crop-monitoring-sar-fused

○unverified

Cloud-gap-resilient crop monitoring by fusing Sentinel-1 SAR (VV/VH) with the Sentinel-2 NDVI time series. SAR backscatter is weather-independent: where optical scenes are cloud-contaminated, S1 VH temporal features (mean, std, p10/p90) and the VH/VV ratio carry canopy-structure and canopy-moisture signal that tracks crop growth stages independently of cloud cover. The fusion is honest gap-filling: on dates where S2 passes a cloud gate the NDVI observation anchors the harmonic_fit; on cloudy dates the SAR-derived canopy proxy fills the temporal slot so the season is not truncated. Per-field zonal_stats then aggregate the fused phenology signal to one row per field — the same crop-monitoring product table as the optical-only recipe, but with continuous temporal coverage through cloudy periods (Central Valley foggiest months: November–February). This is the reliability upgrade that commercial crop-monitoring products use (Indigo Ag, Granular, Proagrica). The SAR leg does not require a trained model — VH mean and VH/VV ratio are direct empirical proxies (Veloso 2017). The recipe deliberately keeps the fusion simple enough to inspect: every input to every merged date is recorded in the provenance block.