First retrievals of peroxyacetyl nitrate (PAN) from ground-based FTIR solar spectra recorded at remote sites, comparison with model and satellite data

Abstract

Peroxyacetyl nitrate (PAN) is the main tropospheric reservoir of NOx (NO + NO2). Its lifetime can reach several months in the upper cold troposphere. This enables the long-range transport of NOx radicals, under the form of PAN, far from the regions of emission. The subsequent release of NOx through the PAN thermal decomposition leads to the efficient formation of tropospheric ozone (O3), with important consequences for tropospheric oxidative capacity and air quality. The chemical properties of PAN have stimulated the progressive development of remote-sensing products by the satellite community, and recent additions open the prospect for the production of decadal and near-global time series. These products will provide new constraints on the distribution and evolution of this key trace gas in the Earth’s atmosphere, but they will also require reliable measurements for validation and characterization of performance. We present an approach that has been developed to retrieve PAN total columns from ground-based high-resolution solar absorption Fourier transform infrared (FTIR) spectra. This strategy is applied to observations recorded at remote FTIR stations of the Network for the Detection of Atmospheric Composition Change (NDACC). The resulting data sets are compared with total column time series derived from IASI (Infrared Atmospheric Sounding Interferometer) satellite observations and to a global chemical transport model. The results are discussed in terms of their overall consistency, mutual agreement, and seasonal cycles. Noticeable is the fact that the FTIR data point to substantial deficiencies in the global model simulation over high latitudes, a poorly sampled region, with an underestimation of the PAN columns during spring, at the peak of the seasonal cycle. Finally, we suggest avenues for development that should make it possible to limit intra- or intersite biases and extend the retrieval of PAN to other NDACC stations that are more affected by water vapor interferences.

Determination and analysis of time series of CFC-11 (CCl3F) from FTIR solar spectra, in situ observations, and model data in the past 20 years above Jungfraujoch (46°N), Lauder (45°S), and Cape Grim (40°S) stations

“…This is particularly true when a broad window is used, as is also the case for peroxyacetyl nitrate (PAN). 41 The first adjustment was to harmonise the two instruments (homemade and Bruker) time series by multiplying the Bruker time series by a factor of 0.9692 between 12/02/1999 and 09/10/2001. Afterwards, we multiplied the homemade instrument whole time series by a factor of 0.9467.…”

Exceptional Wildfire Enhancements of PAN, C2H4, CH3OH, and HCOOH Over the Canadian High Arctic During August 2017

“…For the retrievals of CO, CH 3 OH, and HCOOH spectroscopic parameters are from the HITRAN 2008 line list database (Rothman et al, 2009). For the retrieval of PAN, H 2 O lines from HITRAN 2016 (Gordon et al, 2017) were used based on the recommendations of Mahieu et al (2021), while the spectroscopic parameters of all other species were sourced from HITRAN 2008. For the retrieval of C 2 H 4 , the updated ATM20 line list was used (Toon, 2022).…”

Measurement report: Spatiotemporal variability of peroxy acyl nitrates (PANs) over Mexico City from TES and CrIS satellite measurements

“…Further details of the CrIS PANs retrieval can be found in Payne et al (2022). TES PAN could be biased high relative to CrIS PANs (Mahieu et al, 2021). In retrievals based on groundbased FTIR measurements covering the spectral regions used by both instruments, Mahieu et al (2021) showed that PAN values retrieved using the retrievals using the 790 cm −1 spectral feature utilized by CrIS were biased low relative to those using the 1150 cm −1 spectral feature used for the TES PAN retrievals.…”