edu.ucar.opensky::articles:16892 UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact 2025-12-26T03:05:44.372247 ISO 19115-2 Geographic Information - Metadata - Part 2: Extensions for Imagery and Gridded Data ISO 19115-2:2009(E) https://n2t.org/ark:/85065/d7zg6tfp Explaining solar cycle effects on composition as it relates to the winter anomaly 2015-07-01T00:00:00Z publication https://n2t.org/ark:/85065/d7zg6tfp https://doi.org/10.1002/2015JA021220 Burns, Alan author Solomon, Stanley C. author Wang, Wenbin author Qian, Liying author Zhang, Y. author Paxton, L. author Yue, X. author Thayer, J. author Liu, Hanli author UCAR/NCAR - Library publisher The solar cycle variation of F₂ region winter anomaly is related to solar cycle changes in the latitudinal winter-to-summer difference of O/N₂. Here we use the National Center for Atmospheric Research-Global Mean Model to develop a concept of why the latitudinal winter-to-summer difference of O/N₂ varies with solar cycle. The main driver for these seasonal changes in composition is vertical advection, which is expressed most simply in pressure coordinates. Meridional winds do not change over the solar cycle, so the vertical winds should also not change. The other component of vertical advection is the vertical gradient of composition. Is there any reason that this should change? At solar maximum vertical temperature gradients between 100 and 200 km altitude are strong, whereas they are weak at solar minimum. To maintain the same pressure, the weak vertical temperature gradients at solar minimum must be balanced by weak density gradients and the strong temperature gradients at solar maximum must be balanced by strong density gradients to obtain the same pressure profile. Changes in the vertical density gradients are species dependent: heavy species change more and light species change less than the average density change. Hence, vertical winds act on stronger O/N₂ gradients at solar maximum than they do at solar minimum, and a stronger winter-to-summer difference of O/N₂ occurs at solar maximum compared with solar minimum UCAR/NCAR - Library OpenSky Support PO Box 3000 Boulder CO 80307-3000 opensky@ucar.edu http://opensky.ucar.edu/ homepage pointOfContact PDF Text theme Resource Type 2016-01-01T00:00:00Z publication Copyright 2015 American Geophysical Union. None eng geoscientificInformation