Detection and analysis of Lhù'ààn Mân' (Kluane Lake) dust plumes using passive and active ground-based remote sensing supported by physical surface measurements
Authors: Sayedain Seyed Ali , O'Neill Norman T. , King James , Hayes Patrick L. , Bellamy Daniel , Washington Richard , Engelstaedter Sebastian , Vicente-Luis Andy , Bachelder Jill , Bernhard Malo 
Published: September 2023

Abstract. There is growing recognition that high-latitude dust
(HLD), originating from local drainage-basin flows, is the dominant source
for certain important phenomena such as particle deposition on snow/ice.
The analysis of such local plumes (including a better exploitation of remote sensing data) has been targeted as a key aerosol issue by the HLD community.
The sub-Arctic Lhù'ààn Mân' (Kluane Lake) region in the
Canadian Yukon is subject to regular drainage-basin, wind-induced dust plumes.
This dust emission site is one of many current and potential proglacial dust sources in the Canadian north. In situ ground-based measurements are, due to constraints in accessing these types of regions, rare. Ground- and
satellite-based remote sensing accordingly play an important role in helping to characterize local dust sources in the Arctic and sub-Arctic. We compared ground-based passive and active remote sensing springtime (May
2019) retrievals with microphysical surface-based measurements in the
Lhù'ààn Mân' region in order to better understand the
potential for ground- and satellite-based remote sensing of HLD plumes. This included correlation analyses between ground-based coarse mode (CM) aerosol optical depth (AOD) retrievals from AERONET AOD spectra, CM AODs derived from co-located Doppler lidar profiles, and OPS (optical particle sizer) surface measurements of CM particle-volume concentration (vc(0)). An automated dust classification scheme was developed to objectively identify local dust events. The classification process helped distinguish lidar-derived CM AODs which covaried with vdust(0)
(during recognized dust events) and those that varied at the same columnar
scale as AERONET-derived CM AOD (and thus could be remotely sensed). False
positive cloud events for dust-induced, high-frequency variations in
lidar-derived CM AODs in cloudless atmospheres indicated that the AERONET
cloud-screening process was rejecting CM dust AODs. The persistence of a
positive lidar ratio bias in comparing the CIMEL/lidar-derived value with a
prescribed value obtained from OPS-derived particle sizes coupled with
dust-speciation-derived refractive indices led to the suggestion that the
prescribed value could be increased to optically derived values of 20 sr by the presence of optically significant dust particles at an effective radius of 11–12 µm. Bimodal CM PSDs (see Appendix B for a glossary) from full-fledged AERONET inversions (the combination of AOD spectra and almucantar radiances) also showed CM peaks at ∼ 1.3 and 5–6.6 µm radius: this, we
argue, was associated with springtime Asian dust and Lhù'ààn Mân' dust, respectively. Correlations between the CIMEL-derived fine
mode (FM) AOD and FM OPS-derived particle-volume concentrations suggest that
remote sensing techniques can be employed to monitor FM dust (which is
arguably a better indicator of the long-distance transport of HLD).