Publication Abstracts

Koch and Mann 1996

Koch, D.M., and M.E. Mann, 1996: Spatial and temporal variability of 7Be surface concentrations. Tellus, 48B, 387-396, doi:10.1034/j.1600-0889.48.issue3.1.x.

7Be (t1/2=53 days) is generated from cosmic rays in the upper troposphere and stratosphere, and is a tracer of downward aerosol transport. We apply a singular value decomposition (SVD)-based technique, which simultaneously determines patterns of significant spatial and temporal variability, to 7Be surface concentration records that are 22 years long, from 19 locations distributed globally. Significant variability occurs on time scales corresponding to the solar cycle (∼ ∼11 years), El Niño/Southern Oscillation (∼ ∼2-3 years), an annual cycle, and a semi-annual cycle. The phase of the solar cycle signal varies little globally, except at the south pole, where low magnetic shielding may permit direct penetration of solar particles during times of high solar activity. The spatial variability of the phase of the ENSO signals corresponds with the effects of observed rainfall anomalies during ENSO. The phases of the annual and semi-annual signals depend on upon the spatial distribution of vertical transport and precipitation. The temporal variabilities, or modes, corresponding to these signals sum together to form a variety of annual 7Be cyclicities at different locations. We compare reconstructions of the time series based on the SVD analysis with the observed time series at 6 locations. The 4 modes explain between 19% and 47% of the monthly variance at these 6 sites. We show how various locations are affected by differing relative amounts and phases of the 4 signals. We also calculated the spatial variability of the annual cycle phase from a larger data set, by fitting a sinusoid to the average annual cycles at the sites. The agreement between the SVD and the sine-fitting results serves to validate both approaches.

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BibTeX Citation

  author={Koch, D. M. and Mann, M. E.},
  title={Spatial and temporal variability of 7Be surface concentrations},

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RIS Citation

ID  - ko01000b
AU  - Koch, D. M.
AU  - Mann, M. E.
PY  - 1996
TI  - Spatial and temporal variability of 7Be surface concentrations
JA  - Tellus
VL  - 48B
SP  - 387
EP  - 396
DO  - 10.1034/j.1600-0889.48.issue3.1.x
ER  -

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