Preprints
https://doi.org/10.5194/egusphere-2022-1331
https://doi.org/10.5194/egusphere-2022-1331
 
02 Dec 2022
02 Dec 2022

Using portable low-resolution spectrometers to evaluate TCCON biases in North America

Nasrin Mostafavi Pak1,2,3, Jacob Hedelius1,a, Sebastien Roche1,b, Liz Cunningham1, Bianca Baier5,7, Colm Sweeney5, Coleen Roehl4, Joshua Laughner6, Geoffrey Toon6, Paul Wennberg4, Harrison Parker4, Colin Arrowsmith1, Joseph Mendonca1,2, Pierre Fogal1, Tyler Wizenberg1, Beatriz Herrera1,3, Kimberly Strong1, Kaley A. Walker1, Felix Vogel2, and Debra Wunch1 Nasrin Mostafavi Pak et al.
  • 1Department of Physics, University of Toronto
  • 2Environment and Climate Change Canada, Climate Research Division
  • 3Department of Physical and Environmental Sciences, University of Toronto Scarborough
  • 4Division of Geological and Planetary Sciences and Division of Engineering and Applied Science, California Institute of Technology
  • 5NOAA Global Monitoring Laboratory, Boulder, CO
  • 6Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA
  • 7Cooperative Institute for Research in Environmental Sciences, University of Colorado-Boulder, Boulder, CO
  • anow at: Space Dynamics Laboratory, Utah State University
  • bnow at: John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA

Abstract. EM27/SUNs are portable solar-viewing Fourier Transform Spectrometers (FTSs) that are being widely used to constrain measurements of greenhouse gas emissions and validate satellite trace gas measurements. On a six-week-long campaign in the summer of 2018, four EM27/SUNs were taken to five Total Carbon Column Observing Network (TCCON) stations in North America to measure side-by-side to better understand their durability, as well as the accuracy and precision of retrievals from their trace gas measurements and to constrain site-to-site bias among TCCON sites. We developed new EM27/SUN data products using both previous and current versions of the retrieval algorithm (GGG2014 and GGG2020) and used coincident AirCore measurements to tie the gas retrievals to the World Meteorological Organization (WMO) trace gas standard scales. We also derived airmass-dependent correction factors for the EM27/SUNs. Pairs of column-averaged dry-air mole fractions (denoted with an X) measured by the EM27/SUNs remained consistent compared to each other during the entire campaign, with a 10-minute averaged precision of 0.3 ppm for XCO2, 1.7 ppb for XCH4 and 2.5 ppb for XCO. The maximum biases between TCCON stations were reduced in GGG2020 relative to GGG2014 from 1.3 ppm to 0.5 ppm for XCO2 and from 5.4 ppb to 4.3 for XCH4 but increased for XCO from 2.2 to 6.1 ppb. The increased XCO biases in GGG2020 are driven by measurements at sites influenced by urban emissions (Caltech and AFRC) where the priors overestimate surface CO. In addition in 2020, one EM27/SUN instrument was sent to the Canadian Arctic TCCON station at Eureka and side-by-side measurements were performed in March–July. In contrast to the other TCCON stations that showed an improvement in the biases with the newer version of GGG, the biases between Eureka's TCCON measurements and those from the EM27/SUN degraded with GGG2020, but this degradation was found to be caused by a temperature dependence in the EM27/SUN oxygen retrievals that is not apparent in the GGG2014 retrievals.

Nasrin Mostafavi Pak et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-1331', Benedikt Herkommer, 20 Dec 2022
  • RC2: 'Comment on egusphere-2022-1331', David Griffith, 23 Dec 2022

Nasrin Mostafavi Pak et al.

Data sets

EM27/SUN Retrievals from US and Canada TCCON Road Trip (2018) (GGG2020) Mostafavi Pak, Nasrin; Wunch, Debra; Hedelius, Jacob; Parker, Harrison; Arrowsmith, Colin; Mendonca, Joseph; Cunningham, Liz; Vogel, Felix; Wennberg, Paul https://doi.org/10.5683/SP3/OW4LMR

EM27/SUN Retrievals from US and Canada TCCON Road Trip (2018) (GGG2014) Mostafavi Pak, Nasrin; Wunch, Debra; Hedelius, Jacob; Parker, Harrison; Arrowsmith, Colin; Mendonca, Joseph; Vogel, Felix; Wennberg, Paul; Cunningham, Liz https://doi.org/10.5683/SP3/CBSJMC

EM27/SUN measurements coincident with AirCore launches at AFRC, Lamont, Parkfalls in 2018 (GGG2020) Mostafavi Pak, Nasrin; Wunch, Debra; Hedelius, Jacob; Parker, Harrison; Arrowsmith, Colin; Cunningham, Liz; Vogel, Felix; Wennberg, Paul https://doi.org/10.5683/SP3/UPBJCK

EM27/SUN measurements coincident with AirCore launches at AFRC, Lamont, Parkfalls in 2018 (GGG2014) Mostafavi Pak, Nasrin; Wunch, Debra; Hedelius, Jacob; Parker, Harrison; Arrowsmith, Colin; Cunningham, Liz; Vogel, Felix; Wennberg, Paul https://doi.org/10.5683/SP3/BSZVSO

EM27/SUN Retrievals from Eureka 2020 Campaign (GGG2020) Mostafavi Pak, Nasrin; Wunch, Debra; Roche, Sebastien; Fogal, Pierre; Wizenberg, Tyler; Herrera, Beatriz; Strong, Kimberly; Walker, Kaley A., 2022, "", Borealis, V1 https://doi.org/10.5683/SP3/F8AGKJ

EM27/SUN Retrievals from Eureka 2020 Campaign (GGG2014) Mostafavi Pak, Nasrin; Wunch, Debra; Roche, Sebastien; Fogal, Pierre; Wizenberg, Tyler; Herrera, Beatriz; Strong, Kimberly; Walker, Kaley A. https://doi.org/10.5683/SP3/E4OSA7

Model code and software

EM27/SUN GGG interferogram processing suite (EGI) Jacob Hedelius, & Paul Wennberg https://doi.org/10.22002/D1.306

Nasrin Mostafavi Pak et al.

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Short summary
The TCCON is a network of ground based remote sensing instruments that measure greenhouses in the atmosphere. The consistency between the TCCON measurements is crucial to accurately infer changes in atmospheric composition. In this work, we use portable remote sensing instruments (EM27/SUNs) as traveling standards to evaluate biases between TCCON stations in North America. We also improve the retrievals of EM27/SUNs and evaluate the previous (GGG2014) and newest (GGG2020) retrieval algorithms.