Climatology of snow cover and snow water equivalent

• Chapter X: Summary and references
•  
• Summary
• References

Summary

Satellite-based measurements already cover a period of 30 years, which makes it possible to do climatological assessments of global and regional snowpack conditions based only on remote sensing data. Snow cover can be determined from space using satellite instruments in visible, infrared and microwave spectrums, while SWE can be determined using only microwave instruments. In this module you have learned how MODIS and GlobSnow-2 products are generated and how to use this data to make a time series of SCD and SWE. A few main points:

• Satellite data provides a good overview of snow cover conditions in large areas.
• Temporal filtering of cloud-covered pixels can help to reduce data gaps and ensure temporal continuity of snow cover data. The approach described in this module cannot be used for operational activities, but it is applicable for climatological purposes.
• MODIS-based annual and monthly SCDs show a good agreement with in-situ data from the Baltic States. Validation scores are higher for continental stations and lower in coastal areas. In a maritime climate the snow cover is ephemeral and satellite-based measurements are not able to capture frequent variations.
• Gaps in the satellite-based SWE time series cannot be filled using temporal filtering due to the high temporal variability of SWE values. This limits the applications of satellite-based SWE for climatological assessments.
• The validation scores of GlobSnow-2 SWE data were lower than for snow cover days derived from MODIS. The erroneous retrievals of SWE values may be related to very thin or very thick snow, forest cover, snowpack morphology, distance to significant open water bodies and topographic factors.

Despite some limitations, satellite-based snow cover data can be applied for climatological assessments as well as hydrological and numerical weather modelling. Snow cover plays an important role in the hydrological cycle, which includes evaporation, water storage, soil moisture, river discharge and freshwater transport to the seas and oceans.