Comment on npg-2021-20

Abstract

“An approach for constraining mantle viscosities through assimilation of paleo sea level data into a glacial isostatic adjustment model” by Schachtschneider et al., present a data assimilation approach to recover mantle viscosity parameters for a 3-layer glacial isostatic adjustment (GIA) model using synthetic relative sea-level change data. Based on a range of experiments, they conclude their particle filter based method was able to find the ground truth mantle viscosity parameters given different initial ensemble probabilities, observational uncertainties and spatial-temporal data coverage. This is a novel application of the data assimilation approach for GIA modelling studies, which has a good potential to help the community to better constrain the mantle viscosity parameters of a commonlyused 3-layer GIA model. This is a well-written manuscript which explains a complex subject in a very clear way. I have two major points and other minor comments. Provided the authors address these points in a subsequent revision I would certainly support the publication of this manuscript.