1. S. F. B. Tett, J. F. B. Mitchell, D. E. Parker, Hadley Centre for Climate Prediction and Research, UK Meterological Office, London Road, Bracknell, Berkshire RG12 2SY, UK.
2. M. R. Allen, Space Science Department, Rutherford Appleton Laboratory, Chilton, Didcot, OX11 0QX, UK.