Intraseasonal oscillations in 15 atmospheric general circulation models: Results from an AMIP diagnostic subproject by Slingo, J, Sperber, K, Boyle, J, Ceron, J, Dix, M, Dugas, B, Ebisuzaki, W, Fyfe, J, Gregory, D, Gueremy, J, Hack, J, Harzallah, A, Inness, P, Kitoh, A, Lau, W, McAvaney, B, Madden, R, Matthews, A, Palmer, T, Park, C, Randall, D, Renno, N