Empirical Modeling of the Redshift Evolution of the [NII]/H$\alpha$ ratio for Galaxy Redshift Surveys

We present an empirical parameterization of the [NII]/H$\alpha$ flux ratio as a function of stellar mass and redshift valid at 0 43.0 and systematically under-estimated by ~50 at log(L) < 42.5 at redshifts z ~ 1.5. This has implications on the prediction of H-alpha emitters for Euclid and WFIRST. We also study the impact of blended H$\alpha$ and [NII] on the accuracy of measured spectroscopic redshifts.