Ed Sholkovitz, Geoff Allsup, Richard Arthur, Dave Hosom Woods Hole Oceanographic Institution, Woods Hole, MA, USA
contact: esholkovitz@whoi.edu

The Long-Term Scientific Objectives Aerosol collectors and sensors from buoys are a new line of research for the oceanic and atmospheric community. Buoys represent platforms for the more precise sampling of continental dust depositing on the oceans, seasalt particles being generated at air/ocean boundary and non-seasalt sulfate (NSS) aerosols being produced from the phytoplankton-derived DMS (dimethylsulfide).

Areas of research that can be addressed with aerosol data from buoys: Environmental - Directly determining the off shore transport of contaminants to ocean, estuaries and lakes Oceanic - Effect of mineral dust on the ocean's trace element composition and biological productivity vis-à-vis the Fe Hypothesis Climate Forcing - Sulfur Cycle vis-à-vis the production of NSS aerosols from DMS Radiation balance - Role of anthropogenic mineral aerosols on the Earth's climate Marine Meteorology - Production and transport of sea spray and seasalt droplets under different wind and wave conditions Optics - Attenuation of electromagnetic radiation above the ocean

Why use a buoy?
Aerosol Sampler Block diagram of entire system		The episodic nature and large variability in aerosols concentrations and fluxes are difficult to capture in any systematic fashion using ships or aircraft. Shipboard measurement inevitably misses many important events. Buoys can stay on station for 3-6 months, thus providing a less expensive and alternative platform for long-term time-series research and monitoring programs and for short-term field experiments.
Buoys can be moved to strategic regions for atmospheric and oceanographic research. By mooring an array of buoys in the coastal or open ocean, it would be possible to replace ships with buoys in both long-term measurement programs and short-term field experiments.	Control and Filter Module Pictorial
Control Module	Filter Module - 4 views	Having buoy-mounted aerosol samplers and sensors remotely controlled from shore would open up new research possibilities. Sampling could be event-based, that is, based on satellite pictures of outbreaks of dust and biomass burning from the continents, increased biological productivity or volcanic eruptions.
Filter Holder	Filters from buoy off Woods Hole, Aug '97

Island Test on Bermuda AEROCE Tower Aug-Nov 1996
Back view of 5 filter modules on tower	AEROCE Sampling Tower	Time Series Comparison

(II) Develop buoy-mounted sensors for the real-time measurement of the chemical composition of aerosols embedded on filters. Focus will be on using x-ray fluorescence to measure the elemental concentrations of dust (Fe, Al), seasalt (Cl, S, K and Mg) and non-seasalt sulfur compounds. NSF grant (OCE-97-11891) will commence on 1 Jan. 1998.

Sea Test on Buoy off Woods Hole - Jun-Aug 1997
Buoy Tower Top	WHOI Aerosol Sampling Buoy

One can envision a remotely controlled field laboratory in which buoy-mounted sensors allow one to study in real time the response of upper ocean biology and chemistry to pulses of dust. Real-time data on the Fe concentration of aerosols and rainwater reaching the ocean's surface would allow researchers to trigger buoy-mounted water sensors and water samplers and sediment traps. These, in turn, could measure light scattering, chlorophyll, nutrients, dissolved O2 and collect water and particles for the measurement of Fe, trace metals, Th-isotopes, organic carbon, phytoplankton species, dust, etc.

Block Diagram of an Autonomous Aerosol Sensor	Complete Buoy System