Research about Alaska, Idaho

USGS2022

Uncertainty of ICESat-2 ATL06- and ATL08-derived snow depths for glacierized and vegetated mountain regions

Seasonal snow melt dominates the hydrologic budget across a large portion of the globe. Snow accumulation and melt vary over a broad range of spatial scales, preventing accurate extrapolation of sparse in situ observations to watershed scales. The lidar onboard the Ice, Cloud, and land Elevation, Satellite (ICESat-2) was designed for precise mapping of ice sheets and sea ice, and here we assess the feasibility of snow depth-mapping using ICESat-2 data in more complex and rugged mountain landscapes. We explore the utility of ATL08 Land and Vegetation Height and ATL06 Land Ice Height differencing from reference elevation datasets in two end member study sites. We analyze ∼3 years of data for Reynolds Creek Experimental Watershed in Idaho's Owyhee Mountains and Wolverine Glacier in southcentral Alaska's Kenai Mountains. Our analysis reveals decimeter-scale uncertainties in derived snow depth and glacier mass balance at the watershed scale. Both accuracy and precision decrease as slope increases: the magnitudes of the median and median of the absolute deviation of elevation errors (MAD) vary from ∼0.2 m for slopes <5° to >1 m for slopes >20°. For glacierized regions, failure to account for intra- and inter-annual evolution of glacier surface elevations can strongly bias ATL06 elevations, resulting in under-estimation of the mass balance gradient with elevation. Based on these results, we conclude that ATL08 and ATL06 observations are best suited for characterization of watershed-scale snow depth and mass balance gradients over relatively shallow slopes with thick snowpacks . In these regions, ICESat-2 elevation residual-derived snow depth and mass balance transects can provide valuable watershed scale constraints on terrain parameter- and model-derived estimates of snow accumulation and melt.

Alaska, Idaho↗

USGS2016

Physiological comparisons of plasma and tissue metrics of selected inland and coastal steelhead kelts.

The physiological status of migrating steelhead kelts ( Oncorhynchus mykiss ) from the Situk River, Alaska, and two tributaries of the Clearwater River, Idaho, was evaluated to explore potential differences in post-spawning survival related to energy reserves. Blood plasma samples were analyzed for metrics related to nutritional and osmotic status, and samples of white muscle tissue collected from recent mortalities at weirs were analyzed for proximate constituents. Female kelts from the Situk River had significantly higher plasma cholesterol, triglycerides, glucose and calcium concentrations, all of which suggested higher lipid and energy stores. Additional support for energy limitation in kelts was provided by evaluating the presence of detectable proteins in the plasma. Most all kelts sampled from the Situk River populations had detectable plasma proteins, in contrast to kelts sampled from the Clearwater River tributary populations where 27 % of kelts from one tributary, and 68 % of the second tributary were below the limits of detection. We found proximate constituents of kelt mortalities were similar between the Situk and Clearwater River populations, and the lipid fraction of white muscle averaged 0.1 and 0.2 %. Our findings lend support to the hypothesis that energetic limitations likely affect post-spawn survival in the Clearwater River kelts.

Alaska, Idaho↗