GSOP/GODAE heat content intercomparison CLIVAR GSOP Air-Sea Flux Workshop, WHOI, Nov 2012

1. GSOP/GODAE heat content intercomparison CLIVAR GSOP Air-Sea Flux Workshop, WHOI, Nov 2012 Matt Palmer, Magdalena Balmaseda, You-Soon.Chang, Gennady Chepurin, Yosuke Fujii, Stéphanie Guinehut, Fabrice Hernandez, Shuhei Masuda, Takahiro Toyoda, Maria Valdivieso, Guillaume Vernieres and Ou Wang

2. Key objectives - to determine the degree of consistency among the analyses and identify key differences - to compare the analyses to conventional ocean heat content change estimates that use statistical infilling methods Definition of depth-integrated temperature: The depth-integrated potential temperature, <θ>, over some layer H, from the surface to a fixed depth, is defined as: <θ> = ∫ θ (x,y,z,t) dz Please note that the layer integral should be inclusive of all model levels shallower than H. This will ensure that layer ocean heat content can be added/subtracted conservatively. To compliment the steric height analysis, the following 2-D fields for depth-integrated potential temperature are requested: • 0 to 100 m of depth; • 0 to 300 m of depth; • 0 to 700 m of depth: • 0 to 1500 m of depth; • 0 to 3000 m of depth; • 0 to 4000 m of depth • 0 to full depth Assumptions: Reference Density = 1025 kg m-3 Specific Heat = 3985.0 J kg-1 K-1

3. 0-100m 1993-2007 mean removed

4. 0-300m 1993-2007 mean removed

5. 0-700m 1993-2007 mean removed

6. 0-1500m 1993-2007 mean removed

7. 0-3000m 1993-2007 mean removed

8. 0-4000m 1993-2007 mean removed

9. 0-700m Palmer et al. (2010). "Future Observations for Monitoring Global Ocean Heat Content" in Proceedings of OceanObs’09: doi:10.5270/OceanObs09.cwp.68

10. 0-100m 0-300m 1993-2007 mean removed 0-700m 0-1500m

11. 0-3000m 0-4000m 1993-2007 mean removed

12. Summary so far.. Analyses show good consistency for the 0-100m layer. This is a useful check and re-assures me that there are no gross errors For deeper layers the analyses being to diverge. Some products appear to show a large ocean heat content gain (ARMOR3D, ECDA, MOVEC, MOVEG2) – is this model “spin-up”? Are we seeing a range of responses to volcanic eruptions in the subset that span the historical eruptions? “To do” and open questions.. Not all groups who have submitted data are present. I will work with data providers to resolve this a.s.a.p. Investigate the spatial trends and differences among the analyses Amplitude of the seasonal cycle – spatial maps Further comparison with model-free analyses - GSOP is well placed to do this Consideration of the depth structure of ocean heat uptake (c.f. Magdalena's presentation)

13. Xue et al. (2012) J. Climate, 25, 6905–6929.doi: http://dx.doi.org/10.1175/JCLI-D-11-00542.1

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