11-member RCM: Technical notes

• Technical note on projections of lightning

Key findings for lightning projections by 2080s (Medium emission scenario):

• Increase in the number of lightning days across the UK for all seasons.
• Projected increases are largest in summer. There is a north-south gradient of change with projected increase greatest in Scotland and Northern Ireland and smallest in south east England.
• Projected increases in autumn are largest over south England and Wales.
• Projected increases in spring and winter are small in all locations.

Download the Technnical note on Future change in lightning in the 11-member RCM (pdf, 4.5 MB).

• Technical note on snow projections

Key findings for snow projections by the 2080s (Medium emission scenario):

• Mean of the ensemble shows reductions in snow days in all regions.
• Largest reductions (typically >70%) occur in spring and autumn, with 40–70% reductions in winter.
• Reductions are smallest for the highlands of Scotland.
• The general pattern of heavy snow events shows large reductions but with greater intra-ensemble uncertainty.
• For the whole of the UK the reductions in heavy snow events may be >80% for winter and autumn while reductions in spring may be >40%.

Download the Technnical note on Interpretation and use of snow projections from the 11-member RCM (pdf, 1.7 MB).

• Technical note on fog projections

Key findings for fog projections by 2080s (Medium emission scenario):

• Projected changes in Winter are for a decrease in fog of >50% in north Britain and north Wales with increases of 1–30% over south and central England.
• Projected changes in spring are similar to winter in pattern but exhibit greater reductions.
• Projected changes for summer show large reductions across the UK.
• Project changes for autumn show reductions of 10–30% across the UK with greater reductions over the Scottish highlands.

Download a Technical note on the Future frequency of fog from the 1-member RCM (pdf, 3.6 MB).

• Technical note on surface wind speed

To address the lack of wind speed data available directly from the initial results from UKCP09, the Met Office have provided a Technical note that looks at the 11-member RCM. (pdf, 10.6 MB).

Key findings for surface wind speed under the Medium emission scenario:

• The 11-member RCM projections show lower than observed wind speeds over mountainous regions of Scotland and Wales, and higher than observed wind speeds over low-lying regions of England.
• The 11-member RCM provides time series and distributions of daily wind speed which replicate observed characteristics more realistically than in their driving global climate model simulations.
• Projected future changes in 30 year averages are relatively small within the RCM ensemble.
• Seasonal changes at individual locations across the UK lie within the range of –15% to +10%.  

A supplement to the wind speed note was added in October 2010. (pdf, 340 KB).