Assessment of Arctic seasonal snow cover rates of change

Arctic snow cover extent (SCE) trends and rates of changereported across recent climate assessments vary due to the time period ofavailable data, the selection of snow products, and methodological considerations. While all reported trends are strongly negative duringspring, more uncertainty exists in autumn. Motivated to increase theconfidence in SCE trends reported in climate assessments, we quantify theimpact of (1) year-over-year increases in time series length over the past2 decades, (2) the choice of reference period, (3) the application of astatistical methodology to improve inter-dataset agreement, (4) the dataset ensemble size, and (5) product version changes. Results show that the rate of change during May and June has remained consistent over the pastdecade as time series length has increased and is largely insensitive tothe choice of reference period. Although new product versions have increasedspatial resolution, use more advanced reanalysis meteorology to force snowmodels, and include improved remote sensing retrieval algorithms, these enhancements do not result in any notable changes in the observed rate ofArctic SCE change in any month compared to a baseline set of older products.The most impactful analysis decision involves the scaling of datasetclimatologies using an updated version of the NOAA snow chart climate datarecord as the baseline. While minor for most months, this adjustment caninfluence the calculated rate of change for June by a factor of 2 relativeto different climatological baselines.