Comparing v11.2 OCO‐2 and v11 OCO‐3 XCO2 Retrievals With Ground‐Based COCCON Measurements
Saswati Das, Mahesh Kumar Sha, Darko Dubravica, Thomas E. Taylor, Matthäus Kiel, Joshua L. Laughner, Gregory B. Osterman, Christopher W. O’Dell, Brendan Fisher, Robert R. Nelson, Carlos Alberti, Bianca C. Baier, Dimitrios Balis, Hartmut Bösch, Andre Butz, Zhaonan Cai, Jia Chen, Frédéric Chevallier, Alexandru Dandocsi, Nicholas M. Deutscher, Manvendra K. Dubey, Dietrich G. Feist, Lena Feld, Jonathan E. Franklin, Matthias M. Frey, Omaira Garcia, Elaine Gottlieb, Konstantin Gribanov, David W. T. Griffith, Michel Grutter, Frank Hase, Eliezer S. Hernández, Neil Humpage, Laura T. Iraci, Nicole Jacobs, Sujong Jeong, Pascal Jeseck, Tomi Karppinen, Rigel Kivi, Morgan Lopez, Andreas Luther, Maria Makarova, Moritz Makowski, Erin McGee, Marios Mermigkas, Isamu Morino, Justus Notholt, Hirofumi Ohyama, Thomas Panou, Hayoung Park, Robert Parker, David F. Pollard, Markus Rettinger, Sébastien Roche, Coleen M. Roehl, Constantina Rousogenous, Kei Shiomi, William R. Simpson, Wolfgang Stremme, Kimberly Strong, Ralf Sussmann, Noemie L. Taquet, Yao Té, Chrysanthi Topaloglou, Geoffrey Toon, Qiansi Tu, Mihalis Vrekoussis, Pucai Wang, Thorsten Warneke, Steven C. Wofsy, Debra Wunch, Minqiang Zhou, Elizabeth Spicer, Annmarie Eldering, Susan Kulawik, Abhishek Chatterjee, Vivienne H. PayneAbstract
The Orbiting Carbon Observatory‐2 and ‐3 (collectively termed “OCO‐2/3,” hereafter) missions, together, provide precise and accurate global data records that contribute to a better understanding of the variability in atmospheric carbon dioxide (CO 2 ). The retrieval algorithm used to process the satellite data, Atmospheric Carbon Observations from Space (ACOS), continues to be updated. The latest v11.2 OCO‐2 and v11 OCO‐3 data releases include significant improvements compared to past data versions. The Total Carbon Column Observing Network (TCCON), a network of ground‐based Fourier Transform Spectrometers (FTS), has historically, been the validation data source for OCO‐2/3. The COllaborative Carbon Column Observing Network (COCCON), an emerging network of ground‐based portable Fourier Transform Infrared Spectrometers (EM27/SUN), aids satellite validation efforts by providing observations in geographic locations where there are no TCCON measurements being made. This study provides the first global comparison between the OCO‐2/3 data sets and the COCCON observations. Currently, the COCCON data set, most useful for global analysis, is version 1 (v1), which our analysis shows is typically lower than the satellites by ∼0.50–1.00 ppm, with scatter against OCO‐2/3 roughly similar to TCCON versus OCO‐2/3. This analysis includes comparisons of results from the latest v2.x COCCON data version for the sites with the data available. Comparisons with the v2.x COCCON data version generally show improved comparisons against OCO‐2/3. Our analysis illustrates the ways in which the COCCON data set, used globally, regionally, or in specific locations, can provide insight into the quality of satellite observations of atmospheric CO 2 .