MASS2ANT Snowfall Dataset: Information for users November 2020 N. Ghilain1, S. Vannitsem1, Q. Dalaiden2, H. Goosse2, L. De Cruz1 1Royal Meteorological Institute, Uccle, Belgium 2UCLouvain, Earth and Life Institute, Louvain-la-Neuve, Belgium contacts RMI: stephane.vannitsem@meteo.be, nicolas.ghilain@meteo.be, lesley.decruz@meteo.be contacts UCLouvain: hugues.goosse@uclouvain.be, quentin.dalaiden@uclouvain.be We provide in this dataset maps at 5.5 km resolution of the daily and yearly accumulated snowfall over emerged land (Ice Sheet) of Dronning Maud Land (Antarctica) from 1850 to 2014. We used a statistical method to derive fine resolution maps from GCM runs (CESM2, 10 runs). In the method, we searched for analogs in a database we constructed from the association between re-analyses large-scale meteorological fields (ERA5 and ERA-Interim) and RCM daily accumulated snowfall (RACMO2.3p5.5). RACMO2.3p5.5 data are available freely on request (https://www.projects.science.uu.nl/iceclimate/models/antarctica.php). CESM2 CMIP6 runs are also freely available (https://esgf-node.llnl.gov/search/cmip6/). The complete description of the algorithm and performance is described in: Ghilain N., Vannitsem S., Dalaiden Q., Goosse H., De Cruz L., Wei W., Reconstruction of daily snowfall accumulation at 5.5km resolution over Dronning Maud Land, Antarctica, from 1850 to 2014 using an analog-based downscaling technique, submitted to Earth System Science Data (ESSD). The MASS2ANT Snowfall dataset is composed of the annual estimations of snowfall over Dronning Maud Land, the daily time series for the total period for all the emerged grid points of the domain (2 files are given in example, the all set is available on zenodo: 10.5281/zenodo.6355455, 10.5281/zenodo.6359385, 10.5281/zenodo.6362299), the principal components time series and Empirical Orthogonal Functions (EOF) offering the possibility to analyze the synoptic weather patterns associated to snowfall over the ice sheet and the Principal Component weights (PCs) time series from the re-analysis in case one wants to extend or improve the database. Realistic weather patterns can be recomposed in associating (product of matrices) the PCs with the EOFs The method could be easily expanded to other sources (other GCM, other reference RCM or other reanalysis), and potentially for other parts of Antarctica. Samples of the programs used to generate this database are therefore also provided here. Refer to MASS2ANT_Snowfall_Dataset_InfoUsers.pdf

The study was funded in the framework of the MASS2ANT project (\url{https://www.elic.ucl.ac.be/users/klein/Mass2Ant/index.html}, contract No BR/165/A2) by the Belgian Science Policy.