Pg. Simmonds et al., SEGREGATION AND INTERPRETATION OF OZONE AND CARBON-MONOXIDE MEASUREMENTS BY AIR-MASS ORIGIN AT THE TOR STATION MACE HEAD, IRELAND FROM 1987TO 1995, Journal of atmospheric chemistry, 28(1-3), 1997, pp. 45-59
Three independent methods have been used to sort the ozone, carbon mon
oxide, and other radiatively important trace gases measured at Mace He
ad, Ireland, and thereby distinguish clean air masses transported over
the North Atlantic from the more polluted air masses which have recen
tly travelled from the European continent. Over the period April 1987-
June 1995 the Northern Hemisphere surface ozone baseline concentration
s exhibited a mean concentration of 34.8 ppb, with a small positive tr
end (+0.19 ppb yr(-1)), while the corresponding trend in air originati
ng from the polluted European areas was negative (-0.39 ppb yr(-1)). C
arbon monoxide measurements from March 1990 to December 1994 showed ne
gative trends for both the unpolluted (-0.17 ppb yr(-1)) and polluted
data (-13.6 ppb yr(-1)). Overall the continent of Europe was shown to
be a small net sink of 2.6 ppb for all occasions when European air was
transported to the North Atlantic.