Soil Moisture Content, Cosmic Ray Soil Moisture Sensor, Far North Queensland Rainforest SuperSite, Robson Creek, 2012

A cosmic ray soil moisture sensor was installed at Robson Creek node of the FNQ Rainforest Supersite on 28 Oct 2010 by the Australian Cosmic Ray Soil Moisture Monitoring Network (CosmOz; http://www.ermt.csiro.au/html/cosmoz.html). CosmOz represents just one of a growing number of networks around the World. Other networks are found in USA, Germany, and the UK with other projects adopting the technology in South America, Africa and Europe. These sensors use cosmic rays originating from outer space to measure average soil moisture over an area of about 40 hectares to a depth up to 90 cm. The system measures fast neutrons that are produced from interactions of cosmic rays with the atmosphere and top few meters of soil. The intensity of these neutrons are moderated largely by water molecules in the soil. The number of neutrons counted over a period of time is inversely proportional to the amount of water in the soil. To estimate volumetric water content, each system is calibrated against soil samples that are collected from dry and wet moisture regimes using a standard protocol. Data is collected every 60 min and uploaded to data portal infrastructure which is maintained by the University of Arizona. This infrastructure and associated web interface were established as part of the US based Cosmic-ray Soil Moisture Observation System (COSMOS, http://cosmos.hwr.arizona.edu/). Collaboration between Australian and US researchers has facilitated a data hosting agreement which has now resulted in a growing international data portal for delivering and processing data from cosmic-ray probes. The Robson Ck data can be downloaded from http://cosmos.hwr.arizona.edu/Probes/StationDat/073/index.php2010年10月28日，澳大利亚宇宙射线土壤湿度监测网络（Australian Cosmic Ray Soil Moisture Monitoring Network, CosmOz；http://www.ermt.csiro.au/html/cosmoz.html）在FNQ雨林超级站点（FNQ Rainforest Supersite）的罗布森克里克节点安装了一台宇宙射线土壤湿度传感器（cosmic ray soil moisture sensor）。CosmOz仅是全球日益增多的监测网络之一，此类网络还分布于美国、德国与英国，南美、非洲及欧洲的诸多项目也已采用该技术。 该类传感器依托源自外太空的宇宙射线，可对面积约40公顷、深度可达90厘米的区域内的土壤平均湿度进行测量。系统会探测宇宙射线与大气及表层数米土壤相互作用产生的快中子（fast neutrons），中子强度主要受土壤内水分子的慢化作用调控。单位时段内计数的中子总数与土壤含水量呈反比关系。为估算体积含水量（volumetric water content），每套系统均需依据标准规程，对从干湿不同湿度状态下采集的土壤样本开展校准工作。 数据采集间隔为60分钟，随后上传至由亚利桑那大学维护的数据门户基础设施。该基础设施及配套Web界面是美国宇宙射线土壤湿度观测系统（Cosmic-ray Soil Moisture Observation System, COSMOS；http://cosmos.hwr.arizona.edu/）的组成部分。澳美两国研究人员的合作促成了数据托管协议，如今该协议已推动形成了不断发展的国际数据门户，用于提供宇宙射线探测探头（cosmic-ray probes）的数据处理与分发服务。罗布森克里克站点的数据可从http://cosmos.hwr.arizona.edu/Probes/StationDat/073/index.php 下载。