Spatial variability of the extreme-precipitation threshold

Determine whether and how the 50 mm d⁻¹ intensity boundary for mechanism saturation varies among subregions of Hunan Province by conducting subregional intensity analyses with sufficient samples.

Background

The study identifies precipitation intensity of at least 50 mm d⁻¹ as an operational boundary at which SHAP disorder increases and correction reliability declines. However, the extreme-precipitation sample contains only 522 grid-day observations, limiting the statistical power of subregional analyses.

The unresolved issue is whether the saturation frontier occurs at the same intensity across spatial subregions or interacts with the spatial mechanism-purity boundary. Resolving this would clarify whether a single domain-wide threshold is appropriate for operational screening.

References

Yet the spatial variability of the 50 mm d⁻¹ threshold cannot be determined with current samples. Future work should stratify intensity analysis by subregion to test whether spatial and intensity boundaries interact.

— Machine learning correction of satellite precipitation is governed by mechanism purity, not algorithmic complexity: a proof-of-concept study in Hunan, China, with pre-registered cross-regional validation  (2608.12988 - Xu, 13 Aug 2026) in Section 4.4, second limitation paragraph