Auxiliary Material for
Skilful Long Range Prediction of European and North American
Winters
Adam A. Scaife, A. Arribas, E. Blockley, A. Brookshaw, R.T. Clark, N. Dunstone,
R. Eade, D. Fereday, C.K. Folland, M. Gordon, L. Hermanson, J.R. Knight, D.J.
Lea, C. MacLachlan, A. Maidens, M. Martin, A.K. Peterson, D. Smith, M.
Vellinga, E. Wallace, J. Waters and A. Williams.
Met Office Hadley Centre, UK
Manuscript No: 2014GL059637R
Geophysical Research Letters, 2014
Introduction
This auxiliary material quantifies the skill of retrospective winter forecasts of slowly
varying elements of the climate system and winter climate around the Atlantic basin.
Correlations scores of winter mean climate variables are provided in table “ts01.doc”
for the period 1992/3 – 2011/12 and ensemble mean sea level pressure anomalies for
each of the twenty hindcast winters are provided in Figure fs01.tif.
1. ts01.doc: Seasonal forecast skill of predictions of ENSO, Sub-Polar Gyre
Temperature, Arctic Sea Ice in the Kara Sea and the tropical Quasi-Biennial
Oscillation. All scores are for DJF predictions of the ensemble mean of
forecasts beginning around November the 1st. Niño3.4 index is used for
ENSO (120W-170W, 5S-5N), the North Atlantic heat content is averaged over
(90W-0E, 50-60N) and the upper 500m of the ocean. The Kara Sea Ice is
defined by surface temperature proxy over (45-75E, 67-80N) and the QBO is
defined at 30hPa as the average of zonal winds between 5N and 5S.
2. fs01.tif: Winter sea level pressure anomalies in observations and individual
winter forecasts. Ensemble mean forecast anomalies and corresponding
observed winter (DJF) anomalies are plotted with a contour interval of 1hPa
for all winters from 1992/3 to 2011/12, relative to the mean of all 20 winters.