Estimating aerodynamic roughness over complex surface terrain

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dc.contributor.authorNield, Joanna M
dc.contributor.authorKing, James
dc.contributor.authorWiggs, Giles F S
dc.contributor.authorLeyland, Julian
dc.contributor.authorBryant, Robert G
dc.contributor.authorChiverrell, Richard C
dc.contributor.authorDarby, Stephen E
dc.contributor.authorEckardt, Frank D
dc.contributor.authorThomas, David S G
dc.contributor.authorVircavs, Larisa H
dc.contributor.authorWashington, Richard
dc.date.accessioned2021-10-08T07:08:09Z
dc.date.available2021-10-08T07:08:09Z
dc.date.issued2013
dc.description.abstractSurface roughness plays a key role in determining aerodynamic roughness length (zo) and shear velocity, both of which are fundamental for determining wind erosion threshold and potential. While Zocan be quantified from wind measurements, large proportions of wind erosion prone surfaces remain too remote for this to be a viable approach. Alternative approaches therefore seek to relate Zoto morphological roughness metrics. However, dust-emitting landscapes typically consist of complex small-scale surface roughness patterns and few metrics exist for these surfaces which can be used to predict Zofor modeling wind erosion potential. In this study terrestrial laser scanning was used to characterize the roughness of typical dust-emitting surfaces (playa and sandar) where element protrusion heights ranged from 1 to 199 mm, over which vertical wind velocity profiles were collected to enable estimation of zo. Our data suggest that, although a reasonable relationship (R2> 0.79) is apparent between 3-D roughness density and Zo, the spacing of morphological elements is far less powerful in explaining variations in Zothan metrics based on surface roughness height (R2 > 0.92). This finding is in juxtaposition to wind erosion models that assume the spacing of larger-scale isolated roughness elements is most important in determining Zo. Rather, our data show that any metric based on element protrusion height has a higher likelihood of successfully predicting Zo. This finding has important implications for the development of wind erosion and dust emission models that seek to predict the efficiency of aeolian processes in remote terrestrial and planetary environments.
dc.identifier.apacitationNield, J. M., King, J., Wiggs, G. F. S., Leyland, J., Bryant, R. G., Chiverrell, R. C., ... Washington, R. (2013). Estimating aerodynamic roughness over complex surface terrain. <i>Journal of Geophysical Research</i>, 118(23), 12948 - 12961. http://hdl.handle.net/11427/34513en_ZA
dc.identifier.chicagocitationNield, Joanna M, James King, Giles F S Wiggs, Julian Leyland, Robert G Bryant, Richard C Chiverrell, Stephen E Darby, et al "Estimating aerodynamic roughness over complex surface terrain." <i>Journal of Geophysical Research</i> 118, 23. (2013): 12948 - 12961. http://hdl.handle.net/11427/34513en_ZA
dc.identifier.citationNield, J.M., King, J., Wiggs, G.F.S., Leyland, J., Bryant, R.G., Chiverrell, R.C., Darby, S.E. & Eckardt, F.D. et al. 2013. Estimating aerodynamic roughness over complex surface terrain. <i>Journal of Geophysical Research.</i> 118(23):12948 - 12961. http://hdl.handle.net/11427/34513en_ZA
dc.identifier.issn0022-1406
dc.identifier.issn0148-0227
dc.identifier.issn1934-2098
dc.identifier.issn2156-2202
dc.identifier.ris TY - Journal Article AU - Nield, Joanna M AU - King, James AU - Wiggs, Giles F S AU - Leyland, Julian AU - Bryant, Robert G AU - Chiverrell, Richard C AU - Darby, Stephen E AU - Eckardt, Frank D AU - Thomas, David S G AU - Vircavs, Larisa H AU - Washington, Richard AB - Surface roughness plays a key role in determining aerodynamic roughness length (zo) and shear velocity, both of which are fundamental for determining wind erosion threshold and potential. While Zocan be quantified from wind measurements, large proportions of wind erosion prone surfaces remain too remote for this to be a viable approach. Alternative approaches therefore seek to relate Zoto morphological roughness metrics. However, dust-emitting landscapes typically consist of complex small-scale surface roughness patterns and few metrics exist for these surfaces which can be used to predict Zofor modeling wind erosion potential. In this study terrestrial laser scanning was used to characterize the roughness of typical dust-emitting surfaces (playa and sandar) where element protrusion heights ranged from 1 to 199 mm, over which vertical wind velocity profiles were collected to enable estimation of zo. Our data suggest that, although a reasonable relationship (R2> 0.79) is apparent between 3-D roughness density and Zo, the spacing of morphological elements is far less powerful in explaining variations in Zothan metrics based on surface roughness height (R2 > 0.92). This finding is in juxtaposition to wind erosion models that assume the spacing of larger-scale isolated roughness elements is most important in determining Zo. Rather, our data show that any metric based on element protrusion height has a higher likelihood of successfully predicting Zo. This finding has important implications for the development of wind erosion and dust emission models that seek to predict the efficiency of aeolian processes in remote terrestrial and planetary environments. DA - 2013 DB - OpenUCT DP - University of Cape Town IS - 23 J1 - Journal of Geophysical Research LK - https://open.uct.ac.za PY - 2013 SM - 0022-1406 SM - 0148-0227 SM - 1934-2098 SM - 2156-2202 T1 - Estimating aerodynamic roughness over complex surface terrain TI - Estimating aerodynamic roughness over complex surface terrain UR - http://hdl.handle.net/11427/34513 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/34513
dc.identifier.vancouvercitationNield JM, King J, Wiggs GFS, Leyland J, Bryant RG, Chiverrell RC, et al. Estimating aerodynamic roughness over complex surface terrain. Journal of Geophysical Research. 2013;118(23):12948 - 12961. http://hdl.handle.net/11427/34513.en_ZA
dc.language.isoeng
dc.publisher.departmentDepartment of Environmental and Geographical Science
dc.publisher.facultyFaculty of Science
dc.sourceJournal of Geophysical Research
dc.source.journalissue23
dc.source.journalvolume118
dc.source.pagination12948 - 12961
dc.source.urihttps://dx.doi.org/10.1002/2013JD020632
dc.subject.otheraerosols
dc.subject.otherTerrestrial environment
dc.subject.otherefficiency
dc.subject.othermodels
dc.subject.otherdensity
dc.subject.otherVelocity distribution
dc.subject.otherWind field
dc.subject.otherWind velocity
dc.subject.otherVertical profile
dc.subject.otherVertical speed
dc.subject.otherModeling
dc.subject.otherdust
dc.subject.otherwinds
dc.subject.otherwind erosion
dc.subject.otherVelocity shear
dc.subject.otherRoughness length
dc.subject.otherComplex terrain
dc.subject.otherroughness
dc.subject.otherAérosol
dc.subject.otherMilieu terrestre
dc.subject.otherEfficacité
dc.subject.otherModèle
dc.subject.otherDensité
dc.subject.otherDistribution vitesse
dc.subject.otherDistribution vent
dc.subject.otherVitesse vent
dc.subject.otherProfil vertical
dc.titleEstimating aerodynamic roughness over complex surface terrain
dc.typeJournal Article
uct.type.publicationResearch
uct.type.resourceJournal Article
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