Overview
• Northern hemisphere extra-tropics
• El Niño
Seasonal Climate – Winter 2009-10
Mike Blackburn
Seasonal Climate Discussion, 14 April 2010
Winter in the UK DJF averages
Reading: Tmax, Tmin DJF 0910
Temperature
• Mean 1.6°C
• 2.1°C below 1971-2000 average
Precipitation (%)
• Total 249mm
• 75% of average
Mike Stroud
Surface air temperatureDecember 2009 January 2010 February 2010
DJF average
• Persistence
• Warm Arctic + sub-tropics
NOAA ESRL
Percentage of days with significant anomaly of same sign (>15m)
Z500 – persistence….
NOAA Climate Diagnostics Bulletin
Persistence
(%)
December 2009 January 2010 February 2010
Monthly Mean
(dm)
First month for which 60% anomaly correlation reached 10 days for Europe and northern hemisphere
…and February forecast skill
www.ecmwf.int
Arctic Oscillation (AO)
North Atlantic Oscillation (NAO)
Z500
PMSL
PMSL anomaly
NCEP reanalysis DJF 2009/10
Z500 anomaly
NAO and AO time-series
NOAA CPC DJF average
Arctic Oscillation (AO)
North Atlantic Oscillation (NAO)
Z500
PMSL
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