Beryllium-7 as a tracer of surface water subduction and mixed-layer history

David Kadko, Donald Olson

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Beryllium-7 is a cosmic-ray-produced radioactive nuclide (half-life 53.3 days) that is deposited upon the ocean surface by rainfall. Beryllium-7 profiles were collected and analyzed in May 1991 and March 1992 as part of the ONR SUBDUCTION program. The 7Be activities were homogeneous in the mixed layer and ranged approximately from 100 to 200 dpm/1000 l. The activities dropped off rapidly in the upper thermocline. The 7Be profiles were modeled using a simple seasonal progression of mixed-layer depth, indicating that seasonal changes in the mixed-layer depth control the main features of the profile. The observed temperature, salinity and 7Be profiles from the May 1991 cruise show warm salinity maxima associated with a layer of high 7Be penetrating into the upper seasonal thermocline. The high 7Be concentration suggests that these waters were in relatively thin mixed layers within, approximately, the past month. The model results indicate that in late spring both salinity and 7Be can respond to a shoaling mixed layer on a similar timescale leading to the observed anomalies in the subducted water layer.

Original languageEnglish (US)
Pages (from-to)89-116
Number of pages28
JournalDeep-Sea Research Part I: Oceanographic Research Papers
Volume43
Issue number2
DOIs
StatePublished - Jan 1 1996

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beryllium
mixed layer
tracer techniques
surface water
subduction
tracer
salinity
history
thermocline
radionuclides
half life
oceans
rain
cosmic ray
sea surface
temperature
timescale
anomaly
water
rainfall

ASJC Scopus subject areas

  • Oceanography
  • Aquatic Science

Cite this

Beryllium-7 as a tracer of surface water subduction and mixed-layer history. / Kadko, David; Olson, Donald.

In: Deep-Sea Research Part I: Oceanographic Research Papers, Vol. 43, No. 2, 01.01.1996, p. 89-116.

Research output: Contribution to journalArticle

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