NOAA XBT Fall Rate Workshop

NOAA/AOML, Miami, Florida

March 10-12, 2008

Organizers: Gustavo J. Goni and Molly O. Baringer (Contact)

This Workshop is financially supported by the Climate Program Office (CPO) and endorsed by:


Analyses of concurrent XBT, CTD and Argo float observations indicate that there is a systematic difference in temperature profiles, which is likely due to an error in the XBT fall-rate equation. This error has introduced a warm bias in the global XBT data base. This workshop is dedicated to discuss the findings related to this issue by different groups. As a consequence, a new fall rate equation may need to be developed and applied to both past and future XBT data.

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Agenda (PDF)

Day 1 (March 10, 9:30AM-5:00PM)

Chair: Josh Willis

  1. XBT fall rate equation issues (G. Goni) (PPT)
  2. Reports of XBT deployments (H. Viola) (PPT)
  3. The history of XBT design, manufacture and quality from 1962 - present (D. Maher) (PPT)
  4. XBT fall rate problem: a historical perspective (W. Emery) (Abstract) (PPT)
  5. XBT data acquisition systems and AOML XBT fall rate experiments (M. Baringer) (PPT)
  6. Factors affecting quality of XBT data: results of analyses on profiles from the western Mediterranean Sea (F. Reseghetti) (Abstract) (PPT)
  7. Fall rates for different XBT types (D. Snowden) (PPT)
  8. A review of XBT fall rate and quality control studies carried out in the Indian Ocean (V. Gopalakrishna) (Abstract) (PPT)
  9. XBT deployed during French cruises 1999-2007 (G. Reverdin) (Abstract) (PPT)
  10. Looking for ship-speed dependency of XBT fall rates (J. Gilson) (Abstract) (PPT)
  11. XBT and Argo profile comparison (C. Schmid) (Abstract) (PPT)
  12. Identifying and estimating biases between XBT and Argo observations using satellite altimetry (P. Di Nezio) (Abstract) (PPT)
  13. Using altimeter and Argo data to estimate biases in XBT fall rate equations (J. Willis) (Abstract) (PPT)
  14. Collecting and Utilizing an XBT/CTD comparison reference database for XBT bias estimation (T. Boyer) (Abstract) (PPT)
  15. Impact of fall rate on estimates of the steric component of sea level rise (S. Wijffels) (Abstract) (PPT)
  16. Global ocean heat content 1955-2006 in light of recently revealed instrumentation problems (S. Levitus) (Abstract) (PPT)
  17. Managing XBT Data in the Global Temperature-Salinity Profile Program Data Base (M. Hamilton)
  18. XBT metadata effects on fall rate corrections (A. Gronell Thresher) (Abstract) (PPT)
  19. Water Temperature instrumental Metadata Pilot Project (META-T) (E. Charpentier) (Abstract) (PPT)
  20. Data base issues with a change in fall rate (C. Sun) (PPT)
  21. Instrument-related temperature biases and their impact on estimation of the long-term ocean temperature variability (V. Gouretski) (Abstract) (PPT)
  22. AOML's notes on migrating from FM 63 XI Ext. BATHY to BUFR (J. Trinanes) (Abstract)

Day 2 (March 11, 9:30AM-5:00PM)

Chair: Molly O. Baringer

  1. Discussion of issues brought up during the presentations on day 1

Day 3 (March 12, 9:30AM-5:00PM)

Chair: Gustavo J. Goni

  1. Preparation of a white paper with recommendations
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The workshop will be held in the first floor conference room at NOAA/AOML, 4301 Rickenbacker Causeway, Miami, FL 33149.

We have blocked 20 rooms at Grand Bay Miami, 2669 South Bayshore Dr, Miami, Florida 33133, a hotel located in Coconut Grove at a short distance to AOML (Map).

The rate for each room is $119.00 plus taxes, and is available from three days before until three days after the meeting. To make a reservation, please call the hotel at 786-206-7151 or 786-206-7154 and say that you are with the NOAA Group. You can also make your reservation by email: Please make your reservation as soon as possible since March is still high season in Miami.

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List of participants

Molly Baringer (NOAA/AOML)
Tim Boyer (NOAA/NODC)
Francis Bringas (UM/CIMAS)
Etienne Charpentier (WMO, Switzerland)
Pedro Di Nezio (UM/CIMAS)
William Emery (U. Colorado)
John Gilson (SIO)
Gustavo Goni (NOAA/AOML)
Vissa Gopalakrishna (NIO, India)
Viktor Gouretski (AWI, Germany)
Ann Gronell Thresher (CSIRO, Australia)
Vicki Halliwell (UM/CIMAS)

Melanie Hamilton (NOAA/NODC)
Sydney Levitus (NOAA/NODC)
Dave Maher (Sippican)
Robert Molinari (NOAA/AOML)
Franco Reseghetti (ENEA, Italy)
Gilles Reverdin (LOCEAN, France)
Claudia Schmid (NOAA/AOML)
Derrick Snowden (NOAA/OCO)
Charles Sun (NOAA/NODC)
Joaquin Trinanes (NOAA/AOML)
Hester Viola (IOC/JCOMMOPS, France)
Susan Wijffels (CSIRO, Australia)
Josh Willis (NASA/JPL)

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Reading Material

[1]. Instrument-related temperature biases and their impact on estimation of the long-term ocean temperature variability. V. Gouretski. (PDF)

[2]. Managing XBT data in the Global Temperature-Salinity Profile Program data base. C. Sun, N. Hall and M. Hamilton. (PDF)

[3]. Changing eXpendable Bathythermograph fall-rates and their impact on estimates of thermosteric sea level rise. S.E. Wijffels, J. Willis, C.M. Domingues, P. Barker, N.J. White, A. Gronell, K. Ridgway and J.A. Church. (PDF)

[4]. Factors affecting the quality of XBT data - results of analyses on profiles from the Western Mediterranean Sea. F. Reseghetti, M. Borghini and G.M.R. Manzella. Ocean Sci., 3, 59-75 (2007). (PDF)

[5]. How much is the ocean really warming? V. Gouretski and K.P. Koltermann. Geophys. Res. Lett. V34, L01610, doi:10.1029/2006GL027834 (2007). (PDF)

[6]. A new fall-rate equation for T-5 expendable bathythermograph (XBT) by TSK. S. Kizu, H. Yoritaka and K. Hanawa. J. Oceanogr. 61, 115 (2005) (PDF)

[7]. Inter-manufacturer difference and temperature dependency of the fall-rate of T-5 expendable bathythermograph. S. Kizu, S. Ito and T. Watanabe. J. Oceanogr. 61, 905 (2005) (PDF)

[8]. XBT fall rate in waters of extreme temperature: a case study in the Antarctic Ocean. P. Thadathil, A.K. Saran, V.V. Gopalakrishna, P. Vethamony and N. Araligidad. J. Atmos. Oceanic Technol. 19, 391 (2002) (PDF)

[9]. Start-up transient of XBT measurement. S. Kizu and K. Hanawa. Deep-Sea Res. I, 49, 935 (2002) (PDF)

[10]. Recorder-dependent temperature error of expendable bathythermograph. S. Kizu and K. Hanawa. J. Oceanogr. 58, 469 (2002) (PDF)

[11]. An interactive graphical system for XBT data quality control and visualization. P. Thadathil, A.K. Ghosh, J.S. Sarupria and V.V. Gopalakrishna. Comp. Geosci. 27, 867 (2001) (PDF)

[12]. An evaluation of XBT depth equations for the Indian Ocean. P. Thadathil, A.K. Ghosh and P.M. Muraleedharan. Deep-Sea Res. I, 45, 819 (1998). (PDF)

[13]. A quality-control procedure for surface temperature and surface layer inversion in the XBT data archive from the Indian Ocean. P. Thadathil, A.K. Ghosh, J. Pattanaik and L. Ratnakaran. J. Atmos. Oceanic Technol. 16, 980 (1998) (PDF)

[14]. The water temperature instrumental metadata pilot project (META-T). Etienne Charpentier. Presentation at the XBT fall rate workshop, AOML, Miami, 10-12 March 2008 (PDF)

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