Washington, July 11 (ANI): Scientists have explained the reason for the record low mass density of the upper thermosphere during the 2008 solar minimum.
During a solar minimum, EUV (extreme ultraviolet) irradiance is lower than it is during more active times in the solar cycle, producing a cooler, contracted thermosphere and decreased density at a given altitude.
Solar EUV irradiance during the recent prolonged solar minimum was somewhat lower on average than during the prior minimum.
However, the rest of the density anomalies are attributable to lower-than-expected upper thermospheric temperatures and low concentrations of atomic oxygen near the base of the thermosphere.
While enhanced cooling due to increased levels of atmospheric carbon dioxide explains one bit, to explain the other side, the researchers hypothesize that changes in the chemical and dynamical processes of the underlying mesosphere and lower thermosphere may play a role. (ANI)