PAN in the eastern Pacific free troposphere: A satellite view of the sources, seasonality, interannual variability, and timeline for trend detection

Peroxyacetyl nitrate (PAN) is an important trace gas that serves to transport nitrogen oxide radicals throughout the troposphere. We present an analysis of satellite observations of PAN from the Tropospheric Emission Spectrometer (TES) over the eastern Pacific Ocean for April and July 2006-2010 and the spring-to-summer seasonal transition for 2006. TES can provide quantitative estimates of free tropospheric PAN in clear-sky or thin cloud conditions where elevated PAN (>0.2ppbv) is present. The percentage of successful PAN detections increases from April to July and then decreases in August and September. However, there are no significant differences in the tropospheric average PAN either interannually or between these months. Plumes containing elevated PAN are present almost every day in July. Elevated PAN observed in July has multiple sources, including fires in Siberia, anthropogenic sources in eastern China, and recirculated pollution from the continental U.S. We combined the observed variability in the TES PAN retrievals over the eastern Pacific Ocean with a range of possible trends in PAN to determine the observational requirements to detect such trends. Based on the variability observed in the PAN retrievals over this region, we predict that it would be faster to detect a trend of a given magnitude in PAN using satellite observations over the eastern Pacific Ocean region rather than in situ surface observations and that a trend of a given magnitude would be more quickly detected in summer than spring.

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Copyright 2017 American Geophysical Union.


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Author Zhu, L.
Payne, V. H.
Walker, T. W.
Worden, J. R.
Jiang, Zhe
Kulawik, S. S.
Fischer, E. V.
Publisher UCAR/NCAR - Library
Publication Date 2017-03-27T00:00:00
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Topic Category geoscientificInformation
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Metadata Date 2025-07-11T19:50:21.273344
Metadata Record Identifier edu.ucar.opensky::articles:19750
Metadata Language eng; USA
Suggested Citation Zhu, L., Payne, V. H., Walker, T. W., Worden, J. R., Jiang, Zhe, Kulawik, S. S., Fischer, E. V.. (2017). PAN in the eastern Pacific free troposphere: A satellite view of the sources, seasonality, interannual variability, and timeline for trend detection. UCAR/NCAR - Library. https://n2t.org/ark:/85065/d7vd71bk. Accessed 04 August 2025.

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