3-11 July 2007
Merida, Mexico
Mexico/General timezone
Home > Timetable > Session details > Contribution details

Contribution Poster

Merida, Mexico - Regency (Hyatt)

Atmospheric Transport Inferred from Seasonal Variations in Cosmogenic Be-7 Concentrations

Speakers

  • Prof. Masato YOSHIMORI

Primary authors

Abstract content

A cosmogenic radionuclide Be-7 (half life 53.3 days) results from nuclear interactions of galactic cosmic rays in the Earth's atmosphere. Most of Be-7 is produced in the lower stratosphere and slowly tranported to the surface. Be-7 plays a role of atmospheric tracer and its measurements provide an important clue on atmospheric air mass motions. Since 2002 we have continuously measured surface Be-7 concentrations in Tokyo. The data in 2002-2006 indicated apparent increases of the Be-7 concentrations in spring and autumn. It was found from analysis of precipitation data that the seasonal variations are not associated with scavenging by precipitation. We suggested the possibility that the stratospheric Be-7 are brought to the upper troposphere through a large-scale air mass exchange between the stratosphere and troposphere. The air mass exchange is inferred to occur in association with a periodic passage of a pair of traveling high pressure and extratropical low pressure over Japan in spring and autumn.

Reference

Proceedings of the 30th International Cosmic Ray Conference; Rogelio Caballero, Juan Carlos D'Olivo, Gustavo Medina-Tanco, Lukas Nellen, Federico A. Sánchez, José F. Valdés-Galicia (eds.); Universidad Nacional Autónoma de México, Mexico City, Mexico, 2008; Vol. 1 (SH), pages 669-672