The aim of this project is to improve the characterization of radiative and microphysical properties of aerosols and clouds
in the atmosphere. These two atmospheric components and their interactions are among the main sources of uncertainty
in the numerical forecast of climate change. In this context, we have designed a new airborne polarimeter for measuring
directional, total and polarized radiances in the 440 to 2200 nm spectral range. This instrument is based on the POLDER
concept, instrument that is currently aboard the PARASOL microsatellite. This new sensor consists in two optical
systems for the visible to near infrared range (440 to 940 nm) and the shortwave infrared (940 to 2200 nm). Each optical
system is composed of a wide field-of-view optics (114° and 105° respectively) associated to two rotating wheels for
interferential filters and analysers respectively, and a 2D array of detectors. For each channel, the total and polarized
radiances are computed using the measurements performed with the three analysers shifted by an angle of 60°. Thanks to
the large field of view of the optics, any target is seen under several viewing angles during the aircraft motion. This type
of instrument has been designed for the retrieval of optical thickness and microphysical properties of aerosols as well as
for the determination of microphysical, macrophysical and radiative properties of clouds. In this paper, we will present
this new instrument design and some preliminary results recently obtained during the first field campaign in May 2008
over Europe.
A new method is proposed to solve inverse problems with new types of a prior partial information about physical parameters to retrieve. The partial information are relative to integrals of the functions over an arbitrary range of a variable, and/or first and second derivatives of desired functions. They might be provided either form common features of desired solutions or from independent measurements. This inverse problem was solved in the framework of the iterative inversion method under the assumption of log-normal probability density function of measurements. As a typical example of the approach, we examined particle sizing of stratospheric aerosol from multi-wavelength extinction and angular aureole measurements in the visible.
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