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Use of Argo data to infer subsurface property changes. Brian King Southampton Oceanography Centre. What sort of changes might we hope to identify using float data ?. Indian Ocean 32S cruise tracks. 1936 1965 1987 1995 2002. Temperature and salinity in the upper 1500m.
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Use of Argo data to infer subsurface property changes Brian King Southampton Oceanography Centre
What sort of changes might we hope to identify using float data ?
Indian Ocean 32S cruise tracks 1936 1965 198719952002
Can a change of this magnitude (0.02 to 0.04) be detected and monitored using floats ?
Salinity anomaly relative to 1987 1 degree band, centered on PV minimum 1987 CTD 2002 CTD2002 Floats
Signal-to-noise ratios: HadCM3 B2 Arctic + Atlantic Pacific Indian + Southern (Banks & Wood 2002)
Salinity changes in the SE Indian Helen Phillips, CSIRO
Salinity changes in the N Pacific Li Ren, UW
Stratification changes in N Atlantic subpolar gyre Poster by Mercier and Hascoet, IFREMER
What are the prospects for using Argo data to compare the state of the global ocean in the early 2000s with the previous decade ?
Argo profiles held at GDAC(number of profiles in brackets) 2000 (2 394) 2001 (6 712) 2002 (15 662) 2003 (20 319 to Oct)
Argo profiles held at GDAC 2000 to present (October 2003) > 45 000 profiles
WOCE one-time CTDs 9 200 stations WOCE repeat CTDs 10 054 stations
All WOCE CTD coverage > 19 000 stations
Argo profiles and WOCE CTD stations Argo profiles WOCE CTD
Argo profiles near to WOCE CTD stations Argo profiles within 100km of a WOCE CTD (> 20 000)
Summary of WOCE CTD and Argo coverage
Summary • Subsurface property changes occur that are coherent over scales significantly larger than Argo resolution • There are basin-scale changes for which the timescale is longer than annual but shorter than decades (at least in some places) • The magnitude of salinity changes (order 0.03 or greater) are sufficiently large that Argo can detect them
Summary (continued) • So long as Argo float density and data quality are sustained, Argo will provide a means of monitoring the properties of thermocline and intermediate waters, at all timescales relevant to climate • When the array is complete in all basins, Argo will enable a direct comparison to be made between the state of the global upper ocean in the present decade and in the 1990s.
Stratification changes in N Atlantic subpolar gyre Poster by Mercier and Hascoet, IFREMER Thmoas Hascoet, IFREMER