26 Aug 2022
26 Aug 2022
Status: this preprint is currently under review for the journal ESSD.

Retrievals of XCO2, XCH4 and XCO from portable, near-infrared Fourier transform spectrometer solar observations in Antarctica

David Frank Pollard1, Frank Hase2, Mahesh Kumar Sha3, Darko Dubravica2, Carlos Alberti2, and Dan Smale1 David Frank Pollard et al.
  • 1National Institute of Water & Atmospheric Research Ltd (NIWA), Lauder, New Zealand
  • 2Karlsruhe Institute of Technology, IMK-ASF, Karlsruhe, Germany
  • 3Royal Belgian Institute for Space Aeronomy (BIRA-IASB), Brussels, Belgium

Abstract. The Collaborative Carbon Column Observing Network (COCCON), uses low-resolution, portable EM27/SUN Fourier Transform Spectrometers (FTSs) to make retrievals of dry air mole fractions (DMFs, represented as Xgas) of CO2, CH4, CO and H2O from near infrared solar absorption spectra. The COCCON has developed rapidly over recent years and complements the Total Carbon Column Observing Network (TCCON). In this work we provide details of the first seasonal timeseries 5 of near infrared XCO2 , XCH4 and XCO retrievals from measurements made in Antarctica during the deployment of an EM27/SUN to the Arrival Heights laboratory on Ross Island (77.83° S, 166.66° E, 205 m AMSL) over the austral summer of 2019/20 under the auspices of the COCCON.

The DMFs of all three species were lower in Antarctica than at mid-latitude and for XCO2 and XCO the retrieved values were less variable. For XCH4 however, the variability was significantly greater and it was found that this was strongly correlated to the proximity of the polar vortex.

In order to ensure the stability of the instrument and the traceability of the retrievals, side-by-side comparisons to the TCCON station at Lauder, New Zealand (45.04° S, 169.68° E, 370 m AMSL) and retrievals of the Instrument Line Shape (ILS) were made before and after the measurements in Antarctica. These indicate that over the course of the deployment the instrument stability was such that the change in retrieved XCO2 was well below 0.1 %.

The value of this data for satellite validation is demonstrated by making comparisons with the Tropospheric Monitoring Instrument (TROPOMI) on the Sentinel-5 Precursor (S5P) satellite.

The data set is available from the COCCON Central Facility hosted by the ESA Atmospheric Validation Data Centre (EVDC)  (Pollard, 2021).

David Frank Pollard et al.

Status: open (until 21 Oct 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

David Frank Pollard et al.

Data sets

COCCON Version 2 dataset from Antarctica New Zealand's Arrival Heights atmospheric observatory available at the EVDC Data Handling Facilities covering start date Nov 5th 2019 to end date Mar 9th 2020 Pollard, D. F.

David Frank Pollard et al.


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Short summary
We describe measurements made in Antarctica using an EM27/SUN, near infrared, portable, low resolution spectrometer from which we can retrieve the average atmospheric concentration of several greenhouse gases. We show that these measurements are reliable and comparable to other, similar ground-based measurements. Comparisons to the ESA Sentinel 5-precursor satellite demonstrate the usefulness of this data for satellite validation.