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Abstract In the mountainous headwaters of the Colorado River episodic dust deposition from adjacent arid and disturbed landscapes darkens snow and accelerates snowmelt, impacting basin hydrology. Patterns and impacts across the heterogenous landscape cannot be inferred from current in situ observations. To fill this gap daily remotely sensed retrievals of radiative forcing and contribution to melt were analyzed over the MODIS period of record (2001–2023) to quantify spatiotemporal impacts of snow darkening. Each season radiative forcing magnitudes were lowest in early spring and intensified as snowmelt progressed, with interannual variability in timing and magnitude of peak impact. Over the full record, radiative forcing was elevated in the first decade relative to the last decade. Snowmelt was accelerated in all years and impacts were most intense in the central to southern headwaters. The spatiotemporal patterns motivate further study to understand controls on variability and related perturbations to snow water resources.
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Two Decades of Dust Radiative Forcing on Snow Cover Across the Great Salt Lake Basin
Abstract Seasonal snowpacks in mountain drainages of the Great Salt Lake Basin (GSLB), western United States, are the primary surface water supply to regional agriculture, the metropolitan Wasatch Front, and the terminal Great Salt Lake. Spring dust emissions from the eastern Great Basin result in a dust‐darkened GSLB snowpack, locally accelerating snowmelt relative to dust‐free conditions. Such acceleration has been linked to streamflow forecasting errors in the adjacent Colorado River Basin, but snow darkening impacts within the GSLB are largely uninvestigated. To quantify the dust impact, we analyzed patterns in dust radiative forcing (RFdust) over the MODIS record (2001–2023) using spatially and temporally complete RFdustand fractional snow‐covered area products. For validation, retrievals were cross‐referenced with in situ RFdustobservations. Results showed that RFdustwas present every year and had no significant trend over the record. Spatially, RFdustwas similar across all three subbasins. Temporally, RFdustexhibited high interannual variability (−30 to +40 Wm−2from record means) and has declined slightly in regions of the eastern GSLB. Controls of RFdustmay be linked to seasonal meteorology and drought conditions, but drivers remain uncertain. Further understanding of the distribution and controls of RFdustin the GSLB during changing climate and weather patterns may allow us to predict snowmelt more accurately.
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- Award ID(s):
- 2012091
- PAR ID:
- 10573088
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Earth Surface
- Volume:
- 130
- Issue:
- 2
- ISSN:
- 2169-9003
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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