Assimilating aerosol optical properties related to size and absorption from POLDER/PARASOL with an ensemble data assimilation system

Abstract. A data assimilation system for aerosol, based on an ensemble Kalman filter, has been developed the ECHAM – Hamburg Aerosol Model (ECHAM-HAM) global aerosol model and applied to POLarization Directionality of Earth's Reflectances (POLDER)-derived observations optical properties. The advantages this is that ECHAM-HAM modal scheme carries both particle numbers mass which are used in as state vectors, while POLDER retrievals addition depth (AOD) Ångström exponent (AE) also provide information related absorption like (AAOD) single scattering albedo (SSA). can simultaneously assimilate combinations multiple variables (e.g., AOD, AE, SSA) optimally estimate mixing ratio number different species. We investigate added value assimilating AAOD SSA, commonly by conducting experiments where retrieved properties assimilated. Results evaluated with (independent) POLDER, Moderate Resolution Imaging Spectroradiometer (MODIS) Dark Target, MODIS Deep Blue Robotic Network (AERONET) observations. experiment AE SSA assimilated shows systematic improvement mean error, absolute error correlation compared only AOD same reduces ME against AERONET from 0.072 0.001 0.273 0.009 ?0.012 0.002 AAOD. Additionally, sensitivity reveal benefits over at a second wavelength or AAOD, possibly due simpler observation covariance matrix present framework. conclude currently available do positively impact assimilation.