CLAMS is the Chesapeake Lighthouse and Aircraft Measurements for Satellites field campaign sponsored by CERES, MISR, MODIS-Atmospheres and the NASA/GEWEX Global Aerosol Climatology Project (GACP). The centerpiece of CLAMS is the Chesapeake Lighthouse sea platform 20 km east of Virginia Beach, at which NASA and NOAA make continuous, long-term measurements of radiation, meteorology, and ocean waves. Members of the CERES, MISR and MODIS instrument teams are collaborating to accomplish a common set of objectives tied to the validation of EOS data products. A first CLAMS campaign, currently being planned for July 2001 to validate Terra data products, is a shortwave closure experiment targeting clear (cloud-free) sky conditions and focused on obtaining:

1. more accurate spectral and broadband radiative fluxes at the surface and within the atmosphere,
2. characterization of ocean optics in the vicinity of the lighthouse, and
3. description of the atmospheric aerosol amounts, micro-physical and optical properties, and their variability.

The observation strategy being designed for CLAMS to accomplish these goals will help satisfy a more specific set of objectives which includes validating retrievals of aerosol properties from satellites. These objectives are:

1. comparisons with in-situ measurements, surface-based measurements, and sensor intercomparisons,
2. assessing the impact of scene variability on measurement uncertainty, on ten meter to tem kilometer spatial scales,
3. testing the impact of improved boundary specification using CLAMS measurements, and
4. improving retrievals in sunglint regions.

A final object is to derive a more accurate description of the shortwave radiation budget of the cloud-free earth-atmosphere system that includes:

1. improved characterization of ocean optics including BRDF as a function of sun angle, aerosol loading, wind and sea state,
2. assessing the radiative impacts of aerosols,
3. extending the interpretation of CLAMS data to the open ocean.