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   Manual Sections
Data Acquisition
Preparing to Run ARTOA-II
Program ARTOA-II
Appendix A: Input/Output
Appendix B: Related Programs
   Relevant Links
Service Argos U.S. office
Service Argos head office
Perl link

Contact | WHOI Internal Home  

RAFOS Float Processing at Woods Hole Oceanographic Institution

Christine M. Wooding

Heather H. Furey

Marguerite A. Pacheco


Oceanographers have used acoustically tracked sub-surface floats since the 1960's. There have been many improvements, but tracking them remains a challenge because the submerged locations are only available indirectly.

In the early 1980's, Bill Schmitz established a small group at WHOI dedicated to using acoustic floats to measure ocean currents. Tracking software was adapted by Breck Owens from that used by Tom Rossby at URI. During the next 14 years around 150 SOFAR floats were tracked by the group. In order to decrease the cost of float experiments, Rossby developed the RAFOS float, which is smaller and cheaper than SOFARs and could be used in larger numbers. As part of WOCE, Breck Owens and Jim Valdes developed an improved version which was deployed in large numbers as part of the Brazil Basin Experiment starting in 1994. WHOI scientists have now tracked over 350 RAFOS floats, have 50 currently deployed, and have more planned to deploy in the future.

When we switched to RAFOS floats we modified the SOFAR processing and tracking software to track RAFOS floats. Recently it was decided to switch to a newer MATLAB-based tracking scheme. ARTOA-II is a single integrated package of Matlab routines which makes it possible to track a float in a single session. It represents a complete overhaul of previous programs and has been developed in stages by Claudia Schmid (at IFM, Kiel), Martin Menzel (IFM, then IFREMER in Brest), and Olaf Boebel (IFM, URI) (Anderson-Fontana et al., 2001). Heather Furey and Roger Goldsmith (WHOI) have worked with Olaf Boebel (now at AWI) to be sure the package includes options such as least-square tracking and doppler-shift calculations.

The current tracking program, ARTOA-II, takes the float from raw data through final track. By having all the steps in a single program, one can go back and correct the track by making changes at any point in the process - removing or replacing a bad point in the times-of-arrival (TOA) series; adding or subtracting a time-constant or drift to the float or any sound-source. The results can be compared and the best one selected.