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Seamless prediction systems prove potential for skillful Arctic sea-ice forecasts far beyond weather time scales IUP Seminar Bremen, May 4 th , 2018 Lorenzo Zampieri Alfred Wegener Institute Outlook Predictability and ensemble forecasting


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Seamless prediction systems prove potential for skillful Arctic sea-ice forecasts far beyond weather time scales

IUP Seminar Bremen, May 4th, 2018 Lorenzo Zampieri Alfred Wegener Institute

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Outlook Predictability and ensemble forecasting Research Motivation The S2S Prediction Project Verification metrics Predictive skills Dynamical models vs Climatology

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Predictability and Ensemble Forecasting

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A simple set of equations… !" !# = −&" + &( !" !# = −") + *" − ( !) !# = "( − +)

Lo Lorenz, E. N. (1963) De Dete termi rministic no nonp nper eriodic fl flow.

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…with an interesting solution

J.

  • J. Sl

Sling ngo an and T.

  • T. Palmer (2011)
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Ensemble Forecasting

J.

  • J. Sl

Sling ngo an and T.

  • T. Palmer (2011)
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Research Motivations

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Im Images from the YOPP PP Pr Promotional Video

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Im Images from the YOPP PP Pr Promotional Video

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S2S

Sub-seasonal to Seasonal Prediction Project

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The S2S timescale

Im Image from the S2S Pr Promotional Video

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The S2S Database

  • Coupled models from operational weather

forecast centers

  • Ensemble forecasts
  • Dynamical sea ice components
  • Assimilated sea surface temperature and

sea-ice concentration

  • Long temporal coverage (25 years)

UK Met Office ECMWF KMA CMA Météo France NCEP

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Verification Metrics

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The sea-ice edge position

Sea-ice edge Observation Sea-ice edge Model

Integrated Ice Edge Error IIEE = " + $

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The Spatial Probability Score Ensemble sea-ice forecasts Probabilistic verification metric required

Spatial Probability Score !"! = $

%

('( − '*), -% Spatial Probability Skill Score !"!! = . − !"! !"!/012

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Ensemble Forecasting

J.

  • J. Sl

Sling ngo an and T.

  • T. Palmer (2011)
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Methods Summary

Ensemble S2S sea-ice forecasts

UKMO ECMWF KMA CMA MF NCEP

Verification against satellite observations through the SPS Forecast SPS compared with the climatological CSPS Assessment of the forecast predictive skills Evaluation of the forecast errors and biases

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Skills of S2S forecast systems

  • ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Lead Time [Days] 10 20 30 40 50 60 0.25 0.75 1 SPS [106฀km2] 0.5

ECMWF UKMO KMA NCEP CMA (out of range) MF ECMWF Pres. Climatology

  • ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●

Lead Time [Days] 10 20 30 40 50 60

  • 0.5

0.5 1 SPSS

Results averaged over 12 years

  • f hindcasts (1999-2010)
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Forecasting the 2007 minimum

NCEP Day 30 - 2007.09.15 MF Day 30 - 2007.09.13 CMA Day 30 - 2007.09.15 ECMWF Pres. Day 30 - 2007.09.16 ECMWF Day 30 - 2007.09.15 KMA Day 30 - 2007.09.15 UKMO Day 30 - 2007.09.15

Sea Ice Probability

15% sic OSI-SAF Climatology 2007.09.16

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The CSPS seasonal cycle

  • Time

Jan 01 Apr 01 Jul 01 Oct 01 Jan 01 0.25 0.5 0.75 1 CSPS [106฀km2]

  • Time

Jan 01 Apr 01 Jul 01 Oct 01 Jan 01 20 40 60 80 100 100 80 60 40 20 ME [%] AEE [%]

  • Time

Jan 01 Apr 01 Jul 01 Oct 01 Jan 01 20 40 60 80 100 100 80 60 40 20 U [%] O [%]

Skills of the climatological forecasts based on the previous 10 years of observations 15/09/2007 forecast is based on: 15/09/1996, 15/09/1997, … , 15/09/2006

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ECMWF & UKMO

−2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20

Initial

−2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20

SPSS AEE and ME O and U ECMWF UKMO

  • −2.0
−1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 SPSS
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 ME [%] AEE [%]
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 U [%] O [%]
  • −2.0
−1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 SPSS
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 ME [%] AEE [%]
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 U [%] O [%] −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20
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CMA & Météo France

ECMWF Pres.

100

SPSS AEE and ME O and U CMA MF

  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 U [%] O [%] −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0
  • −2.0
−1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 SPSS
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 ME [%] AEE [%]
  • −6
−5 −4 −3 −2 −1 1 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 SPSS
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 U [%] O [%] 100
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 ME [%] AEE [%] −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20

Initial

−2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20
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Improvements in ECMWF system

−2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20

Initial

−2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20

SPSS AEE and ME O and U ECMWF

  • −2.0
−1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 SPSS
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 ME [%] AEE [%]
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 U [%] O [%] −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20

ECMWF Pres.

  • ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 ME [%] AEE [%]

Target Time

  • ● ●
  • ● ● ● ● ●
  • ● ●
  • ● ● ●
  • −2.0
−1.5 −1.0 −0.5 0.0 0.5 1.0 Jan 01 Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 SPSS −2.0 −1.5 −1.0 −0.5 0.0 0.5 1.0 −6 −5 −4 −3 −2 −1
  • ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ●
  • Jan 01
Mar 01 May 01 Jul 01 Sep 01 Nov 01 Jan 01 20 40 60 80 100 100 80 60 40 20 U [%] O [%]

N E W ! O L D !

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Improvements in ECMWF system

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Conclusions

  • Spread of predictive skills between different

forecast systems

  • Errors during the data assimilation and

relevant model biases affect the forecasts

  • Lack of model tuning
  • The ECMWF system shows encouraging
  • results. Predictive skills after 46 days.
  • Assimilation of new sea-ice thickness
  • bservations could be beneficial