Local wind regime induced by giant linear dunes: comparison of ERA5-land reanalysis with surface measurements
Emergence and growth of sand dunes results from the dynamic interaction between topography, wind flow and sediment transport. While feedbacks between these variables are well studied at the scale of a single and relatively small dune, the average effect of a periodic large-scale dune pattern on atmo...
| Main Authors: | , , , , , , |
|---|---|
| Format: | Journal article |
| Language: | English |
| Published: |
Springer
2022
|
| _version_ | 1797110628362485760 |
|---|---|
| author | Gadal, C Delorme, P Narteau, C Wiggs, GFS Baddock, M Nield, JM Claudin, P |
| author_facet | Gadal, C Delorme, P Narteau, C Wiggs, GFS Baddock, M Nield, JM Claudin, P |
| author_sort | Gadal, C |
| collection | OXFORD |
| description | Emergence and growth of sand dunes results from the dynamic interaction between topography, wind flow and sediment transport. While feedbacks between these variables are well studied at the scale of a single and relatively small dune, the average effect of a periodic large-scale dune pattern on atmospheric flows remains poorly constrained, due to a pressing lack of data in major sand seas. Here, we compare local measurements of surface winds to the predictions of the ERA5-Land climate reanalysis at four locations in Namibia, both within and outside the giant linear dune field of the Namib Sand Sea. In the desert plains to the north of the sand sea, observations and predictions agree well. This is also the case in the interdune areas of the sand sea during the day. During the night, however, an additional wind component aligned with the giant dune orientation is measured, in contrast to the easterly wind predicted by the ERA5-Land reanalysis. For the given dune orientation and measured wind regime, we link the observed wind deviation (over 50°) to the daily cycle of the turbulent atmospheric boundary layer. During the night, a shallow boundary layer induces a flow confinement above the giant dunes, resulting in large flow deviations, especially for the slower easterly winds. During the day, the feedback of the giant dunes on the atmospheric flow is much weaker due to the thicker boundary layer and higher wind speeds. Finally, we propose that the confinement mechanism and the associated wind deflections induced by giant dunes could explain the development of smaller-scale secondary dunes, which elongate obliquely in the interdune areas of the primary dune pattern. |
| first_indexed | 2024-03-07T07:57:29Z |
| format | Journal article |
| id | oxford-uuid:6bea5004-4573-46c1-be1c-ee512d336a6b |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T07:57:29Z |
| publishDate | 2022 |
| publisher | Springer |
| record_format | dspace |
| spelling | oxford-uuid:6bea5004-4573-46c1-be1c-ee512d336a6b2023-08-30T09:09:03ZLocal wind regime induced by giant linear dunes: comparison of ERA5-land reanalysis with surface measurementsJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:6bea5004-4573-46c1-be1c-ee512d336a6bEnglishSymplectic ElementsSpringer2022Gadal, CDelorme, PNarteau, CWiggs, GFSBaddock, MNield, JMClaudin, PEmergence and growth of sand dunes results from the dynamic interaction between topography, wind flow and sediment transport. While feedbacks between these variables are well studied at the scale of a single and relatively small dune, the average effect of a periodic large-scale dune pattern on atmospheric flows remains poorly constrained, due to a pressing lack of data in major sand seas. Here, we compare local measurements of surface winds to the predictions of the ERA5-Land climate reanalysis at four locations in Namibia, both within and outside the giant linear dune field of the Namib Sand Sea. In the desert plains to the north of the sand sea, observations and predictions agree well. This is also the case in the interdune areas of the sand sea during the day. During the night, however, an additional wind component aligned with the giant dune orientation is measured, in contrast to the easterly wind predicted by the ERA5-Land reanalysis. For the given dune orientation and measured wind regime, we link the observed wind deviation (over 50°) to the daily cycle of the turbulent atmospheric boundary layer. During the night, a shallow boundary layer induces a flow confinement above the giant dunes, resulting in large flow deviations, especially for the slower easterly winds. During the day, the feedback of the giant dunes on the atmospheric flow is much weaker due to the thicker boundary layer and higher wind speeds. Finally, we propose that the confinement mechanism and the associated wind deflections induced by giant dunes could explain the development of smaller-scale secondary dunes, which elongate obliquely in the interdune areas of the primary dune pattern. |
| spellingShingle | Gadal, C Delorme, P Narteau, C Wiggs, GFS Baddock, M Nield, JM Claudin, P Local wind regime induced by giant linear dunes: comparison of ERA5-land reanalysis with surface measurements |
| title | Local wind regime induced by giant linear dunes: comparison of ERA5-land reanalysis with surface measurements |
| title_full | Local wind regime induced by giant linear dunes: comparison of ERA5-land reanalysis with surface measurements |
| title_fullStr | Local wind regime induced by giant linear dunes: comparison of ERA5-land reanalysis with surface measurements |
| title_full_unstemmed | Local wind regime induced by giant linear dunes: comparison of ERA5-land reanalysis with surface measurements |
| title_short | Local wind regime induced by giant linear dunes: comparison of ERA5-land reanalysis with surface measurements |
| title_sort | local wind regime induced by giant linear dunes comparison of era5 land reanalysis with surface measurements |
| work_keys_str_mv | AT gadalc localwindregimeinducedbygiantlineardunescomparisonofera5landreanalysiswithsurfacemeasurements AT delormep localwindregimeinducedbygiantlineardunescomparisonofera5landreanalysiswithsurfacemeasurements AT narteauc localwindregimeinducedbygiantlineardunescomparisonofera5landreanalysiswithsurfacemeasurements AT wiggsgfs localwindregimeinducedbygiantlineardunescomparisonofera5landreanalysiswithsurfacemeasurements AT baddockm localwindregimeinducedbygiantlineardunescomparisonofera5landreanalysiswithsurfacemeasurements AT nieldjm localwindregimeinducedbygiantlineardunescomparisonofera5landreanalysiswithsurfacemeasurements AT claudinp localwindregimeinducedbygiantlineardunescomparisonofera5landreanalysiswithsurfacemeasurements |