Time, Probe Type, and Temperature Variable Bias Corrections to Historical Expendable Bathythermograph Observations

Lijing Cheng International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, China

Search for other papers by Lijing Cheng in
Current site
Google Scholar
PubMed
Close
,
Jiang Zhu International Center for Climate and Environment Sciences, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, China

Search for other papers by Jiang Zhu in
Current site
Google Scholar
PubMed
Close
,
Rebecca Cowley CSIRO Wealth from Oceans Flagship, and Centre for Australian Weather and Climate Research, Hobart, Tasmania, Australia

Search for other papers by Rebecca Cowley in
Current site
Google Scholar
PubMed
Close
,
Tim Boyer NOAA/National Oceanographic Data Center, Silver Spring, Maryland

Search for other papers by Tim Boyer in
Current site
Google Scholar
PubMed
Close
, and
Susan Wijffels CSIRO Wealth from Oceans Flagship, and Centre for Australian Weather and Climate Research, Hobart, Tasmania, Australia

Search for other papers by Susan Wijffels in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

Systematic biases in historical expendable bathythermograph (XBT) data are examined using two datasets: 4151 XBT–CTD side-by-side pairs from 1967 to 2011 and 218 653 global-scale XBT–CTD pairs (within one month and 1°) extracted from the World Ocean Database 2009 (WOD09) from 1966 to 2010. Using the side-by-side dataset, it was found that both the pure thermal bias and the XBT fall rate (from which the depth of observation is calculated) increase with water temperature. Correlations between the terminal velocity A and deceleration B terms of the fall-rate equation (FRE) and between A and the offset from the surface terms are obtained, with A as the dominant term in XBT fall-rate behavior. To quantify the time variation of the XBT fall-rate and pure temperature biases, global-scale XBT–CTD pairs are used. Based on the results from the two datasets, a new correction scheme for historical XBT data is proposed for nine independent probe-type groups. The scheme includes corrections for both temperature and depth records, which are all variable with calendar year, water temperature, and probe type. The results confirm those found in previous studies: a slowing in fall rate during the 1970s and 2000s and the large pure thermal biases during 1970–85. The performance of nine different correction schemes is compared. After the proposed corrections are applied to the XBT data in the WOD09 dataset, global ocean heat content from 1967 to 2010 is reestimated.

Corresponding author address: Jiang Zhu, Institute of Atmospheric Physics, Chinese Academy of Sciences, P.O. Box 9804, Beijing 100029, China. E-mail: jzhu@mail.iap.ac.cn; chenglij@mail.iap.ac.cn; rebecca.cowley@csiro.au; tim.boyer@noaa.gov; susan.wijffels@csiro.au

Abstract

Systematic biases in historical expendable bathythermograph (XBT) data are examined using two datasets: 4151 XBT–CTD side-by-side pairs from 1967 to 2011 and 218 653 global-scale XBT–CTD pairs (within one month and 1°) extracted from the World Ocean Database 2009 (WOD09) from 1966 to 2010. Using the side-by-side dataset, it was found that both the pure thermal bias and the XBT fall rate (from which the depth of observation is calculated) increase with water temperature. Correlations between the terminal velocity A and deceleration B terms of the fall-rate equation (FRE) and between A and the offset from the surface terms are obtained, with A as the dominant term in XBT fall-rate behavior. To quantify the time variation of the XBT fall-rate and pure temperature biases, global-scale XBT–CTD pairs are used. Based on the results from the two datasets, a new correction scheme for historical XBT data is proposed for nine independent probe-type groups. The scheme includes corrections for both temperature and depth records, which are all variable with calendar year, water temperature, and probe type. The results confirm those found in previous studies: a slowing in fall rate during the 1970s and 2000s and the large pure thermal biases during 1970–85. The performance of nine different correction schemes is compared. After the proposed corrections are applied to the XBT data in the WOD09 dataset, global ocean heat content from 1967 to 2010 is reestimated.

Corresponding author address: Jiang Zhu, Institute of Atmospheric Physics, Chinese Academy of Sciences, P.O. Box 9804, Beijing 100029, China. E-mail: jzhu@mail.iap.ac.cn; chenglij@mail.iap.ac.cn; rebecca.cowley@csiro.au; tim.boyer@noaa.gov; susan.wijffels@csiro.au
Save
  • Abraham, J., Gorman J. , Reseghetti F. , Sparrowa E. , Stark J. , and Shepard T. , 2014: Modeling and numerical simulation of the forces acting on a sphere during early-water entry. Ocean Eng., 76, 19, doi:10.1016/j.oceaneng.2013.11.015.

    • Search Google Scholar
    • Export Citation
  • Anderson, E. R., 1980: Expendable bathythermograph (XBT) accuracy studies. Naval Ocean Systems Center Tech. Rep. 550, 201 pp.

  • Bailey, R., , Gronell, A. , Phillips, H. , Tanner E. , and Meyers G. , 1994: Quality control cookbook for XBT data. CSIRO Marine Laboratories Rep. 221, 83 pp.

  • Biggs, D. C., 1992: Nutrients, plankton, and productivity in a warm-core ring in the western Gulf of Mexico. J. Geophys. Res., 97, 21432154, doi:10.1029/90JC02020.

    • Search Google Scholar
    • Export Citation
  • Boyd, J. D., and Linzell R. S. , 1993: Evaluation of the Sparton tight-tolerance AXBT. J. Atmos. Oceanic Technol., 10, 892899, doi:10.1175/1520-0426(1993)010<0892:EOTSTT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Boyer, T., and Levitus S. , 1994: Quality control and processing of historical oceanographic temperature, salinity and oxygen data. NOAA Tech. Rep. NESDIS 81, 64 pp.

  • Boyer, T., and Coauthors, 2009: World Ocean Database 2009. S. Levitus, Ed., NOAA Atlas NESDIS 66, 216 pp.

  • Cheng, L. J., Zhu J. , Reseghetti F. , and Liu Q. P. , 2011: A new method to estimate the systematical biases of expendable bathythermograph. J. Atmos. Oceanic Technol., 28, 244265, doi:10.1175/2010JTECHO759.1.

    • Search Google Scholar
    • Export Citation
  • Church, J. A., and Coauthors, 2011: Revisiting the Earth’s sea-level and energy budgets from 1961 to 2008. Geophys. Res. Lett., 38, L18601, doi:10.1029/2011GL048794.

    • Search Google Scholar
    • Export Citation
  • Cowley, R., Wijffels S. , Cheng L. , Boyer T. , and Kizu S. , 2013: Biases in expendable bathythermograph data: A new view based on historical side-by-side comparisons. J. Atmos. Oceanic Technol., 30, 11951225, doi:10.1175/JTECH-D-12-00127.1.

    • Search Google Scholar
    • Export Citation
  • DiNezio, P. N., and Goni G. J. , 2011: Direct evidence of a changing fall-rate bias in XBTs manufactured during 1986–2008. J. Atmos. Oceanic Technol., 28, 15691578, doi:10.1175/JTECH-D-11-00017.1.

    • Search Google Scholar
    • Export Citation
  • Domingues, C. M., Church J. A. , White N. J. , Gleckler P. J. , Wijffels S. E. , Barker P. M. , and Dunn J. R. , 2008: Improved estimates of upper-ocean warming and multi-decadal sea-level rise. Nature, 453, 10901096, doi:10.1038/nature07080.

    • Search Google Scholar
    • Export Citation
  • Flierl, G. R., and Robinson A. R. , 1977: XBT measurement of thermal gradients in the MODE eddy. J. Phys. Oceanogr., 7, 300302, doi:10.1175/1520-0485(1977)007<0300:XMOTGI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Good, S. A., 2011: Depth biases in XBT data diagnosed using bathymetry data. J. Atmos. Oceanic Technol., 28, 287300, doi:10.1175/2010JTECHO773.1.

    • Search Google Scholar
    • Export Citation
  • Gouretski, V., 2012: Using GEBCO digital bathymetry to infer depth biases in the XBT data. Deep-Sea Res. I, 62, 4052, doi:10.1016/j.dsr.2011.12.012.

    • Search Google Scholar
    • Export Citation
  • Gouretski, V., and Koltermann K. P. , 2007: How much is the ocean really warming? Geophys. Res. Lett., 34A, L01610, doi:10.1029/2006GL027834.

    • Search Google Scholar
    • Export Citation
  • Gouretski, V., and Reseghetti F. , 2010: On depth and temperature biases in bathythermograph data: Development of a new correction scheme based on analysis of a global ocean database. Deep-Sea Res. I, 57, 812833, doi:10.1016/j.dsr.2010.03.011.

    • Search Google Scholar
    • Export Citation
  • Green, A. W., 1984: Bulk dynamics of the expendable bathythermograph (XBT). Deep-Sea Res., 31A, 415426, doi:10.1016/0198-0149(84)90093-1.

    • Search Google Scholar
    • Export Citation
  • Hallock, Z. R., and Teague W. J. , 1992: The fall rate of the T-7 XBT. J. Atmos. Oceanic Technol., 9, 470483, doi:10.1175/1520-0426(1992)009<0470:TFROTT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Hamon, M., Reverdin G. , and Le Traon P.-Y. , 2012: Empirical correction of XBT data. J. Atmos. Oceanic Technol., 29, 960973, doi:10.1175/JTECH-D-11-00129.1.

    • Search Google Scholar
    • Export Citation
  • Hanawa, K., Rual P. , Bailey R. , Sy A. , and Szabados M. , 1995: A new depth–time equation for Sippican or TSK T-7, T-6 and T-4 expendable bathythermographs (XBT). Deep Sea Res. I, 42, 14231451, doi:10.1016/0967-0637(95)97154-Z.

    • Search Google Scholar
    • Export Citation
  • Heinmiller, R., Ebbesmeyer C. , Taft B. , Olson T. , and Nikitin O. , 1983: Systematic errors in expendable bathythermograph (XBT) profiles. Deep-Sea Res., 30A, 11851197, doi:10.1016/0198-0149(83)90096-1.

    • Search Google Scholar
    • Export Citation
  • Ingleby, B., and Huddleston M. , 2007: Quality control of ocean temperature and salinity profiles—Historical and real-time data. J. Mar. Syst., 65, 158175, doi:10.1016/j.jmarsys.2005.11.019.

    • Search Google Scholar
    • Export Citation
  • Ishii, M., and Kimoto M. , 2009: Reevaluation of historical ocean heat content variations with time-varying XBT and MBT depth bias corrections. J. Oceanogr., 65, 287299, doi:10.1007/s10872-009-0027-7.

    • Search Google Scholar
    • Export Citation
  • Kizu, S., and Hanawa K. , 2002a: Recorder-dependent temperature error of expendable bathythermograph. J. Oceanogr., 58, 469476, doi:10.1023/A:1021261214950.

    • Search Google Scholar
    • Export Citation
  • Kizu, S., and Hanawa K. , 2002b: Start-up transient of XBT measurement. Deep-Sea Res. I, 49, 935940, doi:10.1016/S0967-0637(02)00003-1.

    • Search Google Scholar
    • Export Citation
  • Kizu, S., Ito S. I. , and Watanabe T. , 2005: Inter-manufacturer difference and temperature dependency of the fall-rate of T-5 expendable bathythermograph. J. Oceanogr., 61, 905912, doi:10.1007/s10872-006-0008-z.

    • Search Google Scholar
    • Export Citation
  • Kizu, S., Onishi H. , Suga T. , Hanawa K. , Watanabe T. , and Iwamiya H. , 2008: Evaluation of the fall rates of the present and developmental XCTDs. Deep-Sea Res. I, 55, 571586, doi:10.1016/j.dsr.2007.12.011.

    • Search Google Scholar
    • Export Citation
  • Kizu, S., Sukigara C. , and Hanawa K. , 2011: Comparison of the fall rate and structure of recent T-7 XBT manufactured by Sippican and TSK. Ocean Sci., 7, 231244, doi:10.5194/os-7-231-2011.

    • Search Google Scholar
    • Export Citation
  • Levitus, S., Antonov J. I. , Boyer T. P. , Locarnini R. A. , Garcia H. E. , and Mishonov A. V. , 2009: Global ocean heat content 1955–2008 in light of recently revealed instrumentation problems. Geophys. Res. Lett., 36, L07608, doi:10.1029/2008GL037155.

    • Search Google Scholar
    • Export Citation
  • Levitus, S., and Coauthors, 2012: World Ocean heat content and thermosteric sea level change (0–2000 m), 1955–2010. Geophys. Res. Lett., 39, L10603, doi:10.1029/2012GL051106.

    • Search Google Scholar
    • Export Citation
  • Lyman, J. M., Good S. A. , Gouretski V. V. , Ishii M. , Johnson G. C. , Palmer M. D. , Smith D. M. , and Willis J. K. , 2010: Robust warming of the global upper ocean. Nature, 465, 334337, doi:10.1038/nature09043.

    • Search Google Scholar
    • Export Citation
  • Palmer, M. D., and Haines K. , 2009: Estimating oceanic heat content change using isotherms. J. Climate, 22, 49534969, doi:10.1175/2009JCLI2823.1.

    • Search Google Scholar
    • Export Citation
  • Prater, M. D., 1991: A method for depth and temperature correction of expendable probes. J. Atmos. Oceanic Technol., 8, 888894, doi:10.1175/1520-0426(1991)008<0888:AMFDAT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Reseghetti, F., Borghini M. , and Manzella G. M. R. , 2007: Factors affecting the quality of XBT data—Results of analyses on profiles from the western Mediterranean Sea. Ocean Sci., 3, 5975, doi:10.5194/os-3-59-2007.

    • Search Google Scholar
    • Export Citation
  • Reverdin, G., Marin F. , Bourles B. , and L’Herminier P. , 2009: XBT temperature errors during French research cruises (1999–2007). J. Atmos. Oceanic Technol., 26, 24622473, doi:10.1175/2009JTECHO655.1.

    • Search Google Scholar
    • Export Citation
  • Seaver, G. A., and Kuleshov S. , 1982: Experimental and analytical error of the expendable bathythermograph. J. Phys. Oceanogr., 12, 592600, doi:10.1175/1520-0485(1982)012<0592:EAAEOT>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Singer, J. J., 1990: On the error observed in electronically digitized T-7 XBT data. J. Atmos. Oceanic Technol., 7, 603611, doi:10.1175/1520-0426(1990)007<0603:OTEOIE>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Thadathil, P., Saran A. K. , Gopalakrishna V. V. , Vethamony P. , Araligidad N. , and Bailey R. , 2002: XBT fall rate in waters of extreme temperature: A case study in the Antarctic Ocean. J. Atmos. Oceanic Technol., 19, 391396, doi:10.1175/1520-0426-19.3.391.

    • Search Google Scholar
    • Export Citation
  • Wijffels, S. E., Willis J. , Domingues C. M. , Barker P. , White N. J. , Gronell A. , Ridgway K. , and Church J. A. , 2008: Changing expendable bathythermograph fall rates and their impact on estimates of thermosteric sea level rise. J. Climate, 21, 56575672, doi:10.1175/2008JCLI2290.1.

    • Search Google Scholar
    • Export Citation
  • Wright, D., and Szabados M. , 1989: Field evaluation of real-time XBT systems. Diving Safety and Physiology, Ocean Engineering/Technology, D. Anderson, Ed., Vol. 5, Oceans ʼ89: An International Conference Addressing Methods for Understanding the Global Ocean, Publ. 89CH2780-5, IEEE, 1621–1626, doi:10.1109/OCEANS.1989.587130.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 2132 850 33
PDF Downloads 1202 278 23