I use the Goddard Institute for Space Studies ModelE general circulation model to examine the how beryllium-10, 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 &phis; 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.