Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain
Differentially mapping snow depth in mountain watersheds from airborne laser altimetry is a valuable hydrologic technique that has seen an expanded use in recent years. Additionally, lidar systems also record the strength of the returned light pulse (i.e. intensity), which can be used to characteriz...
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Taylor & Francis Group
2024-12-01
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| Series: | GIScience & Remote Sensing |
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| Online Access: | https://www.tandfonline.com/doi/10.1080/15481603.2024.2427326 |
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| author | Chelsea Ackroyd Christopher P. Donahue Brian Menounos S. McKenzie Skiles |
| author_facet | Chelsea Ackroyd Christopher P. Donahue Brian Menounos S. McKenzie Skiles |
| author_sort | Chelsea Ackroyd |
| collection | DOAJ |
| description | Differentially mapping snow depth in mountain watersheds from airborne laser altimetry is a valuable hydrologic technique that has seen an expanded use in recent years. Additionally, lidar systems also record the strength of the returned light pulse (i.e. intensity), which can be used to characterize snow surface properties. For near-infrared lidar systems, return intensity is relatively high over snow and inversely related to the effective grain size, a primary control on snow albedo. Raw intensity is also sensitive to laser range and incidence angle, however, and requires a correction for snow property retrieval that is especially pertinent in mountainous terrain. Here, we describe a workflow to correct the intensity using the plane trajectory, lidar scan angle, and lidar-derived topography. As a proof of concept for snow retrievals, we apply the workflow to an airborne 1064 nm lidar flight over a snow-covered mountain basin in the Colorado Rockies. Corrected intensity was empirically related to reflectance before delineating snow extent and retrieving grain size. Relative to the traditional snow classification derived from optical imagery, the lidar-derived snow extent covered 5.4% more area due to the fine resolution point cloud and absence of shadows common in optical imagery. The lidar-derived grain size retrievals had a MAE of 32 µm compared to those from field spectroscopy, which translated to a 1% error in snow albedo. We found high incidence angles yielded an overcorrection in intensity that introduced a high bias in the grain size distribution and, therefore, suggest using an incidence angle threshold (40°). Developing methods specifically for quantitative snow surface property retrievals from lidar intensity is timely and relevant as aerial lidar is increasingly being used to map snow depth for hydrologic and cryospheric studies. |
| format | Article |
| id | doaj-art-3b24c83d5f1541a4a8f184ce4d1242a7 |
| institution | Kabale University |
| issn | 1548-1603 1943-7226 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Taylor & Francis Group |
| record_format | Article |
| series | GIScience & Remote Sensing |
| spelling | doaj-art-3b24c83d5f1541a4a8f184ce4d1242a72025-01-20T08:36:26ZengTaylor & Francis GroupGIScience & Remote Sensing1548-16031943-72262024-12-0161110.1080/15481603.2024.2427326Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrainChelsea Ackroyd0Christopher P. Donahue1Brian Menounos2S. McKenzie Skiles3School of Environment, Society & Sustainability, University of Utah, Salt Lake City, UT, USADepartment of Geography, Earth, and Environmental Sciences, University of Northern British Columbia, Prince George, BC, CanadaDepartment of Geography, Earth, and Environmental Sciences, University of Northern British Columbia, Prince George, BC, CanadaSchool of Environment, Society & Sustainability, University of Utah, Salt Lake City, UT, USADifferentially mapping snow depth in mountain watersheds from airborne laser altimetry is a valuable hydrologic technique that has seen an expanded use in recent years. Additionally, lidar systems also record the strength of the returned light pulse (i.e. intensity), which can be used to characterize snow surface properties. For near-infrared lidar systems, return intensity is relatively high over snow and inversely related to the effective grain size, a primary control on snow albedo. Raw intensity is also sensitive to laser range and incidence angle, however, and requires a correction for snow property retrieval that is especially pertinent in mountainous terrain. Here, we describe a workflow to correct the intensity using the plane trajectory, lidar scan angle, and lidar-derived topography. As a proof of concept for snow retrievals, we apply the workflow to an airborne 1064 nm lidar flight over a snow-covered mountain basin in the Colorado Rockies. Corrected intensity was empirically related to reflectance before delineating snow extent and retrieving grain size. Relative to the traditional snow classification derived from optical imagery, the lidar-derived snow extent covered 5.4% more area due to the fine resolution point cloud and absence of shadows common in optical imagery. The lidar-derived grain size retrievals had a MAE of 32 µm compared to those from field spectroscopy, which translated to a 1% error in snow albedo. We found high incidence angles yielded an overcorrection in intensity that introduced a high bias in the grain size distribution and, therefore, suggest using an incidence angle threshold (40°). Developing methods specifically for quantitative snow surface property retrievals from lidar intensity is timely and relevant as aerial lidar is increasingly being used to map snow depth for hydrologic and cryospheric studies.https://www.tandfonline.com/doi/10.1080/15481603.2024.2427326Lidarlidar intensitysnowsnow grain sizetopographic correction |
| spellingShingle | Chelsea Ackroyd Christopher P. Donahue Brian Menounos S. McKenzie Skiles Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain GIScience & Remote Sensing Lidar lidar intensity snow snow grain size topographic correction |
| title | Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain |
| title_full | Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain |
| title_fullStr | Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain |
| title_full_unstemmed | Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain |
| title_short | Airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain |
| title_sort | airborne lidar intensity correction for mapping snow cover extent and effective grain size in mountainous terrain |
| topic | Lidar lidar intensity snow snow grain size topographic correction |
| url | https://www.tandfonline.com/doi/10.1080/15481603.2024.2427326 |
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