Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping
The aerodynamic roughness length ( z 0 ) is an important parameter in the bulk approach for calculating turbulent fluxes and their contribution to ice melt. However, z 0 estimates for heavily crevassed tidewater glaciers are rare or only generalised. This study used uncrewed aerial vehicles (UAVs) t...
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ftdoajarticles:oai:doaj.org/article:65832a12c70149afbdae9a0ce2c77938 2023-05-15T18:32:28+02:00 Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping A. Dachauer R. Hann A. J. Hodson 2021-12-01T00:00:00Z https://doi.org/10.5194/tc-15-5513-2021 https://doaj.org/article/65832a12c70149afbdae9a0ce2c77938 EN eng Copernicus Publications https://tc.copernicus.org/articles/15/5513/2021/tc-15-5513-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-5513-2021 1994-0416 1994-0424 https://doaj.org/article/65832a12c70149afbdae9a0ce2c77938 The Cryosphere, Vol 15, Pp 5513-5528 (2021) Environmental sciences GE1-350 Geology QE1-996.5 article 2021 ftdoajarticles https://doi.org/10.5194/tc-15-5513-2021 2022-12-31T07:27:56Z The aerodynamic roughness length ( z 0 ) is an important parameter in the bulk approach for calculating turbulent fluxes and their contribution to ice melt. However, z 0 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 z 0 values of the mapped area. The results point out that the range of z 0 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 z 0 value, accounts for the high spatial variability in z 0 across the glacier. The z 0 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 z 0 values, again presenting a range of up to 1 order of magnitude each. On average, z 0 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 z 0 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 Directory of Open Access Journals: DOAJ Articles The Cryosphere 15 12 5513 5528 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 A. Dachauer R. Hann A. J. Hodson Aerodynamic roughness length of crevassed tidewater glaciers from UAV mapping |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
The aerodynamic roughness length ( z 0 ) is an important parameter in the bulk approach for calculating turbulent fluxes and their contribution to ice melt. However, z 0 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 z 0 values of the mapped area. The results point out that the range of z 0 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 z 0 value, accounts for the high spatial variability in z 0 across the glacier. The z 0 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 z 0 values, again presenting a range of up to 1 order of magnitude each. On average, z 0 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 z 0 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://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 |
https://tc.copernicus.org/articles/15/5513/2021/tc-15-5513-2021.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-15-5513-2021 1994-0416 1994-0424 https://doaj.org/article/65832a12c70149afbdae9a0ce2c77938 |
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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1766216589532725248 |