Observations of NO2 densities from 28 to 40 km as measured by the Solar Mesosphere Explorer (SME) satellite are compared to model calculations for the month of January. Low densities are obtained in the tropics and in high latitude winter, with much larger values in the summer middle and high latitude regions in both the observations and the model. The reasons for areas of agreement and disagreement between the model and the model and the observations are explored. The observed NO2 distribution is also used to infer the N2O5 distribution based on presently accepted chemistry and suggests that very large amounts of N2O5 are present in high latitude winter.