Open AccessThe seasonally varying isotopic composition of the sources of carbon monoxide at Barbados, West Indies
Author(s) -
Mak John E.,
Kra Gabriel,
Sandomenico Theodore,
Bergamaschi Peter
Publication year - 2003
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2003jd003419
Subject(s) - latitude , southern hemisphere , seasonality , west indies , atmospheric sciences , northern hemisphere , environmental science , climatology , amplitude , geology , δ13c , stable isotope ratio , physics , geodesy , statistics , ethnology , mathematics , quantum mechanics , history
We have collected and analyzed air samples for 13 CO, C 18 O, and CO concentration at Barbados, West Indies (13°N, 59°W), from July 1996 to May 2000. The δ 13 C values during the summer of 1996 and 1997 are among the lowest values reported for atmospheric CO, at less than −34‰ (Peedee belemnite‐CO 2 ), but seasonal maxima are close to that reported at other stations. Seasonal lows for 1998 and 1999 are between −32.5‰ and −33‰, which is also lower than observations at higher‐latitude sites. Such low values are difficult to simulate by considering the well‐established CO sources alone, and may indicate a small, but very isotopically depleted, source of CO from the marine boundary layer, such as chlorine‐catalyzed destruction of CH 4 . We directly compare the observations at Barbados with data from middle‐latitude and high‐latitude Northern Hemisphere sites and construct a latitudinal dependence in the seasonal amplitude of both 13 CO and C 18 O. We then investigate the source strengths of CO at this site using a three‐dimensional inverse model analysis, which has also been used to simulate the other data sets. Model simulations reproduce the seasonal variations in [CO], δ 13 C, and δ 18 O but do not predict the large amplitude of δ 13 C (which is due to the very depleted summertime δ 13 C values) or the absolute values for 18 O. We also include a calculation of the relative strengths of certain sources based on the model inversion.