Requirements for improved modeling of the orbital atmosphere

Satellite accelerometer data are available for seven time periods during the period 1974 to the present. All seasons and latitudes up to 83 deg are covered. Deviations between the accelerometer data and current models are greatest for high geographic latitudes and high geomagnetic index, although about a 15 percent standard deviation persists between the models and the accelerometer data even at low latitudes and geomagnetically quiet times. Accelerometer data give density times the ballistic coefficient and it is therefore necessary to estimate the time-line of the ballistic coefficient in order to obtain density.