The shrinking Great Salt Lake contributes to record high dust-on-snow deposition in the Wasatch Mountains during the 2022 snowmelt season

This site contains inputs/outputs used for atmospheric backward trajectory analyses (.zip files) and snowmelt mass and energy balance modeling (all other files) in this study. The abstract of the study is below: Seasonal snowmelt from the Wasatch Mountains of northern Utah, USA is a primary control on water availability for the metropolitan Wasatch Front, surrounding agricultural valleys, and the Great Salt Lake (GSL). Prolonged drought, increased evaporation due to warming temperatures, and sustained agricultural and domestic water consumption have caused GSL water levels to reach record low stands in 2021 and 2022, resulting in increased exposure of dry lakebed sediment. When dust emitted from the GSL dry lakebed is deposited on the adjacent Wasatch snowpack, the snow is darkened, and snowmelt is accelerated. Regular observations of dust-on-snow (DOS) began in the Wasatch Mountains in 2009, and the 2022 season was notable for both having the most dust deposition events and the highest snowpack dust concentrations. To understand if record high DOS concentrations were linked to record low GSL levels, dust source regions for each dust event were identified through a backward trajectory model analysis combined with aerosol measurements and field observations. Backward trajectories indicated that the exposed lakebed of the GSL likely contributed 23% of total dust deposition and had the highest dust emissions per surface area. The other potential primary contributors were the Great Salt Lake Desert (45%) and the Sevier + Tule dry lakebeds (17%), both with lower per-area emissions. The impact on snowmelt, quantified by mass and energy balance modeling in the presence and absence of snow darkening by dust, was over two weeks (17 days) earlier. The impact of dust on snowmelt could have been more dramatic if the spring had been drier, but frequent snowfall buried dust layers, delaying dust-accelerated snowmelt later into the melt season.本数据集包含本研究中用于大气后向轨迹分析（.zip压缩文件）以及融雪质量与能量平衡建模（其余全部文件）的输入/输出数据。以下为本研究的研究摘要：美国犹他州北部瓦萨奇山脉的季节性融雪，是瓦萨奇前沿都会区、周边农业河谷以及大盐湖（Great Salt Lake, GSL）水资源供给的核心调控因素。长期干旱、气温升高导致的蒸发加剧，以及持续的农业和生活用水消耗，使得大盐湖水位在2021年和2022年降至有记录以来的最低值，导致裸露湖床沉积物面积大幅扩张。当从大盐湖裸露湖床扬起的粉尘沉降至邻近的瓦萨奇积雪层时，积雪反照率降低，融雪过程随之加速。瓦萨奇山脉的雪面粉尘（Dust-on-Snow, DOS）常规观测始于2009年，而2022年雪季的粉尘沉降事件次数与积雪粉尘浓度均创下历史纪录。为探究破纪录的高雪面粉尘浓度是否与大盐湖极低水位存在关联，本研究结合气溶胶观测与实地观测，通过后向轨迹模型分析识别了每一次粉尘事件的尘源区域。后向轨迹分析结果显示，裸露的大盐湖湖床约贡献了总粉尘沉降量的23%，且单位表面积粉尘排放量最高。其他潜在主要尘源包括大盐湖沙漠（占比45%）以及塞维尔+图莱里裸露湖床（占比17%），这两处的单位面积粉尘排放量均相对较低。通过开展有无粉尘暗化积雪情景下的质量与能量平衡建模，本研究量化了粉尘对融雪的影响：融雪过程提前了两周以上（17天）。若当年春季更为干旱，粉尘对融雪的影响本会更为显著，但频繁的降雪掩埋了粉尘层，使得粉尘加速融雪的效应在整个融雪季中出现得更晚。