http://dx.doi.org/10.1016/j.cities.2014.02.011 0264-2751/ 2014 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/3.0/). ⇑ Corresponding author. Tel./fax: +86 25 85891347. E-mail addresses: [email protected], [email protected] (Q. Wu), J.Cheng@ mmu.ac.uk (J. Cheng), [email protected] (G. Chen), Dan.Hammel@utoledo...

Moderate ionospheric disturbances combined with storm signatures are characterized by the positive index (WU), negative (WL), and range (WE = WU – WL). We assign weights to these indices as a function of magnitude W-index, observation latitude critical frequency F2 layer, foF2 (the layer peak electron density, NmF2) or total content (TEC). It is shown that moderate irregularities (W ±2) occur m...

While the Euler characteristic χ(G) = ω1(G) = ∑ x ω(x) super counts simplices, the Wu characteristics ωk(G) = ∑ x1∼x2···∼xk ω(x1) · · ·ω(xk) super counts simultaneously pairwise interacting k-tuples of simplices in a finite abstract simplicial complex G. More generally, one can define the k-intersection number ωk(G1, . . . Gk), which is the same sum but where xi ∈ Gi. For every k ≥ 1 we define ...