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Detailed model description

Page containing details for all model configurations available in S2S since the project start => JMA model description

Overview of the model changes

Model version

Implement. date in S2S

Time range

Resolution

Ens. Size

Frequency

Re-forecasts

Rfc period

Rfc frequency

Rfc size

Ocean resolutionActive Sea IceRemarks

GEPS2103

30/03/2021d 0-34Tl479/Tl319L12849+1

weekly

(Wed) lagged eps created from 2 runs (*5)

fixed

1981-2020

(model version date 31/03/2021)

2/month

(always on the 15th and the last day of month *3)

12+1N/AN/A

GEPS2003

24/03/2020d 0-34Tl479/Tl319L10049+1

weekly

(Wed) lagged eps created from 4 runs (*4)

fixed

1981-2010

(model version date 31/03/2020)

2/month

(always on the 15th and the last day of month *3)

12+1N/AN/A

GEPS1701

22/03/2017d 0-34Tl479/Tl319L10049+1

weekly

(Wed) lagged eps created from 4 runs (*4)

fixed

1981-2012

(model version date 31/01/2017)

3/month

(always on the 10th, 20th and the last day of month *3)

4+1N/AN/A

GSM1403C

06/01/2015d 0-34Tl319/L6024+1

2/week

(Tue, Wed)

fixed

1981-2010

(model version date 04/03/2014)

3/month

(always on the 10th, 20th and the last day of month *3)

4+1N/AN/A

Description of the main changes

GEPS2103

  • The new JMA real-time ensemble system includes 2 start dates (Tuesdays and Wednesdays at 12Z) instead of the previous 4 runs (see the description in GEPS1701 below). The ensemble size is 25 members for both days and the resulting new lagged ensemble for S2S is a single 50-member ensemble starting on Wednesdays at 12Z.
  • operational from  

GEPS2003

  • two-tiered Sea Surface Temperature (SST) method is implemented in addition to improved physical parameterization schemes in the forecast model. In this approach, the oceanic lower-boundary condition is relaxed from the anomaly-fixed SST to the ensemble-mean SST based on prediction using the Seasonal Ensemble Prediction System (Seasonal EPS).

  • There is no change in the number of fields for real-time data but the number of reforecast ensemble members is  increased from 5 to 13, and the number of frequency is reduced from 3 to 2 per month.

  • operational from  

GEPS1701

  • The new JMA real-time ensemble system includes 4 start dates (Tuesdays at 00Z and 12Z + Wednesdays at 00Z + 12Z) instead of the previous 2 only (25-member ensembles starting on Tuesday 12Z and Wednesday 12 Z). The ensemble size is 13 members for Tuesdays 12Z and Wednesdays 00 and 12Z and 11 members for Tuesdays 00Z. Because the usage of such data  would be very difficult for users, a lagged ensemble  is being created for S2S archive instead. The resulting new lagged ensemble is a single 50-member ensemble starting on Wednesdays at 12Z
  • operational from  
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