutrients and chlorophyll
J2 POLRIG#800 Near-bed attenuance, nutrients and chlorophyll
L POLRIG#801 Mooring lost, no data returned
R POLRIG#802 Water column temperature
S POLRIG#803 Water column temperature
U POLRIG#804 ADCP currents
Water level
Near-bed temperature
V POLRIG#805 ADCP currents
Near-bed temperature
X POLRIG#806 Water level
Y POLRIG#807

CTD data

A total of 352 CTD casts were also collected during the four cruises surveying this area. These include:

Cruise identifier Cruise dates No. of CTD casts
FS Valdivia (#174) 05 September - 17 September 1998 168
Dana (#1198) 14 October - 26 October 1998 51
RV Pelagia (#125) 19 October - 30 October 1998 73
RRS Challenger (#140) 21 October - 11 November 1998 60

Additonal data

Complementary meteorological and sea state data for PROVESS Northern North Sea Experiment were obtained from Marine Weather Stations located on Beryl and Frigg oil platforms in the Northern North Sea.

Other Series linked to this Fixed Station for this cruise - 517613 517625 517637 517649 517650 517662 517674 517686 517698 517705 517717 517729 517730 517742 517754 517766 518087 518099 518106 518118 524173 524185 524197 524204 524751 524763 524775 524799 524923 524935 524947 524959 529208 529221 529233 541883 541951 541963 541975 541987 553128

Other Cruises linked to this Fixed Station (with the number of series) - CH140 (PROVESS N-4) (2) PE125 (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

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