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Characterizing the lifetime and occurrence of stratospheric‐tropospheric exchange events in the rocky mountain region using high‐resolution ozone measurements
Author(s) -
Sullivan John T.,
McGee Thomas J.,
Thompson Anne M.,
Pierce R. Bradley,
Sumnicht Grant K.,
Twigg Laurence W.,
Eloranta Edwin,
Hoff Raymond M.
Publication year - 2015
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2015jd023877
Subject(s) - tropopause , troposphere , ozone , environmental science , atmospheric sciences , tropospheric ozone , stratosphere , air quality index , lidar , air mass (solar energy) , altitude (triangle) , ozone layer , climatology , meteorology , geography , geology , remote sensing , physics , geometry , mathematics , boundary layer , thermodynamics
The evolution of a Stratospheric‐Tropospheric Exchange (STE) event from 4 to 8 August 2014 at Fort Collins, Colorado, is described. The event is characterized with observations from the Goddard Space Flight Center TROPospheric OZone (TROPOZ) Differential Absorption Lidar, the University of Wisconsin High Spectral Resolution Lidar, and multiple ozonesondes during NASA's Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality and the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) campaigns. Based on the extended TROPOZ observations throughout the entire campaign, it was found that STE events have largely contributed to an additional 10–30 ppbv of ozone at Fort Collins. Additional measurements of ozone and relative humidity from the Atmospheric Infrared Sounder are characterize the transport of the intrusion. The Real‐time Air Quality Modeling System simulated ozone agrees well with the TROPOZ ozone concentrations and altitude during the STE event. To extend the analysis into other seasons and years, the modeled ozone to potential vorticity ratio is used as a tracer for stratospheric air residing below the tropopause. It is found that at Fort Collins, CO, and depending on season from 2012 to 2014, between 18 and 31% of tropospheric ozone corresponds to stratospheric air. A relationship to determine the lifetime of stratospheric air below the tropopause is derived using the simulated ratio tracer. Results indicate that throughout summer 2014, 43% of stratospheric air resided below the tropopause for less than 12 h. However, nearly 39% persisted below the tropopause for 12–48 h and likely penetrated deeper in the troposphere.