The period of September 6 – 11, 2017 was an active period in which multiple solar flares and a major geomagnetic storm occurred. The two largest flares, an X9.3 and an X8.2 flares, were a disk flare and a limb flare, respectively.

We investigate trends and solar irradiance effects in the mesosphere using the Whole Atmosphere Community Climate Model with eXtended thermosphere and ionosphere (WACCM‐X) and radar measurements of winds at Collm (51°N, 13°E), for the period of 1980–2014.

Solomon & Qian show that solar minima are not all the same, and may have implications for understanding the Sun during the extended periods of very low activity known as “grand minima” that have sometimes occurred in the past, the best known of which was the Maunder Minimum during 1650–1700.

H.Liu et al. have improved a comprehensive numerical model, the Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X).

The Whole Atmosphere Community Climate Model with thermosphere and ionosphere extension (WACCM-X) is a numerical model of the

Stan Solomon and others have performed the first whole-atmosphere simulations of global change that include the lower atmosphere (0-15 km), middle atmosphere (15-90 km), thermosphere-ionosphere (90-500 km), and all relevant physics and chemistry.

Liying Qian et al investigate atomic hydrogen (H) variability from the mesopause to the upper thermosphere, on time scales of solar cycle, seasonal, and diurnal.

Numerical studies have shown that there is a lower thermospheric winter-to-summer circulation that is driven by wave dissipation and that it plays a significant role in trace gas distributions in the mesosphere and lower thermosphere, and in the composition of the thermosphere.

Plain Language Summary or Abstract: Gravity wave forcing near the mesopause drives a summer-to-winter residual circulation in the mesosphere and a reversed, lower thermospheric winter-to-summer residual circulation.