Satellite chlorophyll-front inference is sensitive to observation coverage and control-period selection: analysis code, results, and figures

Marine heatwave (MHW) impact assessments increasingly use satellite chlorophyll-a (CHL) front metrics as ecological indicators. This record contains the frozen analysis code, result tables, and figures behind the claim that such inference is sensitive to satellite observation coverage and to control-period selection. The primary analysis uses 46 resolved MHW events across six frontal regions with daily CHL fields at 1/24 degree resolution under a day-level, coverage-stratified, matched-control design; semi-empirical coverage-conditioned simulations and a cross-algorithm mask-perturbation validation (Kuroshio and Sargasso) support the coverage-sensitivity claim. Key numbers (frozen 2026-11-03): three primary metrics show no significant mean shift (paired t-test p = 0.216, 0.444, 0.499); realistic coverage asymmetry inflates event-aggregated false-positive rates to 66% and 41%, reduced to 5-7% by day-level coverage-stratified standardization; an empirical coverage-dependent bias correction reduces out-of-sample mean bias to zero for all eight detector-metric-region combinations without establishing detector-independent validity.