HR: 0800h
AN: A41B-01    [Abstracts]
TI: Transport, Evolution and Entrainment of Asian Dust/Pollution into the Pacific Marine Boundary
AU: * Clarke, A D
EM: tclarke@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, United States
AU: McNaughton, C S
EM: cameronm@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, United States
AU: Kapustin, V
EM: kapustin@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, United States
AU: Vetter, O
EM: oliver@soest.hawaii.edu
AF: School of Ocean and Earth Science and Technology, University of Hawaii, Honolulu, HI 96822, United States
AU: Dibb, J E
EM: jack.dibb@unh.edu
AF: Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824, United States
AU: Anderson, B E
EM: b.e.anderson@larc.nasa.gov
AF: NASA Langley Research Center, Hampton, Mail Stop 483, Hampton, VA 23681, United States
AU: Browell, E V
EM: edward.v.browell@nasa.gov
AF: NASA Langley Research Center, Hampton, Mail Stop 483, Hampton, VA 23681, United States
AU: Carmichael, G
EM: gregory-carmichael@uiowa.edu
AF: Center for Global and Regional Environmental Research, University of Iowa, Iowa City, IA 52242, United States
AU: Landing, B
EM: landing@fsu.edu
AF: Department of Oceanography, Florida State University, Tallahassee, FL , United States
AB: Various airborne and ship based studies over the past several years have allowed us to measure Asian dust and pollution aerosol from near its source to locations up to 10,000km downwind where it was entrained into the marine boundary layer (MBL). Dust was found to accumulate up to half of the soluble species such as sulfate and nitrate during passage through pollution regions in Asia before being lofted into the free troposphere near Japan. At times, transport in the free troposphere included regions of subsidence in high pressure regions that brought these "rivers" of dust and pollution down to the top of the MBL. Shipboard measurements and lidar data indicated both clear air entrainment and convective activity, associated with the passage of low pressure systems, facilitated dust transport through the inversion. High temperature volatilization of particles in the MBL up to 900C was used to remove most sulfates, nitrates, carbon and sea-salt to leave only dust measured and sized by an optical particle counter. These shipboard data and concurrent chemical measurements revealed the relation between entrainment of pollution and dust into the MBL associated with passage of high pressure systems. Subsequent passage of low pressure systems also revealed scavenging and removal of aerosol through precipitation to the ocean surface. This process appears to be a common removal pathway for dust over the Pacific and a mechanism for supplying the ocean surface with soluble iron and aluminum to the ocean surface. Measurements in the free troposphere and MBL also captured various aspects of these processes. Airborne missions flown north of Hawaii during the NASA PEM-Tropics and IMPEX missions characterized the vertical structure of subsiding dust and pollution. In-flight mapping of the dust/pollution layers and structure using the NASA Langley DIAL LIDAR show a sloping, subsiding Asian air-mass entraining into the marine boundary layer (MBL). In-situ measurements of the aerosol size distribution, chemistry, optical properties and the increase in light scattering as a function of relative humidity [f(RH)] were able to characterize and discriminate between MBL air, FT Asian dust/pollution and an external mixture of the two air-mass types during entrainment. Dusty air-masses were transported from Asia to the Pacific Ocean north of Hawai`i via the free troposphere (FT) and were even evident as a pronounced event the NOAA Mauna Loa Observatory (19.54N, 155.58W, 3,397m alt.). In situ measurements confirmed that regional and global chemical transport models (CTM) successfully predicted several Asian dust/pollution outbreaks and subsidence into the MBL. One episode is put into broader context using models, satellite observations and data from the Mauna Loa Observatory. We include a discussion of dust-flux to the ocean surface due to wet-deposition, a potentially important source of iron to the oligotrophic waters of the North Pacific Subtropical Gyre.
DE: 0312 Air/sea constituent fluxes (3339, 4504)
DE: 0345 Pollution: urban and regional (0305, 0478, 4251)
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Joint Assembly