Tropical mid-tropospheric CO_2 variability driven by the Madden–Julian oscillation
Carbon dioxide (CO_2) is the most important anthropogenic greenhouse gas in the present-day climate. Most of the community focuses on its long-term (decadal to centennial) behaviors that are relevant to climate change, but there are relatively few discussions of its higher-frequency forms of variability, and none regarding its subseasonal distribution. In this work, we report a large-scale intraseasonal variation in the Atmospheric Infrared Sounder CO_2 data in the global tropical region associated with the Madden–Julian oscillation (MJO). The peak-to-peak amplitude of the composite MJO modulation is ~1 ppmv, with a standard error of the composite mean < 0.1 ppmv. The correlation structure between CO2 and rainfall and vertical velocity indicate positive (negative) anomalies in CO_2 arise due to upward (downward) large-scale vertical motions in the lower troposphere associated with the MJO. These findings can help elucidate how faster processes can organize, transport, and mix CO_2 and provide a robustness test for coupled carbon–climate models.
Additional Information© 2010 National Academy of Sciences. Edited by Richard M. Goody, Harvard, Falmouth, MA, and approved September 21, 2010 (received for review June 10, 2010). Published online before print October 26, 2010. We thank Dr. Moustafa T. Chahine, Dr. Edward T. Olsen, and Mr. Luke Chen of the AIRS Science Team for providing information on the quality of AIRS data and comments on this work. We also thank Miss Le Kuai, Mr. Michael R. Line, Mr. Da Yang, Dr. Hartmut H. Aumann, Dr. David Crisp, Prof. Andrew P. Ingersoll, Prof. Xun Jiang, Dr. Brian H. Kahn, Dr. Susan S. Kulawik, Dr. Jack S. Margolis, Dr. Run-Lie Shia, Prof. Ka-Kit Tung, Dr. John R. Worden, and two anonymous reviewers for reviewing the manuscript and providing useful comments. This research was supported in part by National Science Foundation (NSF) Grant ATM-0840787 and Grant ATM-0934303 to the California Institute of Technology and NSF Grant ATM-0840755 to University of California, Los Angeles. Y.L.Y. was supported by Jet Propulsion Laboratory Grant P765982 to the California Institute of Technology. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration. AIRS Level 3 daily CO2 products were obtained from AIRS Data Server (http://disc.sci.gsfc.nasa.gov/AIRS/dataholdings/ by-data-product/AIRX3C2D). AIRS Level 3 daily H2O products were obtained from AIRS Data Server (http://disc.sci.gsfc.nasa.gov/AIRS/dataholdings/ by-data-product/airsL3_STD_AIRS_AMSU.shtml). NCEP/NCAR reanalysis data used in this study were provided by the NOAA/Office of Oceanic and Atmospheric Research (OAR)/ESRL Physical Sciences Division (PSD) Data Server (http://www.esrl.noaa.gov/psd/data/reanalysis/). ERA-interim reanalysis data used in this study were obtained from the ECMWF Data Server (http://data.ecmwf.int/data/). The NOAA ESRL CO2 data from the Carbon Cycle Cooperative Global Air Sampling Network, 1968–2008, Version 2009- 07-15, were obtained from the NOAA FTP server (ftp://ftp.cmdl.noaa.gov/ccg/co2/flask/event/). CONTRAIL data were obtained from theWorld Meteorological Organization World Data Centre for Greenhouse Gases (http://gaw.kishou.go.jp/cgi-bin/wdcgg/accessdata.cgi). RMM indices were obtained from http://www.cawcr.gov.au/bmrc/clfor/cfstaff/matw/maproom/RMM/. Author contributions: K.-F.L., B.T., D.E.W., and Y.L.Y. designed research; K.-F.L. performed research; K.-F.L. analyzed data; and K.-F.L. wrote the paper.
Published - Li2010p11988P_Natl_Acad_Sci_Usa.pdf
Supplemental Material - pnas.1008222107_SI.pdf