AURORAL IONOSPHERE - COMPARISON OF A TIME-DEPENDENT MODEL WITH COMPOSITION MEASUREMENTS

A time-dependent model of the auroral ionosphere including the odd nitrogen species, NO, N(**2D), and N(**4S), is used for comparison with data from a coordinated rocket-satellite measurement of an auroral event. The chemical scheme and the adopted rate coefficients have been shown to be compatible with daytime mid-latitude ionospheric chemistry. The electron flux and neutral atmospheric parameters measured on the satellite are used to compute the appropriate ionization and dissociation rates. The calculated NO** plus , O//2** plus , O** plus , Ne, and NO densities agree well with the rocket measurements. The calculated N//2** plus densities are larger than the measured densities by a factor of 3 at most altitudes. The calculations show that the nitric oxide content of the aurora ( similar 1. 2 multiplied by 10**9 NO molecules/cm**3 at 105 km) is below the saturation value.