the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 03 Apr 2024
Local and Regional Enhancements of CH4, CO, and CO2 Inferred from TCCON Column Measurements
Abstract. In this study, we demonstrate the utility of available correlative measurements of carbon species to identify regional and local airmass characteristics and their associated source types. In particular, we combine different regression techniques and enhancement ratio algorithms with CO, CO2, and CH4 data of total column abundance from 11 sites of the Total Carbon Column Observing Network (TCCON) to infer relative contributions of regional and local sources to each of these sites. The enhancement ratios provide a viable alternative to univariate measures of relationships between the trace gases that are insufficient in capturing source type and transport signatures. Regional enhancements are estimated from the difference between bivariate regressions across a specific time window of observed total abundance of these species (BEHr) and inferred anomalies (AERr) associated with a site-specific background. Since BEHr and AERr represent the bulk and local species enhancement ratio, respectively, its difference simply represents the site-specific regional component of these ratios. We can then compare these enhancements for CO2 and CH4 with CO to differentiate combustion versus non-combustion associated airmasses. Our results show that while the regional and local influences in enhancements vary across sites, dominant characteristics are found to be consistent with previous studies over these sites and with bottom-up anthropogenic and fire emission inventories. The site in Pasadena shows a dominant local influence (>60 %) across all species enhancement ratios, which appear to come from a mixture of biospheric and combustion activities. In contrast, Anmyeondo shows more regionally influenced (>60 %) air masses associated with high temperature and/or biofuel combustion activities. Ascension appears to only show a large regional influence (>80 %) on CO/CO2 and CO/CH4 which is indicative of transported and combustion-related CO from nearby African region, consistent with sharp rise in column CO (3.51±0.43 % ppb/year) in this site. These methods have important application to source analysis using space-borne column retrievals of these species.
- Preprint
(2173 KB) - Metadata XML
-
Supplement
(1386 KB) - BibTeX
- EndNote
Status: open (until 03 Jun 2024)
-
RC1: 'Comment on egusphere-2024-705', Anonymous Referee #1, 23 Apr 2024
reply
General Comments:
In this study, Mottungan et al. demonstrate the use of correlative measurements of CO, CO2, and CH4 data from eleven TCCON sites to identify local and regional airmass characteristics and estimate the relative contributions of local and regional sources at each TCCON site. They use different regression techniques and enhancement ratio algorithms in the analysis. The paper addresses important science questions, is well-structured, and contains informative figures. It fits into the scope of AMT. The current TCCON GGG2020 data are available for several more years than shown in the analysis, and it might be nice to have the new data included in the analysis. The paper is suitable for publication in AMT after minor revisions, data updation/extension, and technical changes.
Specific Comments:
L91: This is just a personal preference – maybe equations could be used instead of text to explain the two methods. Some of the text could also be moved to the ‘Data and Methods’ section.
L115: "While previous studies have used enhancement ratios to examine the source attribution of CH4, CO, and CO2 at regional and/or local scale, we note that few have investigated bulk characteristics on a source type basis using all these 3 species and using these combinations of regression algorithms for globally distributed column-integrated measurements." – Please cite a few examples of studies that have used all 3 species and combinations of regression algorithms.
L123 and Table 1: The TCCON data are used from 2012 to 2019, as also mentioned in Table 1. The Public TCCON data (GGG2020) are currently available until 2023 for Pasadena/Caltech, Garmisch, Sodankyla, Burgos, and Wollongong. The data are available until 2022 for Hefei and Darwin and until 2020 for Reunion. In Table 1, the data for these sites are listed for shorter time periods (and in Figure S1). I am curious if the analysis can be expanded and updated to include the additional years of available data.
The data link provided in the ‘Data Availability Statement' points to the TCCON website, which currently does not list the TCCON data for Ascension Island and Anmyeondo (for GGG2020).
Please indicate the data version used. Is it GGG2014 (data for Ascension Island and Anmyeondo are available) or GGG2020? In Table 1, the References are used for both data versions (e.g., Sodankyla – Kivi et al. (2014) for GGG2014 and Kivi et al. (2022) for GGG2020).
Oh et al. (2018) are cited in Table 1. Please add it to the References section.
Liu et al. (2018) are listed in the References section but not cited in the manuscript.
L124: If the data version is GGG2020, please consider citing Laughner et al. (2023) (https://doi.org/10.5194/amt-16-1121-2023) and https://doi.org/10.5194/essd-2023-331.
Figure 1: Please consider listing location names on all sub-plots/panels. The background colors make it difficult to focus on the makers. Please consider changing the maker type and color.
L137: “Qualitatively, MOPITT and GOSAT retrievals show reasonable agreement between the retrieval of CO, CO2, and CH4 column abundance relative to TCCON at these locations.” – Please elaborate.
L219: Wu and Yu, 2018 has been cited but not listed in the References section.
Figure 2: This is just a personal preference - maybe the position of the legends that indicate the name of the species could be fixed.
The CO between ~ 2015 and 2017 is very high for Darwin. Do we know why this is the case?
L250: “The figure shows a clear seasonal cycle in the abundance of CO over all the locations and the seasonal amplitude is higher over Hefei (38.3±0.0 ppb), Sodankyla (37.2±3.9 ppb) and Pasadena (36.0±4.5 ppb) compared to other locations.” – Hefei isn’t plotted in Figure 2.
L253: “Furthermore, a large variability in CO is observed in the seasonal amplitude over Burgos (15.5 ppb), Darwin (10.2 ppb), Reunion (9.2 ppb) and Wollongong (8.5 ppb) during this period.” – Burgos isn’t plotted in Figure 2. Please consider stating “(not shown)” next to “Burgos”.
L271: “We also see a decreasing trend in CO in most of the selected TCCON sites (-0.20 to -0.98 % ppb/year), except at Ascension (3.51±0.43 % ppb/year), Pasadena (0.01±0.22 % ppb/year), and Wollongong (0.27±0.35 % ppb/year).” – Why is the trend different over these three TCCON sites?
L277: Does Anmyeondo show the highest CO2 trend and Ascension the lowest? If so, please consider stating this explicitly.
Technical Comments:
L116: “all three species” instead of “all these 3 species”
L123: “during 2012 to 2019” instead of “during the period 2012 to 2019”
L146: “than its western counterpart” instead of “than its the western counterpart”
L246: “Firstly, it is informative to understand…” – Please consider changing “informative” to “pertinent”.
L264: “as” instead of “like that is”
L276: Please consider rephrasing “CO2 and CH4 are showing an increasing trend in all locations” to “Increased CO2 and CH4 trends are observed at all locations”.
L278: For Sodankyla, “high” instead of “higher” and “low” instead of “lower”.
L279: “This is possibly due to”, not “This is may due to”.
L281: over “the” Atlantic Ocean
L287: “necessary” instead of “needed”.
L296: “… we show in Figure 3” instead of “… we also show in Figure 3”
L297: “We provide estimates” instead of “We also provide estimates”.
L298: “… for the period listed in Table 2” instead of “… for the whole analysis period as presented in Table 2”.
L300: “suggest” instead of “suggests”.
L321: “sites in SH” instead of “sites in SH locations”.
L352: “The local enhancement ratio appears to dominate over the regional ratios for Pasadena in all seasons and relative to the regional ratio, the magnitude of local enhancement ratios in CO/CO2 and CO/CH4 are more significant during Fall.” – Please consider splitting the sentence into two.
L410: “comes from” instead of “is coming from”
Citation: https://doi.org/10.5194/egusphere-2024-705-RC1
Viewed
| HTML | XML | Total | Supplement | BibTeX | EndNote | |
|---|---|---|---|---|---|---|
| 192 | 55 | 11 | 258 | 15 | 7 | 8 |
- HTML: 192
- PDF: 55
- XML: 11
- Total: 258
- Supplement: 15
- BibTeX: 7
- EndNote: 8
Viewed (geographical distribution)
| Country | # | Views | % |
|---|
| Total: | 0 |
| HTML: | 0 |
| PDF: | 0 |
| XML: | 0 |
- 1