Wind downscaling and land-surface aggregation reshape event-scale dust source contributions

Event-scale dust-source contributions can change when models resolve terrain-modified winds and heterogeneous land-surface fields, yet separation and quantification of these influences remain difficult. A WRF–WindNinja dust-emission framework was developed to isolate wind-downscaling effects from land-surface aggregation effects and applied to two April 2023 dust events in northwestern Utah. The framework compared three configurations: a 4 km WRF-CMAQ-style baseline, a 150 m WindNinja wind field paired with 4 km land-surface fields, and a configuration with 150 m wind and land-surface fields. Across both events, the highest resolution configuration decreased domain-total emissions relative to the coarse baseline by approximately 15%. Wind downscaling accounted for most of this reduction, whereas high-resolution surface fields partially recovered emitted mass and redistributed activation within the source network. The 12 April southwesterly event produced a broader, multi-source footprint, whereas the 18 April westerly event was concentrated in the Great Salt Lake Desert. Configuration differences were most significant over the Great Salt Lake exposed lakebed, where the high-resolution configuration doubled the active erodible surface area and increased emitted mass by more than 80% relative to the coarse baseline. Taken together, these results show that near-surface wind fields and surface heterogeneity interact nonlinearly to reshape dust-source contributions through thresholded emission physics. GOES-18 Dust RGB imagery and surface wind observations supported the timing and source-region plausibility of modeled activation during the 18 April event. The framework provides a diagnostic approach for interpreting resolution-dependent dust-emission estimates in heterogeneous dryland source regions.