Collaborative Research: CEDAR--Quantifying Ion Drifts in the Mid-latitude Ionosphere and Their Coupling to the Neutral Atmosphere

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The Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) program is a broad-based, community-guided, upper atmospheric research program. It is aimed at understanding the behavior of atmospheric regions from the middle atmosphere upward through the ionized upper layers of the atmosphere and into outer space in terms of coupling, energetics, chemistry, and dynamics on regional and global scales. The mid-latitude ionosphere serves as the intermediary between the active ionospheres of the polar and equatorial regions, but it has not been studied very thoroughly. This Collaborative CEDAR award involving University of Texas at Dallas, Virginia Tech University, and the University of Colorado is aimed at developing the first quiet-time empirical model of the ionosphere electric field distribution to fill in the necessary ground truth needed to produce a true understanding of the global dynamics of the ionosphere. The research effort would use 15 years of Air Force Defense Meteorological Space Plasma (DMSP) measurements of ion zonal flow speeds in the mid-latitude ionosphere to construct an empirical model of mid-latitude ionospheric quiet-time electric fields. This data set would be supplemented by ion drift data obtained from the mid-latitude SuperDARN sites. This database would be made available to outside users, and thus, would be a valuable ionospheric community resource. Following the completion of the development of the quiet time model, observations from storm times will be compared to predictions based upon application of the new quiet time model. The determined differences would be analyzed within the guidance and context of the CTIP (Coupled thermosphere ionosphere plasmasphere)-RCM model runs to understand the underlying physical mechanisms causing the observed variability relative to the baseline model established, to quantify the magnitude and extent of storm-time disturbances, and finally, to quantify the coupling of the mid-latitude ion drifts to the neutral atmosphere and the transfer of energy between the polar and equatorial regions. Finally, making use of nearly two decades of DMSP data to understand and develop empirical models goes to the heart of one of the fundamental challenges of the CEDAR Aeronomy program, which is to quantify a baseline model of mid-latitude electric fields. Consequently, the question of variability as a function of solar phase, geomagnetic activity, and dynamical coupling to the lower atmosphere and to the magnetosphere regions can be more carefully assessed. The results achieved would be of great interest and use to the ionosphere and thermospheric modeling community and also relevant to the CEDAR mission of "understanding the fundamental properties of the space-atmosphere interaction region (SAIR); identify the interconnected processes that define the SAIR's global behavior, evolution, and influence on the Sun-Earth system". The main goal of this project is to quantify the response of the ionosphere relative to direct, spectrally separated measurements of solar extreme ultraviolet (EUV) radiation from the TIMED and SDO spacecraft. This approach constitutes an immense improvement over previous studies based on proxies. The C/NOFS and DMSP spacecraft at a range of altitudes will provide corresponding measurements of ionospheric parameters. This dataset, spanning more than a solar cycle, allows for the use of advanced statistical analysis techniques and will be used together with the SAMI-2 model to address outstanding science questions related to understanding the ionospheric response to solar EUV variability. Interesting questions to be investigated include the relative importance of and interaction between the responses in the neutral and ionized components of the upper atmosphere.