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11-member RCM: technical notes

This page provides technical notes about the 11-member RCM.

1.    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 Technical Note on Future change in lightning [4Mb] in the 11-member RCM.

2.    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 reductions of 40-70% 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 Technical Note on  Interpretation and use of snow projections [1Mb] from the 11-member RCM.

3.    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 [3Mb] from the 1-member RCM.

4.    Technical note on surface wind speed

As wind speed data was not available directly from the initial UKCP09 results, the Met Office provided a  Technical note [1Mb] that provides information on surface wind speed from the 11-member RCM.

Key findings for surface wind speed under the medium emission scenario are:

  • 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%.  

supplement to the wind speed note [334kb] was added in October 2010.