Calibration Signal Limitations
No xBD/DINS equivalent for hail. Hail damage (granule loss, small punctures) is
sub-visual from satellite imagery — no federal per-building hail damage survey program exists.
Roofing permits are the best publicly available proxy for physical damage: they are not insurance
data, they are geocoded, and they indicate actual roof repair activity.
The calibration signal is therefore probabilistic: P(permit filed | MESH) is
compared to model P(damage | MESH). Permits systematically undercount minor damage (unpermitted
repairs) and may overcount in marginal cases (pre-storm wear). These biases are noted in
the spatial r values below — lower r may reflect permit noise, not model error.
Reference: Schmid et al. (2024, NHESS) — Swiss open-source hail damage model
using C-band MESHS. V_half ≈ 74mm for residential buildings. Parameters not directly transferable
(Swiss C-band vs US S-band, different building stock) but validates sigmoidal MDR vs MESH approach.