This is an award to a new NSF principle investigator. The award is for the study of a comprehensive data set involving incoherent scatter radars and optical interferometers in order to investigate the changes in global thermospheric circulation from one solstice (June) to another (December). These changes have important implications for seasonal changes of temperature and composition of the thermosphere. The PI has led the analysis of the campaign activity as a Visiting Scientist at NCAR (National Center for Atmospheric Research). This award will allow the continuation of his effort at the University of Lowell. This study has become a show case for a new philosophy in the iterative process of developing models and geophysical understanding hand-in-hand. Much of the work has been driven by the TGCM (Thermosphere Global Circulation Model) modelling effort, both in developing the model and understanding the features in the data. This continued work will study selected campaign intervals to verify the NCAR-TCGM model using temperature and density data, analyze the TCGM simulations to investigate wind, temperature and density features observed during the selected periods, and simulate the properties of the thermosphere for a specific period. 7/11/89
