{
  "certificateVersion": "2026.11-V2",
  "sku": "AW-TJ-021",
  "slug": "girdwood",
  "name": "Girdwood — Turnagain Arm & Mount Alyeska",
  "category": "Coastal / Alpine (Mixed)",
  "gnisId": "1402695",
  "gnisUrl": "https://edits.nationalmap.gov/apps/gaz-domestic/public/search/names/1402695",
  "coordinates": {
    "latitude": 60.9425,
    "longitude": -149.1664
  },
  "boundingBox": [
    -149.49970821243082,
    60.78062399272566,
    -148.83311530956914,
    61.10437955727442
  ],
  "horizontalCrs": "EPSG:3338 (NAD83 / Alaska Albers Equal Area Conic)",
  "verticalDatum": "MLLW (<0m marine soundings) / NAVD88 (>0m terrestrial elevation)",
  "maxElevationM": 1920,
  "maxDepthM": -18,
  "chartId": "NOAA Chart 16660 (Cook Inlet — Northern Part / Turnagain Arm)",
  "verifiedFeatures": [
    "GIRDWOOD",
    "ALYESKA BASE",
    "TURNAGAIN ARM",
    "VIRGIN CREEK",
    "GLACIER CREEK",
    "MAX'S MOUNTAIN",
    "CHUGACH RANGE",
    "CROW CREEK PASS",
    "MT. ALYESKA"
  ],
  "sources": [
    {
      "provider": "NOAA National Centers for Environmental Information (NCEI)",
      "dataset_name": "NOAA NCEI Regional Alaska Bathymetric-Topographic DEM Mosaic (DEM_global_mosaic) & NOAA Chart 16660 (Cook Inlet — Northern Part / Turnagain Arm)",
      "dataset_id": "NOAA-NCEI-DEM-MOSAIC-AW-TJ-021",
      "acquisition_method": "Compiled bathymetric-topographic DEM mosaic (integrating NOAA hydrographic survey soundings and USGS 3DEP/IfSAR land elevation)",
      "resolution": "1/3 arc-second (~10m) to 1 arc-second regional coastal DEM mosaic (1400x1400 Float32 extract)",
      "horizontal_crs": "EPSG:4326 (WGS84/NAD83) projected to EPSG:3338 (Alaska Albers)",
      "vertical_datum": "Mixed coastal mosaic: MLLW/MHW marine soundings + NAVD88/MSL terrestrial elevation (requires explicit VDatum separation review per Rule 4)"
    }
  ],
  "contactSheetUrl": "/products/AW-TJ-021/qa/contact-sheet-8panel.webp",
  "verifiedAt": "2026-11-09T17:00:00Z"
}