Peatland hydrology: From tropical to subarctic latitudes

Soil moisture is one of the key variables controlling the exchanges of water and energy at the land surface. One particularly interesting climate zone is the Eastern Tibetean Plateau with its dry cold winters and wet monsoon summers at high altitudes. To better understand hydrological processes and the response of the hydrological cycle to climate change the novel method of Cosmic-Ray Neutron sensing had been tested in the northeast of the Qinghai-Tibet Plateau  with a highly hetereogeneous organic soil profile. Using this technique one can relate the flux density of albedo neutrons generated in cosmic-ray induced air showers to the amount of water in the environment on the scale of several hectares. Instrumented with in-situ sensors and cosmic ray probes we discuss the effective measurement depth of CRNS retrieval and vertical weights of different layers up to 50 cm depth in this semi-humid alpine meadow. During the non-frozen period we analyzed and validated the representativeness of CRNS in an extensive comparison of in-situ data, two soil moisture retrieval algorithms and full-scale neutron Monte Carlo simulations using the transport model URANOS. As the CRNS method gains traction and evolves towards large-scale applications, the findings from this study are pivotal for the understanding of the technology and its limitations.