We deployed 7 PALACE floats in the Irminger Basin of the North Atlantic in late Autumn 1996. 81 died quite early on, 79 and 82 expired in the winter of 1997/8. The other four were still going when the figure below was made. It shows the floats' launch positions; the depth contour is 1500 m. Only float 83K is still reporting as of October 2001. All others are presumed dead.
Start and end point of deep drift are NOT extrapolated but actual satellite fixes. All floats were ballasted to 'cruise' at 1500 dbar.
We are particularly interested in the long-term performance of the conductivity sensors on CTD-PALACE floats. Our floats were manufactured by Webb Research Inc. with conductivity sensors by Falmouth Scientific Inc. We seem to have been very fortunate because our four CTD floats appear accurate and stable over 18 months to +/- 0.005 in salinity and, allowing for the apparent effects of biofouling on one float, to +/- 0.010 over 2.5 years. A report on the salinity calibration of the floats is available.
Bacon,S, Centurioni, L.R., Gould J.W, 2000, The evaluation of salinity measurements from PALACE floats, JAOT, 18,1258.
Bacon,S, Centurioni, L.R., Gould J.W, 1998, Evaluation of profiling ALACE floats performance, SOC Int. Doc, 39, 78 pp, unpublished.
Link to the webpage for this experiment.