Climate-change, Environment, Earth Observation, Satellites, Ocean, Land, Atmosphere, Essential-Climate-Variables (ECVs), Essential Ocean Variables (EOVs), SI traceability and measurement uncertainty, Marine measurement standards, Ocean observation systems, Quality Assurance/Quality control (QA/QC) schemes, Calibration infrastructure, Marine sensors, On-site measurements, air monitoring networks, Data Quality Objectives (DQO), greenhouse gases, aerosols, reactive gases.