The diurnal variation of NO, N(D-2), and ions in the thermosphere - A comparison of satellite measurements to a model

A data base of parameters important to understanding the diurnal variation of odd-nitrogen and ions in the thermosphere near equinox, at low latitudes, and for quiet geomagnetic conditions is presented. The data base includes profiles of the odd-nitrogen species NO and N(D-2), the ions NO(+), O2(+), O(+), N2(+), and N(+); the total ion density; O and N2; and the neutral, ion, and electron temperatures. The measured time-dependent variations of NO, N(D-2), O2(+), and NO(+) compare favorably to the results of a time-dependent, photochemical, diffusion model for odd-nitrogen and ion chemistry. In particular, the model reproduces the rapid increase in NO density in the morning hours, the midafternoon maximum, and the late afternoon decrease. The model also reproduces the measured absolute densities for NO to within 20 percent over most of the diurnal cycle but falls below the measured density by as much as a factor of two in the late afternoon.