The CSIRO XBT Program uses Expendable Bathythermographs (XBTs) which are devices designed to measure the temperature of the upper ocean. They are deployed from moving vessels, thus enabling a large coverage of the world's oceans, mostly between 30 degrees North and 30 degrees South, and up to a depth of 800m. The XBT temperatures are then used to obtain a description of the large-scale thermal structure of the upper opcean, as a time-dependent system, on a long term basis.

CSIRO developed an XBT network under the auspices of the international Tropical Ocean Global Atmosphere (TOGA) program, starting in 1983, and the World Ocean Circulation Experiment (WOCE), starting in 1990. CSIRO's XBT coverage is a contribution to the international TOGA/WOCE/IGOSS XBT network. Since 1997, the XBT network has been an operational Australian contribution to the Global Ocean Observing System (GOOS), jointly supported by the Bureau of Meteorology and CSIRO.

Ongoing activities of the The CSIRO XBT Program includes :

· ANALYSIS OF FREQUENTLY REPEATED XBT LINES,
Seasonal and interannual variations in thermal structure are analyzed along frequently repeated XBT routes in the Indian and Pacific Oceans. The methods and results are presented here.

· WOCE INDIAN OCEAN THERMAL DATA ASSEMBLY CENTER
The Centre's objective is to assemble the most comprehensive UOT ( Upper Ocean Temperature ) data set available for the Indian Ocean over the WOCE period (1990-96) from both WOCE and non-WOCE contributors. Links to details of the WOCE QC process, the WOCE data and analyses of that data can be found here.

· OCEAN OBSERVING NETWORK
On-going projects of the Ocean Observing Network include analysis of high density sampling on routes in the Tasman Sea and development of new sampling techniques and instrumentation. Links to these and other data products can be found here.