Impact of Dust Source Patchiness on the Existence of a Constant Dust Flux Layer During Aeolian Erosion Events

• Published in: Journal of Geophysical Research: Atmospheres
• Main Authors: Dupont, S., Klose, M., Irvine, M. R., González-Flórez, C., Alastuey, Andrés, Bonnefond, J. M., Dagsson-Waldhauserova, P., Gonzalez-Romero, A., Hussein, T., Lamaud, E., Meyer, H., Panta, A., Querol, Xavier, Schepanski, K., Vergara Palacio, S., Wieser, A., Yus-Díez, J., Kandler, K., Pérez García-Pando, C.
• Other Authors: European Commision, European Research Council, orcid:
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2024
• Subjects: Soil wind erosion; Constant flux layer; Dust flux; Size distribution; Ensure access to affordable; reliable; sustainable and modern energy for all; Make cities and human settlements inclusive; safe; resilient and sustainable; Iceland
• Online Access: http://hdl.handle.net/10261/361891; https://doi.org/10.1029/2023JD040657; https://api.elsevier.com/content/abstract/scopus_id/85195946437

Dust emission fluxes during wind soil erosion are usually estimated using a dust concentration vertical gradient, by assuming a constant dust flux layer between the surface and the dust measurement levels. Here, we investigate the existence of this layer during erosion events recorded in Iceland and Jordan. Size-resolved dust fluxes were estimated at three levels between 2 and 4 m using the eddy-covariance method. Dust fluxes were found mainly constant only between the two upper levels in Iceland, the lower dust flux being often stronger and richer in coarse particles, while dust fluxes in Jordan were nearly constant across all levels. The wind dynamics could not explain the absence of a constant dust flux layer in Iceland. We show that the presence of stationary dust source patches in Iceland, related to surface humidity, created a non-uniform dust layer near the surface, named dust roughness sublayer (DRSL), where individual plumes behind each patch interact but do not fully mix. The lowest dust measurement level was probably located within this sublayer while the upper ones were located above, such that there the emitted dust became spatially well-mixed. This explains near the surface in Iceland, the more intermittent dust concentration, its low correlation with the dust concentrations above, and the richer dust flux in coarse particles due to their lower deposition contribution. Our findings highlight the importance of estimating dust fluxes above a dust blending height whose characteristics depend on the dust source patchiness caused by surface humidity or the presence of sparse non-erosive elements. We acknowledge the European Research Council under the Horizon 2020 research and innovation programme through the ERC Consolidator Grant FRAGMENT (Grant agreement no 773051), and the AXA Research Fund through the AXA Chair on Sand and Dust Storms at BSC for financial support of the field campaigns in Iceland and Jordan. S. Dupont acknowledge the financial support of the Department Agroecosystem of INRAE. K. ...