Auxiliary Material for
“Distinctive climate signals in reanalysis of global ocean heat content”
by M. A. Balmaseda1, K. Trenberth2 and E. Kallen1
1. European Centre for Medium Range Weather Forecasts, Shinfield Park, Reading RG2
9AX, UK
2. National Center for Atmospheric Research, Boulder, CO 80307, USA.
Geophysical Research Letters
Introduction
TextS01 contains 6 Supplementary Figures and Legends S01–S06, Supplementary Table S01,
and Auxiliary Discussion Text.
Figure S01: Evolution of ORAS4 OHC (1022J) for different ocean layers: the upper
300m (grey), 300-700m (blue), and below 700m (purple).
Figure S02: (left) Upper 700m OHC from NODC (yearly values, updated from Levitus
et al. (2012), http://www.nodc.noaa.gov/OC5/3M_HEAT_CONTENT/), from CSIRO (
updated from Domingues et al. (2008),
http://www.cmar.csiro.au/sealevel/sl_data_cmar.html, 3-year running mean) and from
ORAS4 (12-month running mean). (right) Upper 2000m OHC from NODC (5-year
running mean) and from ORAS4 (total column, 12-month running mean). The magnitude
of the long-term warming is comparable, but the interannual variability in the
observation-only estimates is weaker. It is suppressed from the Lv2012 0-2000m OHC
by the 5-year running mean (right), but more readily apparent for the upper 700m (left).
Here the variability in Domingues08 is also damped by the 3-year running mean.
Figure S03: (left) Total OHC in ORAS4 (shaded purple curves) and in an equivalent
experiment without bias correction (grey). (right) Vertical profile of the linear trend (19752009) in global temperature (shading represents 1-standard deviation from the linear trend).
Without bias correction the 700m-2000m depth range exhibits stronger warming trend. The
total OHC converges after 2001 when Argo data play a major role. See also figure 4 of
BMW13.
Figure S04: Zonal wind stress in the tropical Pacific (30°S-30°N) from the 5 ensemble
members in ORAS4. The trades winds have noticeably intensified in the last decade, after the
sharp La Niña 1998-1999 episode. There is also a pronounce minimum after 2007, again in
La Niña conditions in 2008. Units are Nm-2.
Figure S05: (left) Surface fluxes from atmospheric reanalyses (red), from total ocean
assimilation (blue) and residual black). right) The assimilation heat flux (blue) is the sum of
SST relaxation flux (green), and subsurface data (including altimeter), decomposed into bias
correction (pink) and assimilation increment (brown). Units are W m-2.
Figure S06: Spatial distribution of the linear trend in OHC for depths above (left) and below
700m (right), for the periods 1975-2009 top); 1993-2009 (middle); and 2000-2009 (bottom).
The trend for the global ocean is given at top of each panel in Wm-2.
Table S01: Heat flux (W/m2) inventory from the terms contributing to the OHC of a single
ORAS4 ensemble member for the whole period and stratified by decades. The meaning of the
terms is explained in auxiliary section S02.
Auxiliary Text Contains sections and references
S01: Auxiliary Methods
This section provides more details of the assimilation method used in the production of
ORAS4.
S02: Inventory of data assimilation terms
This section provides a discussion on the inventory of terms contributing to the ocean heat
summarized in FigS05 and supplementary table S01.