Southwest PacIfic Ocean Circulation and Climate Experiment: SPICE A. Ganachaud JISAO/PMEL/NOAA LEGOS / IRD Nouméa-Toulouse Laboratoire d Etudes Géophysiques et d Océanographie Spatiale W. Kessler (PMEL/NOAA) G. Brassington(BOM) S. Wijffels, K. Ridgway, W. Cai (CSIRO) N. Holbrook (MU) P. Sutton, M. Bowen (NIWA) B. Qiu, A. Timmermann (UH) D. Roemmich, J. Sprintall (SIO), H. Diamond (NOAA) S. Cravatte, L. Gourdeau (LEGOS) P. Eastwood (SOPAC/Fiji) T. Aung (USP/Fiji) Black (1851)
Outline A. Thermocline waters PNG SOLOMON IS. Solomon Sea B. SPCZ C. Impacts D. Context and strategy Coral Sea VANUATU N. CALEDONIA Fiji AUSTRALIA Tasman Sea NEW ZEALAND
Interests in the Coral and Tasman Sea circulation Rotschi, Legand, Hamon R/V ORSOM III, 1956 interisland flows Cronulla, August 1958 Conference on the Coral and Tasman Sea Oceanography Cairns, August 2005 Workshop on the Southwest Pacific Ocean Circulation and its relation with Climate
Decadal influences: Thermocline water connection between the subduction zone of the South East Pacific and the equator Lines show geostrophic streamlines on the isopycnal (courtesy B. Kessler)
A-The South Pacific "Thermocline" waters South Equatorial Current Salinity maximum Z=100:300m Temperature/salinity diagram (Argo floats, 2007)
Thermocline water currents: 0-300m ~25 Sv
Thermocline water currents 0-300m ~15 Sv + 70 % EUC waters ~25 Sv
Thermocline water currents 0-300m ~15 Sv + ~25 Sv ~10 Sv
Thermocline water currents 0-300m 3-Solomon Sea 1-Inflows 2-Tasman Sea
Thermocline waters: 1-inflow to the Coral Sea 1. Formation of 3 "jets" 2. Bifurcation (northward bias in GCM/CGCMs) 3. Outflows and budget Bifurcation: Qu and Lindstrom 2002 Kessler and Gourdeau 2006, 2007
Thermocline waters: 2-EAC and EAUC Ridgway and Dunn, (2003); Cai et al. (2003); Bowen et al. (2005)
Thermocline waters: 2-EAC and EAUC Ridgway and Dunn, (2003); Cai et al. (2003); Bowen et al. (2005) SSH variability C. Ken Ridgway Variability dominates the mean flow Inflows/outflows variations; eddy dynamics Tasman Outflow linkage between S. Pacific gyre and Indian/global circulation Heat balance in the Tasman Sea
Thermocline waters: 3-North Coral Sea: A WBC pathway to feed the EUC and ITF N S O ST GE OM Z R L A I O O T E I S V G NVJ NCJ Quasi undocumented circulation WEPOCS cruises, 1985 CARS dynamic Ht relative to 2000m (C. W. Kessler) (Lindstrom et al., 1987; Tsuchiya et al., 1989; Fine et al., 1994) Narrow straits, difficult to model Strong WBC, mixing Strong variability: monsoon, ENSO
The Southwest Pacific Atmosphere SPCZ Trade winds Trade winds A A
B-South Pacific Convergence Zone COADS cloudiness 1960-1970 20th century climate model High convective activity, precipitation, wind convergence -Dominant convective feature in the Southern Hemisphere -Substantial variability: (intra) seasonal; interannual;equatorward shift 1976 -Unresolved southward bend, poorly modelled -Strong local effects (SSS, oceanic heat content)
C-Ocean and climate impacts on environment in the southwest Pacific Consequences of ocean and climate fluctuations: Biodiversity, Coral reefs Freshwater-agriculture and health Tropical cyclones Sea surface height Pacific Island Countries: Fragile ecosystems, low-lying populated areas, isolated places SST Trend ( C/century) ERSST data (1944-2005) Australia and New Zealand: Climate depends on heat content in the Tasman Sea Freshwater resources critical Important changes in biodiversity
D. Context and strategy: unadapted observations Sokolov and Rintoul (2000) Qu and Lindstrom (2002) Ridgway and Dunn (2003) Maximenko (2005) Distribution of the (T,S) casts (Ridgway and Dunn, 2003) Sattelite-derived surface currents Active Argo floats on 11/15/2007
D. Context and strategy: existing large scale programs UW/CSIRO/IRD IRD SIO/CSIRO/IRD BOM/MF IMOS/Bluewater and climate BOM/IRD
D. Context and strategy: SPICE benefits Observations: Ocean and O-A Related programs: Operational oceanography Meteorology Local applications Global observations Modelling: Ocean and coupled Modelling: Atmosphere Observations: Atmosphere
D. Context and strategy: SPICE benefits Observations: Ocean and O-A Related programs: Operational oceanography Meteorology Local applications Global observations Modelling: Ocean and coupled Modelling: Atmosphere? SPICE: Coordination Data sharing National funding Observations: Atmosphere
Modelling strategy: regional zooms 1. Help to design observation / monitoring program 2. Sensitivity experiments 3. Regional applications CSIRO/BOM UH/LOCEAN UH/LEGOS IRD/NIWA IRD/CNRS/CNES/IFREMER/METEO- FRANCE/SHOM
Regional field experiment 2010 2007+ 2007+ 2005+ 2004+ 2008 2007+ 2008 running TBS TBS
SPICE Challenges "Add-on" Costs 2008-2011 1-Fieldwork: Shiptime: 1.5month/yr Wet measurements: $1.6M/yr HRXT, Air-sea fluxes: funded 2-Modelling: Infrastructures exist Specific analyses costs