CEDAR: Solar Cyclic and Climatic Influences on Upper Atmospheric Hydrogen Distributions

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This project addresses the influence of solar variability and greenhouse gas increases on upper atmospheric hydrogen distributions from both an observational and modeling perspective. Fabry-Perot observations of upper atmospheric hydrogen Balmer-alpha emissions from Northern mid-latitudes over the time period spanning three solar minima establish a reference data set that can be used to compare with future observations and with atmospheric models. This data set shows an apparent upward trend in hydrogen optical emissions of greater magnitude than predicted alone from increases in hydrogen abundance due to the rise in greenhouse gases. In order to ensure that this is not a result of a calibration artifact, the accuracy of the Northern hemisphere long-term Balmer-alpha data set will be improved through use of updated knowledge of the background Galactic emission intensity, current analysis tools, and an updated tropospheric scattering correction code. In addition, observations from the Northern and Southern Hemisphere will be compared. The major science questions to be addressed by this project are as follows: What are the solar cyclic and climatic influences on mechanisms governing lower to upper atmospheric coupling of hydrogenous species? What are the solar cyclic and possibly longer-term trends in emission observations from geocoronal hydrogen, the upper boundary of the Earth's hydrogenous species distribution? What are the predicted magnitudes for changes in hydrogen-containing species? To address this, the Whole Atmosphere Community Climate Model (WACCM) will be used to carry out sensitivity studies of solar cyclic and climatic influences on middle and upper atmospheric hydrogeneous species distributions. The NCAR Global Mean Model will be used to study how these forcings propagate through the thermosphere.A faculty member at a two-year UW college campus and undergraduate students will be involved in this work. Public outreach activities will be carried out aimed at increasing public literacy about the science of climate change, and facilitating opportunities for youth exposure and involvement in the sciences.