Dr. Emma Yates Studies Stratospheric Ozone Intrusions

Dr. Emma Yates of BAER has begun analyzing atmospheric data collected this spring and summer by the Alpha Jet Atmospheric eXperiment (AJAX). The AJAX project, which has supported NASA Earth Science objectives since 2011, measured ozone and greenhouse gas concentrations at varying altitudes over California and Nevada. Ozone (O₃) is present in the upper atmosphere (stratosphere) in high concentrations, providing critical protection from ultraviolet solar radiation (the ozone layer). However, ozone is also a pollutant and greenhouse gas when present in the atmosphere near the ground (the troposphere), and its surface concentrations are regulated by the US EPA Clean Air Act. Stratospheric ozone (high concentrations) can be transported to the lower atmosphere under certain meteorological conditions, aided by vertical mixing in the mountainous Western US. NASA, BAER, and H211 have conducted AJAX flights every spring-summer (the time of year most prone to stratospheric intrusions) since 2012 to target stratospheric intrusions and to determine whether any stratospheric ozone made its way into the lower troposphere to impact surface concentrations. Dr. Yates is compiling the AJAX dataset and plans to analyze the impacts of vertical transport on surface ozone concentrations.

Image Caption: Stratospheric intrusion observed by AJAX on 5 June 2012 over California at 3-4 km altitude. The following day, this air affected surface level ozone in Wyoming, causing exceedances of the EPA ground level ozone standard.