Variations of the Nightglow 557.7 nm Emission Intensity during Solar Cycle 23

The results of photometric measurements of the intensity of 557.7 nm nightglow emission at a high geographical latitude of 63° N at the Yakutsk meridian (130° E) on days in 1997–2008 with low geomagnetic activity are presented. Statistical analysis shows that the long-term variations in the intensity of the green line of atomic oxygen are consistent with earlier observations at low and midlatitudes. The average intensity of the 557.7 nm emission for February and March had the largest values, ~400 and ~300 rayleighs, respectively, in the years of the maximum of solar cycle 23. This is likely determined by the growth in the concentration of atomic oxygen at the height of the green line emission upon an increase in solar activity according to the MSIS-90 empirical model. It is known that the green-line intensity may significantly vary at nighttime. Analysis of the coefficient of this emission variation shows that there is no close relationship between this parameter and solar activity.