ALBERT

Description: As a fundamental physical property of snowpack, snow density is used to describe many essential features of snowpack behaviour. However, the variability in snow density across the Northern Hemisphere (NH) is largely unknown. Here, we investigate snow density variability in conjunction with snow classes and geographic elements in the NH based on 6,954 snow sites from 1909 to 2019. Precipitation, air temperature, and snowfall based on meteorological sites, as well as the aridity index (AI) and wind speed from reanalysis data, are also applied to describe the effect of climate on snow density. The results present that the long-term mean snow density is 246 ± 70 kg/m3 considering all in-situ measurement sites. Considerable spatial heterogeneity in snow density exists with contrasting snow densities among differing snow classes. The values range from 198 ± 79 kg/m3 for ephemeral snow to 363 ± 63 kg/m3 for maritime snow. For the seasonal evolution of snow density, the different snow classes share a general characteristic with the overall NH, a slight decrease from October to September, followed by a sustained increase. Moreover, the densification rate in the snow stable period varies over a much smaller range than that during the snowmelt period. Furthermore, the longitudinal trends in the variability of snow density are more pronounced compared to altitudinal and latitudinal trends. High snow densities are typically associated with adequate precipitation, warm air temperature, large aridity index, a long snow season, and heavy snowfall for different snow classes. The results will deepen the understanding of the snow density distribution at hemispherical scale, and provide basic data for the remote sensing of snow water equivalent and parameterization of snow models.

Description: Multi-antenna global navigation satellite systems (GNSS) can provide attitude measurement information for GNSS/INS integrated system. However, once the wrong attitude measurement is used in the tight coupled model, it is easy to lead to filtering divergence. Therefore, fault detection and exclusion (FDE) is very important for multi-antenna attitude determination. Because the baseline length information is often used as prior information in attitude determination, it cannot be used as the statistic of FDE again. In this paper, we propose a new statistic for attitude FDE, differential inter-system biases (DISB), and jointly use DISB, baseline length, standard deviation, and ratio to perform FDE for multi-antenna GNSS attitudes. The obtained attitudes with high reliability is added to the GNSS/INS tight coupled positioning model for measurement update. A set of urban vehicular data is used to verify the method. The results show that the DISB has FDE capabilities comparable to the baseline length information, which will be a powerful supplement when the baseline length information cannot be used. Compared to the single-antenna GNSS/INS tight coupled model, The accuracy of yaw,pitch and roll of the RTK/INS tightly coupled model with multi-antenna attitude measurement is improved by 57-64%,26-29% and 26-32% respectively, and the accuracy of the PPP/INS tightly coupled model with multi-antenna attitude measurement is improved by 60-61%,51-53% and 41-44% respectively.

Description: Drainage channels are widely used for discharging debris flows into deposition basins or rivers. However, the current drainage channel designs for guiding rapid debris flows downstream do not account for the variations of the gullies’ gradient and debris flow energy. In this study, we evaluated the performance of different step-baffle geometries (square, triangle, and trapezoid) in regulating debris flows. Specifically, their effects on the flow patterns, sediment transport, energy dissipation, and impact pressure are investigated using flume experiments. Results here showed that the square baffles promote highly turbulent flows which in turn result in the highest lift height relative to the triangular and trapezoidal baffles. Maximum sediment interception and highest energy dissipation are obtained using the trapezoidal baffle, whereas the triangular baffle exhibits minimal solid interception and the lowest energy dissipation. Trapezoidal baffles generally experience the greatest impact forces relative to both square and triangular baffles. However, when only the first baffle in the channel is considered, it is the square baffles that experience the largest impact forces. The present work improves the understanding of the effectiveness of step-baffle drainage channels in mitigating debris flows.

Description: Understanding the interactions (synergies and trade-offs) among the Sustainable Development Goals (SDGs) is crucial for enhancing policy coherence between different sectors. However, spatial differences in the SDG interactions and their temporal variations at the sub-national scale are still critical gaps that need to be urgently filled. Here, we assess the spatial and temporal variation of the SDG interactions in China based on the systematic classification framework of SDGs. The framework groups the seventeen SDGs into three categories, namely “Essential Needs,” “Objectives,” and “Governance.” Spatially, we found that the SDGs in “Essential Needs” & “Objectives” and “Essential Needs” & “Governance” generally show trade-offs in the eastern provinces of China. Synergies among all three SDG categories are observed in some central and western China provinces, which implies that these regions conform to sustainable development patterns. In addition, temporally, the synergies of the three SDG categories have shown a weakening trend in the last decade, mainly due to the regional differences in the progress of SDG7 (Affordable and Clean Energy). Overall, our results identify the necessity for provinces to enhance the synergies between SDG12 (Responsible Production and Consumption) and other SDGs to tackle the trade-offs between the “Essential Needs” and “Objectives.” Meanwhile, promoting the progress of SDG7 will also contribute to balanced development across provinces.

Description: The nexus approach offers an important heuristic tool for the sustainable management of resources by considering the links among different sectors. The food-energy-water (FEW) nexus corresponds to links among the three of seventeen United Nations Sustainable Development Goals (SDGs), namely SDG2 (No Hungry), SDG6 (Clean Water and Sanitation), and SDG7 (Affordable and Clean Energy), and their interlinkages have a direct or indirect impact on other SDGs. However, there is still a lack of a systematic and quantitative analysis of how the nexus approach could promote achieving SDGs. Here, taking China as a case, we built an expanded FEW nexus framework from the lens of SDGs, which consists of six sectors, including food (SDG2), water (SDG6), energy (SDG7), economic (SDG8), consumption and production (SDG12), and forest (SDG15). We quantified the two-way interactions between the six sectors by the panel vector autoregressive (PVAR) model. Results indicate that sectors exhibit different response characteristics (positive or negative) in their interactions, and these responses could change over time. These results imply that changing the priorities of actions may be an effective measure to transform trade-offs into synergies. Moreover, the contribution of different sectors to each other varies considerably, with economic growth (SDG8) generally having a higher impact on changes in the FEW nexus than consumption and production patterns (SDG12). Our research suggests that strengthening the quantitative assessment of two-way interactions among the FEW nexus has crucial implications for leveraging nexus approaches effectively to achieve sustainable development for all.