The importance of digital elevation model accuracy in XCO2 retrievals: improving the OCO-2 ACOS v11 product
Knowledge of surface pressure is essential for calculating column average dry-air mole fractions of trace gases, such as CO 2 (X CO 2 ). In the NASA Orbiting Carbon Observatory 2 (OCO-2) Atmospheric Carbon Observations from Space (ACOS) retrieval algorithm, the retrieved surface pressures have been...
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ftcopernicus:oai:publications.copernicus.org:amtd113308 2023-10-01T03:54:23+02:00 The importance of digital elevation model accuracy in XCO2 retrievals: improving the OCO-2 ACOS v11 product Jacobs, Nicole O'Dell, Christopher W. Taylor, Thomas E. Logan, Thomas L. Byrne, Brendan K. Kiel, Matthäus Kivi, Rigel Heikkinen, Pauli Merrelli, Aronne Payne, Vivienne H. Chatterjee, Abhishek 2023-09-01 application/pdf https://doi.org/10.5194/amt-2023-151 https://amt.copernicus.org/preprints/amt-2023-151/ eng eng doi:10.5194/amt-2023-151 https://amt.copernicus.org/preprints/amt-2023-151/ eISSN: 1867-8548 Text 2023 ftcopernicus https://doi.org/10.5194/amt-2023-151 2023-09-04T16:24:18Z Knowledge of surface pressure is essential for calculating column average dry-air mole fractions of trace gases, such as CO 2 (X CO 2 ). In the NASA Orbiting Carbon Observatory 2 (OCO-2) Atmospheric Carbon Observations from Space (ACOS) retrieval algorithm, the retrieved surface pressures have been found to have unacceptable errors, warranting a parametric bias correction. This correction depends on the difference between retrieved and a priori surface pressures, which are derived from a meteorological model that is hypsometrically adjusted to the surface elevation using a digital elevation model (DEM). As a result, the effectiveness of the OCO-2 bias correction is contingent upon the accuracy of the referenced DEM. Here, we investigate several different DEM datasets for use in the OCO-2 ACOS retrieval algorithm: the OCODEM used in ACOS v10 and previous versions, the NASADEM+ used in ACOS v11, the Copernicus DEM, and two polar regional DEMs (ArcticDEM and REMA). We find that variations of 10 m in DEM elevations lead to variations in X CO 2 of approximately 0.4 ppm. Given large-scale differences north of 60° N between the OCODEM and NASADEM+, we find that replacing the OCODEM with NASADEM+ yields a ∼ 100 TgC shift in inferred carbon uptake for the zones spanning 30–60° N and 60–90° N, which is on the order of 5–7 % of the estimated pan-Arctic land sink. Our analysis suggests that the Copernicus DEM has superior global continuity and accuracy compared to the other DEMs, motivating a post-processing update from OCO-2 v11 lite files (which used NASADEM+) to OCO-2 v11.1 by substituting the Copernicus DEM globally. We find that OCO-2 v11.1 improves accuracy and spatial continuity in the bias-corrected X CO 2 product relative to both v10 and v11 in high latitude regions, while resulting in marginal or no change in most regions within ± 60° latitude. In addition, OCO-2 v11.1 provides increased data throughput after quality control filtering in most regions, partly due to the change in DEM, but mostly due to other ... Text Arctic Copernicus Publications: E-Journals Arctic |
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description |
Knowledge of surface pressure is essential for calculating column average dry-air mole fractions of trace gases, such as CO 2 (X CO 2 ). In the NASA Orbiting Carbon Observatory 2 (OCO-2) Atmospheric Carbon Observations from Space (ACOS) retrieval algorithm, the retrieved surface pressures have been found to have unacceptable errors, warranting a parametric bias correction. This correction depends on the difference between retrieved and a priori surface pressures, which are derived from a meteorological model that is hypsometrically adjusted to the surface elevation using a digital elevation model (DEM). As a result, the effectiveness of the OCO-2 bias correction is contingent upon the accuracy of the referenced DEM. Here, we investigate several different DEM datasets for use in the OCO-2 ACOS retrieval algorithm: the OCODEM used in ACOS v10 and previous versions, the NASADEM+ used in ACOS v11, the Copernicus DEM, and two polar regional DEMs (ArcticDEM and REMA). We find that variations of 10 m in DEM elevations lead to variations in X CO 2 of approximately 0.4 ppm. Given large-scale differences north of 60° N between the OCODEM and NASADEM+, we find that replacing the OCODEM with NASADEM+ yields a ∼ 100 TgC shift in inferred carbon uptake for the zones spanning 30–60° N and 60–90° N, which is on the order of 5–7 % of the estimated pan-Arctic land sink. Our analysis suggests that the Copernicus DEM has superior global continuity and accuracy compared to the other DEMs, motivating a post-processing update from OCO-2 v11 lite files (which used NASADEM+) to OCO-2 v11.1 by substituting the Copernicus DEM globally. We find that OCO-2 v11.1 improves accuracy and spatial continuity in the bias-corrected X CO 2 product relative to both v10 and v11 in high latitude regions, while resulting in marginal or no change in most regions within ± 60° latitude. In addition, OCO-2 v11.1 provides increased data throughput after quality control filtering in most regions, partly due to the change in DEM, but mostly due to other ... |
format |
Text |
author |
Jacobs, Nicole O'Dell, Christopher W. Taylor, Thomas E. Logan, Thomas L. Byrne, Brendan K. Kiel, Matthäus Kivi, Rigel Heikkinen, Pauli Merrelli, Aronne Payne, Vivienne H. Chatterjee, Abhishek |
spellingShingle |
Jacobs, Nicole O'Dell, Christopher W. Taylor, Thomas E. Logan, Thomas L. Byrne, Brendan K. Kiel, Matthäus Kivi, Rigel Heikkinen, Pauli Merrelli, Aronne Payne, Vivienne H. Chatterjee, Abhishek The importance of digital elevation model accuracy in XCO2 retrievals: improving the OCO-2 ACOS v11 product |
author_facet |
Jacobs, Nicole O'Dell, Christopher W. Taylor, Thomas E. Logan, Thomas L. Byrne, Brendan K. Kiel, Matthäus Kivi, Rigel Heikkinen, Pauli Merrelli, Aronne Payne, Vivienne H. Chatterjee, Abhishek |
author_sort |
Jacobs, Nicole |
title |
The importance of digital elevation model accuracy in XCO2 retrievals: improving the OCO-2 ACOS v11 product |
title_short |
The importance of digital elevation model accuracy in XCO2 retrievals: improving the OCO-2 ACOS v11 product |
title_full |
The importance of digital elevation model accuracy in XCO2 retrievals: improving the OCO-2 ACOS v11 product |
title_fullStr |
The importance of digital elevation model accuracy in XCO2 retrievals: improving the OCO-2 ACOS v11 product |
title_full_unstemmed |
The importance of digital elevation model accuracy in XCO2 retrievals: improving the OCO-2 ACOS v11 product |
title_sort |
importance of digital elevation model accuracy in xco2 retrievals: improving the oco-2 acos v11 product |
publishDate |
2023 |
url |
https://doi.org/10.5194/amt-2023-151 https://amt.copernicus.org/preprints/amt-2023-151/ |
geographic |
Arctic |
geographic_facet |
Arctic |
genre |
Arctic |
genre_facet |
Arctic |
op_source |
eISSN: 1867-8548 |
op_relation |
doi:10.5194/amt-2023-151 https://amt.copernicus.org/preprints/amt-2023-151/ |
op_doi |
https://doi.org/10.5194/amt-2023-151 |
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