Argo Technologies Argo TC Inputs by S Riser

Argo Technologies Argo TC Inputs by S. Riser (UW) DBCP #22, Technical Workshop La Jolla, California

Argo Fleet • 2576 Active Floats 2

Argo Floats • A fleet of US, French, German and Japanese profiling floats Remark: IFREMER & JAMSTEC work on a new float generation 3

Argo Floats NEMO APEX Provor SOLO 4

Argo Cycle • Standard mission 150 -200 cycles, t = 10 days, profile to 2000 m, Sensors: T, S, p sampling ~100 levels 5

Float Lifetime • Float lifetime improving but not yet optimal Solutions: -Alkaline to Lithium batteries -Park & profile -New float generation 6

Argo Sensors Most of floats use a Sea. Bird CTD. About 200 floats (WHOI) use a FSI CTD T accurate to 0. 005 C p accurate to 5 dbar S accurate to 0. 01 Psu The SBE CTD unit pumps seawater through a fluid circuit; temperature and conductivity are measured inside this loop, pressure is measured outside. A biocide prevents fouling (growth) inside the loop. 7

Argo Profile [data from 71 levels] 8

CTD stability UW float 063 was recovered after 3 years and recalibrated. The results showed that salinity, temperature, and pressure had all remained stable to within the manufacturer’s specifications. 9

Iridium Floats • About 25 iridium floats are operating (UW) High resolution T and S data ( p = 2 dbar) over a 2000 m profile sampling 1000 levels surface time 6 minutes 10

Iridium Floats • • • High resolution profile (75 to 1000 levels) More bandwidth (required for other sensors) A few min at surface vs. ~10 hours Downlink available to e. g. upload new conf. Collection of T and p data at drift depth • Data management ? – modem/modem, SBD, RUDICS • Cost ? (per byte << Argos, per profile ~= Argos) • Energy budget ? 11

New sensors SST There are plans to modify the CTD sensor on floats in order to measure SST; this will be done by adding a 2 nd thermistor outside of the CTD tube that will collect samples at 1 m intervals between a depth of 20 meters and the sea surface. Accuracy 0. 05 C. Cost $200 per float. First tests ongoing. SSS There a number of scientists interested in making high quality measurements of SSS. This appears to be difficult and perhaps costly and will not be attempted soon. 12

New sensors • Dissolved Oxygen CTD sensors SBE O 2 sensor Optode sensor 13

New sensors • Optical/biogeochemical sensors (chlorophyll, carbon cycle, NO 3, p. H, …) • Acoustic wind/rain gauges The float is drifting at a depth of 700 m … Strong seasonal variation Rainfall and wind speed can be measured acoustically using the spectrum of ambient acoustic noise in the ocean. 14

New features • Acoustically-tracked profiling floats that can operate under seasonal ice; store profiles during winter and transmit during ice-free seasons • Ice avoidance software • POPS for real-time under ice obs. • New battery packs (APEX +50%) • Alkaline vs. Lithium 15

Hurricanes EM-APEX (T, S, V) – Rapid shallow profiling – Electromagnetic velocity measurement – Iridium transmissions switch Argo-mode to rapid-shallow mode if floats cross a hurricane …. – More Info: Thomas Sanford, sanford@apl. washington. edu – CBLAST project Hurricane Frances, 2004 16

Summary • • New sensors use impacts Argo core mission SST should be feasible Iridium technology is ready Float lifetime should be improved with the batteries • “Exotic” sensors should be taken into consideration in the future for other components of the GOOS … 17