Most of the large events affecting the thermosphere and ionosphere part of the space environment come from the Sun, the solar wind, and Earth’s magnetosphere. However, even in “quiet time” periods lacking those sources of variability, conditions in the thermosphere and ionosphere continue to fluctuate.

This figure shows the monthly mean, globally integrated total gravity wave flux of energy, including contribution from both pressure-work and advection of kinetic energy, over one year. It is calculated from the mesoscale-resolving Whole Atmosphere Community Climate Model (WACCM). Log10 scale is used, and the unit is Gigawatts (10$^9$ W).

This daily "weather" points to meteorological forcing caused by processes in the lower atmosphere, which statistically can produce up to 35% of the ionosphere’s variability. The study of this coupling, and the implications for forecasting the thermosphere and ionosphere variability, has grown rapidly in recent years. In a Space Weather Journal paper, Liu reviewed the progress of the research, especially with regard to the understanding of how various types of waves from the lower atmosphere may cause variations in the upper atmosphere.

Liu, H.-L. (2016), Variability and predictability of the space environment as related to lower atmosphere forcing, Space Weather, 14, 634–658, doi: 10.1002/2016SW001450.

This paper is highlighted by an AGU EOS research spotlight article: (http://agupubs.onlinelibrary.wiley.com/hub/article/10.1002/2016SW001450/editor-highlight/).