Recent improvements and remaining challenges in the retrieval of XCO2 from the Orbiting Carbon Observatory-2
Abstract
Since its science mission began in September 2014, the Orbiting Carbon Observatory-2 (OCO-2) has provided 1-2 million estimates of the column average carbon dioxide (CO2) dry air mole fraction, XCO2, each month. The quality of the XCO2 retrievals has improved as new versions have been released, including for the most recent version 9 (V9). Because even small (<< 1 ppm) systematic biases can compromise the accuracy of CO2 flux inversion systems, reducing the bias in OCO-2 XCO2 estimates is critical to progress in understanding regional scale sources and sinks of CO2 via top-down inversion approaches.
While V8 was of generally superior quality to V7, there was a small pointing offset in the instrument that led to larger-than-expected errors in regions with significant topography. This pointing offset was corrected in V9. Additionally, the filtering and bias correction were slightly modified in V9 to allow more data over the Amazon and high latitude land surfaces to pass the quality flag criteria. This presentation will discuss these changes, show how they both improve data accuracy and coverage, and discuss potential ramifications for the use of these data driving flux inversions at both small scales, e.g. for estimating power plant emissions, as well as regional and global scales. We also will discuss remaining challenges in the retrieval that will be addressed in the planned version 10 data product.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A43H..05O
- Keywords:
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- 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0325 Evolution of the atmosphere;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 3337 Global climate models;
- ATMOSPHERIC PROCESSESDE: 0480 Remote sensing;
- BIOGEOSCIENCES