Temporal stability of long-term satellite and reanalysis products to monitor snow cover trends

Monitoring snow cover to infer climate change impacts is now feasible using Earth observation data together with reanalysis products derived from Earth system models and data assimilation. Temporal stability becomes essential when these products are used to monitor snow cover changes over time. While the temporal stability of satellite products can be altered when multiple sensors are combined and due to the degradation and orbital drifts in each sensor, the stability of reanalysis datasets can be compromised when new observations are assimilated into the model. This study evaluates the stability of some of the longest satellite-based and reanalysis products (ERA5, 1950-2020, ERA5-Land, 1950-2020, and the National Oceanic and Atmospheric Administration Climate Data Record (NOAA CDR), 1966-2020) by using 527 ground stations as reference data (1950-2020). Stability is assessed with the time series of the annual bias in snow depth and snow cover duration of the products at the different stations.