Metadata Report for BODC Series Reference Number 946321

• 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

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

Kipp and Zonen CM10/CM11/CM14 pyranometer

General Information

The CM10 is the first release of Kipp and Zonen's secondary standard pyranometer, without sun screen and levelling feet. Later this became standard and the instrument was called CM11.

The pyranometer CM 11 is designed for measuring the irradiance (radiant flux,Watt/m²) on a plane surface, which results from the direct solar radiation and from the diffuse radiation incident from the hemisphere above. Because the CM 11 exhibits no tilt dependence it can measure solar radiation on surfaces inclined as well. In the inverted position reflected solar radiation can be measured.

The albedometer CM14 is based on two CM11 sensors and is suitable for the measurement of net global radiation and/or albedo over surfaces of different nature.

Physical Properties

The pyranometer CM 11 is provided with a thermal detector. This type of detector responds to the total power absorbed and theoretically it is non-selective as to the spectral distribution of the radiation. This implies that the naked thermal detector is also sensitive to long wave infrared radiation (thermal radiation λ > 3000 nm) from the environment. (e.g. the inner dome) The radiant energy is absorbed by a black painted disk. The heat generated flows through a thermal resistance to the heat sink (the pyranometer body). The temperature difference across the thermal resistance of the disk is converted into a voltage. The rise of temperature is easily affected by wind, rain and thermal radiation losses to the environment ('cold' sky). Therefore the detector is shielded by two glass domes. Glass domes allow equal transmitting of the direct solar component for every position of the sun on the celestial sphere. The spectral range of the pyranometer is limited by the transmission of the glass. A desiccator in the body prevents dew on the inner side of the domes, which can cool down considerably, at clear windless nights.

Construction

The sensing element of the pyranometer CM 11 is a black painted ceramic (Al₂O₃) disk. 100 thermocouples forming a thermopile are imprinted on it using thick film techniques. Only the border of the disk is in good thermal contact with the pyranometer body (heat sink), and along this border the 100 cold junctions are located. The 100 hot junctions are near the centre in a rotational symmetric arrangement. This fact plus a proper levelling of the sensor related to the spirit level results in a low azimuth error.

Specifications

Accuracy

Unfortunately the sensitivity is cross-correlated to a number of parameters as temperature, level of irradiance, vector of incidence, etc. The upper limiting values of the resulting sensitivity variations are listed in the specifications. It classifies the pyranometer CM11 as a 'secondary standard' according to the classification of the World Meteorological Organization. Normally, the supplied sensitivity figure is used to calculate the irradiances. If the conditions differ from calibration conditions, errors in the calculated irradiances must be expected. For a secondary standard instrument the WMO expects maximum errors in the hourly radiation totals of 3%. In the daily total an error of 2% is expected, because some response variations cancel out each other if the integration period is long. These errors can be reduced further if the actual sensitivity of the pyranometer is used by the conversion of voltage to irradiance. The actual sensitivity can be calculated when it is a well-known function of simply measured parameters (sometimes called transfer function or sensitivity function). This is especially convenient in connection with a programmable data acquisition system. For the CM11 the effect of each parameter on the sensitivity can be shown separately, because the parameters show less interaction.

More information on the CM10/CM11/CM14 may be found in the Kipp and Zonen CM11/14 manual.

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.

Global Positioning Satellite System

A location system of unspecified make or model that determines location on the Earth's surface using the Global Positioning Satellite Network. Angular co-ordinates are given relative to WGS84 CRS. Other parameters such as platform velocity may be derived from this.

CH119_a Sea surface meteorological instrument details

Meteorological parameters were recorded by a suite of instruments onboard the ship. The PAR meters were recorded as voltages and calibrated to µE m2 by BODC using coefficients determined in February 1990. Instrument details are given in the table below.

CH119_a Sea surface Hydrography, Meteorology and Navigation Series

Instrumentation

Seawater was continuously pumped from the hull of the ship (at a depth of about 4m). This is known as the ship's non-toxic supply. The thermosalinograph was fed through a small (100-litre) header tank. A large plastic tank on the starboard deck was fed directly from the non-toxic manifold and contained the transmissometer and fluorometer. Baffles in the tank ensured that a continuous flow was maintained over the instruments. A selflogging YSI dissolved oxygen probe was also placed in this tank. However, this instrument flooded due to a defective 'O' ring seal and therefore failed to return any useful data.

The nutrient autoanalyser was fed from plastic tubing connected to taps on the non-toxic supply. The electrochemical metal analysers were fed from an all-plastic supply fed from an intake on the port echo sounder fish at approximately 2m depth and driven by a perisaltic pump.

The Endeco dissolved oxygen system electrodes were placed in a Perspex cell (approx. 1 litre volume) supplied from the general non-toxic supply via a constant head device at 2 litres/minute.

Calibration samples were either taken from the non-toxic tap on the wet laboratory sink or the thermosalinograph outlet.

Data Acquisition

For most parameters, data logging and initial processing was handled by the RVS ABC system. The Level A sampling microcomputer digitised an input voltage, applied a time stamp and transferred the data via the Level B disk buffer onto the Level C where the data records were assembled into files. Note that the autoanalyser was included in this arrangement by logging voltages supplied to the instrument chart recorder.

Exceptions to this rule were the electrochemical metal analysers and Endeco dissolved oxygen system, which were logged by dedicated PCs. Sampling rates varied from 10 seconds to 10 minutes. Careful attention was paid to the synchronisation of the PC and logger clocks to the master clock used by the ABC system.

The Level C included a suite of calibration software, which was used to apply initial calibrations to convert raw ADC counts into engineering units. At the end of the cruise the Level C disk base was transferred to BODC for further processing. PC logged data were supplied to BODC on floppy disk for merging with the data from the ship's system.

Meteorology Processing Notes

Photosynthetically Active Radiation (PAR)

Photosynthetically available irradiation was measured using PML 2π PAR sensors mounted on gimballed supports on each side of the ship's monkey island. The starboard location was far from ideal due to a large satellite communication radome, which frequently shaded the instruments. The mountings also included Kipp and Zonen solar radiation meters.

The PAR meters were recorded as voltages and calibrated to µE m^-2 s^-1 by BODC using coefficients determined in February 1990. The calibration equations used were:

Note that the 0.0375 in the calibration equation is an empirical conversion from mW cm^-2 to µE m^-2 s^-1. Consequently, the data may be converted to W m^-2 if desired by dividing by 3.75.

After spikes had been flagged out, a merged PAR channel was produced by taking the maximum of the port and starboard values to eliminate shading effects.

The Kipp and Zonen instruments on Challenger are unique in as much as they are connected to a data integrator. This converted the instrument voltages into W/m² and integrated the values to produce 10 minute and running total integrations in kJ/m². The output from the integrator was logged by a Level A at the end of each integration period.

At BODC, the 10 minute integrations were merged into the underway file by a custom program that divided the integrated energy by the integration interval to give an averaged irradiance value. The time stamp was also adjusted to the mid-point of the averaging interval by subtracting 5 minutes.

Solar Radiation

A merged solar radiation channel was produced, after spikes were flagged out, by taking the maximum of the port and starboard values to eliminate shading effects.

Project Information

LOIS River-Atmosphere-Coast Study (LOIS - RACS)

Introduction

The Land-Ocean Interaction Study (LOIS) was a NERC research programme designed to study processes in the coastal zone. The Rivers, Atmosphere and Coasts Study (RACS) was a major component of LOIS that looked at land-sea interactions in the coastal zone and the major exchanges (physical, chemical and biological) between rivers and estuaries and the atmosphere. The study focused on the east coast of the UK from the Wash to the Tweed.

RACS included several sub-components

• BIOTA - A study of salt marshes of the Humber and Wash
• RACS (A) - An atmospheric chemistry study looking at air mass changes from the Wash into East Anglia
• RACS (C) - A study of the estuaries, coasts and coastal waters between Great Yarmouth and Berwick upon Tweed.
  1. The coastal oceangraphic survey
  2. The Humber estuarine study
  3. The Tweed estuarine study
  4. The Holderness experiment
• RACS (R) - A study of rivers that drain into the North Sea

RACS (A) was coordinated by the University of East Anglia and RACS (C) by the Plymouth Marine Laboratory.

RACS (A)

The bulk of the RACS (A) data set was collected during two field campaigns in the winter (October/November) of 1994 and the summer (May/June) of 1995. During these campaigns data were collected continuously from the University of East Anglia Atmospheric Observatory at Weybourne on the north Norfolk coast. An instrumented vessel was stationed offshore to provide a second sampling site to allow changes in a given air mass to be monitored. The Imperial College Jetstream research aircraft made one flight during each campaign to provide a link between the two surface stations. The Jetstream made four additional flights in 1996 and 1997.

RACS (C)

The coastal oceanographic survey

The coastal oceanographic data set was collected during a series of 17 RRS Challenger cruise legs. Most cruises covered two survey grids. One from Great Yarmouth to the Humber designed around the distribution of the sandbanks and a second simple zig-zag grid from the Humber to Berwick on Tweed. A large number of anchor stations, usually over one or two tidal cycles, were worked in the area of the Humber mouth or the Holderness coast.

The Humber estuarine study

The Humber estuarine data set was collected during a series of 33 campaigns on the Environment Agency vessels Sea Vigil and Water Guardian in the Humber, Trent and Ouse river systems at approximately monthly intervals between June 1993 and December 1996. Each campaign consisted of two or three one-day cruises. The tracks covered the estuary from the tidal limits of both Trent and Ouse to Spurn Point. Instrumental and sample data are available from a series of fixed stations that were sampled during every campaign.

The Tweed estuarine study

The Tweed estuarine data set was collected during a series of 13 campaigns using RV Tamaris in association with a rigid inflatable vessel at approximately monthly intervals between July 1996 and July 1997. Each campaign covered the tidal reaches of the River Tweed.

The Holderness experiment

The Holderness Experiment was designed to monitor the process of sediment transport along the Holderness coastline. It consisted of three moored instrument deployments during the winters of 1993-1994, 1994-1995 and 1995-1996. Mooring platforms were deployed at eight stations along two lines off the Holderness coast. A northerly and a southerly line of four stations each were used (N1 - N4 and S1 to S4) with the lowest numbers being inshore. Both lines were approximately perpendicular to the coast, although the S4 station lay to the south of the S line, off Spurn Head.

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: