We consider solutions to the two-dimensional incompressible Euler system with only integrable
vorticity, thus with possibly locally infinite energy. With such regularity, we use the recently developed theory of Lagrangian flows associated
to vector fields with gradient given by a singular integral in order to define Lagrangian solutions,
for which the vorticity is transported by the flow.
We prove strong stability of these solutions via strong convergence of the flow, under the only assumption
of L1 weak convergence of the initial vorticity. The existence of Lagrangian solutions
to the Euler system follows for arbitrary L1 vorticity.
Relations with previously known notions of solutions are established.
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