Premium
Assessment of tropical OH seasonality using atmospheric 14 CO measurements from Barbados
Author(s) -
Mak John E.,
Southon John R.
Publication year - 1998
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 - 10.1029/98gl02180
Subject(s) - tropics , seasonality , latitude , climatology , atmospheric sciences , environmental science , tropical atlantic , atmospheric chemistry , meteorology , geology , ozone , geography , sea surface temperature , ecology , biology , geodesy
14 CO can be used to assess the mean OH concentration if the atmospheric inventory is determined. However, atmospheric transport must be well represented. The dependence on transport has previously been predicted in model studies to be much smaller in the tropics than in the middle latitudes. To test this, we made weekly measurements of 14 CO from a tropical station in the Atlantic (Barbados, West Indies, 13°10′N, 53°26′W) from July 1996 to July 1997. These data are compared with the 14 CO seasonal cycle predicted from a zero dimensional chemistry model. Results show that the observed seasonal cycle correlates well with predicted 14 CO from the chemistry model during the summer and fall, however significant deviation from the chemistry model becomes apparent in the wintertime, which is probably largely a result of 14 CO being transported to the tropics from the middle latitudes, and is in contrast to earlier modeling studies. Transport has a stronger effect in the winter months because the latitudinal gradient in 14 CO is large and the lifetime is long, since OH concentrations are at their seasonal low.