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

CPS3


19/02/2023d 0-34

Tl319L100

4+1

daily

fixed

1991-2020

(model version date 30/09/2022)

2/month (*3)

4+10.25° L60yes

6-hourly 10u/v added since  

the new reforecast set (model version date 30/09/2022) to be added soon

GEPS2203

15/03/2022d 0-34Tq479/Tq319L12849+1

weekly

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

fixed

1991-2020

(model version date 31/03/2022)

2/month

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

12+1N/AN/A

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

CPS3

  • General changes:
    • model changed from GEPS to  CPS coupled to an ocean model
    • output frequency for 10 metre wind and precipitation changed from 24 hour to 6 hour
    • increased number of vertical layers for  vertical velocity
    • Surface thermal radiation downwards parameter newly provided
  • Real-time forecasts changes:
    • ensemble size decreased from 25 to 5
    • frequency changed from twice a week (every Tuesday and Wednesday at 12Z) to every day (00Z)
    • total data size increased from 6.6 GB to 8.4 GB per week, but decreased from 3.3 GB to 1.2 GB per day due to change the ensemble size and a forecast frequency
  • Re-forecasts changes:
    • ensemble size decreased from 13 to 5
    • total data size for the re-forecast:  ~1TB
    • frequency (twice a month) and period (1991-2020) don't change, but start dates for each re-forecast year changed to:

      Jan: 16 and 31
      Feb: 10 and 25
      Mar: 12 and 27
      Apr: 11 and 26
      May: 16 and 31
      Jun: 15 and 30
      Jul: 15 and 30
      Aug: 14 and 29
      Sep: 13 and 28
      Oct: 13 and 28
      Nov: 12 and 27
      Dec: 12 and 27

GEPS2203

  • The horizontal resolution improved to about 40km up to 18 days and about 55km after that. The physical parameterization schemes and two-tiread SST method are improved.
  • operational from  

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