Two main types of models are used currently for scaling in situ cosmogenic nuclide (CN) production rates in time and space, distinguished primarily by the data on which they are based. The first of these, that of Lal (1991, EPSL 104, p. 424, reparameterized by Stone, 2000, JGR 105, p. 23,753), is based on atmospheric measurements of nuclear disintegrations in photographic emulsions combined with data from various neutron detectors sensitive to different portions of the secondary cosmic-ray (CR) spectrum. The other published scaling models (Dunai, 2001, EPSL 193, p 197; Lifton et al. 2005, EPSL 239, p. 140; Desilets and Zreda, 2006, EPSL 206, p 21) are based on data from neutron monitors, which all sample similar portions of the CR spectrum. While both model types yield similar predictions for sites in middle to high latitudes and altitudes <2 km, predictions diverge at low latitudes and high altitudes. Unfortunately, previously published production rate calibration data were neither sufficiently consistent among sites nor adequately precise to identify which of these models was correct.

The CRONUS-Earth Project, which aims to better characterize production rate systematics for all commonly measured CNs, has been working to resolve this discrepancy. A potential solution uses integral n+p fluxes derived from the atmospheric CR flux models of Sato et al. (2008, Radiation Res. 170, p. 244) (including time-dependence of the geomagnetic field and solar modulation), combined with new, high-precision in situ cosmogenic ¹⁰Be data from several well-characterized production rate calibration sites. The Sato et al. model spectra agree well with measured atmospheric CR spectra. Scaling the new ¹⁰Be data to sea level, high latitude indicates that the Lal and Sato et al. models bring the calibration dataset into tighter agreement overall than do the neutron monitor-based models. While additional work remains, scaling CN production rates using Sato et al. fluxes appears promising.