Changes to the Met Office seasonal prediction system

Up to date news releases from the Met Office.

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

GloSea5-GC2 - February 2015

In February 2015 a new configuration of the coupled model was implemented in the GloSea5 prediction system; products from the new system will be made available around 10 February 2015 in the following way: 
 

  • Products with an issue date of February will be derived from the new system, GloSea5-GC2;
  • Products for all future dates will be derived from the new system until further notice;
  • Forecasts issued prior to February 2015, based on the former system (GloSea5, see below) will remain in place on the website;
  • Corresponding changes will be made to the verification information.

All future references to this new system in the context of real-time forecasts and hindcasts will use the name GloSea5, rather than the full GloSea5-GC2, unless in the context of comparisons with the previous version of the system when the distinction will be clearly made.     

The main change in GloSea5-GC2 is the implementation of a new configuration of the coupled model (GC2.0), which consists of modular component configurations Global Atmosphere 6.0 (GA6.0), Global Ocean 5.0 (GO5.0), Global Sea Ice 6.0 (GSI6.0) and Global Land 6.0 (GL6.0). Key scientific advances to each of these constituents are:

  • GA6.0 - Implementation of new dynamical core ENDGAME
  • GO5.0 - Improvements to oceanic vertical mixing scheme to improve the mixed layer representation of the world's oceans, which is important to seasonal forecasting, marine ecosystems, and many other aspects of the climate system. Changes have also been made to the NEMOVAR assimilation scheme to improve the initialisation of sub-surface temperature and salinity.
  • GSI6.0 - Improvements to the albedo and surface roughness of the sea ice to achieve a more realistic seasonal cycle of sea ice.

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: 9 February 2015