Modulation of Midtropospheric CO^sub 2^ by the South Atlantic Walker Circulation

Midtropospheric CO2 data from the Atmospheric Infrared Sounder (AIRS) are used in this study to explore the variability of CO2 over the South Atlantic Ocean. It was found that the area-averaged CO2 over the South Atlantic Ocean is less than that over South America by about 1 ppm during December-Marc...

Full description

Saved in:
Bibliographic Details
Published in:Journal of the atmospheric sciences 2015-06, Vol.72 (6), p.2241
Main Authors: Jiang, Xun, Olsen, Edward T, Pagano, Thomas S, Su, Hui, Yung, Yuk L
Format: Article
Language:English
Subjects:
Atmosphere
Carbon dioxide
Climate models
Fourier transforms
Influence
Meteorology
Troposphere
Velocity
Vertical distribution
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Midtropospheric CO2 data from the Atmospheric Infrared Sounder (AIRS) are used in this study to explore the variability of CO2 over the South Atlantic Ocean. It was found that the area-averaged CO2 over the South Atlantic Ocean is less than that over South America by about 1 ppm during December-March. This CO2 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 CO2 to the midtroposphere. Meanwhile, air rising over South America brings near-surface air with a higher concentration of CO2 to the midtroposphere. As a result, the AIRS midtropospheric CO2 concentration is lower over the South Atlantic Ocean than over South America during December-March. The detrended AIRS midtropospheric CO2 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 CO2 in the free troposphere and suggest that midtropospheric CO2 measurements can be used as an innovative observational constraint on the simulation of large-scale circulations in climate models.
ISSN:0022-4928
1520-0469