Metadata Report for BODC Series Reference Number 808717

• 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

RAPID Cruise D279 Underway Meteorology Data Quality Report

Solar radiation

Data from the port channel are more reliable than from the starboard. It is thought that the starboard sensor was suffering from ingress of moisture during the cruise. This caused it to log large readings, even at night. The decision was made not to merge port and starboard sensor data due to this fault.

The starboard sensor was stable for the first part of the cruise, but was particularly unreliable during the following periods: 15 April 15:00 to 19 April 10:30; 25 April 05:00 to 18:30; 26 April 17:30 until the end of the cruise. The sensor cables between port and starboard sensors were swapped on 25 April at 18:30 until 17:30 the following day. Data from the port sensor were noticeable more noisy during this period.

Data from the starboard sensor have been flagged during periods when the port sensor is reading zero, ie at night. In addition, any values over 2000 have been flagged N (Null) as these are well outside the limits of natural variability. However, the user should be aware that the remaining unflagged data may also be suspect and should be used with caution. During periods when the starboard sensor was stable and in good agreement with the port sensor, it was used as a screening aid so that drops in the port signal were flagged if the starboard signal was strong, indicating shadows on the port side.

Wind speed and direction

Although wind data were corrected to remove the effects of ship movement, there are residual effects still present in the data. Where obvious, these have been flagged suspect.

Data Access Policy

Open 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.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

Narrative Documents

Vaisala Analog Barometers Models PTB100 (A), (B) and PTB101 (B), (C)

The PTB 100 series analog barometers are designed both for accurate barometric measurements at room temperature and for general environmental pressure monitoring over a wide temperature range. The long-term stability of the barometer minimizes the need for field adjustment in many applications.

Physical Specifications

The barometers use the BAROCAP^* silicon capacitive absolute pressure sensor developed by Vaisala for barometric pressure measurements. The BAROCAP^* sensor combines the elasticity characteristics and mechanical stability of a single-crystal silicon with the proven capacitive detection principle.

Sensor Specifications

^* BAROCAP is a registered trademark of Vaisala

Vaisala Temperature and Relative Humidity HMP Sensors

A family of sensors and instruments (sensors plus integral displays or loggers) for the measurement of air temperature and relative humidity. All are based on a probe containing a patent (HUMICAP) capacitive thin polymer film capacitanece humidity sensor and a Pt100 platinum resistance thermometer. The probes are available with a wide range of packaging, cabling and interface options all of which have designations of the form HMPnn or HMPnnn such as HMP45 and HMP230. Vaisala sensors are incorporated into weather stations and marketed by Campbell Scientific.

All versions operate at up to 100% humidity. Operating temperature ranges vary between models, allowing users to select the version best suited to their requirements.

Further details can be found in the manufacturer's specification sheets for the HMP 45 series, HMP 70 series and HMP 230 series.

Vaisala WA15 Wind Set

The WAA151 combines a WAA151 anemometer and a WAV151 wind vane, to measure wind speed and direction.

WAA151 Anemometer

The anemometer has three lightweight conical cups in the cup wheel. A wind-rotated chopper disc, attached to the cup wheel's shaft, cuts an infrared light beam 14 times per revolution, generating a pulse output from a phototransistor. The output rate can be regarded as directly proportional to the wind speed. However, for the best accuracy, a transfer function is used to compensate starting inertia and slight over-speeding:

U_f = 0.328 + 0.101 x R, where U_f = wind speed and R = output pulse rate

A thermostatically controlled heating element in the shaft tunnel prevents the bearings from freezing in cold environments.

WAV151 Wind Vane

The WAV151 is a counter-balanced optelectronic wind vane. Infrared LEDs and phototransistors are mounted in six orbits around a 6 bit Gray coded disc. Turned by the vane, the disc determines the code received by the phototransistors.

Specifications

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

Didcot Cosine Photosynthetically Available Radiation (PAR) sensors

The silicon cell, blue glass filter and diffuser are bond together using optically clear adhesive, the complete assembly is mounted into the black anodised body and sealed using the same adhesive. The body has a raised rim to provide to provide low angle cosine correction and holes within the rim to provide drainage for surface water which would otherwise affect the instrument's accuracy. Model DRP-5 has an integral clamp to mount on a vertical mast tube, model DRP-5B has round base with three leveling screws and is intended to stand on a flat surface and model DRP-4 has a built in integrator to record total PAR received over a period of time.

Technical Information

RAPID Cruise D279 Underway Meteorology Instrumentation

Meterological data were collected with a Vaisala QLI50 sensor collector (s/n: R381005) using the sensors as detailed in the table below.

RAPID Cruise D279 Underway Meteorology Processing

Originator's processing

Sea surface meteorology measurements were made by the UKORS Surfmet system. Onboard processing was carried out on a daily basis and involved running a sequence of executable programs. The initial stage transferred the underway surfmet data into PSTAR from RVS format. An additional executable was run to determine the true wind speed and direction, taking account of the ship's motion and velocity. Finally, Julian Day time variable data were calculated and the resulting data examined by plotting on a daily and weekly basis.

BODC Processing

Photosynthetically Active Radiation (PAR)

It was discovered during the cruise that the port PAR sensor was, in fact, a solarimeter. As the port and starboard sensors were different types, the data could not be merged to produce the best signal. In addition, the starboard sensor output remains uncalibrated as the sensor serial number (and therefore calibration coefficients), was unknown.

Solar Radiation

The port and starboard data have not been merged due to problems with the starboard sensor.

Wind speed and direction

Wind speed and direction were corrected on board for ship's motion.

RAPID Cruise D279 Underway Meteorology, Surface Hydrography and Navigation Series

Cruise details

D279 travelled from Freeport in the Bahamas across the Atlantic to Tenerife in Spain. After initially focussing on the collection of chemical data from the Florida Current at 27°N, the main focus of the cruise was the collection of hydrographic data across the Atlantic Ocean between approximately 24 and 27.5°N.

It should be noted that the data series supplied by the originator covers 04 April to 08 May 2004, which is less that the duration of the cruise.

Data Processing Procedures

Two minute averaged sea surface hydrographic and meteorological data, together with navigation and bathymetric files, were transferred from PSTAR format into BODC internal format (QXF), using time (UTC) as the primary linking key, to allow use of the in-house visualisation tool (EDSERPLO). Reformatting and data calibration was carried out, and is discussed in the individual instrument sections. Each data channel was visually inspected and any spikes or periods of dubious data flagged as suspect. The capabilities of the workstation screening software allows comparative screening checks between channels.

The qxf file then underwent a further step. This involved using Matlab to split the qxf file into three separate qxf files. One contained data for hydrography, one for meterological data and the final qxf file held the navigation data.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

24.5 degrees N Hydrographic Transatlantic section - A05

The hydrographic transatlantic section at 24.5 degrees North has been occupied 8 times, namely in 1957, 1981, 1992, 1998, 2004, 2010, 2015 and 2020. The section is an attempt to calculate the transports of water and its constituents (heat, salinity, nutrients, biological productivity) along this latitude, and to compare the data so that the degree of change in the North Atlantic transports can be revealed. The Hydrographic Programme of the international World Ocean Circulation Experiment (WOCE) designated this section as A05. Since WOCE, the section occupations contribute to the Global Ocean Ship-Based Hydrographic Investigations Program (GO-SHIP).

Map of stations

The station positions for most of the occupied sections are shown in the above figures. Sections occupied in 1957, 1981, 1992, 1998 and 2004 are shown in the upper figure. The section occupied in 2010 is shown in the lower figure.

The 1957 and 1992 sections each went zonally along 24.5 degrees N from the African coast to the Bahama Islands. Because of diplomatic clearance issues, the 1981, 1998, 2004, 2010 and 2015 sections angled southwestward from the African coast at about 28 degrees N to join the 24.5 degrees N section at about 23 degrees W. The 1998, 2004 and 2010 sections angled northwestward at about 73 degrees W to finish the section along 26.5 degrees N. The 2010 and 2020 sections deviated from the previous sections across the Mid-Atlantic Ridge (MAR) in order to sample the deepest channel and capture the passage of the deep water across the MAR.

Table 1: Occupations of the section

References

Baringer, M. O. N. and R. L. Molinari, 1999. Atlantic Ocean baroclinic heat flux at 24 to 26°N. Geophysical Research Letters, 26, 353-356.

Bryden, H. L., H. R. Longworth, and S. Cunningham, 2005b. Slowing of the Atlantic meridional overturning circulation at 25°N. Nature, 438, 655-657.

Fuglister, F. C., 1960. Atlantic Ocean Atlas of Temperature and Salinity Profiles and Data from the International Geophysical Year of 1957-1958. Vol. 1, Woods Hole Oceanographic Institution Atlas Series, WHOI, Woods Hole, Massachusetts.

King, B. A. et al., 2012. RRS Discovery Cruise 346, 05 Jan-19 Feb 2010. The 2010 transatlantic hydrography section at 24.5N. Southampton, UK, National Oceanography Centre Southampton, 177pp. (National Oceanography Centre Cruise Report, No. 16).

King, B. A. et al., 2016. RRS Discovery Cruise DY040 (RAGNARoCC), 06 Dec 2015 - 22 Jan 2016. The 2015 transatlantic hydrography section at 24.5N. Southampton, UK, National Oceanography Centre Southampton, 159pp. (National Oceanography Centre Cruise Report).

Parilla, G., A.Lavin, H. Bryden, M. Garcia, and R. Millard, 1994. Rising temperatures in the subtropical North Atlantic Ocean over the past 35 years. Nature, 369, 48-51.

Roemmich, D. and C. Wunsch, 1985. Two transatlantic sections: meridional circulation and heat flux in the subtropical North Atlantic Ocean. Deep Sea Research, 32, 619-664.

Sanchez-Franks, A., 2020. RRS James Cook Cruise JC191, 19 January - 1 March 2020. Hydrographic sections from the Florida Straits to the Canaries Current across 24N in the Atlantic Ocean. Southampton, UK, National Oceanography Centre Southampton, 262pp. (National Oceanography Centre Cruise Report, No. 70).

Related Fixed Station activities are detailed in Appendix 1

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:

Appendix 1: 24.5 degrees N Hydrographic Transatlantic section - A05

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

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