Anna Litvak-Hinenzon, Vered Rom-Kedar Parabolic resonances in near integrable Hamiltonian systems (3013K, Gzipped PostScript, Latex2e) ABSTRACT. When an integrable Hamiltonian system, possessing an $m$-resonant lower dimensional normally parabolic torus is perturbed, a parabolic $m$-resonance occurs. If, in addition, the isoenergetic nondegeneracy condition for the integrable system fails, the near integrable Hamiltonian exhibits a flat parabolic $m$-resonance. It is established that most kinds of parabolic resonances are persistent in $n$ ($n\geq 3$) d.o.f. near integrable Hamiltonians, without the use of external parameters. Analytical and numerical study of a phenomenological model of a 3 degrees of freedom (d.o.f.) near integrable Hamiltonian system reveals that in 3 d.o.f. systems new types of parabolic resonances appear. Numerical study suggests that some of them cause instabilities in several directions of the phase space and a new type of complicated chaotic behavior. A model describing weather balloons motion exhibits the same dynamical behavior as the phenomenological model.