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Modulation of Midtropospheric CO_2 by the South Atlantic Walker Circulation

Jiang, Xun and Olsen, Edward T. and Pagano, Thomas S. and Su, Hui and Yung, Yuk L. (2015) Modulation of Midtropospheric CO_2 by the South Atlantic Walker Circulation. Journal of the Atmospheric Sciences, 72 (6). pp. 2241-2247. ISSN 0022-4928.

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Midtropospheric CO_2 data from the Atmospheric Infrared Sounder (AIRS) are used in this study to explore the variability of CO_2 over the South Atlantic Ocean. It was found that the area-averaged CO_2 over the South Atlantic Ocean is less than that over South America by about 1 ppm during December–March. This CO_2 contrast is due to the large-scale vertical circulation over this region. During December–March, there is sinking motion over the South Atlantic Ocean. The sinking motion brings high-altitude air with a slightly lower concentration of CO_2 to the midtroposphere. Meanwhile, air rising over South America brings near-surface air with a higher concentration of CO_2 to the midtroposphere. As a result, the AIRS midtropospheric CO_2 concentration is lower over the South Atlantic Ocean than over South America during December–March. The detrended AIRS midtropospheric CO_2 difference correlates well with the inverted and detrended 400-hPa vertical pressure velocity difference between the South Atlantic and South America. Results obtained from this study demonstrate the strong impact of large-scale circulation on the vertical distribution of CO_2 in the free troposphere and suggest that midtropospheric CO_2 measurements can be used as an innovative observational constraint on the simulation of large-scale circulations in climate models.

Item Type:Article
Related URLs:
URLURL TypeDescription Material
Jiang, Xun0000-0001-8932-3807
Su, Hui0000-0003-1265-9702
Yung, Yuk L.0000-0002-4263-2562
Additional Information:© 2015 American Meteorological Society. Manuscript received 19 November 2014, in final form 19 February 2015. We thank two anonymous reviewers for helpful comments. XJ and YLY were supported by the AIRS project, OCO-2 project, and NASA Grant NNX13AC04G to UH and Caltech. 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.
Funding AgencyGrant Number
Orbiting Carbon Observatory 2 (OCO-2)UNSPECIFIED
Subject Keywords:Walker circulation; Carbon cycle; Carbon dioxide
Issue or Number:6
Record Number:CaltechAUTHORS:20180312-144301289
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85258
Deposited By: Ruth Sustaita
Deposited On:12 Mar 2018 21:56
Last Modified:09 Mar 2020 13:19

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