A contribution of nonlinear tidal phenomena to formation and long-term variability of climatically significant fields of the Euro Arctic seas (Norwegian, Greenland, Barents, White and Pechora seas) is estimated in our research. Characteristics of residual tidal phenomena are received by numerical simulations: residual tidal level achieves significant values (up to 16 cm.) in several regions of Euro Arctic seas (White Sea, areas around Svalbard, Spitsbergen bank, and along seaside of the Russian Arctic). Maps of residual tidal currents were built: intensive residual currents are observed in the White Sea, Pechora Sea, regions near Svalbard, Spitsbergen bank, Bear and Hope islands. A possibility for adjunction of long-period tides by energy of main diurnal and semidiurnal tides is reported; amplitudes of nonlinear long-period tidal waves were evaluated. The impact of nonlinear components of motion and continuity equations on formation of different oceanographic phenomena was determined by means of numerical experiments: it was found that convective nonlinearity noticeably contributes into formation of climatically significant nonlinear tidal phenomena (residual tidal level and currents, and low-frequency tidal waves). On example of the White Sea, it was determined that the tidal phenomena play important role in formation of thermohaline structure of tidal sea waters.