The NASA Plankton, Aerosol, Cloud, ocean Ecosystem (PACE) mission is designed to observe the global ocean and atmosphere and provide extended data records of ocean ecology, biogeochemistry, atmospheric aerosols and clouds. The primary instrument on PACE, the Ocean Color Instrument (OCI), is a UV-VIS-NIR imaging spectrometer with additional discrete channels in the SWIR. Two other instruments have been contributed to PACE with more limited requirements. Both are multi-angle, polarization sensitive (MAP) imagers. The Hyper-Angular Rainbow Polarimeter 2 (HARP2) is a wide swath, four VIS-NIR channel sensor, while the Spectro- Polarimeter for Exploration (SPEXone) has a narrower swath but is a spectrometer.

PACE has requirements to produce ocean, aerosol, and cloud parameters from the OCI instrument. Additionally, a number of advanced science data products have been identified to be produced on a best-effort basis from all three instruments. An essential activity to these efforts is the validation of data product quality. This process involves the comparison of satellite data products to independently gathered observations of ocean, atmosphere, and land parameters. It also entails consideration of differences of scale, acquisition time, expectations of uncertainty, statistical sampling, and other matters by both satellite and independent measurements.

There are several reasons for augmenting PVP ground and ocean-based measurements with a dedicated airborne field campaign. These include, but are not limited to, the following.

1. New products will be created from PACE observations. They will need to be validated to assess quality and guide algorithm development. Dedicated field campaigns can make specific observations to this end. Furthermore, many of these products will be the result of multi-parameter algorithms, and retrieval capability for one geophysical property may depend on another, e.g., the accuracy of ocean chlorophyll-a pigment concentration products depend on the quantity and characteristics of atmospheric aerosols that are a part of atmospheric correction. Field campaigns that gather concurrent observations of multiple geophysical parameters enable a useful assessment of new products, particularly if they are made with airborne analogs of PACE instruments.
2. Field campaigns that include airborne assets can provide for a different scale of observation (spatial and temporal) than other validation sources, and a link between point measurements at the surface and the PACE orbital observatory.
3. Airborne field campaigns can reposition assets within the spacecraft swath. Due to its narrow swath, PACE’s SPEXone instrument will have relatively few coincident observations with ground validation sites within the 3-year mission lifetime. Airborne assets can be directed to fly within the SPEXone swath during an overpass, adding many validation observations to an otherwise limited dataset.
4. Airborne assets can validate PACE radiometric and polarimetric observations prior to their use for retrieval of geophysical parameters.
5. Remote sensing success depends on observation geometry, season, and time of day, which can be directly targeted with field campaigns.
6. Field campaigns can focus on specific systems, processes or phenomena to verify they are properly accounted for in the satellite retrieval scheme.