Remote-sensing detectability of airborne Arctic dust

Journal Article · 06 January 2025 · Atmospheric Chemistry and Physics (Online)

DOI: https://doi.org/10.5194/acp-25-27-2025 · OSTI ID:2503504

O'Neill, Norman T. ^[1]; Ranjbar, Keyvan  ^[2]; Ivănescu, Liviu  ^[2]; Blanchard, Yann  ^[3]; Sayedain, Seyed Ali  ^[1]; AboEl-Fetouh, Yasmin ^[4]

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1. Université de Sherbrooke (Canada)
2. National Research Council Canada, Ottawa (Canada)
3. Université du Québec à Montréal (Canada)
4. Karlsruhe Institute of Technology (Germany)

Remote-sensing (RS)-based estimates of Arctic dust are oftentimes overestimated due to a failure in separating out the dust contribution from that of spatially homogeneous clouds or low-altitude cloud-like plumes. A variety of illustrations are given with a particular emphasis on questionable claims of using brightness temperature differences (BTDs) as a signature indicator of Arctic dust transported from mid-latitude deserts or generated by local Arctic sources. While there is little dispute about the presence of both Asian and local dust across the Arctic, the direct RS detectability of airborne dust, as ascribed to satellite (MODIS and AVHRR) measurements of significantly negative brightness temperature differences at 11 and 12 µm (BTD_11–12), has been misrepresented in certain cases. While it is difficult to account for all examples of strongly negative BTD_11–12 values in the Arctic, it is unlikely that airborne dust plays a significant role. One much more likely contributor would be water clouds in the Arctic inversion layer. The RS detectability of the impact of Arctic dust (notably due to Arctic dust from local sources) can, however, be of significance. Sustained dust deposition can substantially decrease (visible to shortwave IR) snow and ice reflectance albedo (pan-chromatic reflectance) and the signal measured by satellite sensors. Significantly negative BTD_11–12 values would, however, only represent a limited area near the drainage basin sources according to our event-level case studies. The enhanced ice-nucleating particle (INP) role of local Arctic dust can, for example, induce significant changes in the properties of low-level mixed-phase clouds (cloud optical depth changes <~ 1) that can readily be detected by active and passive RS instruments. It is critical that the distinction between the RS detectability of airborne Arctic dust versus the RS detectability of the impacts of that dust be understood if we are to appropriately parameterize, for example, the radiative forcing influence of dust in this climate-sensitive region.

• Research Organization: ARM Data Center, Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: Canadian Space Agency; Natural Sciences and Engineering Research Council of Canada; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Contributing Organization: ANL; BNL; PNNL
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 2503504
• Journal Information: Atmospheric Chemistry and Physics (Online), Journal Name: Atmospheric Chemistry and Physics (Online) Journal Issue: 1 Vol. 25; ISSN 1680-7324
• Publisher: Copernicus Publications, EGUCopyright Statement
• Country of Publication: United States
• Language: English