Added value of AOD assimilation in synergy between MODIS and CALIOP instruments in MOCAGE.

The aim of this study is to evaluate the added value of the assimilation of MODIS and CALIOP in synergy. The observations issued from both instruments will be assimilated in the CTM MOCAGE model in terms of Aerosol Optical Depth (AOD) for MODIS and backscatter, or extinction coefficient for CALIOP.  The objective is to improve the spatial representation of AOD by carrying out a comparison between the analyses and AERONET observations in terms of AOD. The assimilation model will  run with a global configuration of 1° x 1° (longitude x latitude) in a pre-operational context. The analyses concerning the synergy assimilation will be compared first the separate assimilations of the two instruments in order to assess the assimilation scores. 

The methodology will consist of debiasing both observations before the assimilation exercise. We will give more details about the application of this technique. The debiasing coefficient will be  applied to one kind of observation in order to make the two datasets consistent. Finally, we will evaluate the capability of the synergistic assimilation to better represent the tri-dimensional distribution of aerosol within the model compared to the individual assimilations.