Automated Longterm Measurements of Atmospheric Dimethylsulfide at Pt. Barrow, Alaska
Arctic Research Initiative
2008 Funded Project
AbstractCurrent thinking on climate suggests that the impact of global warming will be greatest inpolar regions. The Arctic plays a key role in Earth’s heat budget by reflecting incoming solar radiation (light and heat) from the ice-covered ocean. As the extent of ice cover retreats northward, this component of the Earth’s albedo will decrease. At the same time, increased exposure of the (liquid) ocean surface to the atmosphere will allow accelerated emission of dimethylsulfide – a compound that is formed in abundance under the ice and in the marginal ice zones near the ice edge.
Dimethylsulfide (DMS) is thought to be a major, perhaps the major natural aerosol precursor in the Arctic atmosphere. An increase in the atmospheric concentration of DMS would lead to an increase in cloud albedo, compensating somewhat for the loss of ice cover in this respect. By coincidence, the very issues that make the biology of the polar ocean so unique – high light intensity combined with strong oxidative (UV) stress, the relatively cold environment, and the increasing freshening of the surface water – all converge in the biological basis of DMS formation. Each of these physical parameters impacts the production of the DMS precursor in marine plankton. This interaction of biology and physics and its consequences for atmospheric chemistry and physics are difficult to predict with confidence -- this problem is an important modeling goal in atmospheric chemistry. Models, of course, need data, and it seems imperative to increase our monitoring of changes in the Arctic atmosphere. To this end I am collaborating with two scientists at the University of Alaska Fairbanks. Clara Deal (International Arctic Research Center) has worked on atmospheric and aqueous measurements of DMS, and she models ocean processes related to DMS dynamics. Glenn Shaw (Geophysical Institute) has worked extensively on aerosol dynamics and he is the originator of the idea that DMS plays an important role in climate. We propose to deploy an automated system for measuring the dynamics of atmospheric DMS at Barrow Alaska at a facility managed by NOAA’s Climate Monitoring and Diagnostics Laboratory. Initially, we propose to make measurements every 15 minutes for more than a year (the first such data of this kind anywhere in the Arctic), characterizing DMS variability on tidal, diel, and seasonal time scales. We will relate these measurements with other data collected at the NOAA facility and with data collected in the part of the 2009 OASIS project centered at Barrow.