The baroclinic component of the sea surface height, referred to as steric height, is governed by balanced geostrophic flows and unbalanced internal waves, and thus is the essential indicator of ocean dynamics. In this study, we assess respective effects of submesoscale motions and internal waves on steric height in a typical open ocean of Northeast Atlantic, founded on yearlong mooring and glider observations. Results show that the contributions of submesoscale motions and internal waves to steric height display a strong seasonal cycle and scale dependence, with the submesoscale component larger in winter and/or at horizontal scales of O(10 km). The internal waves are only able to take over in summer at scales of a few kilometers. Additionally, we compare the mooring-derived steric height time series to those derived from ocean gliders. The gliders can capture the low-frequency steric height variability, but appear to underestimate variability associated with internal waves. Overall, these findings provide insights into the issue of balance/unbalanced disentanglement and the design of calibration/validation field campaign for the upcoming next-generation satellite altimetry missions.