Origin of the Tropical Lower Stratospheric Response to 11-Year Solar Forcing: Possible Feedbacks from the Coupled Troposphere-Ocean Response

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This project examines the variations in lower stratospheric ozone and temperature that accompany the 11-year cycle in sunspots and solar (mostly ultraviolet) radiation received by the earth, in which higher ozone values are associated with greater solar radiation. The research tests the hypothesis that the stratospheric response to 11-year solar forcing is influenced by tropical air-sea interactions, as increased insolation leads to enhanced sea surface evaporation, which in turn produces a precipitation pattern that generates an atmospheric flow response extending into the stratosphere. The hypothesis will be tested through simulations of the Whole Atmosphere Community Climate Model (WACCM), in which the upper levels of the atmosphere are resolved and the photochemical reactions that determine stratospheric ozone concentration are represented. In this model, the influence of air-sea interactions can be determined through simulations in which ocean surface temperatures are either fixed or allowed to interact with the overlying atmosphere. Statistical analysis of both simulations and corresponding observations will also be performed to further examine the relevance of the proposed mechanism for real-world stratospheric variability.The work will have broader impacts through the support and training of a graduate student, which will develop the scientific workforce in this scientific area. In addition, a better understanding of the impact of solar variability on climate may prove useful for decision makers concerned with the practical implications of climate variability and climate change.