Summary of space weather worst-case environments: (4th revised edition)

Scope of this document 1. Space weather may be described as disturbances of the upper atmosphere and near Earth space that disrupt a wide range of technological systems – and, in a few cases, pose a direct threat to human health. 2. The systems at risk are very diverse and include power grids, GNSS, many aspects of spacecraft and aircraft operations, many types of radio communications and control systems. 3. This note lists a number of these different systems and outlines what we currently know of: ● The space weather environment parameters that best summarise the threat to those systems; ● A reasonable worst case for those parameters, together with the quality of the knowledge underpinning that estimate of the worst case and the formal provenance of that knowledge, e.g. in the peer reviewed literature; ● What can be done to improve the quality of that knowledge; ● Other useful information. This information is presented in a series of tables – with each table focusing on a specific class of space weather threat to each particular system.