Expendable bathythermograph (XBT)

Topics

• Access
• Description
• Parameters
• Coverage, spatial and temporal resolution
• Data quality
• Contact person
• References
• Data citation and License

Access

UNRESTRICTED:

• Get XPT data in ASCII format via FTP

RESTRICTED: This link to the data set is only available for a restricted user group.  The data set is only accessible in CEN/MPI net or accessible from external nets with a customer account.  Please contact ICDC if you would like to access this data from outside the network.

• Data access via file system: /data/icdc/ocean/xbt

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Description

Expendable bathyhermograph (XBT) measures temperature down to the depth of about 800 m from a moving ship. Since the late 1960s XBTs contributed the majority of the subsurface temperature measurements in the ocean. However the XBT sample depth is not measured but calculated from the estimated fall-rate. The uncertainties in the fall-rate and the malfunctioning of the acquisition system cause XBT temperatures to be biased. This bias was shown to be comparable in magnitude with the typical decadal-scale temperature variability , so that neglecting this bias can seriously distort our estimates of global ocean climate change. Using original XBT data from the World ocean database WOD09 (Boyer et al., 2009) we provide a data product which includes depth- and temperature-corrected XBT profiles. The correction method is based on the recent study by Gouretski and Reseghetti (2010).

Last update of data set at ICDC: Sep 2012

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Parameters

Parameters of the XBT data set

Name	Unit
Depth	m
Temperature	°C

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Coverage, spatial and temporal resolution

Period and temporal resolution:

• 1997 until 2008
• Daily, different number of profiles of different length obtained during various measurement campaigns.

Coverage and spatial resolution:

• Global (see figure on top of page)
• Spatial resolution: None, sampling along the cruise tracks depends on measurement campaign
• Geographic Latitude: -90°N to 90°N
• Geographic Longitude: 0°E to 360°E
• Dimension: 1 column x 1 row x N measurements along the vertical profile
• Altitude: N depths, vertical profiles

Format:

• ASCII

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Data quality

See Gouretski and Reseghetti, 2010 in references.

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Contact

Stefan Kern
ICDC / CEN / University of Hamburg
E-Mail: stefan.kern"AT"uni-hamburg.de

Remon Sadikni
ICDC / CEN / University of Hamburg
E-Mail: remon.sadikni"AT"uni-hamburg.de

Annika Jahnke-Bornemann
ICDC / CEN / University of Hamburg
E-Mail: annika.jahnke-bornemann"AT"uni-hamburg.de

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References

Literature:

• Viktor Gouretski, Franco Reseghetti, On depth and temperature biases in bathythermograph data: Development of a new correction scheme based on analysis of a global ocean database, Deep Sea Research Part I: Oceanographic Research Papers,
  Vol. 57 (6), 2010, p. 812-833, https://doi.org/10.1016/j.dsr.2010.03.011.
• Viktor Gouretski, Using GEBCO digital bathymetry to infer depth biases in the XBT data, Deep Sea Research Part I: Oceanographic Research Papers, Vol. 62, 2012, p. 40-52, https://doi.org/10.1016/j.dsr.2011.12.012.
• T. P. Boyer, J. I. Antonov, O. K. Baranova, H. E. Garcia, D. R. Johnson, R. A. Locarnini, A. V. Mishonov, T. D. O’Brien, D. Seidov, I. V. Smolyar, M. M. Zweng, 2009: World Ocean Database 2009, Chapter 1: Introduction, NOAA Atlas NESDIS 66, Ed. S. Levitus, U.S. Gov. Printing Office, Wash., D.C., 216 pp., DVD.  (pdf, not barrier-free)
• Cheng, L., H. Luo, T. Boyer, R. Cowley, J. Abraham, V. Gouretski, F. Reseghetti, and J. Zhu (2018). How well can we correct systematic errors in historical XBT data? J. Atmos. Ocean. Technol., 35(5), doi:10.1175/JTECH-D-17-0122.1. https://doi.org/10.1175/JTECH-D-17-0122.1

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Data citation, License, and Acknowledgments

Please cite the data as follows:

Gouretski, V., 2012: Expendable bathyhermograph (XBT) data set, provided by ICDC, CEN, University of Hamburg, Hamburg, Germany.

License

The data was published under the Creative Commons Attribution 4.0 International License (CC-BY-4.0).

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