Lidar-derived snow surface elevation data for upper Barry Arm, Southcentral Alaska, collected April 4, 2024

Zechmann, J.M.Wolken, G.J.Wikstrom Jones, K.M.2026Lidar-derived snow surface elevation data for upper Barry Arm, Southcentral Alaska, collected April 4, 2024dataRaw Data FileRDF 2026-18Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys8 p.https://doi.org/10.14509/31521Lidar-derived snow surface elevation data for upper Barry Arm, Southcentral Alaska, collected April 4, 2024, Raw Data File 2026-18, provides aerial lidar derived classified point cloud data, a digital surface model (DSM), a digital terrain model (DTM), and an intensity model of Barry Arm, Southcentral Alaska, during near-peak snow height conditions. The survey provides snow surface elevations for use in snowpack studies. Ground control data collected May 5, 2023, and aerial lidar data were collected April 24, 2024. Data were subsequently merged and processed using a suite of geospatial processing software. These data and accompanying documentation are released as a DGGS Raw Data File and are available from the DGGS website at http://doi.org/10.14509/31521.The survey provides snow surface elevations for use in snowpack studies. This information is essential for assessing hazards, informing risk-mitigation efforts, and supporting decision-making for communities and infrastructure.>boundaries: A boundary, also known as an Area of Interest (AOI) or border, that defines the area covered by the data. >classified_points: Classified point cloud data are provided in LAZ format. Data are classified following ASPRS 2025 guidelines and contain return and intensity information. For classified ground points, the average point density is 3.2 pts/m2, and the average spacing is 55.9 cm. >dsm: The DSM represents surface elevations, including vegetation heights. The DSM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38 (32-bit, floating-point minimum). >dtm: The DTM represents bare-earth or snow-surface elevations, excluding vegetation. The DTM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38. >footprints: Footprints for tiled data. >lidar_intensity: The lidar intensity image describes the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is (1) primarily a function of scanned object reflectance in relation to the signal frequency, (2) dependent on ambient conditions, and (3) not necessarily consistent between separate scans. The intensity image is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38.20240424ground conditioncompleteNone planned-148.187276-148.04743261.18448061.111755ISO 19115 Topic CategorygeoscientificInformationAlaska Division of Geological & Geophysical SurveysAerialAerial GeologyAerial PhotographyCoastalCoastal and RiverCoastal and River HazardsDGGSDigital Elevation ModelDigital Surface Model (DSM)Digital Terrain ModelElevationEmergency PreparednessEngineeringEngineering GeologyEnvironmentalErosionGeologicGeologic HazardsGeological ProcessGeologyGeomorphologyGeotechnicalGlacialGlacial DepositsGlacial GeologyGlacial GeomorphologyGlacial ProcessesGlacier HazardsGlaciersHazardsLandslideLandslide SusceptibilityLiDARLiDAR Intensity ImageLiDAR LAS File FormatPoint Cloud DataRaster ImageRemote SensingRock AvalancheRockfallShaded ReliefSlopeSlope InstabilitySlope Instability HazardsSurfaceSurficialSurficial GeologyTopographyUnconsolidated DepositsWaterAlaska Division of Geological & Geophysical SurveysBarry ArmThis report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.Alaska Division of Geological & Geophysical SurveysMetadata Managermailing and physical

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FairbanksAK99709-3707USA(907)451-5020(907)451-5050dggspubs@alaska.gov8 am to 4:30 pm, Monday through Friday, except State holidaysPlease view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.This survey area is within the traditional homelands of the Chugach Sugpiaq peoples. The United States Geological Survey grant G21AC10362-00 funded this work. We thank Clearwater Air for their expertise and contribution to these data products. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government.Daanen, R.P.Wolken, G.J.Wikstrom Jones, K.M.Herbst, A.M.2021High resolution lidar-derived elevation data for Barry Arm landslide, Southcentral Alaska, June 26, 2020Raw Data FileRDF 2021-3Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys9 phttps://doi.org/10.14509/30593Daanen, R.P.Wolken, G.J.Wikstrom Jones, K.M.Herbst, A.M.2021Lidar-derived elevation data for upper Barry Arm, Southcentral Alaska, June 26, 2020Raw Data FileRDF 2021-1Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys9 phttps://doi.org/10.14509/30589Wikstrom Jones, K.M.Wolken, G.J.2026Lidar-derived elevation data for upper Barry Arm fjord, Southcentral Alaska, collected August 1, 2021Raw Data FileRDF 2026-6Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys10 phttps://doi.org/10.14509/31971Wikstrom Jones, K.M.Wolken, G.J.Daanen, R.P.2026Lidar-derived elevation data for Barry Arm landslide, Southcentral Alaska, October 16, 2020Raw Data FileRDF 2026-5Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys9 phttps://doi.org/10.14509/31970Wikstrom Jones, K.M.Wolken, G.J.Daanen, R.P.2026Lidar-derived elevation data for upper Barry Arm fjord, Southcentral Alaska, collected October 14, 2022Raw Data FileRDF 2026-10Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys10 phttps://doi.org/10.14509/32063Wikstrom Jones, K.M.Wolken, G.J.Daanen, R.P.Herbst, A.M.2021Photogrammetry-derived orthoimagery and elevation data for Barry Arm landslide, Southcentral Alaska, June 27, 2020Raw Data FileRDF 2021-5Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys6 phttps://doi.org/10.14509/30596Wikstrom Jones, K.M.Zechmann, J.M.Wolken, G.J.2026Lidar-derived elevation data for upper Barry Arm fjord, Southcentral Alaska, collected July 27, 2022Raw Data FileRDF 2026-9Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys8 phttps://doi.org/10.14509/32062Zechmann, J.M.Wolken, G.J.Wikstrom Jones, K.M.2025Lidar-derived elevation data for Barry Arm, Southcentral Alaska, collected September 19, 2023Raw Data FileRDF 2025-8Fairbanks, Alaska, United StatesAlaska Division of Geological & Geophysical Surveys9 phttps://doi.org/10.14509/31520Not applicableData quality is consistent throughout the survey, save for gaps over areas of wet snow and ice, where pulses at high incidence angles (greater than approximately 20 degrees) yielded few returns.This is a full-release dataset. There was no over-collect.Horizontal accuracy was not measured for this collection.We measured a mean elevation offset of +30.6 cm between 10 control points and the point cloud. This offset was reduced to -1.5 cm by applying a constant vertical correction to the lidar point data. We used nine checkpoints to determine the vertical accuracy of the point cloud ground class using a Triangulated Irregular Network (TIN) approach. The project's vertical accuracy has a root mean square error (RMSE) of 14.0 cm. We evaluated the relative accuracy for this dataset as the interswath overlap consistency and measured it at 6.8 cm RMSE.Ground survey - Ground control points were collected on May 5, 2023. We deployed a Trimble R10-2 GNSS base receiver on a bedrock island in Barry Arm and surveyed points with a rover Trimble R10-2 GNSS receiver/Mesa controller within the survey area. We collected 130 ground control points and checkpoints, of which 19 were used for this lidar acquisition; the remainder were excluded due to snow cover, either during ground control point collection or lidar collection. The checkpoints and ground control points used for this lidar survey were collected on bare earth. For a GNSS base station occupation to later correct lidar survey flightlines, on April 24, 2024, we set up a Trimble R10-2 on a bedrock island in Barry Arm.20230505Lidar survey - DGGS used a Riegl VUX1-LR22 laser scanner with a global navigation satellite system (GNSS) and a Northrop Grumman LN-200C inertial measurement unit (IMU) integrated by Phoenix LiDAR Systems. The sensor can collect up to 1,500,000 points per second at a range of 230 m, or a minimum of 50,000 points per second at 1,000 m (ranges assume greater than or equal to 20 percent natural reflectance). The scanner operated with a pulse refresh rate of 200,000 pulses per second at a scan rate of 80 revolutions per second. We used a Cessna 180 Skywagon fixed-wing platform to survey from an elevation of approximately 200-370 m above ground level, at a ground speed of approximately 40 m/s, and with a scan angle set from 80 to 280 degrees. The total survey area covers approximately 29.0 km2. The survey area was accessed by air from Merrill Field Airport in Anchorage. Data were collected from 11:40 am to 12:40 pm (AKST). The weather throughout the survey was clear with no wind.20240424Dataset processing - We processed point data in Spatial Explorer for initial filtering and multiple-time-around (MTA) disambiguation. MTA errors, corrected in this process, result from ambiguous interpretations of received pulse time intervals and occur more frequently with higher pulse refresh rates. IMU and GNSS data were processed in Inertial Explorer, and flightline information was integrated with the point cloud in Spatial Explorer. We calibrated the point data at an incrementally precise scale of sensor movement and behavior, incorporating sensor velocity, roll, pitch, and yaw fluctuations throughout the survey. For lidar data collection, the average pulse density is 3.4 pulses/m2, and the average pulse spacing is 54.0 cm. We created a macro (an ordered list of point classification commands tailored to this dataset) in Terrasolid software and classified points according to the American Society for Photogrammetry & Remote Sensing (ASPRS) 2025 guidelines (ASPRS, 2025). Once classified, we applied a geometric transformation and converted the points from ellipsoidal heights to GEOID12B (Alaska) orthometric heights. Raster products were derived from the point cloud in ArcGIS Pro. A 50-cm DSM was interpolated from ground and vegetation classes using a binning method and maximum values. A 50-cm DTM was interpolated from all ground-class returns using a binning method and minimum values. We also produced a 50-cm intensity image using average binning in ArcGIS Pro, with no normalization or corrections applied.2025rasterUniversal Transverse Mercator60.999600-1470500000.0000000coordinate pair.00000001.00000001MetersNAD83 (2011)GRS 806378137298.257222101NAVD88, GEOID12B0.500000metersExplicit elevation coordinate included with horizontal coordinatesboundariesA boundary, also known as an Area of Interest (AOI) or border, that defines the area covered by the data.DGGSboundariesclassified_pointsClassified point cloud data are provided in LAZ format. Data are classified following ASPRS 2025 guidelines and contain return and intensity information. For classified ground points, the average point density is 3.2 pts/m2, and the average spacing is 55.9 cm.DGGSclassified_pointsdsmThe DSM represents surface elevations, including vegetation heights. The DSM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38 (32-bit, floating-point minimum).DGGSdsmdtmThe DTM represents bare-earth or snow-surface elevations, excluding vegetation. The DTM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38.DGGSdtmfootprintsFootprints for tiled data.DGGSfootprintslidar_intensityThe lidar intensity image describes the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is (1) primarily a function of scanned object reflectance in relation to the signal frequency, (2) dependent on ambient conditions, and (3) not necessarily consistent between separate scans. The intensity image is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38.DGGSlidar_intensityAlaska Division of Geological & Geophysical SurveysMetadata Managermailing and physical

3354 College Road

FairbanksAK99709-3707USA(907)451-5020(907)451-5050dggspubs@alaska.gov8 am to 4:30 pm, Monday through Friday, except State holidaysFGDC Content Standard for Digital Geospatial MetadataFGDC-STD-001-1998If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. User specifically agrees not to imply that changes they made were approved by the Alaska Department of Natural Resources or Division of Geological & Geophysical Surveys.https://dggs.alaska.gov/metadata/dggs.extdggs metadata extensions