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Model Description

The information of BSISO prediction system history Show Hide

  • 2023.05 Extension of the forecast period for BSISO impact anomaly (3 → 4 weeks)
  • 2022.05 Climate normal period was changed from 1981-2010 to 1991-2020.
  • 2020.12 Posted information on BSISO prediction system history on website.
  • 2020.05 Launched new impact anomaly forecast and monitoring information based on BSISO index
  • 2020.05 Model descriptions posted on the website.
  • 2020.05 Started providing forecast index in digital data
  • 2016.07 Launched new heavy rainfall probability forecast based on BSISO index
  • 2015.05 CWB joined the APCC BSISO forecast.
  • 2015.05 Started providing monitoring index in digital data
  • 2014.05 Developed verification system and started providing verification for real-time forecast and cumulative forecast skill
  • 2014.05 Developed monitoring system and started providing BSISO monitoring index
  • 2013.07 ECMWF joined the APCC BSISO forecast.
  • 2013.07 Launched operational Boreal Summer Intraseasonal Oscillation (BSISO) forecasts with BOM and NCEP models

The information of 5 models participating in APCC BSISO forecast is listed below. The information can be changed if the corresponding operational model is modified.

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※ Please refer to "Model History" below for the participating model's changes and improvements since 2015.​


  1. Forecast System


USA, National Centers for Environmental Prediction 

 System name

CFS (Climate Forecast System)  

 First operational forecast run from APCC

July 2013

  2. Model Description

Atmospheric model





Vertical (top and type)


0.266 hPa

 3. Real-time forecast Configuration

Is the model coupled to an ocean model


If yes, please describe ocean model briefly including name of model, frequency of coupling, and any ensemble perturbation applied :

The oceanic component (MOM4) uses a zonal resolution of 0.5° and a meridional resolution of 0.25° between 10o S to 10o N, gradually increasing through the tropics until becoming fixed at 0.5° poleward of 30°S and 30°N, 40 vertical levels. Coupling frequency is 10 minutes between atmosphere and sea ice and 1 hour between atmosphere and ocean

Atmospheric initial conditions

Climate Forecast System Reanalysis (CFSR)

Ocean initial conditions

Climate Forecast System Reanalysis (CFSR)​ 

Forecast range

45 days

Update Forecast frequency


Ensemble size


How is the ensemble configured?

Initial conditions for ensemble members are created by adding small fractions (about 5%) of the differences between the initial date and previous days to CFSR analysis for atmospheric and oceanic prognostic variables.

 4. Hindcast Configuration

Hindcast Period


Produced on the fly or fixed?


Update Forecast frequency

Every day starting from 1 January of each year for the period 1999- 2010.

Ensemble size


Atmospheric initial conditions


Ocean initial conditions


Is the ensemble generation the same as for real-time forecast? If not, please describe the difference : 

 The 4 daily ensemble members were initialized directly from CFSR analysis every 6 hours from 00z, 06z, 12z, and 18z. 

 5. More information

Main reference or URL

Focal point (name/e-mail)

 Wassila Thiaw, Miliaritiana Robjhon, Vadlamani Kumar,,

CFS : National Centers for Environmental Prediction - Climate Forecast System
GFS : National Centers for Environmental Prediction - Global Forecast System​
ECM : European Center for Medium Range Weather Forecasts - Ensemble Prediction System
CWB : Taiwan's Central Weather Bureau - Taiwan CWB 1-tier Global Atmosphere-Ocean Coupled Forecast System 
BOM : Australian Bureau of Meteorology - Australian Community Climate and Earth-System Simulator Seasonal 1