The High Altitude Observatory (HAO) explores the Sun and its effects on the Earth's atmosphere and physical environment, in partnerships extending throughout the national and international scientific communities for research, observational facilities, community data services, and education. The Observatory works in various partnerships to address two key issues, in support of the missions of the National Science Foundation and the National Center for Atmospheric Research:

What are the physical processes operating within the Sun to produce variable output of radiation and particulate matter, on time scales from seconds to millennia, and what are the likely ranges of variations in that output, considering the Sun compared to the evolution of Sun-like stars?

How do the Sun's variations influence the energetics, dynamics, chemistry and electrodynamics of the Earth's middle and upper atmosphere, the near-space environment, and planetary physics, and how might those influences evolve and contribute to the Earth's climate variability?

The inter-dependence of these issues unifies HAO's mission across scientific disciplines, and across activities from research, facility development, and instrument operation to education and observational data services to the community. HAO places heavy emphasis on advanced education and scientific visitor exchanges. The Observatory operates six solar instruments at the Mauna Loa Solar Observatory (MLSO), Hawaii, and collaborates with the NSF-supported National Solar Observatory in the operation of two of the MLSO instruments and another at Sacramento Peak, NM. Astronomy and astrophysics research Institutions abroad are strong partners in the development and operation of other instruments.

Solar magnetism and variability are best studied with reference to general physical processes manifest on the Sun and in systems of comparable stars. Therefore, HAO engages in general astrophysical research relevant to the physics of the Sun and Sun-like stars. Further, because the Solar-Terrestrial system is part of the heliosphere in which other planetary objects are embedded, issues addressed by HAO in research on the Earth's atmosphere include relevant aspects of planetary physics and other planetary atmospheres.

HAO's research and facilities programs are supported primarily by NCAR's NSF base funding and by other NSF-supported national initiatives, the National Space Weather Program and the U.S. Global Change Programs of CEDAR, GEM, and SunRISE. As appropriate to the HAO mission, funding also comes from NASA initiatives, for example, Mission to Planet Earth and theoretical and observational research projects sponsored by the Office of Space Science.