Among future multi-directional polarimetric spaceborne missions that will advance cloud and aerosol studies, the Multiviewing, Multi-channel, Multi-polarisation Imager (3MI) on the MetOp Second Generation – A (MetOp-SG-A) satellite is a direct successor of the classic and successful design of Polarisation and Directionality of the Earth’s Reflectance (POLDER) sensors. The POLDER design comprises of three essential elements: a wide field-of-view lens, a rotating wheel holding spectral and polarizer filters, and a two-dimensional imaging sensor. This presentation demonstrates a new geometric calibration technique for an airborne prototype of the 3MI and other POLDER-like sensors. Geometric calibration is often challenging for an airborne sensor because it is frequently mounted to and dismounted from the aircraft. The rotation of the instrument with respect to the aircraft reference frame must be calibrated every time when the instrument is reinstalled, but the opportunity for a stable flight leg over ground control points is limited because of weather and air-traffic conditions. In addition, the precise aircraft position is often more difficult to obtain than the precise aircraft attitude. To mitigate this difficulty, our new technique derives the instrument rotation by detecting three natural angular features: rainbow, glory, and hot spot. These features are often observed during scientific data acquisitions over clouds and land surface, thus enable the direct validation of the geometric calibration quality for every eligible image under the actual acquisition condition. We present the automatic detection technique of these angular features in in-flight data and derived rotation angles and errors for the AEROCLO-SA field campaign.
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 Atmosphérique.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.