Seasonal and climate models
Configurations of the Unified Model for seasonal, decadal and centennial climate predictions run at the Met Office.
These are usually lower resolution than the models used for day to day weather forecasting, and include ocean and sea-ice components coupled to the atmosphere model in order to represent the full coupled climate system. Additional processes associated with atmospheric chemistry and the ecosystem are included in "Earth System" configurations only (due to computational cost).
Seasonal and climate configurations of the Unified Model
Current operational seasonal and climate configurations of the Unified Model are indicated in the table below, with higher horizontal and vertical resolution versions under development.
| Configuration | Atmosphere Resolution | Ocean Resolution | Initial Conditions | Typical Run Length | |
|---|---|---|---|---|---|
| Seasonal |
85 levels to 85 km 0.83° x 0.55° |
75 levels 0.25° x 0.25° |
Atmos: Met Office global analyses Ocean and sea ice (concentrations): data assimilation based on |
42-member ensembles of ~7 month runs, updated monthly | |
| Decadal |
85 levels to 85 km 0.83° x 0.55° |
75 levels 0.25° x 0.25° |
Atmos: ECMWF global analyses Ocean: data assimilation of observed full fields |
10-member ensembles of ~5 year runs, updated annually | |
| Centennial |
38 levels to 40 km 1.875° x 1.25° |
40 levels 1.0° x (1.0° increasing smoothly from 30°N/S to 0.33° at equator) |
Atmos: Met Office global analyses representative of current climate Ocean: Levitus present-day observed ocean conditions Sea ice: present-day conditions taken from previous climate model 20th century simulation |
~100s years | |
| Earth System |
38 levels to 40 km 1.875° x 1.25° |
40 levels 1.0° x (1.0° increasing smoothly from 30°N/S to 0.33° at equator) |
Atmos: Met Office global analyses representative of current climate Ocean: Levitus present-day observed ocean conditions Sea ice: present-day conditions taken from previous climate model 20th century simulation |
~100s years | |
|
Regional climate |
19 levels 0.22° x 0.22° (~24km) to 0.44° x 0.44° (~50km) Limited area |
- | Met Office global analyses; ECMWF reanalyses used at lateral boundaries |
~10 years, or up to 150 years for climate change runs | |
Climate change predictions
Centennial climate predictions from the Met Office Hadley Centre have been included in all of the climate change Assessment Reports of the Intergovernmental Panel on Climate Change. The named climate configurations used in these reports were:
- Second Assessment Report (1995): HadCM2
- Third Assessment Report (2001): HadCM3
- Fourth Assessment Report (2007): HadGEM1
- Fifth Assessment Report (2013): HadGEM2-ES, HadCM3