Submesoscale flows play an important role in ocean dynamics and climate, in particular by inducing large vertical velocities that enhance transport of mass, heat, gases and nutrients. Under certain conditions, these flows become unstable and can affect multi-scale ocean processes in ways that remain unknown. Ekman-Inertial Instability (EII) has recently been theoretically predicted to develop in submesoscale anticyclonic flows forced by a sudden change in surface wind stress. Because its time evolution initially follows that of the atmospheric conditions that triggers it, it may grow at a much faster rate than other common interior submesoscale instabilities, such as the symmetric or inertial instabilities. In this talk, I will present the basic 1D (vertical) description of EII, followed by a numerical study of its development in a 2D submesoscale current, and compare the results to those observed in classical inertial instability on one hand, and Ekman Layer dynamics on the other. Numerical simulations show that vertical pumping is triggered earlier, and the frequency of emitted internal waves is higher in EII unstable flows than in interior inertial instability.