The main purpose of the GlobSnow project is to define, implement and validate a snow monitoring information service on a global scale. The service is supposed to support the Global Climate Observing System (GCOS) implementation plan with systematic satellite-based Earth Observations on global snow areal extent and related products. It should further support snow monitoring activities of governmental institutions, intergovernmental bodies and scientific groups involved in climate change research. GlobSnow develops a monitoring service for two types of snow variables covered, each with a corresponding product series:

• Snow Extent (SE)
• Snow Water Equivalent (SWE)

NR is leading the development of the SE methodology and service in the project. ESA’s Statement of Work requires a SE product of global coverage, a time period of at least 15 years, daily to weekly coverage, 0.3-1 km spatial resolution, sub-pixel positioning and a maximum SE error of 5 %. For the 15 years global time series ERS-2 ATSR-2 and Envisat AATSR data have been chosen. The two satellites were launched in 1995 and 2002, respectively.