Changes to the Met Office seasonal prediction system

The dynamical seasonal prediction system used to produce the global forecast products displayed on these pages is being upgraded.

GloSea5 - July 2013

Products from the new system will be made available around 15 July 2013 in the following way:

  • Products with an issue date of July will be derived from the new system, GloSea5;
  • Products for all future dates will be derived from the new system until further notice;
  • Forecasts issued prior to July 2013, based on the former system (GloSea4, see below) will remain in place on the website;
  • Corresponding changes will be made to the verification information.

The main improvements in the GloSea5 system are listed below:

  • Improvements to the model horizontal resolution for both the atmosphere and ocean components: the new atmosphere and land surface resolution is 0.833 ° by 0.556 ° (~50 km in mid-latitudes); the new resolution for the ocean and sea ice components is 1/ 4°;
  • Upgrade to ocean data assimilation: the new system uses NEMOVAR.

Upgrade to GloSea4 - November 2010

Products from the upgraded system will be made available on 3 December 2010 in the following way:

  • Products with an issue date of November 2010 will be removed and replaced with equivalent products from the upgraded system;
  • Products for all future dates will be derived from the upgraded system until further notice;
  • Forecasts issued with the former system prior to November 2010 will remain in place on the website;
  • Corresponding changes will be made to the verification information.

The main changes made to the GloSea4 system are listed below:

  • Improvements to the coupled-model (HadGEM3) physics, including a scheme to assimilate sea-ice concentrations: sea-ice in both forecast and hindcast mode, is now initialised from observed values rather than climatology;
  • Improvements to the model resolution for both the atmosphere and ocean components: the new atmosphere resolution is ~120 km in the horizontal and 85 levels (improving resolution of the stratosphere); the new ocean resolution is 1 ° and 75 levels. The ocean-atmosphere coupling frequency is 3 hours;
  • The hindcast period used has been updated to a more recent period, 1996 to 2009.

Last updated: 12 July 2013