Evaluation of Seasonal Water Budget Components over the Major Drainage Basins of North America Using an Ensemble-Based Land Surface Model Approach

An ensemble of land surface models and forcing data was developed to assess variability in SWE estimation over North America. In this study, the ensemble output was used to assess how SWE uncertainty impacts stream flow estimation. The analysis was conducted by major basins of North America over the 2009-2017 time period

Snow water equivalent retrieval over Idaho – Part 2: Using L-band UAVSAR repeat-pass interferometry

This study evaluates using interferometry on low-frequency synthetic aperture radar (SAR) images to monitor snow water equivalent (SWE) over seasonal and synoptic scales. We retrieved SWE changes from nine pairs of SAR images, mean 8 d temporal baseline, captured by an L-band aerial platform, NASA's Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR), over central Idaho as part of the NASA SnowEx 2020 and 2021 campaigns. The retrieved SWE changes were compared against coincident in situ measurements (SNOTEL and snow pits from the SnowEx field campaign) and to 100 m gridded SnowModel modeled SWE changes. The comparison of in situ to retrieved measurements shows a strong Pearson correlation (R=0.80) and low RMSE (0.1 m, n=64) for snow depth change and similar results for SWE change (RMSE = 0.04 m, R=0.52, n=57). The comparison between retrieved SWE changes to SnowModel SWE change also showed good correlation (R=0.60, RMSD = 0.023 m, n=3.2×106) and especially high correlation for a subset of pixels with no modeled melt and low tree coverage (R=0.72, RMSD = 0.013 m, n=6.5×104). Finally, we bin the retrievals for a variety of factors and show decreasing correlation between the modeled and retrieved values for lower elevations, higher incidence angles, higher tree percentages and heights, and greater cumulative melt. This study builds on previous interferometry work by using a full winter season time series of L-band SAR images over a large spatial extent to evaluate the accuracy of SWE change retrievals against both in situ and modeled results and the controlling factors of the retrieval accuracy.</p

Evaluating the utility of active microwave observations as a snow mission concept using observing system simulation experiments

Satellite-based synthetic aperture radar (SAR) sensors have the potential to provide the first global measure of snow water equivalent (SWE), with key advantages compared to existing satellite observations (e.g., passive microwave sensors) such as high spatial resolution and capability in mountainous areas. While recent studies have shown some capability in challenging conditions, such as deep snow and forested areas, there is still work to be done to understand the limitations and benefits of these observations in an assimilation system. In this study, we develop an observing system simulation experiment (OSSE) to characterize the expected error levels of active microwave-based volume-scattering SWE retrievals over a western Colorado domain. We found that for a hypothetical SAR snow mission, the root mean square error (RMSE) of SWE improves by about 20 % in the mountainous environment if the retrieval algorithm can estimate SWE up to 600 mm and the tree cover fraction up to 40 %. Results also demonstrate that the potential SWE retrievals have larger improvements in the tundra (43 %) snow class, followed by boreal forest (22 %) and montane forest (17 %). Even though active microwave sensors are known to be limited by liquid water in the snowpack, they still reduced errors by up to 6 %–16 % of domain-averaged SWE in the melting period, suggesting that the SWE retrievals can add value to meltwater estimations and hydrological applications. Overall, this work provides a quantitative benchmark of the utility of a potential snow mission concept in a mountainous domain, helping to prioritize future algorithm development and field validation activities.</p

The work of Josef Váchal in art education at the elementary school

The thesis deals with the art of the modern Czech painter and graphic artist Josef Váchal and follows up its use in creative activities at primary school. The theoretical part is devoted to a detailed analysis of Váchal artistic development and brief psychological study of his personality. It also reflects the creation of other artists, whose artistic expression tends to be close to Váchal works. In fine the thesis follows the possibilities of use of artistic work in art education at the elementary school. The practical part introduce the art education project, inspired by works of Josef Váchal, and documents its complex realization at the elementrary school in Borové Lady with the final reflection