Stratospheric Nudging And Predictable Surface Impacts (SNAPSI): Reference state data

Reference state data derived from the European Centre for Medium-Range Weather Forecasts (ECMWF) ERA5 reanalysis for the nudging experiments of the Stratospheric Nudging And Predictable Surface Impacts (SNAPSI) project. These reference states are used to nudge the stratosphere towards a specified evolution in the ensemble forecasts carried out by the SNAPSI project. The data contain: (a) lightly processed horizontal winds and temperatures from ERA5 spanning three case studies of sudden stratospheric warmings from 2018 to 2019 and (b) climatological horizontal winds and temperatures.