Staff in GML’s Ozone and Water Vapor Division produce and disseminate highly accurate, long-term records of ozone and water vapor measurements from observation sites around the world. These measurements contribute to ongoing assessments of the health of Earth's ozone layer in response to NOAA’s Congressional mandate. NOAA upper troposphere lower stratospheric water vapor measurements are critical for satellite validation and monitoring changes in atmospheric composition at those locations in the atmospheric column. In particular, researchers in GML study the impacts of chemistry and transport on atmospheric composition, including impacts from sources such as volcanic eruptions, wildfire emissions, and anthropogenic activities. Staff measure ozone and water vapor with light-weight, balloon-borne and aircraft in situ instruments, surface monitors, and ground-based remote sensing instruments.