Annual and seasonal variability in high latitude dust deposition, West Greenland

Abstract

High latitude regions (≥ 50°N and ≥ 40°S) are thought to contribute substantially to contemporary global dust emissions which can influence biogeochemical cycling as well as geomorphic, cryospheric and atmospheric processes. However, there are few measurements of the emission or deposition of dust derived from these areas that extend beyond a single event or season. This article reports the deposition of locally-derived dust to an ice-free area of West Greenland over 2 years from 23 traps distributed across five sampling sites. Local dust sources include glacial outwash plains, glacially-derived delta deposits and the reworking of loessic soils. Annual dust deposition is estimated at 37.3 to 93.9 g m−2 for 2017–2018 and 9.74 to 28.4 g m−2 in 2018–2019. This annual variation is driven by high deposition rates observed in spring 2017 of 0.48 g m−2 d−1 compared to the range of 0.03 to 0.07 g m−2 d−1 during the rest of the monitoring period. The high deposition rates in spring 2017 were due to warmer than average conditions and high meltwater sediment supply that delivered large quantities of sediment to local outwash plains in 2016. For other seasons, dust deposition was lower over both autumn–winter periods (0.03 g m−2 d−1) than during the spring and summer (0.04–0.07 g m−2 d−1). When sediment availability is limited, dust deposition increases with increasing temperature and wind speed. Secondary data from dust-related weather type/observation codes and visibility records were found to be inconsistent with measured dust deposition during the period of study. One possible reason for this is the complex nature of the terrain between the observation and sample sites. The dust deposition rates measured here and the infidelity of the observed dust with secondary data sources reveal the importance of direct quantification of dust processes to accurately constrain the dust cycle at high latitudes.