Evaluation of the Budget of Local Sea Level Trends Along the Coast of Canada and Northern USA During 1958–2015

Abstract

Estimates of vertical land motion (VLM) from an updated Canadian crustal velocity model (NAD83v70VG) are used to evaluate the budget of contributions to trends of relative sea level (RSL) at tide gauge sites along the east and west coasts of Canada and northern USA during 1958–2015. The RSL trends result from a combination of the processes of sterodynamics (SD), glacial isostatic adjustment (GIA), and changes in earth Gravity, earth Rotation, and viscoelastic solid earth Deformation (GRD). For these contributions, we used data from a recent study on global RSL trends (Wang et al., 2021, https://doi.org/10.1029/2021gl094502). Incorporating the NAD83v70VG VLM in the derivation of the trends results in an improvement of the RSL budget. Estimates of SD contributions to the observed tide gauge water levels are obtained using this updated VLM, and are compared with the SD-component from the global ocean models used in Wang et al. (2021, https://doi.org/10.5281/zenodo.5554494). The comparison demonstrates the need to include interannual variations of river runoff for modeling the sea level changes in the St. Lawrence River and its estuary, and to improve the model's spatial resolution in the Gulf of St. Lawrence and on the open shelf of the Northwest Atlantic. Along the coast of the Northeast Pacific, the SD sea level changes are well simulated by the global models despite their coarse spatial resolutions and the use of river runoff climatology.