9.1 Sat-J: A Satellite-Derived Dataset of Global Atmospheric Photolysis Rates

Wednesday, 10 January 2018: 12:00 AM
Room 18CD (ACC) (Austin, Texas)
Christopher Holmes, Florida State Univ., Tallahassee, FL

Photolysis—the breaking of chemical bonds by sunlight—is the primary driving force for reactive atmospheric chemistry. Photolysis reactions directly and indirectly control a host of air pollutants and greenhouse, particularly through the production of the hydroxyl radical (OH), the main oxidizing agent in the troposphere, by photolysis of ozone (O3). Despite the critical importance of atmospheric photochemistry for understanding and predicting air pollution and greenhouse gas levels, the rates of photolysis reactions (J values) are highly uncertain. State-of-the-art air quality and climate models differ in their global-mean J values by a factor of 2, and likely much more on regional and seasonal scales. We describe a new, global, 3-D dataset of photolysis rates that is derived from satellite observations of clouds, aerosols, and trace gases, together with a computationally efficient photolysis code. This “Sat-J” product is validated against in situ observations from aircraft and used to evaluate a 3-D atmospheric chemistry model.
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