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Impact on regional winter climate by CO 2 increases vs. by maritime‐air advection
Author(s) -
Otterman J.,
Atlas R.,
Russell G. L.,
Saaroni H.
Publication year - 2003
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 - 10.1029/2003gl017545
Subject(s) - environmental science , advection , climatology , outgoing longwave radiation , longwave , atmospheric sciences , dimensionless quantity , atmospheric circulation , wind speed , meteorology , radiation , geography , geology , physics , convection , quantum mechanics , mechanics , thermodynamics
Fractional Outgoing Radiation, FOR (dimensionless), defined as the ratio of Outgoing Longwave Radiation, OLR (W/m 2 ), to upward Surface Longwave Emission, SLE (W/m 2 ), is a basic parameter for analyzing regional greenhouse effect. Here, FOR values are derived from a General Circulation Model by extracting OLR and SLE over areas in east‐central Europe (at about 60°N) one hour after injecting appropriate CO 2 concentration (adjustments to the atmospheric profile are thus excluded) to the Feb. 1 midnight simulation. The reduction in FOR is 0.00051 when atmospheric CO 2 increases by 14 ppm, which is the currently expected per‐decade increase. Fluctuations in the North‐Atlantic surface winds produce fluctuations in FOR over central Europe: monthly‐mean FOR in strong‐wind February 1990 was 0.679, but 0.758 in weak‐wind, lower cloud‐fraction February 1996. Strong maritime‐air advection in 1990 resulted thus in FOR reduced by 0.079, effect by two orders‐of‐magnitude stronger than the decrease effected by the per‐decade increase in CO 2 .