The Expert Team on Surface and Sub-surface Measurement (ET-SSM), develops and maintains guidance, best practices, standards, and specifications for surface and subsurface measurements to meet Members’ requirements. The team monitors and reports on emerging and state-of-the-art measurement technologies, supports intercomparisons and calibration, updates relevant WMO guidance (including WMO-No. 8), collaborates with international standards organizations, Measurement Lead Centres, and other Expert Teams, and promotes robust, sustainable, and accessible measurement solutions for all Members, including low-cost and innovative technologies.