Development of calibration methods using specular reflection over the ocean for the Multiviewing, Multichannel, Multipolarization Imager (3MI) of the EUMETSAT Polar System - Second Generation (EPS-SG)

The Multi-viewing, Multi-channel, Multi-polarization Imager (3MI) of the EUMETSAT Polar System - Second Generation (EPS-SG) is a radiometer dedicated to aerosol characterization for climate monitoring, air quality forecasting, and Numerical Weather Prediction (NWP). The 3MI aims to provide multi-spectral, multipolarization, and multi-angular images of the Earth upward radiances at the top of the atmosphere (TOA). This particular design, inspired from the POLarisation and Directionality of the Earth's Reflectances (POLDER) instrument, will lead to a better understanding of the microphysical properties of aerosols and clouds. In terms of design, the instrument's calibration will be done using natural targets, exclusively. This particular constraint requires to further study the already existing calibration techniques that were used on the predecessors of 3MI. The main reason is that the instrument will provide spectral bands (mainly in the short-wave infrared) that will require a reliable characterization. In this paper, we present the results based on measurements obtained with the Observing System Including PolaRisation in the Solar Infrared Spectrum (OSIRIS) instrument, a 3MI airborne simulator developed at the Laboratoire d'Optique Atmospherique.