Metadata Report for BODC Series Reference Number 1222880

• 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

RRS James Clark Ross AMT5 (JR23) Meteorological Data Quality Report

Data quality report

Users should be cautious when using ship-borne wind measurements. Although the relative wind data have been corrected for ship's heading and speed, they are still sensitive to shielding effects. Users can consult the ship's E-W and N-S speed alongside the wind speed and direction.

According to the cruise report, the Kipp and Zonen CM-10 pyranometer was installed on the first stage island of the JCR foremast. The instrument was not mounted on gimbals and suffered from shading by the foremast. The data may also be affected by reflection that may occur from the white paint of the mast structure. This effect is difficult to correct for (cruise report p17).

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

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.

Vector Instruments cup anemometer

Instrument used to measure wind speed. The model is unknown. It is assumed to consist of a 3-cup rotor, a precision ball-race mounted shaft and internal modules and components to provide electrical output signals. The outline and mechanical design of Vector Instruments cup anemometers, common to the A100 series, has remained largely unchanged since the introduction of the original Porton Anemometer in 1972.

Vector Instruments wind vane

Instrument used to measure wind direction. The model is unknown. It is assumed to consist of a free-rotating fin that is mounted on a shaft and internal modules and components to provide electrical output signals.

Didcot DRP-1 PAR sensor

Instrument used to measure the photosynthetically active radiation spectral range of solar radiation. It is assumed to have a spectral response of 400-700nm. It could have any type of collector (flat plate cosine collector, spherical or hemispherical).

Trimble 4000DS Global Positioning System receiver

The Trimble 4000DS Differential Surveyor is similar to the 4000RS (a Maxwell-based receiver that is oriented toward precision positioning applications. It is intended for use as a DGPS base station, generating RTCM-104 corrections). The 4000Ds can apply RTCM-104 corrections to the satellite data it receives in order to generate accurate position fixes in real time.

RRS James Clark Ross AMT5 (JR23) Meteorological Instrumentation

The instrumentation has been collated from various sources as historic notation of instrumentation was not well maintained. Care may be required if making assumptions based on the instruments used.

The following instruments were used for meteorological measurements:

N.BA Kipp & Zonen CM10 was mentioned in the cruise report but it is unclear if this replaced the CM5 used on other cruises and why it was replaced for one cruise.

RRS James Clark Ross AMT5 (JR23) Meteorological Data Processing Document

Originator's Data Processing

Raw data were logged as ADC counts on the ship's computers. They were converted into engineering units using initial manufacturers' calibrations.

The data were submitted to BODC in RVS internal format for post-cruise processing and data banking.

BODC Data Processing

Reformatting

Underway data files were merged into a single binary merge file using time as the primary linking key. The time span of the file was from 14/09/1997 04:00:00 to 17/10/1997 13:13:00, with a sampling interval of 30 seconds.

Screening

Each data channel was inspected on a graphics workstation and any spikes or periods of dubious data were flagged. The power of the workstation software was used to carry out comparative screening checks between channels by overlaying data channels. A map of the cruise track was simultaneously displayed in order to take account of the oceanographic context.

Data processing, correction and calibration

Relative wind speed and direction were logged from the meteorological package during the cruise. The ship's speed and heading channels were used with the relative wind data to produce absolute wind speed and direction.

Data quality report

Users should be cautious when using ship-borne wind measurements. Although the relative wind data have been corrected for ship's heading and speed, they are still sensitive to shielding effects. Users can consult the ship's E-W and N-S speed alongside the wind speed and direction.

According to the cruise report, the Kipp and Zonen CM-10 pyranometer was installed on the first stage island of the JCR foremast. The instrument was not mounted on gimbals and suffered from shading by the foremast. The data may also be affected by reflection that may occur from the white paint of the mast structure. This effect is difficult to correct for (cruise report p17).

Institute of Oceanographic Sciences (IOS) Psychrometer

A psychrometer is a meteorological instrument that measures wet and dry bulb temperatures in moving air. These psychrometers were used by the Institute of Oceanographic Sciences, though no information on the specifications of the instrument remain.

There were two platinum resistance elements, each of which had its own separate interface. The change in value of the resistance elements, with respect to temperature, controlled the output frequency of the interface oscillator. In an Air Temperature sensor there is only one element and requires only one interface circuit.

Limited information could be found regarding the specification of the IOS psychrometer. Some information was found in a document (with a focus on circuitry).

Vaisala PA11 Digital Barometer

This barometer was discontinued in the 20th Century and little information remains. Information was requested from Vaisala who managed to supply a PA11A digital barometer brochure. One would expect the information in the brochure to not be too dissimilar to that expected of the PA11.

Project Information

The Atlantic Meridional Transect (AMT) - Phase 1 (1995-2000)

Who was involved in the project?

The Atlantic Meridional Transect (AMT) programme was designed by and implemented as a collaboration between Plymouth Marine Laboratory (PML) and Southampton Oceanography Centre (SOC). The programme was hosted by Plymouth Marine Laboratory and involved additional researchers from UK and international universities throughout its duration.

What was the project about?

When AMT began in 1995 the programme provided a platform for international scientific collaboration, including the calibration and validation of SeaWiFs measurements and products. The programme provided an exceptional opportunity for nationally and internationally driven collaborative research and provided a platform for excellent multi-disciplinary oceanographic research. As an in situ observation system, the data collected by the AMT consortium informed on changes in biodiversity and function of the Atlantic ecosystem during this period of rapid change to our climate and biosphere.

The scientific aims were to assess:

• mesoscale to basin scale phytoplankton processes
• the functional interpretation of bio-optical signatures
• the seasonal, regional and latitudinal variations in mesozooplankton dynamics

When was the project active?

The first phase of the AMT programme ran from 1995 to 2000 and consisted of a total of 12 cruises. A second phase of funding allowed the project to continue for the period 2002 to 2006 with a further 6 cruises.

Brief summary of the project fieldwork/data

The AMT programme undertook biological, chemical and physical oceanographic research during the annual return passage of the RRS James Clark Ross between the UK and the Falkland Islands or the RRS Discovery between the UK and Cape Town, a distance of up to 13,500 km. This transect crossed a range of ecosystems from sub-polar to tropical and from euphotic shelf seas and upwelling systems to oligotrophic mid-ocean gyres. The transect route was covered north-south in September/October and south-north in April/May of each year.

The measurements of hydrographic and bio-optical properties, plankton community structure and primary production completed on the first 12 transects (1995-2000) represent the most coherent set of repeated biogeochemical observations over ocean basin scales. This unique dataset has led to several important discoveries concerning the identification of oceanic provinces, validation of ocean colour algorithms, distributions of picoplankton, identifying new regional sinks of pCO2 and variability in rates of primary production and respiration.

Who funded the project?

The programme was funded by the Natural Environment Research Council (NERC) and further support was received from the National Aeronautics and Space Administration (NASA) with equipment and funding from the Sea-viewing Wild Field-of-view Sensor (SeaWiFS) project.

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: