Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping
The aerodynamic roughness length (z0) is an important parameter in the bulk approach for calculating turbulent fluxes and their contribution to ice melt. However, z0 estimates for heavily crevassed tidewater glaciers are rare or only generalised. This study used uncrewed aerial vehicles (UAVs) to ma...
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Copernicus Publications
2021
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Online Access: | https://doi.org/10.5194/tc-15-5513-2021 https://tc.copernicus.org/articles/15/5513/2021/tc-15-5513-2021.pdf https://doaj.org/article/65832a12c70149afbdae9a0ce2c77938 |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:65832a12c70149afbdae9a0ce2c77938 2023-05-15T18:32:19+02:00 Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping A. Dachauer R. Hann A. J. Hodson 2021-12-01 https://doi.org/10.5194/tc-15-5513-2021 https://tc.copernicus.org/articles/15/5513/2021/tc-15-5513-2021.pdf https://doaj.org/article/65832a12c70149afbdae9a0ce2c77938 en eng Copernicus Publications doi:10.5194/tc-15-5513-2021 1994-0416 1994-0424 https://tc.copernicus.org/articles/15/5513/2021/tc-15-5513-2021.pdf https://doaj.org/article/65832a12c70149afbdae9a0ce2c77938 undefined The Cryosphere, Vol 15, Pp 5513-5528 (2021) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2021 fttriple https://doi.org/10.5194/tc-15-5513-2021 2023-01-22T19:30:57Z The aerodynamic roughness length (z0) is an important parameter in the bulk approach for calculating turbulent fluxes and their contribution to ice melt. However, z0 estimates for heavily crevassed tidewater glaciers are rare or only generalised. This study used uncrewed aerial vehicles (UAVs) to map inaccessible tidewater glacier front areas. The high-resolution images were utilised in a structure-from-motion photogrammetry approach to build digital elevation models (DEMs). These DEMs were applied to five models (split across transect and raster methods) to estimate z0 values of the mapped area. The results point out that the range of z0 values across a crevassed glacier is large, by up to 3 orders of magnitude. The division of the mapped area into sub-grids (50 m × 50 m), each producing one z0 value, accounts for the high spatial variability in z0 across the glacier. The z0 estimates from the transect method are in general greater (up to 1 order of magnitude) than the raster method estimates. Furthermore, wind direction (values parallel to the ice flow direction are greater than perpendicular values) and the chosen sub-grid size turned out to have a large impact on the z0 values, again presenting a range of up to 1 order of magnitude each. On average, z0 values between 0.08 and 0.88 m for a down-glacier wind direction were found. The UAV approach proved to be an ideal tool to provide distributed z0 estimates of crevassed glaciers, which can be incorporated by models to improve the prediction of turbulent heat fluxes and ice melt rates. Article in Journal/Newspaper The Cryosphere Tidewater Unknown The Cryosphere 15 12 5513 5528 |
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English |
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geo envir A. Dachauer R. Hann A. J. Hodson Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping |
topic_facet |
geo envir |
description |
The aerodynamic roughness length (z0) is an important parameter in the bulk approach for calculating turbulent fluxes and their contribution to ice melt. However, z0 estimates for heavily crevassed tidewater glaciers are rare or only generalised. This study used uncrewed aerial vehicles (UAVs) to map inaccessible tidewater glacier front areas. The high-resolution images were utilised in a structure-from-motion photogrammetry approach to build digital elevation models (DEMs). These DEMs were applied to five models (split across transect and raster methods) to estimate z0 values of the mapped area. The results point out that the range of z0 values across a crevassed glacier is large, by up to 3 orders of magnitude. The division of the mapped area into sub-grids (50 m × 50 m), each producing one z0 value, accounts for the high spatial variability in z0 across the glacier. The z0 estimates from the transect method are in general greater (up to 1 order of magnitude) than the raster method estimates. Furthermore, wind direction (values parallel to the ice flow direction are greater than perpendicular values) and the chosen sub-grid size turned out to have a large impact on the z0 values, again presenting a range of up to 1 order of magnitude each. On average, z0 values between 0.08 and 0.88 m for a down-glacier wind direction were found. The UAV approach proved to be an ideal tool to provide distributed z0 estimates of crevassed glaciers, which can be incorporated by models to improve the prediction of turbulent heat fluxes and ice melt rates. |
format |
Article in Journal/Newspaper |
author |
A. Dachauer R. Hann A. J. Hodson |
author_facet |
A. Dachauer R. Hann A. J. Hodson |
author_sort |
A. Dachauer |
title |
Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping |
title_short |
Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping |
title_full |
Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping |
title_fullStr |
Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping |
title_full_unstemmed |
Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping |
title_sort |
aerodynamic roughness length of crevassed tidewater glaciers from uav mapping |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-5513-2021 https://tc.copernicus.org/articles/15/5513/2021/tc-15-5513-2021.pdf https://doaj.org/article/65832a12c70149afbdae9a0ce2c77938 |
genre |
The Cryosphere Tidewater |
genre_facet |
The Cryosphere Tidewater |
op_source |
The Cryosphere, Vol 15, Pp 5513-5528 (2021) |
op_relation |
doi:10.5194/tc-15-5513-2021 1994-0416 1994-0424 https://tc.copernicus.org/articles/15/5513/2021/tc-15-5513-2021.pdf https://doaj.org/article/65832a12c70149afbdae9a0ce2c77938 |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-15-5513-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
12 |
container_start_page |
5513 |
op_container_end_page |
5528 |
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