Heat Flux Intercomparison

Maria ValdiviesoDepartment of Meteorology,

University of Reading, UK

▶ Focus on surface heat fluxes

▶ Timeseries comparison at buoy sites

m.valdiviesodacosta@reading.ac.uk

ProductsSurface

Heat FluxAssimilation

Heat Flux SST Time Frame

ECMWF-ORAS4 X X 1958- 2009

JMA-MOVEG2 X X X 1993-2011

JMA-MOVECORE X X X 1993-2011

Kiel-GECCO2 X X 1993-2010

NCEP-GODAS X X 1985-2010

Reading-UR025.4 X X X 1989-2010

Met Office-GloSea5 X X 1993-2010Mercator-

GLORYS2V1 X X X 1993-2009GFDL-ECDA (Coupled) X X 2004-2011

NCEP-CFSR (Coupled) X X 1985-2010

LEGI-MJM95 (Control) X X 1993-2009

Monthly mean data regridded onto the WOA grid Common period 2004 – 2009

▶Other flux data sets: ISCCP+OAFlux, NOC2.0, ERAI, NCEP –R2

Global Integrals

Surface heat fluxes from ocean reanalysis products averaged over the global ocean (common ocean-land mask). Fluxes are positive into the ocean. Units are in Wm-2

Products 1993 – 2009 2004 – 2009

ECMWF-ORAS4 4.99 ± 0.95 5.38 ± 0.47JMA-MOVEG2 7.90 ± 2.68 10.16 ± 1.97

JMA-MOVECORE 8.60 ± 0.54 8.65 ± 0.50Kiel-GECCO2 0.74 ± 0.64 0.31 ± 0.37NCEP-GODAS 0.10 ± 1.51 1.51 ± 1.29

Reading-UR025.4 3.99 ± 4.84 -0.14 ± 1.35Met Office-GloSea5 8.95 ± 3.36 5.36 ± 2.01

Mercator-GLORYS2V1 2.87 ± 2.26 0.56 ± 1.62GFDL-ECDA (Coupled) − 14.60 ± 1.28NCEP-CFSR (Coupled) 13.96 ± 2.14 14.21 ± 1.06LEGI-MJM95 (Control) 0.30 ± 0.72 0.17 ± 0.56

ISCCP + OAFlux 25.04 ± 3.61 22.28 ± 0.67NOC2.0 16.80 ± 2.86 15.01 ± 2.63

ECMWF-ERAI 7.41± 1.27 7.32 ± 1.32NCEP-R2 1.66 ± 1.88 1.67 ± 1.77

Fluxes are positive into the ocean. Units are in Wm-

2

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Zonal Integrals

Mean 2004 - 09

Zonal IntegralsEquatorial heating in the middle of the range span by other products

Warming pattern in the SH underestimated at all latitudes

Heat loss north of20N seems reasonable

Northward heat transport - global

Also shown are the zonal integrals from Ganachaud and Wunsch (2003) and Lumpkin and Speer (2007) obtained from inverse analysis of WOCE sections

MHT as inferred from estimated surface heat fluxes

The mean transport due to the net heat uptake is ~ 2 PW, representing a non-zero heat storage in these ocean reanalyses

Mean 2004 - 09

Differences in Qsw

ISCCP ERAI NOC2.0 ECDA

168.28 ± 0.98

168.65± 0.51

164.61± 0.66

168.59± 0.41

Global averages over 2004 –2009. Units in Wm-2

Mean 2004 - 09

Cloud estimation from ships

Satellite-based Atmos reanalysis

Coupled reanalysis

SST Diff MapsHadISST (Rayner et al., 2003) combines in situ + satellite-based data

Mean 2004 - 09

Using NCEP-R2 + relaxation to weekly OISST

Using NCEP surface fields

Using COREII surface fields JMA Reanalysis surface fields

Using corrected ERAI Qsw

Assimilating Reynolds SSTs

OSTIA + real time GHRSST after 2008

Coupled Reanalyses

SST Diff Maps(cont.)

Mean 2004 - 09

Differences in the bulk

fluxesEddy-permitting +

Core bulk forcing using ERAI surface fields

Assimilating EN3 T/S profiles Assimilating SST + EN3 data

Assimilating SST + CORA dataNo data assimilation

Mean 2004 - 09

Comparison at buoy sitesCLIMODE: 38.5N, 65WKEO: 32.4N, 144.5EWHOTS: 22N, 158WNTAS: 15N, 51WTAO_w: 0, 165ETAO_e: 0, 110WSTRATUS: 25S, 85W

The underlying map is the annual mean (1993 – 2009) net surface heat flux from the OAFlux + ISCCP product  (Wm-2, positive downward) available at http://oaflux.whoi.edu

CLIMODE [38.5N, 65.0W]

CLICLMODE

ORAS4 MOVEC GECCO GODAS UR025.4

GloSea5

GLORYS MJM95 CFSR ECDA ENSEMBLEemble

MEAN -95.10 -159.17 -70.66 -47.81 -193.11 -196.44 -194.30 -162.88 -207.57 -167.89 -149.49

MeanDIFF 111.30 47.23 135.74 158.59 13.29 9.96 12.10 43.52 -1.17 38.51 56.91

STD 59.52 46.91 85.68 72.39 29.83 20.67 17.18 30.08 12.76 47.69 24.31

Monthly Climatology 2004 -

2009

Mean (ISCCP+OAF) = -206.4 ±22.4 Wm-

2

Sea Surface Temperatures

Interestingly, GODAS net heat flux is much too weak here (only -47 Wm-2), yet the SST is reasonably well reproduced.

GECCO2 is systematically too cold; MOVECORE is too warm

warm winters in 2008 and 2009

Monthly Climatology 2004 -

2009

KEO [32.4N, 144.5E]

Mean (ISCCP+OAF) = -101.35 ±16.2

Wm-2

KEOS ORAS4 MOVEC GECCO GODAS UR025.4

GloSea5

GLORYS MJM95 CFSR ECDA ENSEMBLE

MEAN -85.66 -125.97 -72.35 -124.23 -86.45 -82.62 -82.82 -76.60 -77.36 -116.83 -93.09

MeanDIFF 15.68 -24.62 29.00 -22.88 14.90 18.72 18.53 24.75 23.99 -15.48 8.26

STD 15.81 32.07 14.47 41.15 20.13 14.05 20.33 23.34 21.60 15.81 12.07

WHOTS [22.0N, 158.0W]

Mean (ISCCP+OAF) = +23.53 ± 9.96

Wm-2

WHOTS ORAS4 MOVEC GECCO GODAS UR025.4

GloSea5

GLORYS MJM95 CFSR ECDA Ensemble

MEAN +2.83 +9.22 -0.91 -0.98 +22.55 +15.33 +12.36 +0.08 -7.68 -8.60 +4.42

DIFF -20.70 -14.30 -24.44 -24.50 -0.98 -8.19 -11.17 -23.45 -31.21 -32.12 -19.11

STD 25.63 28.80 33.43 16.43 19.95 18.66 17.58 22.27 27.57 20.12 22.24

Sea Surface Temperatures

Surface Heat Fluxes

NTAS[15N, 51W]

Mean (ISCCP+OAF) = +40.25 ± 8.2 Wm-

2

NTAS ORAS4 MOVEC GECCO GODAS UR025.4

GloSea5

GLORYS MJM95 CFSR ECDA ENSEMBLE

MEAN +10.48 +4.09 -0.43 -1.83 -0.89 +6.13 +5.85 +9.71 +26.54 -23.80 +3.58

DIFF -29.77 -36.16 -40.69 -42.09 -41.14 -34.13 -34.41 -30.54 -13.71 -64.05 -36.67

STD 12.86 23.98 22.85 19.22 10.21 11.82 16.03 14.53 17.27 18.59 +12.99

STRATUS[25S, 85W]Mean (ISCCP+OAF)

= +52.56 ±8.83 Wm-

2

STRATUS

ORAS4 MOVEC GECCO GODAS UR025.4

GloSea5

GLORYS MJM95 CFSR ECDA ENSEMBLE

MEAN +13.44 +41.11 +19.64 +28.53 +16.10 +19.01 +3.85 +18.29 -4.92 +37.71 +19.28

MeanDIFF -39.12 -11.45 -32.92 -24.03 -36.46 -33.55 -48.71 -34.27 -57.48 -14.86 -33.28

STD 9.04 12.03 11.51 12.53 6.79 7.02 10.50 16.45 17.79 11.27 7.32

Sea Surface Temperatures

Surface Heat Fluxes

TAO_w[0, 165E]

Mean (ISCCP+OAF) = +56.68 ±21.62

Wm-2

STRATUS

ORAS4 MOVEC GECCO GODAS UR025.4

GloSea5

GLORYS MJM95 CFSR ECDA ENSEMBLE

MEAN +51.60 +28.91 +44.32 +52.20 +30.44 +42.95 +41.28 +27.99 +100.17 +44.47 +46.43

DIFF -5.08 -27.77 -12.36 -4.48 -26.24 -13.73 -15.40 -28.69 43.49 -12.21 -10.25

STD 7.06 7.34 8.10 12.12 9.70 8.03 7.74 11.19 7.23 7.55 6.06

TAO_e[0, 110W]

Mean (ISCCP+OAF) = +157.8 ± 9.86

Wm-2

STRATUS ORAS4 MOVEC GECCO GODAS

UR025.4

GloSea5 GLORYS MJM95 CFSR ECDA

Ensemble

MEAN +171.24 +125.87 +142.71 +99.82 +137.69 +132.59 +120.19 +108.99 +130.01 +155.24 +132.43

DIFF 13.44 -31.94 -15.09 -57.99 -20.11 -25.21 -37.61 -48.81 -27.79 -2.57 -25.37

STD 15.49 22.71 28.86 18.48 8.10 3.96 7.36 6.72 22.47 6.62 5.37

Mean (2004 -09) differences at buoy sites

ISCCP + OAFlux versus

Ocean Reanalyses

Ocean Reana Based minus

ISCCP+OAFlux

For CLIMODE, the overall biases (less cooling) result primarily from the winter months. Here, fluxes are sensitive to the model resolution.

In the central tropical Pacific (WHOTS) and tropical Atlantic (NTAS), fluxes show less warming during spring and summer.

In the south east Pac (STRATUS), fluxes show less warming in the summer months and more cooling in the winter.

For TAO locations, fluxes provide less warming all year round.

KEO, for the Kuroshio region, and TAO_w have the smallest differences.

Comparing with other flux products

Mean DifferencesProduct - (ISCCP + OAFlux)

Ocean Reana Based minus

ISCCP+OAFlux

Most ocean reanalysis show a positive imbalance in global surface heating (ensemble mean of ~ 4 Wm-2 over 1993-2009). This can be as large as 14 Wm-2 in coupled reanalyses. Generally, the imbalance is reduced as more observations become available after 2004.

Ocean reanalysis-based fluxes are biased low compared to ISCCP+OAFlux data at all buoy locations. Variability is generally well reproduced.

The result that the reanalysis SSTs compare reasonably well with HadISST data while the reanalysis-based fluxes are systematically too low compared to ISCCP+OAFlux data suggests that the models stratify the upper ocean too strongly. This may be a result of inadequate vertical mixing, weak advection, ...

Direct flux measurements are needed for further validation.

Summary