Airborne Multi-angle Spectro Polarimetric Imager (AirMSPI) is an airborne prototype instrument similar to that of the future satellite-borne MSPI instrument for obtaining multi-angle polarization imagery. AirMSPI flies on the NASA-owned ER-2 aircraft. The instrument was built for NASA by the Jet Propulsion Laboratory in Pasadena, California.

AirMSPI is an 8-band (355, 380, 445, 470, 555, 660, 865, 935 nm) pushbroom camera, measuring polarization in the 470, 660, and 865 nm bands, mounted on a gimbal to acquire multiangular observations over a ±67° along-track range. Two principal observing modes are employed: step-and-stare, in which 11 km x 11 km targets are observed at a discrete set of view angles with a spatial resolution of ~10 m; and continuous sweep, in which the camera slews back and forth along the flight track between ±67° to acquire wide area coverage (11 km swath at nadir, target length 108 km) with ~25 m spatial resolution. Step-and-stare provides more angles, but continuous sweep gives greater coverage. Multiple observing modes can be programmed into the instrument and activated under cockpit control. Multiangle radiance and polarization imagery from AirMSPI will (a) provide 3-D scene context where clouds and aerosol plumes are present, plus constraints on radiometric closure, particularly over heterogeneous scenes where 3-D radiative transfer may dominate, and (b) enable retrieval of aerosol and cloud macrophysical properties (distribution, height), microphysical properties (size distribution, single scattering albedo, shape), and optical depth.