Addition and Evaluation of Northern High-Latitude Mineral Dust Sources in the NASA GEOS Model

Mineral dust aerosols play important roles in Earth’s climate, particularly by impacting aerosol radiative forcing and through indirect effects on clouds, including their phase and lifetime. Desert dust, primarily from low latitude sources, has received significant attention from both the observational and modeling communities, but dust emissions from high latitude sources remain understudied. Aircraft, ground, and satellite observations in the Arctic have indicated Alaska, Iceland, Canada, Greenland, and Svalbard, among others, have seasonally or annually varying dust sources that may contribute up to 5% of global dust emissions, and much higher proportions near the surface in the Arctic. Such high latitude dust sources have been suggested to be a major contributor to the Arctic ice nucleating particle population, although the overall dust impact on cloud radiative effects in the region is still uncertain. One challenge is the variability observed in Arctic dust concentrations between models, many of which do not consider high latitude dust sources. This study aims to improve simulation of dust in the Arctic in the NASA Goddard Earth Observing System (GEOS) Earth system model by adding such local sources at high latitudes (≥50°N). The dust emission map created for use with FLEXPART (FLEXDUST; Groot Zwaaftink et al. 2016) has been implemented in GEOS and we are assessing the dust emission sensitivity to model resolution and wind speed threshold. High latitude dust emissions are sensitive to snow cover and possibly soil temperature in addition to soil moisture and vegetation coverage, which contributes to the strong seasonality and regionality of such emissions. Results of sensitivity studies to assess the relative importance of snow cover, vegetation fraction, soil temperature, and soil moisture on high latitude dust emissions will be presented. The magnitude and locations of Arctic dust emissions in GEOS will be validated against CALIPSO retrievals, ground lidar observations from the NASA Micro-Pulse Lidar Network (MPLNET) and aluminum measurements from Villum Research Station (Station Nord) and Alert. Future studies will utilize the improved GEOS dust emissions to help constrain the uncertain impacts of local high latitude dust on Arctic aerosol-cloud interactions.