SEASONAL EMISSIONS OF ISOPRENE AND OTHER REACTIVE HYDROCARBON GASES FROM THE OCEAN

In this paper we show evidence that isoprene emission from the oceans is strongly seasonally dependent and is correlated with the chlorophyl l content of the water from measurements in the North Sea and Southern Ocean. We estimate the seasonally averaged flux of isoprene to the at mosphere to be 1.7 x 10(7) molecules cm(-2) s(-1), which may be signif icant for atmospheric chemistry in locations remote from land as it is the only known source of atmospheric isoprene in these regions. We ob serve a strong seasonal cycle of several other NMHCs in seawater at hi gh latitudes, with a maximum in summer. This will distort current esti mates of the annual marine flux of NMHCs to the atmosphere which may n eed to be reduced by up to an order of magnitude to account for lower emissions in winter.