Comparisons of the meteoric input function derived from model-lidar data assimilation and Arecibo Observatory meteor measurements

A new sodium chemistry model, NaChem, has been developed to study the sodium layer in the mesosphere and lower thermosphere. The NaChem model solves the continuity equation of all species with no steady-state assumption.  This work examines the Meteoric Input Function (MIF) using model data assimilation constrained by lidar observations, as well as the meteor measurements from the Arecibo Observatory (AO).  Sodium number density from the Colorado State University (CSU) Lidar and the Andes Lidar Observatory (ALO) are used as reference profiles in NaChem to infer the MIF, while the AO MIF is derived from micro-meteor radiant distributions.  Our results show that the CSU MIF agrees well with the AO MIF, but the ALO MIF exhibits significant differences.  The inferred meteoroid material input rates are 53+/-23 t/d from CSU and 83+/-28 t/d from ALO.  Our study also indicates that the sodium sink is mainly controlled by smoke uptake which is approximately three times more effective than the NaHCO₃ dimerization process to remove sodium.  Lastly, our sensitivity study reveals that more NO+ will directly lead to fewer observable Na atoms in the atmosphere.