Publication Abstracts

Veeder 2009

Veeder, C., 2009: Modeling Climate and Production-related Impacts on Ice-core Beryllium-10. Ph.D. thesis. Columbia University.

I use the Goddard Institute for Space Studies ModelE general circulation model to examine the how beryllium-10 (10Be), a cosmogenic isotope which has been used in earlier studies as a proxy for changes in solar irradiance, is affected by production-related changes and also by climate-related changes. I focus on changes in total flux and snow concentration over ice-core regions. Experiments involving changes in 10Be production yield latitude-dependent changes in 10Be deposition. Climate-related experiments show changes in 10Be flux and snow accumulation and lead to notable changes in 10Be concentration over both Greenland and Antarctica. This result implies that the effects of climate should be considered carefully when determining production-related impacts on 10Be during periods of large-scale climate change.

Next, I use ModelE to examine 10Be's response to the combined influence of increased production and decreased solar irradiance that are thought to have taken place during historical periods of prolonged solar quiescence, such as the Maunder Minimum. I perform a suite of experiments to capture a range of possible changes in production and irradiance. Production-related changes in 10Be concentration dominate over climate-related changes. Using these results in conjunction with observed values of 10Be, we conclude that the solar modulation parameter phi is estimated to have ranged from 280-395 MeV over the course of the Maunder Minimum.

I also perform transient ensemble simulations of the 20th century, with annually varying 10Be production and a range of climate forcings. Internal variability causes modeled century-scale 10Be concentration trends to vary from the ensemble mean values by up to 50% and more. Lower levels of unforced variability at the Antarctic locations relative to the Greenland location suggests that, in the model at least, 10Be from Antarctica may reflect production changes with greater fidelity.

Additionally, I configure the model with daily-varying beryllium production in order to simulate changes in 7Be caused by an extreme solar energetic particle (SEP) event that took place on January 20, 2005. I also compare the model results with surface observations from January-February 2005. There is generally good agreement between the modeled and observed 7Be air concentration values. The impact of the SEP event is clearly visible in the polar stratosphere and mesosphere, but at the surface the effects are too small to be distinguishable from the intrinsic variability.

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BibTeX Citation

@phdthesis{ve05000n,
  author={Veeder, C.},
  title={Modeling Climate and Production-related Impacts on Ice-core Beryllium-10},
  year={2009},
  school={Columbia University},
  address={New York, N.Y.},
}

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RIS Citation

TY  - THES
ID  - ve05000n
AU  - Veeder, C.
PY  - 2009
BT  - Modeling Climate and Production-related Impacts on Ice-core Beryllium-10
PB  - Columbia University
CY  - New York, N.Y.
ER  -

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