# Data Sources

## USGS Magnetic and Related Derivative GeoTIFF Grids

Source:
https://data.usgs.gov/datacatalog/data/USGS%3A619a9a3ad34eb622f692f961

Downloaded file:
`GeophysicsMag_USCanada.zip`

Direct URL:
`https://www.sciencebase.gov/catalog/file/get/619a9a3ad34eb622f692f961?f=__disk__6b%2F58%2F75%2F6b58759fa9f9d89e3d697a82f67ed0322165e0d6`

Attribution:
McCafferty, A.E., San, C.A., Lawley, C., Graham, G.E., Gadd, M.G., Huston, D.L., Kelley, K.D., Paradis, S., Peter, J.M., and Czarnota, K., 2025, Magnetic and related derivative GeoTIFF grids and data for the United States and Canada: U.S. Geological Survey data release, https://doi.org/10.5066/P970GDD5.

License:
U.S. public domain label: http://www.usa.gov/publicdomain/label/1.0/

License review:
`manifests/licenses/usgs_california.license_review.json`

Notes:
This v0.1 package clips the source layer to California and generates visualization tiles. It does not redistribute the raw source archive.

## NOAA/NCEI EMAG2v3 Upward Continued GeoTIFF

Source:
https://www.ncei.noaa.gov/products/earth-magnetic-model-anomaly-grid-2

Downloaded file:
`EMAG2_V3_UpCont_DataTiff.tif`

Direct URL:
`https://www.ngdc.noaa.gov/geomag/data/EMAG2/EMAG2_V3_UpCont_DataTiff.tif`

Attribution:
Meyer, B., Saltus, R., and Chulliat, A., 2017, EMAG2v3 Earth Magnetic Anomaly Grid, NOAA National Centers for Environmental Information, https://doi.org/10.7289/V5H70CVX.

License / use:
CC-BY-4.0 per the EMAG2v3 Zenodo DOI record. Attribution is required.

License review:
`manifests/licenses/emag2v3_global.license_review.json`

Notes:
This v0.2 package uses the upward-continued global GeoTIFF as a low-resolution background layer. It normalizes the source longitude domain from `0..360` to `-180..180`, clips to Web Mercator latitude limits, and generates visualization tiles. It does not redistribute the raw source GeoTIFF.

## Geoscience Australia TMI Grid 2019, South Australia WCS Subset

Source:
https://ecat.ga.gov.au/geonetwork/srv/api/records/f2e58161-24cf-42d2-b328-a9039f72113b

Downloaded file:
`ga_tmi_au_sa_wcs.tif`

WCS request:
`https://services.ga.gov.au/gis/geophysical-grids/wcs?service=WCS&version=2.0.1&request=GetCoverage&coverageId=geophys__magmap_v7_2019_TMI&format=image/tiff&subset=Long(129.0,141.5)&subset=Lat(-38.5,-25.5)`

Attribution:
Based on Total Magnetic Intensity (TMI) Grid of Australia 2019 - seventh edition - 80 m cell size by Geoscience Australia which is © Commonwealth of Australia and is provided under a Creative Commons Attribution 4.0 International Licence and is subject to the disclaimer of warranties in section 5 of that licence.

License / use:
Creative Commons Attribution 4.0 International Licence per the Geoscience Australia product metadata. Attribution is required.

License review:
`manifests/licenses/ga_tmi_au_sa.license_review.json`

Notes:
This v0.7.1 package uses a native WCS subset of the primary TMI national compilation for South Australia. The full ERS-in-ZIP fallback was not used. The product is a re-levelled national compilation, not raw survey lines and not RTP/VRTP.

## Terrain Context: Mapzen Terrain Tiles on AWS

Source:
https://registry.opendata.aws/terrain-tiles/

Tile URL used by the viewer when Terrain is enabled:
`https://s3.amazonaws.com/elevation-tiles-prod/terrarium/{z}/{x}/{y}.png`

Documentation:
https://github.com/tilezen/joerd/tree/master/docs

Attribution:
`Terrain: Mapzen/Tilezen via AWS Open Data`

Mapzen hosted-service attribution guidance:
`© Mapzen, OpenStreetMap, and others.`

Source attribution notes:
Tilezen/joerd's terrain attribution document lists required source-provider attributions for the underlying elevation datasets. FieldLayers links to the full upstream attribution document rather than treating terrain as a FieldLayers layer package:
https://github.com/tilezen/joerd/blob/master/docs/attribution.md

Notes:
Terrain is optional topographic display context in the viewer. It is not magnetic data, not package evidence, and not listed in `manifests/layers.json`.