1. The global XBT network
Gustavo Jorge Goni(1), Shenfu Dong(1,2), and Francis Bringas(1)
With contributions and work of many in the XBT community
(1) NOAA/AOML, Miami, FL, USA
(2) University of Miami, Miami, FL, USA
Fourth XBT Science Meeting
Beijing, China
November 11-13, 2014

2. Science and the way forward
Fourth XBT Workshop
Science and the way forward
Moving forward with:
The XBT Network (sustainability)
Fall Rate (20 years since H95; geared towards heat content)
FR Impact on current parameters, heat transport, MOC,…
Communicating scientific advances
Discussions

3. (why are we deploying XBTs?)
XBT Network Goals
(why are we deploying XBTs?)
From OceanObs09
Contribute with understanding of boundary currents serving as the backbone of the observations for this type of studies.
Monitor variability of Meridional Heat Transport and MOC.
Complement Argo and other platforms to measure heat content. XBTs provide the largest data set for historical ocean heat content.
Enhance our understanding of the physics, chemistry, ecosystems, etc. of the ocean by providing a synergy with other observing platforms (TSG, pCO2, altimetry, CPRs, …).

4. OceanObs09 Recommendations
The global XBT network
OceanObs09 Recommendations
Deployment Mode
# Transects
High Density only 19
Frequently Repeated only 23
HD and FR 13
Low Density
TOTAL 55

5. The global XBT network Only 2 recommended modes (FR, HD).
A few transects added (AX97), reinstated (AX32, Oleander Project).
Only Australia (BOM) carries out FR transects, IX01, for Indonesian Throughflow monitoring.

6. The global XBT network
55 transects: 38 active ; approximately 18,000 XBTs deployed per year
Is there an inactive transect that we should place special effort to make it active ?

7. The global XBT network Surface Currents Upstream Kuroshio Current:
Antarctic Circumpolar Current
Upstream: PX44 (since 1991)
South of Tasmania: IX28 (1993)
Downstream: PX05 (2009)
Gulf Stream: AX10 (1997), AX32 (1981)
Drake Passage: AX22 (1996)
South of South Africa: AX25 (2004)
Agulhas Current: IX21
East Australian Current:
Brazil Current: AX97 (2004)
at 27S: PX30 (1991)
Brazil/Malvinas Confluence: AX18 (2002)
at 33S: PX34 (1991)
East Auckland Current and Tasman outflow: PX06 (1986)
Agulhas Current at 28S: IX21 (1994)
Benguela Current and Agulhas Current Rings: AX18 (2002) and AX08 (2000)
California Current System:
Undercurrent: PX37 (1991)
California Current: PX37 (1991)
Atlantic Ocean Equatorial Current System: AX08 (2000), AX20 (2010)
Alaska Current: PX38 (1993)
Florida Current: No Number (2000)
Leeuwin Current 32S: IX15 (1987)
North Atlantic Drift Current: AX01 (1997)
Indonesian Throughflow: IX01 (1987)
Solomon Sea current system: PX05 (2009)
Labrador Current: AX02 (2010)

8. Meridional Heat Transport
The global XBT network
Meridional Heat Transport
North Atlantic at ~ 27N
South Atlantic at ~ 35S
XBTs have provided the first time series of MHT and MOC in the South Atlantic (since 2002).
MHT and MOC in the North Atlantic since 1994

9. The global XBT network
Heat content

10. The global XBT network
Successfully transitioned to HD and FR modes for specific scientific applications.
55 transects, 38 active thanks in large part to international collaboration, with ~18,000 annual deployments.
Formed a Science Team, to help improve FRE, highlight scientific applications, make XBTs more visible to the community, support key projects (IQUOD, pCO2,…).

11. International Collaboration
The global XBT network
International Collaboration
Probes
Deployments
Logistics
Transmissions
Equipment
Fall Rate Equation
Science
Contribution to IQUOD US
Australia
France
China
South Africa
Japan
Brazil
Italy
India
Germany
Argentina UK

12. Deployment/Observations
The global XBT network
Deployment/Observations

13. Deployment/Observations
The global XBT network
Deployment/Observations
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
XBT 25 23 29 22 20 21 19 18
Argo 7 17 31 47 72 96
110
121
126
141
151
XBTs now provide approximately 12% of temperature profiles (not counting underwater gliders, pinipeds, moorings, …)

14. The global XBT network Science Team
The XBT Science Team was formed during the First Expendable Bathythermograph Science Workshop (Melbourne Australia, 2011) with the following objectives:
Have a voice in the community to communicate XBT-related scientific results;
Gather the XBT community to discuss scientific advances in the use of XBT observations;
Enhance international scientific collaboration;
Make recommendations and prioritize transects on the XBT network;
Make recommendations on XBT data management;
Create links with other active/recognized scientific and operational panels; and
Assist in activities carried out by the Ship Of Opportunity Program Implementation Panel (SOOPIP).

15. XBT Science Web Page www.aoml.noaa.gov/phod/goos/xbtscience News
Monitoring Currents, variability
Monitoring MHT/MOC, variability
Temperature sections, variability
Meetings
IQUOD
Latest observations
Links to participant institution web pages
Links to where to find data (global and by transect), please check for accuracy.
Please check web pages and submit material to and/or

16. Publications and latest observations
XBT Science
Publications and latest observations

17. Support of Argo and drifter deployments
The global XBT network
Support of Argo and drifter deployments

18. The XBT network Plans and way forward
Maintaining Network, with emphasis on HD transects:
Monitoring of currents
Monitoring of heat transport and MOC
Contribute with observations for heat content …
FRE studies for historical, current, and future data
Start also focusing on FRE for ocean currents and heat transport: What is the impact of depth bias, temperature bias, offsets, in these measurements ?
Improving current probe technology for future operations, temperature sensor, pressure switches, weight tolerance, etc.
As we move forward: what is it that distinguishes XBTs from other platforms ? we need to use them to the advantage of the scientific community.
Next SOT (SOOPIP/VOS) meeting in Cape Town in April 2015.

19. Thank you very much