{ "stac_version": "1.0.0", "stac_extensions": [ "https://stac-extensions.github.io/raster/v1.1.0/schema.json", "https://stac-extensions.github.io/table/v1.2.0/schema.json", "https://stac-extensions.github.io/classification/v1.1.0/schema.json" ], "type": "Collection", "id": "whp-2023-classified-ak", "title": "Wildfire Hazard Potential 2023 \u2014 classified, Alaska", "description": "Wildfire Hazard Potential (WHP) version 2023 for Alaska, at the source resolution of 270 m, published as a WGS84 cloud-optimized GeoTIFF and as H3 hex parquet at native resolution 9 with parents 8, 0.\n\n**Hazard, not risk.** Wildfire Hazard Potential describes the likelihood and intensity of wildfire at a location given its fuels, topography and weather. It says nothing about what is there to lose. A remote wilderness ridge can carry Very High hazard with no exposed assets; a subdivision can sit in Moderate hazard and still dominate a risk ranking. Do not read this layer as a map of communities in danger \u2014 for that, use Wildfire Risk to Communities, which combines hazard with exposure and susceptibility.\n\n**The class breaks are specific to Alaska and are not comparable to CONUS.** Dillon (2023) classifies each domain against its own distribution of the continuous WHP index, so identical class labels mean different absolute hazard in each domain:\n\n| Class | Alaska index | CONUS index |\n|---|---|---|\n| 1: Very Low | \u2264 83 | \u2264 61 |\n| 2: Low | 84\u2013624 | 62\u2013178 |\n| 3: Moderate | 625\u20132,922 | 179\u2013489 |\n| 4: High | 2,923\u20138,912 | 490\u20131,985 |\n| 5: Very High | > 8,912 | > 1,985 |\n\nA Alaska \"Very High\" cell and an CONUS \"Very High\" cell differ by roughly 4.5\u00d7 in underlying index. Never GROUP BY class across the two collections. For any cross-domain comparison use the continuous collections (`whp-2023-continuous-ak` / `whp-2023-continuous-conus`), whose raw index means the same thing everywhere.\n\nClasses 6 (Non-burnable) and 7 (Water) are not hazard levels \u2014 they are the absence of burnable fuel. They are part of the mapped land base and are NOT excluded from any total here. Whether to exclude them is the consumer's decision and it changes every \"share of X that is high hazard\" figure materially: they are 27.0% of CONUS cells and 24.4% of Alaska cells. State which convention a published percentage uses.\n\n**Area truth comes from the source grid, not from pixel counts on the COG.** The source is an equal-area Albers grid; the WGS84 COG published alongside is geographic and therefore is not equal-area, so counting COG pixels is not an area measurement. H3 cells at a given resolution are near-equal-area, so cell counts on the hex asset ARE a valid area proxy \u2014 and they reproduce the source's equal-area class shares to within 0.6 percentage points on every class in both domains.\n\n**Effective resolution.** Native H3 resolution is 9, but the source pixel is 270 m in the equal-area projection, which after reprojection is about 169 m \u00d7 337 m at 60\u00b0N. At resolution 9 that is roughly 1.3\u20131.9 source pixels per cell, so the hex carries slightly finer geometry than the source actually resolves. Resolution 9 was chosen deliberately over 8: the deliverable is a class-share statistic inside polygon boundaries, and at ~9 pixels per cell a `mode` vote is winner-take-all \u2014 a cell that is 4/9 Very High and 5/9 Moderate becomes entirely Moderate, biasing exactly the statistic being measured. Do not read resolution-9 cells as resolution-9 information.\n\n**Alaska extent.** Clipped to 180\u00b0W\u2013129\u00b0W, 48.8\u00b0N\u201371.6\u00b0N, which drops the far-western Aleutians (roughly 157\u00b0E\u2013180\u00b0) where the source grid wraps the antimeridian. No National Forest System land lies in the dropped area \u2014 the Alaska units are the Tongass and Chugach, far to the east \u2014 so nothing relevant to Forest Service analysis is lost, but the collection is not a complete Alaska mosaic and should not be described as one.\n\nHawaii is published by the source as a third domain with its own class breaks and is not ingested here; the raw source raster covering it is retained under `https://s3-west.nrp-nautilus.io/public-fire/raw/whp-2023/`.", "license": "public-domain", "keywords": [ "wildfire", "hazard", "fuels", "WHP", "H3", "Alaska", "USDA Forest Service", "Fire Sciences Laboratory" ], "extent": { "spatial": { "bbox": [ [ -173.19, 54.653, -129.988, 71.37 ] ] }, "temporal": { "interval": [ [ "2023-01-01T00:00:00Z", "2023-12-31T23:59:59Z" ] ] } }, "providers": [ { "name": "Gregory K. Dillon, USDA Forest Service Rocky Mountain Research Station, Fire Sciences Laboratory", "roles": [ "producer", "licensor" ], "url": "https://research.fs.usda.gov/firelab/products/dataandtools/wildfire-hazard-potential" }, { "name": "USDA Forest Service Research Data Archive", "roles": [ "licensor", "host" ], "url": "https://www.fs.usda.gov/rds/archive/products/RDS-2015-0047-4" }, { "name": "Boettiger Lab / cirrus", "roles": [ "processor", "host" ], "url": "https://s3-west.nrp-nautilus.io/public-fire/" } ], "links": [ { "rel": "self", "href": "https://s3-west.nrp-nautilus.io/public-fire/whp-2023-classified-ak/stac-collection.json", "type": "application/json" }, { "rel": "root", "href": "https://s3-west.nrp-nautilus.io/public-data/stac/catalog.json", "type": "application/json" }, { "rel": "parent", "href": "https://s3-west.nrp-nautilus.io/public-fire/stac-collection.json", "type": "application/json" }, { "rel": "license", "href": "https://www.usa.gov/government-works", "type": "text/html", "title": "US Government work \u2014 public domain" }, { "rel": "cite-as", "href": "https://doi.org/10.2737/RDS-2015-0047-4", "title": "Dillon, G.K. 2023. Wildfire Hazard Potential for the United States (270-m), version 2023. 4th Edition. Fort Collins, CO: Forest Service Research Data Archive." }, { "rel": "via", "href": "https://www.fs.usda.gov/rds/archive/products/RDS-2015-0047-4/RDS-2015-0047-4_Data.zip", "type": "application/zip", "title": "Source data package (Research Data Archive)" }, { "rel": "about", "href": "https://research.fs.usda.gov/firelab/products/dataandtools/wildfire-hazard-potential", "type": "text/html", "title": "Wildfire Hazard Potential product page" }, { "rel": "describedby", "href": "https://s3-west.nrp-nautilus.io/public-fire/raw/whp-2023/unpacked/Data/whp2023_GeoTIF/whp2023_cls_ak.tif.xml", "type": "application/xml", "title": "FGDC metadata as published with the source" } ], "assets": { "whp-2023-classified-ak-cog": { "href": "https://s3-west.nrp-nautilus.io/public-fire/whp-2023-classified-ak-cog.tif", "type": "image/tiff; application=geotiff; profile=cloud-optimized", "title": "Wildfire Hazard Potential 2023 \u2014 classified, Alaska \u2014 WGS84 COG", "description": "Reprojected from the source equal-area Albers grid to EPSG:4326 with nearest-neighbour resampling \u2014 required, since the values are class codes and any other resampling invents classes that do not exist in the source. Geographic, therefore NOT equal-area: use the hex asset for area statistics.", "roles": [ "data" ], "raster:bands": [ { "data_type": "uint8", "nodata": 255, "spatial_resolution": 270, "unit": "class code" } ] }, "whp-2023-classified-ak-hex": { "href": "https://s3-west.nrp-nautilus.io/public-fire/whp-2023-classified-ak/hex/h0=*/data_0.parquet", "type": "application/x-parquet", "title": "Wildfire Hazard Potential 2023 \u2014 classified, Alaska \u2014 H3 hex (resolution 9)", "description": "One row per populated H3 resolution-9 cell (16,540,214 rows across 3 h0 partitions). Reducer is `mode`, correct for class codes \u2014 a majority vote preserves values that exist in the source, where a mean would fabricate ones that do not. There is no per-feature attribute repeated across cells here, so unlike a vector hex asset `COUNT(*)` is meaningful: it counts cells, and cells are a valid area proxy.", "roles": [ "data" ], "h3:native_resolution": 9, "h3:parent_resolutions": [ 8, 0 ], "table:columns": [ { "name": "whp_class", "type": "uint8", "description": "Classified Wildfire Hazard Potential, the majority (`mode`) source class within the cell. Values 1\u20135 are hazard levels on a domain-relative scale; 6 and 7 are non-burnable land and water, not hazard levels. Labels are verbatim from the source value attribute table. Source nodata (255) is dropped rather than stored, so this column is never null. Valid values: 1=Very Low, 2=Low, 3=Moderate, 4=High, 5=Very High, 6=Non-burnable, 7=Water.", "values": [ 1, 2, 3, 4, 5, 6, 7 ] }, { "name": "h9", "type": "uint64", "description": "H3 cell identifier at resolution 9." }, { "name": "h8", "type": "uint64", "description": "H3 cell identifier at resolution 8. This is the shared join key across the catalog (AGENTS.md) \u2014 use it to join this layer to roadless-areas-2001 and to the other three whp-2023 collections." }, { "name": "h0", "type": "int64", "description": "H3 cell identifier at resolution 0, used as the partition key for hive-partitioned reads." } ], "classification:classes": [ { "value": 1, "description": "Very Low" }, { "value": 2, "description": "Low" }, { "value": 3, "description": "Moderate" }, { "value": 4, "description": "High" }, { "value": 5, "description": "Very High" }, { "value": 6, "description": "Non-burnable" }, { "value": 7, "description": "Water" } ] } } }