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Gouretski and Koltermann (2007) shows statistics from
Expendable Bathythermograph (XBT) vs. Conductivity-Temperature-Depth (CTD)/reversing thermometer instrument comparisons which reveal a
warm bias in XBT temperatures. This bias varies over time and over depth. The bias may be due to errors in the calculation
of depth or in measurement of the temperature.
A NOAA sponsored XBT Fall Rate Workshop was held in Miami, FL, March 10-12, 2008 to discuss this problem.
The meeting came to no conclusion as to the best way to correct the bias.
Five papers with estimates of corrections have been recently published or submitted to scientific journals. The corrections proposed in
each work are provided here to facilitate intercomparison by the scientific community.
Gouretski, V. V., and K. P. Koltermann, 2007, How much is the ocean really warming? Geophysical Research Letters, L01610,
doi:10.1029/2006GL027834
Wijffels, S. E., J. Willis, C. M. Domingues, P. Barker, N.J. White, A. Gronell, K. Ridgway, J. A. Church, 2008,
Changing eXpendable Bathythermograph Fall-rates and their Impact on Estimates of Thermosteric Sea Level Rise, Journal of Climate, in press.
Wijffels et al. depth corrections: Table 1 (in situ comparison),
Table 2 (in situ-altimeter comparison).
Ishii, M. and M. Kimoto, 2008, Reevaluation of Historical Ocean Heat Content Variations With An XBT depth bias Correction. J. Oceanogr. (submitted).
On line reprint, pdf (0.4 MB)*.
Ishii and Kimoto depth corrections.
Gouretski, V., Instrument-related temperature biases and their impact on estimation of long-term ocean temperature variability (submitted).
Gouretski depth and temperature corrections.
Levitus, S, J. Antonov, T. Boyer, Global ocean heat content 1955-2007 in light of recently revealed instrumentation problems (in preparation).
Levitus et al. temperature corrections.
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