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Long‐term change of CO 2 latitudinal distribution in the upper troposphere
Author(s) -
Matsueda Hidekazu,
Machida Toshinobu,
Sawa Yousuke,
Niwa Yosuke
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2014gl062768
Subject(s) - troposphere , southern hemisphere , northern hemisphere , climatology , biosphere , environmental science , latitude , atmospheric sciences , biosphere model , geology , ecology , geodesy , biology
We analyzed temporal variations in the annual mean latitudinal distribution of upper tropospheric CO 2 using the aircraft measurements taken between Japan and Australia over the period 1993–2013, plus earlier data from 1984 and 1985. The observed CO 2 latitudinal gradient between 30°N and 30°S showed large interannual variations that are clearly associated with El Niño–Southern Oscillation events. We also found long‐term increasing trends of the CO 2 gradients in the most northern latitudes that are proportionally associated with increasing fossil fuel emissions, while decreasing trends were found around the tropical regions. Extrapolation of the changes in the CO 2 gradient back to zero fossil fuel emissions showed a negative north‐south gradient with lower CO 2 in the Northern Hemisphere than in the Southern Hemisphere, as well as a regional CO 2 elevation in the tropical regions. These features provide a useful constraint on model estimates of CO 2 fluxes from the ocean and the land biosphere.