Atmospheric residence times of continental aerosols

Miscellaneous · Tue Jan 01 00:00:00 EST 1991

OSTI ID:6995171

Balkanski, Y J

The global atmospheric distributions of Rn-222 are simulated with a three-dimensional model of atmospheric transport based on the meteorology of the NASA Goddard Institute for Space Studies (GISS) general circulation model. The short-lived radioactive gas Rn-222 (half-life = 3.8d) is emitted almost exclusively from land, at a relatively uniform rate; hence it is an excellent tracer of continental influences. Lead-210 is produced by decay of Rn-222 and immediately condenses to preexisting aerosol surfaces. It provides an excellent measure of aerosol residence times in the atmosphere because its source is accurately defined by the Rn-222 distribution. Results from the three-dimensional model are compared to measurements of Rn-222 and Pb-210 atmospheric concentrations to evaluate model's long-range transport over oceanic regions and to study the deposition mechanisms of atmospheric aerosols. Model results for Rn-222 are used to examine the long-range transport of continental air over two selected oceanic regions, the subantarctic Indian Ocean and the North Pacific. It is shown that the fast transport of air from southern Africa causes substantial continental pollution at southern mid-latitudes, a region usually regarded as pristine. Air over the North Pacific is heavily impacted by continental influences year round, but the altitude at which the transport occurs varies seasonally. Observations of aerosols at island sites, which are commonly used as diagnostics of continental influences, may be misleading because they do not account for influences at high altitude and because aerosols are efficiently scavenged by deposition during transport. The study of Pb-210 focuses on defining the residence times of submicron aerosols in the troposphere. Scavenging in wet convective updrafts is found to provide the dominant sink on a global scale.

• Research Organization: Harvard Univ., Cambridge, MA (United States)
• OSTI ID: 6995171
• Resource Relation: Other Information: Thesis (Ph.D.)
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
LEAD 210
LONG-RANGE TRANSPORT
RADON 210
AEROSOLS
AFRICA
ATLANTIC OCEAN
ATMOSPHERIC CIRCULATION
CONVECTION
GENERAL CIRCULATION MODELS
INDIAN OCEAN
RADIATION MONITORING
RADIOECOLOGICAL CONCENTRATION
SEASONAL VARIATIONS
SPATIAL DISTRIBUTION
TROPICAL REGIONS
TROPOPAUSE
TROPOSPHERE
ALPHA DECAY RADIOISOTOPES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
COLLOIDS
DISPERSIONS
DISTRIBUTION
EARTH ATMOSPHERE
ECOLOGICAL CONCENTRATION
ELECTRON CAPTURE RADIOISOTOPES
ENERGY TRANSFER
ENVIRONMENTAL TRANSPORT
EVEN-EVEN NUCLEI
HEAT TRANSFER
HEAVY NUCLEI
HOURS LIVING RADIOISOTOPES
INTERNAL CONVERSION RADIOISOTOPES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
LEAD ISOTOPES
MASS TRANSFER
MATHEMATICAL MODELS
MONITORING
NANOSEC LIVING RADIOISOT
NUCLEI
RADIOISOTOPES
SEAS
SOLS
SURFACE WATERS
VARIATIONS
YEARS LIVING RADIOISOTOPES
540130* - Environment
Atmospheric- Radioactive Materials Monitoring & Transport- (1990-)