GOVST 5 Meeting, Beijing, 13-17 October 2014

CLIVAR-GSOP reportin association with GOV ST

F. Hernandez

M. Balmaseda, Y. Fujii, K. Haines, T. Lee, Y. Xue

• Outcomes from the ongoing ORA-IP project• New real time ORA intercomparison

GOVST 5 Meeting, Beijing, 13-17 October 2014

CLIVAR-GSOP/GODAE OceanView Ocean Reanalysis Intercomparison

(ORA-IP, 2012-2014)

Reanalysis production is an on-going activity, following the feedbacks and outcomes of GSOP 2006-2009

New vintages are produced approximately every 5 years Improved quality controlled observations (XBT corrections, Argo

corrections and black lists) Improved and extended forcing fluxes Improved models and methods

We need to assess uncertainties among ocean reanalyses (through intercomparison and validation with independent data) due to model errors and bias, and observing system reliability over time

benefits of the ensemble approach both to improve the estimation of the signals and to provide uncertainty ranges

We need to facilitate the use of ocean reanalyses by other communities

We need to prepare for quasi-real time monitoring of the ocean

Courtesy of M. Balmaseda

GOVST 5 Meeting, Beijing, 13-17 October 2014

See a summary athttp://www.clivar.org/sites/default/files/Exchanges/Exchanges_64.pdf

More than 20 participating ORA’s and observed products:• some coupled• from 1° to ¼° resolution• different models, forcing, DA

Balmaseda et al, The Ocean Reanalyses Intercomparison Project (ORA-IP) JOO, accepted 2014

Ocean Heat Content by Matt Palmer

0-300m 0-700m

0-1500m 0-4000m

Less dispersion near the surface, in particular after 2002 (Argo)

DA altimetry since 1993

Steric Sea Level (SSL) by Andrea Storto

Contours indicate 95% confidence level

• The Intercomparison has helped to identify errors in some reanalyses products.

• The Intercomparison has also helped to identify errors in some GRACE products.

• Ensemble of reanalyses (REAENS) outperforms obs-only products (OAENS) (although comparison is not fair, since OAENS has less ensemble members).

• Partition btw haline/thermal component less clear among ORAs, as well as contribution at depth of the SSL trend

Correlation REAENS vs alti-GRACE

Cx REAENS – Cx OAENS

ORA water mass representation impact !

Sea Level by Fabrice Hernandez

SL index (0-12°N, 84-108°W)

SL index validation against SL-CCI

Correlation of ORA-EM (detrended and no seas. Cycle) Against Tide Gauges

• GSLR not assessed• Good performance of

ORA assimilating satellite altimetry

• ORA-EM smooth out noisy signals

• Valuable for regional sea level indices

• 97-98 Niño, Kelvin Waves

• 3-4 mm/y negative trend (strengthening Trade Winds)

• Consistent pattern, small spread

What can we learn from ORA when altimetry derived

products look more reliable ?

Mixed Layer Depth (MDL) by Takahiro Toyoda

Validation of MLDs from syntheses without model (EN3v2a, ARMOR3D) and ensemble mean of 17 reanalyses (ENSMEAN) Differences from MILA-GPV deduced from individual TS profiles of Argo data(x)Month-(y)latitude diagram for temporal (2005-2011) and zonal mean values

• Issues on the way MLD is computed, monthly time scales and vertical averaging: Smaller negative biases due to higher vertical resolution in the reanalyses

• Negative biases in syntheses without model due to vertical, horizontal (within a grid) and temporal averaging of profiles (c.f., de Boyer Montegut, 2004)

• Model biases in ensemble members largely canceled out in ENSMEAN

Strongly dependent on forcing errors and vertical mixing,

technical issues

Surface Fluxes and Transports by Maria Valdivieso

Most ocean model products have positive bias into the ocean (mean net surface heat flux into the ocean).The bias is often smaller than observational products, e.g., ISCCP/OAFlux and NOC2.0

The bias is comparable than atmospheric reanalyses in some cases. Interannual variations are usually few Wm-

2 ,smaller than the bias.

Time mean Global net surface Heat Flux and increment corrections

Interannual Std

Negative contribution of assimilation increments (removing heat from the ocean on global average)Total neat heat flux still positive 2 W/m2,

consistent with net ocean warming

ORA integrated assessment

Mean March Sea Ice Thickness: 2007

Too thin

ICESat

GFDL UR025.4

GLOSEA5 GMAO

MOVEG2MOVECORE

CMCC

ERAN G2V3Too thick

Sea Ice by Greg SmithMean March Sea Ice Thickness: 2007

(Predictor for seasonal sea ice extent)

LIM too thickCICE too thinLarge variability central Arctic/Siberia

Large discrepancies among ORAs

Summary and Outlook1. Open Assessment of products

• Ensemble mean appears to be a robust estimation• Ensemble spread useful to estimate structural uncertainty• Some relevant indices have been defined

NEXT step: Dissemination of results in scientific literature. GODAE Special Issue in JOO. Summary paper

Special Issue in Clim Dyn. Individual contributions2. We need to facilitate data access and usage:

• Data repository of data entering the intercomparison (unified grid and format)

• Data repository with ensemble mean and spread. With a version number to assess progress in the future. ORAIP v1

3. Monitoring of relevant indices still pending.4. Balance between “Ensemble of All System” versus “Best

Systems” needs to be addressed.

Courtesy of M. Balmaseda

1. Intercomparison brought to assess the reliability of multi model ensemble approach

JOO paper accepted, Clim Dyn. Contribution ongoing

2. Under discussion: CMIP like repository (only ENS or all ORA?)

3. Highly expected from some GOV participant… ongoing acions

4. Multi-model ensemble approach versus ensemble from individual systems: common issues with Native Class 1 consensus forecasting approach

Extend CLIVAR-GSOP/GODAE OceanView Ocean Reanalyses Intercomparison Project (ORA-IP) into real time

Assess uncertainties in temperature analysis of tropical Pacific in support of ENSO monitoring and prediction

Explore any connections between gaps in ocean observations and spreads among ensemble ORAs

Articulate needs for sustained ocean observing systems in support of TPOS2020

Monitor signal-to-noise ratio in the global ocean temperature, 300m heat content, depth of 20C isotherm Yan Xue Climate Prediction Center 11

Real-Time Ocean Reanalyses IntercomparisonY. Xue, Y. Fujii, M. Balmaseda proposal

http://www.cpc.ncep.noaa.gov/products/GODAS/multiora_body.html

6 OOS, joining FOAM (UK-Met) and PSY3 (Mercator)

Duplicating with 1992-2013 climatology

-The ensemble mean (ensemble

spread) can be used to measure

signal (noise).

- The signal-to-noise (SN) ratio is

relatively low in the western (central-

eastern) Pacific where negative

(positive) anomalies presented.

- The low signal-to-noise ratio may

be partially attributed to the sparse

observations in those regions.

GODAS

Signal, Noise and Signal-to-Noise Ratio (1985-2013)

Influences of ocean observations on spread among ocean reanalyses

Warm Water Volume Index Derived

From Ensemble Mean of Ocean Reanalyses

MJ 82

MJ 97 MJ 14

Jun 2014Jun 1997 (DJF NINO3.4=+2.2)

Jun 1982 (DJF NINO3.4=+2.2)

Jun 1991 (DJF NINO3.4=+1.6)

Jun 2009 (DJF NINO3.4=+1.6)

Jun 2006 (DJF NINO3.4=+0.7)

Jun 2002 (DJF NINO3.4=+1.1)

MJ 02MJ 91 MJ 06 MJ 09

- Warm Water Volume averaged in May-June 2014 is similar to that in May-June of 2009, 2006 and 1991. However, the pattern of subsurface temperature anomaly averaged in 5S-5N in Jun 2014 is mostly similar to Jun 1991.

82/83 91/92 97/98

02/03 06/07 09/10

Upper 300m Heat Content Anomaly Averaged in 5S-5N

12/13

14/15

GOVST 5 Meeting, Beijing, 13-17 October 2014

CLIVAR-GSOP together with GOV• The GOV OSEval-TT workshop is hosting CLIVAR-GSOP discussions

next december

• The ORA-IP is a success, we are learning a lot from it (obs, model, forcing, DA limits and errors), and it will continue

• The starting real time ORA intercomparison is:– Proposed to be endorsed and supported by GOV IV-TT– Participants are operational centres involved in GOV– The climate monitoring and ocean state reporting activity corresponds to what

GOV OOC wanted to implement by participating to the CLIVAR-GSOP ORA-IP project

• Near Real Time Ocean climate monitoring:– Could it be a GOV showcase, in association with OOPC?– There is an obvious link with seasonal prediction (at least for ENSO), which

was not addressed specifically inside GOV– Status of the ocean observing system to be linked with OSEval-TT