Transport-induced interannual variability of carbon monoxide (CO) is studied during 1989-1993 using the Goddard chemistry and transport model (GCTM) driven by assimilated data. ...
...By fixing the location and magnitude of chemical sources and sinks, the importance of transport-induced variability is investigated at CO monitoring sites. Transport-induced interannual variability can explain 1991-1993 decreases in CO at Mace Head, Ireland and St. David's Head, Bermuda and also 1991-1993 increases in CO at Key Biscayne, FL. Transport-induced variability does not explain decreases in CO at southern hemisphere locations. The model-calculation explains 80-90% of interannual variability in seasonal residuals at Mace Head, St. David's Head, and Key Biscayne and at least 50% of variability in detrended seasonal resuals at Ascension Island and Guam. ...
Interannual fluctuations in monthly mean CO (ppbv) after removing mean and trend over measurement period at selected sites. Residuals from CMDL measurements (model output) are shown with solid (dashed) lines.
