A Time Dependent Investigation of the Effect of Particle Ionization on the Earth's middle Atmosphere Using a two-Dimensional Model

The amount of NO transported to the stratosphere is determined by mesospheric processes where uncertainties in the production, loss and transport of odd nitrogen exist. We have used the NRL 2 Dimensional model of atmospheric chemistry and dynamics to investigate aspects of the transport of odd nitrogen from the mesopause region to the upper stratosphere. An important aspect of the NOx transport problem is determining the influence of time varying ionization rates on the flux of odd nitrogen into the lower atmosphere. This problem is investigated with the two dimensional model employing a time dependent ionization source scaled to the measured particle energy incident on the atmosphere. The model results are guided by comparisons to HALOE and PAOM measurements of mesospheric and stratospheric odd nitrogen. In particular we will use the data to provide information on the interannual and seasonal variability of odd nitrogen in the upper stratosphere/mesosphere. These data will be compared over several years with the model results employing the time dependent energy measurements to calculate the flux of odd nitrogen into the lower atmosphere.