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Atmosphere beryllium‐7 concentrations over the Pacific Ocean
Author(s) -
Uematsu Mitsuo,
Duce Robert A.,
Prospero Joseph M.
Publication year - 1994
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/94gl00391
Subject(s) - troposphere , intertropical convergence zone , subsidence , aerosol , westerlies , environmental science , atmospheric sciences , atmosphere (unit) , precipitation , latitude , climatology , planetary boundary layer , geology , oceanography , boundary layer , meteorology , geography , geomorphology , geodesy , structural basin , thermodynamics , physics
Atmospheric 7 Be is used as a tracer of stratospheric and upper tropospheric air, but most measurements of 7 Be in surface air have been restricted to continental regions. We report here the extensive temporal and areal distribution of atmospheric aerosol 7 Be concentration in the marine boundary layer. Measurements of 7 Be have been carried out for the weekly filter samples collected at the Pacific island stations where are located between 30° N and 30° S in 1981 and 1985. High annual mean concentrations among the stations are observed at latitude between 20° and 30° in both hemispheres. There is little seasonal variation of 7 Be at the nine stations. The lowest concentrations are found in the equatorial region due to relatively little subsidence of the air from the upper layer in this area and high precipitation within the ITCZ (intertropical convergence zone) resulting in rapid removal of the aerosol containing the 7 Be. The significant correlation between the 7 Be concentrations and the nitrate concentrations at the stations in the North Pacific supports the assumption that nitrate is transported from continental sources to the marine boundary layer through the free troposphere by the westerlies.