"Earth's upper atmosphere is an open system that is strongly influenced by energy and momentum inputs from above, including solar radiation, solar wind, the magnetosphere, and from below by coupling with the lower atmosphere through large-scale waves. The upper atmosphere is a weakly ionized plasma. The neutral part is the 'thermosphere' and the ionized part is the 'ionosphere'. The upper atmosphere plasma is largely produced by photoionization of neutral species by solar extreme ultraviolet radiation. The thermosphere and ionosphere are strongly coupled together through ionneutral interactions, including heat and momentum transfer and the effects of the so-called 'wind dynamo'. The solar wind and magnetosphere affect the upper atmosphere through Joule heating and ion drag by imposing external electric fields and auroral particle precipitation during magnetically active periods. Changes in solar radiation on different time scales ranging from transient events such as solar flares or even an eclipse; day-to-day variability due to the rotation of the Earth and Sun; and the 11-year solar cycle introduce variability in the global wind field. Furthermore, lower atmospheric waves, by propagating upward and depositing energy and momentum in the upper atmosphere, modify the circulation pattern, vertical thermal structure, dynamo electric fields, and neutral composition. Advances in our understanding of the upper atmosphere dynamics and chemical processes also benefit from new techniques that probe the state and variability of the upper atmosphere. Understanding the system drivers enables a more accurate space weather nowcast and forecast which is critical for the safe conduct of human space activity"-- Provided by publisher.
Series:
Space Physics and Aeronomy Collection ; Volume 4 Geophysical monograph series ; 261
This resource is supported by the Institute of Museum and Library Services under the provisions of the Library Services and Technology Act as administered by State Library of Iowa.