Age Spectra and Other Transport Diagnostics in the North American Monsoon UTLS from SEAC<sup>4</sup>RS In Situ Trace Gas Measurements | CU Experts

Abstract. The upper troposphere and lower stratosphere (UTLS) during the summer monsoon season over North America (NAM) is influenced by the transport of air from a variety of source regions over a wide range of time scales (hours to years). Age spectra are useful for characterizing the transport into such a region and in this study we use and build on recently developed techniques to infer age spectra from trace gas measurements with photochemical lifetimes from days to centuries. We show that the measurements taken by the Whole Air Sampler instrument during the SEAC4RS campaign can be used to not only derive age spectra, but also path-integrated lifetimes of each of the trace gases and surface source regions. The method used here can also clearly identify and adjust for measurement outliers that were influenced by polluted surface source regions. The results are generally consistent with expected transport features of the NAM but also provide a range of transport diagnostics that have not previously been computed solely from in situ measurements. These methods may be applied to many other existing in situ datasets and the transport diagnostics can be compared with chemistry-climate model transport in the UTLS.;

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