The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI): a new tool for aerosol and cloud remote sensing

Abstract

Abstract. The Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) is an eight-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. The instrument has been flying aboard the NASA ER-2 high altitude aircraft since October 2010. AirMSPI employs a photoelastic modulator-based polarimetric imaging technique to enable accurate measurements of the degree and angle of linear polarization in addition to spectral intensity. A description of the AirMSPI instrument and ground data processing approach is presented. Example images of clear, hazy, and cloudy scenes over the Pacific Ocean and California land targets obtained during flights between 2010 and 2012 are shown, and quantitative interpretations of the data using vector radiative transfer theory and scene models are provided to highlight the instrument's capabilities for determining aerosol and cloud microphysical properties and cloud 3-D spatial distributions. Sensitivity to parameters such as aerosol particle size distribution, ocean surface wind speed and direction, cloud-top and cloud-base height, and cloud droplet size is discussed. AirMSPI represents a major step toward realization of the type of imaging polarimeter envisioned to fly on NASA's Aerosol-Cloud-Ecosystem (ACE) mission in the next decade.

Retrieval of Aerosol Optical Depth Over North China From Polarized Satellite Observations Using Re‐derived Surface Properties

“…The Chinese polarized camera (Directional Polarized Camera, DPC) has also been used for aerosol remote sensing. Additionally, the Airborne Multi-angle SpectroPolarimetric Imager (AirMSPI) and the algorithm applied to its measurements (Diner et al, 2013;Xu et al, 2017) have made numerous achievements. The space version of the DPC is carried on the GaoFen-5 platform and was launched in 2018. and Zheng et al (2019) evaluated the potential retrievals and their errors.…”

Joint retrieval of aerosol and water-leaving radiance from multispectral, multiangular and polarimetric measurements over ocean

“…Motivated by the development of a multiangle imaging polarimeter at JPL -the Airborne Multiangle SpectroPolarimetric Imager (AirMSPI) (Diner et al, 2013) -this paper describes the development of a coupled aerosol-ocean retrieval methodology. Our method (1) employs a simplified bio-optical model to obtain a reasonable estimate of nLw in the first retrieval step, followed by an empirical refinement in the subsequent step; (2) applies constraints on the spatial smoothness of aerosol and Chl loadings across neighboring image patches and spectral constraints on aerosol optical properties and on nLw across relevant bands to improve the convergence and stability of the algorithm; and (3) models and stores the RT fields in the aerosol/Rayleigh mixed layer, the pure Rayleigh-scattering layers, and the ocean medium separately, then couples them to obtain the radiative field at the sensor -thereby enhancing the Jacobian evaluations by reusing RT fields in the unperturbed layers.…”

“…These have been incorporated into AirMSPI, as described in Diner et al (2013). AirMSPI is an ultraviolet-visible-near-infrared imager that has been flying aboard the NASA ER-2 high-altitude aircraft since October 2010.…”

Cloud information content analysis of multi-angular measurements in the oxygen A-band: application to 3MI and MSPI

“…Like MISR, a suite of MSPI cameras would view Earth at a variety of angles with an intrinsic pixel size of a few hundred metres, which for certain channels would be averaged up to about 1 km. At present, MSPI has ground-based (Diner et al, 2010) and airborne (Diner et al, 2013) versions with only VNIR (visible near infrared) spectral coverage. The latter, AirM-SPI development is currently entering a new phase.…”