French oceanographic cruisesG. Reverdin, F. Marin

• French oceanographic cruises with XBTs launched ship steaming arond 10-12 knots between two CTDs typically 20-40 km apart from XBT. The launch is done manually from a position fairly low above water, typically near the aft of the ship or along the side (a little higher on DTX, seems to be)

• There seems to be generally no documentation on the equation used in the French archives (‘unknown’). And for the recent ones, different choices have been done on the total depth of reported data (and no correlation with the equation used)

• Comparisons of XBT T(3m) with intake temperatures have not been done, but this is possible in a large number of cases.

• Cruises are in the tropical Oceans mostly (from 1979, 1980, 1983, 1985, 1986, 1991, some of the PIRATA cruises since 1997, EGEE cruises, 2005-2007); also mid-latitude North Atlantic (Semaphore, 1993; POMME 2000-2001 among others)

POMME winter-early spring 2001Hanawa

POMME late summers 2000 and 2001original

POMME winter-early spring 2001original

EGEE1 June 2005Hanawa

EGEE3 June 2006Hanawa

EGEE2 Sep 2005original

EGEE4 Nov 2006original

EGEE5 June 2007original

EGEE6 Oct 2007original

• EGEE1: numerous problems. Why?• All EGEE (except EGEE5, 6 on the R.V. Antea) show positive SST

anomaly (0.06°C) and upper thermocline too warm (suggesting depth overestimated down to 80m). Is same software used (MK12 EGEE1 MK21 others, but I dont know for EGEE5, 6)

• Pomme winter data on Atalante dont have a positive SST bias. On the other hand the late summer Thalassa ones have a 0.12°C bias (same software, same batch of XBTs). The DTX winter ones also seem to have a small bias (0.04°C).

Questions:Do we trust the CTD SSTs during ‘warm’ season? (mixing by the ship in station: what is its effect?).

• Conditions on research vessels very different than the ones on merchant vessels (height of launch of XBTs; also position on the ship somewhat different)