This week the close-island phase of the Nauru99 campaign began in which the Ron Brown moved to various sites around the perimeter of the island. The data gathered simultaneously by the NOAA ship and the U.S. Department of Energy site on Nauru will help scientists better understand island effects on the measurement of atmospheric conditions in the tropics.

As this phase began, two meetings were held on the Ron Brown. At the first meeting, scientists discussed lidar scanning operations around Nauru so that the effects of the island on boundary layer and aerosol distributions could be mapped out. The scientists decided to use wind direction as the relative coordinate system for studying upwind and downwind aerosols rather than compass direction. At the second meeting, they viewed some preliminary results of the lidar scanning measurements made during the Ron Brown circumnavigations of the island. They also scheduled ship operations through July 15 and ending on the 16th with a downwind cloud/island stream study.

The Ron Brown began repetitive circumnavigations of Nauru 1 km from the coast on the morning of July 10. By the next day, it had completed 11 circumnavigations of the island in 23.8 hours. The ship held its position 2 km offshore on the windward side of the island until the morning of July 12. That same day, 18 hours of good aerosol characterization occurred before the wind died, ending the planned plume work.

During the close-island configuration, it was suggested that some measurements be taken while a phosphate ship was being loaded at the docks near the island to determine what effects it may have. However, because of concerns that the phosphate dust would overload the aerosol sampling system shipboard and possibly present a health risk to those downwind of the loading, scientists decided not to make those measurements. Instead, they gathered information from lidar scans and other measurements each time the Ron Brown passed by on its lidar scanning circumnavigations. They also collected some phosphate samples near the mining location, which they hope will be suitable for chemical and property analysis.

A preliminary analysis of data gathered during overflights of the Airborne Research Australia Cessna 404 was initiated. After arriving in Adelaide, Australia, scientists began processing the data from their flights, and scientists at Nauru began a preliminary analysis of the portable meteorological stand data and broadband measurements.

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