TITLE: Quasi-periodic H\'enon-like attractors in the Lorenz-84 climate model with seasonal forcing AUTHORS: H.W. Broer^(1), R. Vitolo^(1), C. Sim\'o^(2) (1) Department of Mathematics and Computing Science, University of Groningen, PO Box 800, 9700 AV Groningen, The Netherlands. (2) Departament de Matem\`atica Aplicada i An\`alisi, Universitat de Barcelona, Gran Via, 585, 08071 Barcelona, Spain ABSTRACT: A class of strange attractors is described, occurring in a low-dimensional model of general atmospheric circulation. The differential equations of the system are subject to periodic forcing, where the period is one year -- as suggested by Lorenz in 1984. The dynamics of the system is described in terms of a Poincar\'e map, computed by numerical means. It is conjectured that certain strange attractors observed in the Poincar\'e map are of quasi-periodic H\'enon-like type, {\it i.e.}, they coincide with the closure of the unstable manifold of a quasi-periodic invariant circle of saddle type. A route leading to the formation of such strange attractors is presented. It involves a finite number of quasi-periodic period doubling bifurcations, followed by the destruction of an invariant circle due to homoclinic tangency.