2407.18268
Spatial analysis of tails of air pollution PDFs in Europe
Hankun He, Benjamin Schäfer, Christian Beck
correctmedium confidence
- Category
- Not specified
- Journal tier
- Specialist/Solid
- Processed
- Sep 28, 2025, 12:56 AM
- arXiv Links
- Abstract ↗PDF ↗
Audit review
The paper states that heavy-tailed air-pollution PDFs are well fit by q-exponentials (its Eq. (1)) and motivates this via superstatistics, asserting q = ⟨λ̂²⟩/⟨λ̂⟩² (its Eq. (2)), with T determined by the local-window kurtosis Kexp = 9 (its Eq. (3)) . The candidate solution derives, in detail, that a normalized exponential snapshot mixed with a Gamma prior yields an exact Lomax/Pareto-II law that equals the q-exponential with q = (α+2)/(α+1), and explains that this corresponds to using the λ-tilted prior for the mixing (Type-B), rather than the bare prior implicit in Eq. (2) (Type-A). Both are standard in superstatistics and differ by whether one mixes unnormalized Boltzmann factors (∼e^{-λx}) or normalized exponentials (λe^{-λx}). The kurtosis-9 criterion and the scaling E[X] ∝ λ^{-1} are correctly used by the paper and are rigorously justified by the model; the paper’s statement on E[X] being proportional to λ^{-1} is conceptually correct but silently assumes q < 3/2 for finiteness of the mean . Overall: same phenomenon, different (Type-A vs Type-B) derivations, plus minor missing assumptions in the paper.
Referee report (LaTeX)
\textbf{Recommendation:} minor revisions \textbf{Journal Tier:} specialist/solid \textbf{Justification:} The work compellingly demonstrates that air-pollution tails across Europe are well captured by q-exponentials and adds a valuable spatial perspective. Two technical clarifications would strengthen the methodology section: (i) explicitly state whether the superstatistical mixing is Type-A (unnormalized Boltzmann factors) or Type-B (normalized snapshots), and reconcile Eq. (2) accordingly; (ii) note the condition for the existence of the mean when discussing the λ−1 scaling. These changes are minor and do not affect the main empirical conclusions.