s111-surface-currents

name

s111-surface-currents

description

Expert knowledge of IHO S-111 Surface Currents Product Specification. Covers HDF5-encoded current speed/direction time-step grids, SurfaceCurrent feature, Group_NNN time-series groups, data coding formats (regular grid, ungeorectified grid, time series at fixed stations, moving platform, etc.), and current portrayal (arrows, colour bands). USE FOR: S-111 datasets, surface currents, current speed and direction, S111DatasetReader, S111CoverageSource, S111PortrayalCatalogue, time-step iteration of currents, adding S-111 features, S-111 tests. DO NOT USE FOR: S-104 water levels (use s104-water-level), S-102 bathymetry (use s102-bathymetry), generic HDF5 (use s100-framework).

S-111 Surface Currents expert

When engaged

• Tasks touching src/EncDotNet.S100.Datasets.S111/** or tests/EncDotNet.S100.Datasets.S111.Tests/**
• Changes to CoveragePipeline/ICoverageSource affecting S-111
• Current vector portrayal (arrow rendering, colour scaling)

Spec anchors

• Canonical: S-111 Edition 2.0.0 Surface Currents PS
• S-100 Part 8: Coverages
• S-100 Part 10c: HDF5 encoding
• S-111 Annex A: Feature Catalogue
• S-111 Annex B: Portrayal Catalogue

Review checklist

1. HDF5 layout under /SurfaceCurrent/SurfaceCurrent.NN/Group_NNN/values matches spec; root attributes include dataCodingFormat, methodCurrentsProduct, typeOfCurrentData, numberOfTimes, timeRecordInterval, dateTimeOfFirstRecord, dateTimeOfLastRecord, commonPointRule.
2. dataCodingFormat selects layout — regular grid (2), ungeorectified grid (3), time series at fixed stations (4), stationwise (1), moving platform (5). Do not assume regular grid.
3. Compound dataset values: surfaceCurrentSpeed (float32, knots) and surfaceCurrentDirection (float32, degrees true, 0–360).
4. Direction convention is degrees true, "going to" (oceanographic), not "coming from". Document/cite this when surfacing it.
5. Times derived from dateTimeOfFirstRecord + timeRecordInterval unless explicit time dataset is present.
6. Public API changes have xunit tests using SkippableFact.

Known pitfalls in this repo

• Speed units vary by producer — spec says knots, but always honor the file's surfaceCurrentSpeedUom attribute.
• Wrap-around at 360° must be handled when interpolating directions.
• Multiple SurfaceCurrent.NN sub-groups can coexist (analysis vs. forecast); iterate.