We present a semi-empirical model for the reconstruction of polar winter descent of reactive nitrogen (NO_y) produced by energetic particle precipitation (EPP) into the stratosphere. It can be used to prescribe NO_y in chemistry climate models with an upper lid below the EPP source region. We also found a significant reduction of the EPP-generated NO_y during the last 30 years, likely affecting the long-term NO_y trend by counteracting the expected increase caused by growing N₂O emission.