Nonlinear Processes in Geophysics www.nonlin-processes-geophys.net 1023-5809 1607-7946 9 5/6 2002 10.5194/npg-9-389-2002 http://www.nonlin-processes-geophys.net/9/389/2002/ http://www.nonlin-processes-geophys.net/9/389/2002/npg-9-389-2002.html http://www.nonlin-processes-geophys.net/9/389/2002/npg-9-389-2002.pdf 389 397 0000-00-00 Scaling in the space climatology of the auroral indices: is SOC the only possible description? N. W. Watkins British Antarctic Survey, High Cross, Madingley Rd., Cambridge CB3 0ET, UK The study of the robust features of the magnetosphere is motivated both by new "whole system" approaches, and by the idea of "space climate" as opposed to "space weather". We enumerate these features for the AE index, and discuss whether self-organised criticality (SOC) is the most natural explanation of the "stylised facts" so far known for AE. We identify and discuss some open questions, answers to which will clarify the extent to which AE's properties provide evidence for SOC. We then suggest an SOC-like reconnection-based scenario drawing on the result of Craig (2001) as an explanation of the very recent demonstration by Uritsky et al. (2001b) of power laws in several properties of spatiotemporal features seen in auroral images.