Abstract
<jats:p>Areal precipitation series inherit their network’s composition: no record separates a station discontinuity from a regional shift; changing which gauges report moves the mean with none changing. The screen is two-layer, implementable on any network: a four-test relative-homogeneity battery on each gauge’s neighbour-ratio series, then propagation of those verdicts through realized rather than static Thiessen weights. Of Greece’s 187 weight-carrying gauges, 168 were testable and 19 were not; 96 classified useful, 30 doubtful and 42 suspect; relative and absolute verdicts agreed for only 87 of 168 (κ = 0.17). A drop-only screen cannot change a retained slope, so the suspect gauges are deleted, the weights renormalized over the survivors and every areal series rebuilt: of 16 field-significant increases, 14 survive, 2 lose field significance and 3 new detections appear on two distinct series. Individual catchment verdicts are fragile; the field verdict is not: it holds under nulls recalibrated for persistence, skewness and calendar gaps, and under every removal rule but the most aggressive, which leaves 10. That invariance is to detectable, non-shared inhomogeneity only. Deletion itself amplifies, 7 of 71 catchments rising to 16 of 66. Homogeneity screening alone is insufficient: the one field-significant decrease passes it yet is composition-dominated.</jats:p>