ARGO float activities in 2014

During 2014, 7 floats were deployed by ARGO -ITALY in the SO.

Five Italian profiling floats were deployed in the SO between 30 December 2013 and 3 January 2014 from R/V Italica in order to sample water column characteristics in the Antarctic circumpolar Current.

These floats are Apex instruments manufactured by Teledyne Webb Research in the USA. They cycle between the surface and 2000 dbar every 10 days and drift at the parking depth of 1000 dbar. They measure temperature and salinity at each ascent, and transmit data to the ARGO’s satellite system when at surface. Their position is also estimated by the ARGO’s system. Unfortunately, two of the floats did not function properly due to a software problem.

One float was deployed in the Ross Sea on 11 January 2014 from R/V Italica. This float is an Arvor-L instrument manufactured by NKE in France which measures temperature and salinity at each ascent, and transmits data to the ARGO’s satellite system when at surface. Its position is also estimated by the ARGO’s system. This float was anchored and was supposed to cycle between the surface and 1000 dbar every 1 day . This deployment in ice-free coastal Ross Sea in winter 2014 is part of the T-Rex experiment. Unfortunately, the float stopped transmitting just after deployment.

An additional profiling float was deployed in correspondence of the ACC streamlines on 15 February 2014 from R/V Italica . This float is an Provor-CTS2 instrument manufactured by NKE in France which measures temperature and salinity at each ascent, and transmits data to the ARGO’s satellite system when at surface. Its position is also estimated by the ARGO’s system. Unfortunately, this float malfunctioned and drifted at the surface without executing profiles.

Table 3 Status information for the 7 Italian floats deployed in the SO and Ross Sea during 2014. Updated positions, status and cycles number are available at http://nettuno.ogs.trieste.it/sire/medargo/active/it_table_out.php?live=*

In the SO, the Apex floats WMO 6901849 and WMO 6901855 were incorrectly programmed and did not stay at the surface enough time to transmit their data via the ARGO’s satellite system. As a result, float WMO 6901849 provided only 19 incomplete profiles (out of 37 cycles) and no data were obtained from float WMO 6901855. The problem was discussed with Teledyne Webb Research but there was nothing that we could do to solve the problem since the floats were at sea and ARGO’s telemetry does not allow downlink commands.

The Provor CTS 2 WMO 6901854 which was refurbished by NKE apparently went into “end of mission” mode just after deployment and stayed at surface without profiling until 11 May 2014.

Unfortunately, float WMO 6901853, which was tethered to act as a virtual mooring in Ross Sea had transmission/floatation problems and never transmitted data.