The Contribution of the Global Space-based InterCalibration System to US-International Partnerships

The Global Space-based InterCalibration System (GSICS) is an international collaborative effort initiated in 2005 by WMO and the Coordination Group for Meteorological Satellites (CGMS). Within GSICS, satellite operators and science teams collaborate to define, implement and share community-agreed best practices, standards, procedures and tools. These enable users to monitor, improve and harmonize the calibration of instruments aboard operational meteorological, climate and other environmental satellites of the Global Observing System (GOS). The focus of GSICS is the systematic generation of on-orbit inter-calibration information to correct the individual calibration of Level 1 satellite data. This is however part of a comprehensive strategy, which involves a range of activities including, prelaunch instrument characterization, instrument bias monitoring, level 1 data quality control and validation, on-orbit instrument intercomparison and calibration, traceability to absolute calibration standards, metadata provision (provenance, lineage), enabling recalibration of archived data, and documenting state-of-the-art calibration techniques. Through these activities, GSICS promotes greater understanding of instrument absolute calibration and root causes of biases, supports instrument global inter-operability and measurement quality, and enables better accuracy and global consistency of Level 2 environmental, climate and weather forecasting products. GSICS promotes capacity building within the operational agencies of CGMS. We ensure that each agency has the tools and expertise to be responsible for their own calibration and intercalibration of their satellites. This “ownership” enriches the entire international community because we not only work together, we learn together and we can rely on the accuracy of each other's satellite observations because consistent and understandable methodologies are being used. The involvement of CGMS members from Asia was critical in the realization of GSICS. Our Asian partners have geostationary satellites that cover 1/3 of the globe, and they embraced the GSICS methodologies and quickly made them operational.