Nature's neutron probe: Land surface hydrology at an elusive scale with cosmic rays

Darin Desilets, Marek Zreda, Ty P.A. Ferré

Research output: Contribution to journalArticlepeer-review

243 Scopus citations


Fast neutrons are generated naturally at the land surface by energetic cosmic rays. These "background" neutrons respond strongly to the presence of water at or near the land surface and represent a hitherto elusive intermediate spatial scale of observation that is ideal for land surface studies and modeling. Soil moisture, snow, and biomass each have a distinct influence on the spectrum, height profile, and directional intensity of neutron fluxes above the ground, suggesting that different sources of water at the land surface can be distinguished with neutron data alone. Measurements can be taken at fixed sites for long-term monitoring or in a moving vehicle for mapping over large areas. We anticipate applications in many previously problematic contexts, including saline environments, wetlands and peat bogs, rocky soils, the active layer of permafrost, and water and snow intercepted by vegetation, as well as calibration and validation of data from spaceborne sensors.

Original languageEnglish (US)
Article numberW11505
JournalWater Resources Research
Issue number11
StatePublished - 2010

ASJC Scopus subject areas

  • Water Science and Technology


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