Launch and Primary Objective
CALIPSO launched on April 28, 2006. CALIPSO’s measurements filled a crucial, well-recognized need for high-resolution atmospheric profiles, and proved essential in reducing the uncertainties that limit our understanding of the roles of aerosols and clouds in the Earth’s global climate system.
Orbital Configuration
CALIPSO initially flew in the international Afternoon or "A-Train" constellation for coincident Earth observations until September 13, 2018 when it began lowering its orbit from 705 km to 688 km (428 miles) above the Earth to resume formation flying with CloudSat, and resumed matched lidar/radar cloud profile measurements, as part of the "C-Train".
Key Discoveries and Applications
CALIPSO’s co-aligned lidar and IIR measurements and robust retrieval techniques led to significant advances in retrieving cloud and aerosol distributions and optical properties, both by themselves and in synergy with CloudSat and the other A-Train instruments. Observationally-based estimates of all- sky aerosol direct radiative effect were made possible by CALIPSO’s unique ability to measure aerosols in cloudy skies.
CALIPSO directly observed cloud altitude and thermodynamic phase, providing key new insights in understanding the feedback between Arctic cloud cover, sea ice extent and life cycle, and the thinning of Greenland’s ice sheets. CALIPSO’s vertical profile measurements of clouds and aerosols provided an unprecedented resource for evaluating weather and climate models, air quality models, and models used to forecast the dispersion of volcanic and fire plumes.
Mission Conclusion and Data Availability
The CALIPSO science mission ended on August 1, 2023. CALIPSO was truly a pathfinder spaceborne lidar mission (CALIPSO Final Report NASA TP-20260000771). Not only did its measurements open doors to new scientific discoveries and applications that benefit society, but the team also created innovative techniques and tools to analyze a new class of Earth science observations. The mission learned that lidar profile observations are highly valued by operational weather centers for improving the skill of their forecasts and can uniquely address a broad spectrum of scientific questions.
The mission also demonstrated that lasers could operate in space for long periods and that the measurement technique is stable and resilient – if proper preparations are taken. Designed for a lifetime of 3 years, CALIPSO delivered unprecedented measurements of the vertical structure of the Earth's atmosphere for 17 years. This long duration data record established by continuous global measurements now provides an invaluable reference dataset that is widely used by the science community to better understand the processes that influence climate.
