Snow_cci project focuses on generation of homogeneous multi-sensor time series for the main parameters of global snow cover focusing on snow extent and snow water equivalent. To accomplish this, reliable fully validated processing lines are developed and implemented. The requirements for these parameters are assessed using the outcome of workshops and questionnaires addressing users dealing with different climate applications. The global Snow extent product generation applies algorithms accounting for fractional snow extent and cloud screening in order to generate consistent daily products for snow on the surface (viewable snow) and snow on the surface corrected for forest masking (snow on ground). The cloud screening method for the newest sensors is developed by SYKE. Input data are medium resolution optical satellite images (AVHRR-2/3, AATSR, MODIS, VIIRS, SLSTR/OLCI) from 1981 to present. Independent validation of the snow products is performed for different seasons and climate zones around the globe from 1985 onwards, using as reference high resolution snow maps from Landsat and Sentinel- 2as well as in-situ snow data following standardized validation protocols.
Global time series of daily snow water equivalent (SWE) products are generated from passive microwave data from SMMR, SSM/I, and AMSR from 1978 onwards, combined with in-situ snow depth measurements. Long-term stability and quality of the product is assessed using independent snow survey data and by intercomparison with the snow information from global land process models.
The Climate Research Group will perform case studies related to long term trends of seasonal snow as well as evaluations of CMIP-6 and other snow-focused climate model experiments. This will ensure the usability of snow_cci products.
More info:
International website of the project ESA Snow Climate Change Initiative
Senior remote sensing scientist Sari Metsämäki, Finnish Environment Institute SYKE, firstname.lastname@syke.fi
Publications:
Pulliainen, J., Luojus, K., Derksen, C., Mudryk, L., Lemmetyinen, J., Salminen, M., Ikonen, J., Takala, M., Cohen, J., Smolander, T., and Norberg, J.:
Patterns and trends of Northern Hemisphere snow mass from 1980 to 2018. Nature, 581, 294-298, 2020.