CONCEPTS Global Ice-Ocean Prediction System

G. Smith, F. Roy, M. Reszka, Z. He, M. Buehner, C. Beaudoin, F. Dupont, J.-F. Lemieux, H. Ritchie F. Davidson, Y. Lu C.-E. Testut, G. Garric

CMOS, Montreal, May 31, 2012

Page 2 – July-4-12

Contents • What is CONCEPTS? • System d’Assimilation Mercator 2 (SAM2). • CONCEPTS Global Ice-Ocean Prediction System

– Evaluation of sea surface temperature (SST) forecasts – Evaluation of sea ice forecasts

• Ongoing and future developments

CONCEPTS

• Several new coupled systems under development as part of CONCEPTS

– Canadian Operational Network of Coupled Environmental Prediction Systems

• Tri-departmental collaboration – To develop coupled atmosphere-ice-

ocean forecasting systems • Model development

– Coupling GEM to NEMO (Nucleus for European Modelling of the Ocean)

• Collaboration with Mercator – French operational oceanographic group

CONCEPTS

Page 4 – July-4-12

The Need for a Canadian Ice-Ocean Forecasting Capability

• Weather prediction (days to seasons) • Sea ice prediction • Coast Guard Operations, e.g.: seal hunt, navigation • Fisheries and aquaculture management • Increased understanding of biological field observations • Attribution and mitigation of regional climate change impacts • Risk assessment for extreme events (sea level, waves,

currents) • Emergency response: Search and Rescue, dispersion of

pollutants

• Provide initial and boundary conditions to regional ice-ocean forecasting system for METAREAs

• Surface currents for emergency reponse (e.g. oil spill) • Initial conditions for monthly-seasonal coupled forecasts • Surface BC and IC for GDPS and coupling

Canada requires ice-ocean forecasts and information services for:

Specific Applications:

Hierarchy of CONCEPTS Systems

– Global ice-ocean analysis and forecasting system: ▪ Daily 1/4° resolution global ice-ocean analyses ▪ 10 day global ice-ocean forecasts

– Regional short-term forecasting system ▪ Domain covers N. Atlantic and Arctic at 3-8km

resolution ▪ Couple to Regional Prediction System

– Local forecasting systems ▪ Coupled atmosphere-ice forecasts at 2-5km

resolution

GEM 10km

Mercator-Océan

• 1/4° Global system (PSY3) – Operational since April 2008

• 1/12° Global system (PSY4) – Operational since Feb. 2011

• Produces weekly analysis and 10 day forecasts

• Global Forecasting Centre for EU MyOcean project.

• Presentation: – O. Le Galloudec (Fri., 2pm)

Mercator SAM2v1 Assimilation System

• Reduced-order Extended Kalman Filter (~SEEK) • Error covariance matrix is represented by an ensemble of

anomalies from a reference simulation: – ~240 multivariate modes with SSH, T, S, U, V

• Adaptivity: – Background error variance adjusted at each assimilation cycle to

be consistent with innovation statistics (Talagrand, 1998) • Localization applied

– e.g. Houtekamer and Mitchell, 2001 – Spatially-varying decorrelation radii used

• Spatially varying representivity error for all observation types

Weekly Analysis System

• Analysis produced every Wednesday from two 7-day cycles – 1 week period required to have sufficient data for optimality of analysis – 2 cycles required because in situ and altimetry data has ~24-72hr delay

T=0 T=-7d T=-14d T=+7 T=+10

G2 G1

Analysis time

10 day forecast

G2 analysis

Initialize with G2 analysis from previous week

T=0 T=-7d T=-14d T=+7 T=+10

G2 G1

Analysis time

10 day forecast

G2 analysis

Observations assimilated

• Sea level anomalies – AVISO SSALTO/DUACS

▪ Jason1, Jason2 and ENVISAT ▪ Near-coast representivity error

– Mean dynamic topography : ▪ Rio et al., 2005

• Sea surface temperature :

– NCEP SST RTG (~0.7C errors)

• In situ profile T and S data – E.g. Argo, XBT, TAO, CTD, … – CORIOLIS (Brest) – Quality Controlled by CLS (Toulouse)

• No sea ice data assimilation • No assimilation under sea ice

Page 13 – July-4-12

Global Ice-Ocean Prediction System (GIOPS)

• AIM: Produce daily analyses and 10day forecasts

• Based on Mercator operational system, with following modifications: – Updated SAM2 to use NEMOv3.1, with LIM2-EVP – Assimilate CMC-SST analysis (in place of RTG) with reduced obs error – SAM2 ocean analysis blended with CMC ice analysis – Weekly in situ and SLA update cycle, with daily SST and ice increments – Forced by CMC GDPS (33km) fields (in place of ECMWF)

• Status:

– Routine production of weekly ice-ocean analyses since Dec. 2010 (Mateusz Reszka)

– Evaluation of ice-ocean forecasts continues (Francois Roy) – Testing of daily analyses and improved ocean-ice blending underway

(Zhongjie He)

Comparison with Mercator PSY3V2R2

• Example for 2009-05-20

• Difference between analyses and CMCSST – GIOPS – CMCSST (top) – PSY3V2R2 – CMCSST (bottom)

• Same version of SAM2, diff due to:

– Assimilation of CMCSST instead of RTG – Reduced obs error to 0.3C (from ~0.9C) – Rejection criteria and treatment near ice – Blending with CMC ice analysis – CMC forcing instead of ECMWF

Comparison with Mercator PSY3V2R2

• Difference after 28 cycles (valid 20091125)

• Cycle started 20090513 • Impact of changes to

SST assimilation • Difference in SSS due to

relaxation timescale, atm forcing and ice assimilation

SST Analysis Error

• Background and Analysis minus CMC SST for 2009-07-29

• Analysis under-constrained near ice edge – larger errors in CMC SST near ice edge

• Results in cold bias in summer • Project underway to improve SST in MIZ

and blending with ice analysis – Zhongjie He

A-O

B-O

Evaluation of SST Forecast Error

FCST Day 10

CMC SST Pers. CMC SST Anom. Pers

RMS difference for forecasts for 2011-06-01 to 2011-08-31

• Difference between forecasts and CMC SST

• New 0.2° CMC SST analyses used

• Persistence of CMC SST Analysis

– Error in GDPS SST for Day 10

• Anomaly persistence of CMC SST

– Error in Day10 of monthly forecasts

FCST Day 1

Evaluation of SST Forecast Error: Comparison with AVHRR

• Differences taken between AVHRR SST data and hourly output from weekly forecasts (made at 00Z).

• Statistics accumulated for each day for forecasts made from June 1, 2011 to Aug. 24, 2011.

• Results shown for day 10 of forecasts (hours 216-240)

• Poor coverage in polar regions and due to cloud cover

Mean

Std. dev.

Number of comparisons

RMS difference with AVHRR and CMC SST

FCST-CMCSST

CMC SST Pers. - AVHRR CMC SST Pers. - CMCSST

Evaluated using day 10 of forecasts for 2011-06-01 to 2011-08-31

FCST-AVHRR

Regional RMS differences with AVHRR SST

• Forecasts beat persistence of SAM2 analysis for all regions

• Forecasts have lower RMS than persistence of CMC for North mid-latitudes

• SST clearly under-constrained in polar regions

Forecasts Persistence of SAM2 analyses Persistence of CMC analyses

Evaluated using forecasts for 2011-06-01 to 2011-08-31

Evaluation against IMS analyses

• IMS Analyses: – Interactive Multisensor Snow and Ice

Mapping System (NOAA-NIC) – Daily Northern Hemisphere ice analyses

on 4km grid (ice/water) – Assimilates : AVHRR, GOES, SSM/I

• Evaluation Methodology: – Interpolate model forecasts to IMS grid – Calculate contingency table values

using 0.4 ice concentration cutoff – Bin results on 1° lat-lon grid – Compare to persistence

IMS Ice IMS No ice

Forecast Ice

Hit ice False Alarm

Forecast No ice

Miss Hit water

Page 22 – July-4-12

Accumulated statistics for 5 day lead Jan-Dec, 2011 (52 forecasts)

Persistence of ice analysis Model forecasts

Misses

False Alarms

Ice? YIMS NIMS

YFcst Hit ice False

Alarm

NFcst Miss Hit

water

Page 23 – July-4-12

• Proportion Correct Ice – PCI= Hits ice / (Hits + Misses) – Skillful forecasts along ice

edge – Some errors near coast

• Proportion Correct Water – PCW= Hits water / (Hits water

+ False Alarms) – Small errors along ice edge – Correct lead formation near

coast

ΔPCI ( Fcst – Pers)

ΔPCW ( Fcst – Pers)

Accumulated statistics for 5 day lead Jan-Dec, 2011 (52 forecasts)

Ice? YIMS NIMS

YFcst Hit ice False

Alarm

NFcst Miss Hit

water

10 day forecast for 2011-02-05

Misses

False Alarms

Persistence of ice analysis Model Forecast

Ice? YIMS NIMS

YFcst Hit ice False

Alarm

NFcst Miss Hit

water

10 day forecast for 2011-02-05

Misses

False Alarms

Ice? YIMS NIMS

YFcst Hit ice False

Alarm

NFcst Miss Hit

water

Persistence of ice analysis Model Forecast

• Proportion Correct Ice – PCI= Hits ice / (Hits + Misses) – Skillful forecasts along ice

edge – Some errors near coast

• Proportion Correct Water – PCW= Hits water / (Hits water

+ False Alarms) – Small errors along ice edge – Correct lead formation near

coast

ΔPCI ( Fcst – Pers)

ΔPCW ( Fcst – Pers)

Accumulated statistics for 5 day lead Jan-Dec, 2011 (52 forecasts)

Ice? YIMS NIMS

YFcst Hit ice False

Alarm

NFcst Miss Hit

water

Plans for Global ice-ocean forecasting system

• Continue routine analysis production and evaluate analyses and forecasts

• Possible transfer to operations in 2012

Further Development: • Coupled atm-ice-ocean forecasting • Improve blending of SAM2 and 3DVAR ice analysis

system (Zhongjie He) • Evaluate use of Cryosat2 altimetry data

Page 28 – July-4-12

Merci!

• Main contributors & collaborators – Francois Roy, CMDN – Matteusz Reszka, CMDA – Jean-Marc Belanger, RPN-E – Frederic Dupont, CMDN – Gilles Garric, Mercator-Ocean – Jean-Francois Lemieux, RPN-E – Christiane Beaudoin, RPN-E – Fraser Davidson, DFO – Youyu Lu, DFO – Hal Ritchie, RPN-E – Mark Buehner, ARMA – Alain Caya, ARMA – Tom Carrieres, CIS – Zhongjie He, RPN-E – …

Extras…

Impact of coupling + SST I.C. on 96H T forecast DTa(h=0.995)

CPL –

GEM (constant CMC SST)

Mercator SST -

CMC SST

DSST at initial time

5(K)

-5

2(K)

-2

J-M Belanger

GODAE Intercomparison

• Global Ocean Data Assimilation Experiment (GODAE) comparison of global ocean forecasting systems

• BRAN/OMAPS: – 1/10° BODAS EnOI

• HYCOM(NRL): – 1/12 ° NCODA MvOI

• UKMet: – ¼ ° FOAM AC/OI

• Mercator: – ¼ ° PSY3 SAM2

Sea level anomaly Sea surface temperature

Zonal velocity Meridional velocity

Improvements to SAM2

• PSY3V3 released Dec. 2010 • Main modifications:

– Bias correction to T&S – New mean dynamic

topography used for SLA – Incremental analysis updating

• Significant impact on fit to insitu observations

• Example: 0-500m RMS of innovations for OND 2010

PSY3V2

PSY3V3

Bias in Radiative Forcing

• Compare GDPS-RF SW+LW radiation with GEWEX data

• Mean difference for May Hr21

– over years 2002-2007 • Errors present in SW of

more than 200 W/m2

iweb/~armngcs/Compare_RECAST_GEWEX.html

SW

LW

Bias in Radiative Forcing

• Compare GDPS-RF SW+LW radiation with GEWEX data

• Daily mean difference for May

– over years 2002-2007 • Errors present in SW on

the order of 50-100 W/m2

iweb/~armngcs/Compare_RECAST_GEWEX.html

SW

LW

ERA-Interim shows similar errors of smaller magnitude Courtesy G. Garric

SST Analysis Error

• Background and Analysis minus CMC SST for last week: 2012-02-15

• Analysis under-constrained near ice edge

– larger errors in CMC SST near ice edge • Results in cold bias in summer

A-O

B-O