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Methane retrieved from TROPOMI: improvement of the data product and validation of the first 2 years of measurements

Lorente, Alba and Borsdorff, Tobias and Butz, Andre and Hasekamp, Otto and aan de Brugh, Joost and Schneider, Andreas and Wu, Lianghai and Hase, Frank and Kivi, Rigel and Wunch, Debra and Pollard, David F. and Shiomi, Kei and Deutscher, Nicholas M. and Velazco, Voltaire A. and Roehl, Coleen M. and Wennberg, Paul O. and Warneke, Thorsten and Landgraf, Jochen (2021) Methane retrieved from TROPOMI: improvement of the data product and validation of the first 2 years of measurements. Atmospheric Measurement Techniques, 14 (1). pp. 665-684. ISSN 1867-8548. doi:10.5194/amt-14-665-2021. https://resolver.caltech.edu/CaltechAUTHORS:20210318-105725134

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Abstract

The TROPOspheric Monitoring Instrument (TROPOMI) on board the Sentinel 5 Precursor (S5-P) satellite provides methane (CH₄) measurements with high accuracy and exceptional temporal and spatial resolution and sampling. TROPOMI CH₄ measurements are highly valuable to constrain emissions inventories and for trend analysis, with strict requirements on the data quality. This study describes the improvements that we have implemented to retrieve CH₄ from TROPOMI using the RemoTeC full-physics algorithm. The updated retrieval algorithm features a constant regularization scheme of the inversion that stabilizes the retrieval and yields less scatter in the data and includes a higher resolution surface altitude database. We have tested the impact of three state-of-the-art molecular spectroscopic databases (HITRAN 2008, HITRAN 2016 and Scientific Exploitation of Operational Missions – Improved Atmospheric Spectroscopy Databases SEOM-IAS) and found that SEOM-IAS provides the best fitting results. The most relevant update in the TROPOMI XCH₄ data product is the implementation of an a posteriori correction fully independent of any reference data that is more accurate and corrects for the underestimation at low surface albedo scenes and the overestimation at high surface albedo scenes. After applying the correction, the albedo dependence is removed to a large extent in the TROPOMI versus satellite (Greenhouse gases Observing SATellite – GOSAT) and TROPOMI versus ground-based observations (Total Carbon Column Observing Network – TCCON) comparison, which is an independent verification of the correction scheme. We validate 2 years of TROPOMI CH₄ data that show the good agreement of the updated TROPOMI CH₄ with TCCON (−3.4 ± 5.6 ppb) and GOSAT (−10.3 ± 16.8 ppb) (mean bias and standard deviation). Low- and high-albedo scenes as well as snow-covered scenes are the most challenging for the CH₄ retrieval algorithm, and although the a posteriori correction accounts for most of the bias, there is a need to further investigate the underlying cause.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.5194/amt-14-665-2021DOIArticle
https://doi.org/10.5281/zenodo.4447228DOIData
https://ftp.sron.nl/open-access-data-2/TROPOMI/tropomi/ch4/14_14_Lorente_et_al_2020_AMTDRelated ItemData
https://tccondata.orgRelated ItemTCCON Data Archive
ORCID:
AuthorORCID
Lorente, Alba0000-0002-2287-4687
Borsdorff, Tobias0000-0002-4421-0187
Butz, Andre0000-0003-0593-1608
Wu, Lianghai0000-0001-7797-1719
Kivi, Rigel0000-0001-8828-2759
Wunch, Debra0000-0002-4924-0377
Pollard, David F.0000-0001-9923-2984
Deutscher, Nicholas M.0000-0002-2906-2577
Velazco, Voltaire A.0000-0002-1376-438X
Wennberg, Paul O.0000-0002-6126-3854
Warneke, Thorsten0000-0001-5185-3415
Landgraf, Jochen0000-0002-6069-0598
Additional Information:© Author(s) 2021. This work is distributed under the Creative Commons Attribution 4.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 13 July 2020 – Discussion started: 5 August 2020; Revised: 9 November 2020 – Accepted: 24 November 2020 – Published: 28 January 2021. The TROPOMI data processing was carried out on the Dutch National e-Infrastructure with the support of the SURF Cooperative. Data availability: The SRON S5P-RemoTeC scientific TROPOMI CH4 dataset from this study is available for download at https://doi.org/10.5281/zenodo.4447228 (Lorente et al., 2021) or at https://ftp.sron.nl/open-access-data-2/TROPOMI/tropomi/ch4/14_14_Lorente_et_al_2020_AMTD/ (last access: 27 January 2021). TCCON data are available from the TCCON Data Archive: Total Carbon Column Observing Network (TCCON), available at https://tccondata.org/ (last access: 12 January 2021). Author contributions: AL, TB, OH, JdB, AS, AB and JL provided the TROPOMI CH4 retrieval and data analysis. The TCCON partners provided the validation datasets. AL wrote the original draft with input from TB and JL. All authors discussed the results and reviewed and edited the paper. Competing interests: The authors declare that they have no conflict of interest. Disclaimer: The presented work has been performed in the frame of Sentinel-5 Precursor Validation Team (S5PVT) or Level 1/Level 2 Product Working Group activities. Results are based on preliminary (not fully calibrated or validated) Sentinel-5 Precursor data that will still change. The results are based on S5P L1B version 1 data. Plots and data contain modified Copernicus Sentinel data, processed by SRON. Financial support: Funding through the TROPOMI national program from the NSO and Methane+ is acknowledged. Darwin and Wollongong TCCON sites are funded by the Australian Research Council (DP140101552, DP160101598, LE0668470) and NASA (NAG5-12247, NNG05-GD07G). Nicholas M. Deutscher is supported by an ARC Future Fellowship (FT180100327). Review statement: This paper was edited by Dominik Brunner and reviewed by two anonymous referees.
Funders:
Funding AgencyGrant Number
Netherlands Space Office (NSO)UNSPECIFIED
Australian Research CouncilDP140101552
Australian Research CouncilDP160101598
Australian Research CouncilLE0668470
NASANAG5-12247
NASANNG05-GD07G
Australian Research CouncilFT180100327
Issue or Number:1
DOI:10.5194/amt-14-665-2021
Record Number:CaltechAUTHORS:20210318-105725134
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210318-105725134
Official Citation:Lorente, A., Borsdorff, T., Butz, A., Hasekamp, O., aan de Brugh, J., Schneider, A., Wu, L., Hase, F., Kivi, R., Wunch, D., Pollard, D. F., Shiomi, K., Deutscher, N. M., Velazco, V. A., Roehl, C. M., Wennberg, P. O., Warneke, T., and Landgraf, J.: Methane retrieved from TROPOMI: improvement of the data product and validation of the first 2 years of measurements, Atmos. Meas. Tech., 14, 665–684, https://doi.org/10.5194/amt-14-665-2021, 2021
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108481
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Mar 2021 18:27
Last Modified:19 Mar 2021 18:27

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