MOSAIC Digital Environment Feasibility Study

人们越来越意识到空间天气带来的危害，这些危害现已列入英国国家风险登记册（内阁办公室，2018年）。一个重大风险是由“硬”太阳粒子事件造成的，其中包含大量高能粒子，可能导致现代微电子技术在地面上的腐败和损坏。一般来说，这样的太阳活动可以通过地面中子监测仪在地球表面探测到，并被称为地面增强（GLEs）：它们通常持续几个小时，有史以来测量到的最强烈的是1956年2月在英国。然而，在20世纪40年代之前，我们只能间接测量冰芯和树木年轮的GLEs （Miyake et al, 2012; Mekhaldi et al, 2015）。10Be、36Cl和14C的结果显示，AD774年的事件比1956年2月大30倍，AD994年大15倍。在当今的技术社会中，GLEs对复杂系统构成了危害，例如自动驾驶汽车，铁路，核电站，特别是迄今为止暴露最多的飞机（包括无人驾驶空中平台）。目前英国没有地面中子测量能力，因为这在1980年代被放弃了。大气电离协作湿度传感器（MOSAIC）项目的主要目标是研究英国COSMOS土壤湿度传感器网络的双重用途，以提供前所未有的、高密度的、可持续的和具有成本效益的英国空间天气测量能力，为关键基础设施提供实时警报，并使新的环境科学成为可能。COSMOS是一个相对较新的、不断扩大的传感器网络，目前在英国有近50个探测器，由NERC生态和水文中心（CEH）运营。宇宙射线在大气层高处产生的中子可以到达地面，其中一些中子会被反射，这取决于土壤含水量：COSMOS站测量反射的中子来确定当地的平均土壤湿度。除了研究基础设施（包括航空）运行预警的前景外，还有机会在英国建立地面中子辐射的长期记录，这可以作为更好的环境模型和改进政府风险评估的基础。该研究考察了COSMOS对GLEs的敏感性以及当网络具有双重用途时可能出现的数字网络可行性问题。鉴于GLE上升时间可以达到几分钟的数量级，最初的优先事项是检查明显更高的时间分辨率的实用性，这将是MOSAIC所需的。我们将研究实现从传感器到中心的数据快速通信的可行性，中心决定是否需要发出警报，以及这可能需要多长时间。与传统的“单点”监测器相比，COSMOS数字网络的地理多样性和分布式特性很可能通过固有冗余为鲁棒性提供显著的好处。为了协助这项工作，气象局将作为该系统的主要“用户”，就其数据分布和处理要求提供建议，我们将调查人工智能如何更好地区分所需信号并提高决策准确性。我们还将研究MOSAIC如何与萨里智能手机大气电离辐射网络（SAIRA）集成，该网络已经展示了一种公民科学方法，可以从飞机上获得互补的辐射数据。

There is growing awareness of the hazards arising from space weather which are now listed on the UK National Risk Register (Cabinet Office, 2018). One significant risk is created by 'hard' solar particle events containing a significant flux of highly energetic particles which can lead to corruption and damage in modern microelectronic technology at ground level. In general such solar events are detectable at the earth's surface by ground level neutron monitors and are termed ground level enhancements (GLEs): they typically have durations of some hours and the most intense ever measured was in February 1956 in the UK. Prior to the 1940s however we have only indirect measurements of GLEs from ice cores and tree rings (Miyake et al, 2012; Mekhaldi et al, 2015). Results on 10Be, 36Cl and 14C show events some 30 times larger than February 1956 in AD774 and 15 times larger in AD994. In today's technological society GLEs present a hazard to complex systems, such as autonomous vehicles, railways, nuclear power stations and especially aircraft (including unmanned aerial platforms) which are by far the most exposed. At present the UK has no ground level neutron measurement capability as this was abandoned in the 1980s. The main objective of the Moisture Sensors for Atmospheric Ionising Collaboration (MOSAIC) project is to study dual-purposing the UK COSMOS soil moisture sensor network to provide an unprecedented, high-density, sustainable and cost-effective UK space weather measurement capability to provide real-time alerts for critical infrastructure as well as enabling new environmental science. COSMOS is a relatively new and expanding network of sensors and there are now nearly 50 detectors across the UK operated by the NERC Centre for Ecology and Hydrology (CEH). Neutrons generated by cosmic-rays high in the atmosphere can reach ground level, some of which will be reflected dependent on the soil moisture content: COSMOS stations measure the reflected neutrons to determine average soil moisture over the local area. Besides studying the prospect of operational warnings for infrastructure (including aviation) there is an opportunity to create a long term record of ground level neutron radiation in the UK which can be the basis of better environmental models and improved risk assessments for government. The study examine COSMOS sensitivity to GLEs along with the digital network feasibility issues which would arise when dual-purposing the network. An initial priority is to examine the practicality of significantly higher temporal resolution which will be needed for MOSAIC given that GLE rise times can be of the order of minutes. We will examine the feasibility of achieving very rapid communication of data from the sensors to the centre(s) where decisions are taken on the need to issue alerts and how long this might take. It is likely that the geographical diversity and distributed nature of the COSMOS digital network could offer significant benefits for robustness via the inherent redundancy compared to conventional 'single point' monitors. To assist this work the Met Office will act as the primary 'user' of the system and will advise on their data distribution and processing requirements and we will investigate how artificial intelligence can better distinguish the wanted signal and enhance decision accuracy. We will also investigate how MOSAIC can be integrated with the Surrey Smartphone Atmospheric Ionising RAdiation network or SAIRA which has already demonstrated a citizen science approach to obtain complementary radiation data from aircraft.