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

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

(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, …).

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

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.

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 ?

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)

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

The global XBT network Heat content

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,…).

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

Deployment/Observations The global XBT network Deployment/Observations

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, …)

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).

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 Gustavo.Goni@noaa.gov and/or Ricardo.Domingues@nooa.gov

Publications and latest observations XBT Science Publications and latest observations

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

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.

Thank you very much Gustavo.Goni@noaa.gov