Multimodel assessment of the upper troposphere and lower stratosphere: Extratropics per Hegglin, M, Gettelman, A, Hoor, P, Krichevsky, R, Manney, G, Pan, L, Son, S, Stiller, G, Tilmes, S, Walker, K, Eyring, V, Shepherd, T, Waugh, D, Akiyoshi, H, Añel, J, Austin, J, Baumgaertner, A, Bekki, S, Braesicke, P, Brhl, C, Butchart, N, Chipperfield, M, Dameris, M, Dhomse, S, Frith, S