Seminar

Abstract

Tropospheric ozone is an important greenhouse gas, is detrimental to human health and crop and ecosystem productivity, and controls the oxidizing capacity of the troposphere. Due to its high spatial and temporal variability and limited observations, quantifying net tropospheric ozone changes across the entire Northern Hemisphere on time scales of two decades had not been possible. I will show, using newly available observations from an extensive commercial aircraft monitoring network that tropospheric ozone has increased above eleven regions of the Northern Hemisphere since the mid-1990s, and we can finally verify model estimates of increasing ozone. The net result of shifting anthropogenic ozone precursor emissions has led to an increase of ozone and its radiative forcing across the Northern Hemisphere, despite NOx emissions reductions at mid-latitudes.

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Audrey Gaudel earned a PhD from Universite Pierre et Marie Curie (Paris VI) in 2013, where her research focused on European air quality and trends. After completing a postdoctoral fellowship at CNRS in France, she joined the NOAA Chemical Sciences Division. She is the chapter lead author on "Ozone Distribution/Trends for Climate Change" in the Tropospheric Ozone Assessment Report.