Stratospheric Air Sub-sampler (SAS) and its application to analysis of Δ<sup>17</sup>O(CO<sub>2</sub>) from small air samples collected with an AirCore

Abstract

Abstract. We present the set-up and a scientific application of the Stratospheric Air Sub-sampler (SAS), a device to collect and to store the vertical profile of air collected with an AirCore (Karion et al., 2010) in numerous sub-samples for later analysis in the laboratory. The SAS described here is a 20 m long 1/4 inch stainless steel tubing that is separated by eleven valves to divide the tubing into 10 identical segments, but it can be easily adapted to collect smaller or larger samples. In the collection phase the SAS is directly connected to the outlet of an optical analyzer that measures the mole fractions of CO 2 , CH 4 and CO from an AirCore sampler. The stratospheric part (or if desired any part of the AirCore air) is then directed through the SAS. When the SAS is filled with the selected air, the valves are closed and the vertical profile is maintained in the different segments of the SAS. The segments can later be analysed to retrieve vertical profiles of other trace gas signatures that require slower instrumentation. As an application, we describe the coupling of the SAS to an analytical system to determine the 17 O excess of CO 2 , which is a tracer for photochemical processing of stratospheric air. For this purpose the analytical system described by (Mrozek et al., 2015) was adapted for analysis of air directly from the SAS. The performance of the coupled system is demonstrated for a set of air samples from an AirCore flight in November 2014 near Sodankylä, Finland. The standard error for a 25 mL air sample at stratospheric CO 2 mole fraction is 0.

LISA: a lightweight stratospheric air sampler

“…The vertical resolution and sample 5 size of the LISA sampler is compared to the performance of AirCore subsampled air in Table 5. Its shows that sampler outperforms the subsample method described in Paul et al, 2016 andMrozek et al, 2016. As mentioned previously, the vertical resolution depends on the ascending speed and the effective sampling time, and the sample size also depends on the effective sampling time. To this end, the effort in collecting more air samples by increasing 10 the effective sampling time will compromise the vertical resolution.…”

“…This is problematic for accurate analysis of isotopic compositions or multiple tracers. Sub-sampling of the stratospheric part of the AirCore samples has been used for measurements of Δ 17 O in CO2 (Mrozek et al, 2016) and radiocarbon analysis (Paul et al, 10 2016). The samples have small sample size, which limits the analytical precision of their analyses.…”

“…On the other hand, the model assumes a constant upstream pressure, whereas the upstream pressure decreases during flight, and hence the total sampled volume at STP would be then smaller than the modelled. Observing Network (TCCON) facility (Kivi and Heikkinen, 2016). The facility includes a high-resolution Fourier Transform Spectrometer installation to retrieve column-averaged abundances of atmospheric constituents, gas analysers for in situ measurements and both manual and automatic radiosonde systems.…”

Atomic spectrometry update – a review of advances in environmental analysis

“…The AirCore sampler is a balloon-mounted air sampler which collects a continuous air profile during descent through the stratosphere. A new sub-sampler, dubbed the SAS (Stratospheric Air Sub-sampler) was developed 22 to extract aliquots of collected air from this AirCore device, for subsequent determination of 14 CO2 by IRMS, whilst maintaining vertical height profile information.…”

Simultaneous measurement of δ<sup>13</sup>C, δ<sup>18</sup>O and δ<sup>17</sup>O of atmospheric CO<sub>2</sub> – Performance assessment of a dual-laser absorption spectrometer

“…With the direct measurement of δ 17 O in addition to δ 18 O (triple oxygen isotope composition) of atm-CO 2 , the δ 17 O excess (∆ 17 O) can be calculated. ∆ 17 O measurements can be a tracer for biosphere activity (Hoag et al, 2005), atmospheric circulation patterns (Mrozek et al, 2016) and different combustion processes (Horváth et al, 2012). The ∆ 17 O is usually defined as: Variations in the ∆ 17 O signal in the troposphere are mainly depending on biosphere activity and the influx of stratospheric CO 2 (Koren et al, 2019;Hofmann et al, 2017;Hoag et al, 2005).…”