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Accurate snow depth observations are critical to assess water resources. More than a billion people rely on water from snow, most of which originates in the Northern Hemisphere mountain ranges. Yet, remote sensing observations of mountain snow depth are still lacking at the large scale. Here, we show the ability of Sentinel-1 to map snow depth in the Northern Hemisphere mountains at 1 km² resolution using an empirical change detection approach. An evaluation with measurements from ~4000 sites and reanalysis data demonstrates that the Sentinel-1 retrievals capture the spatial variability between and within mountain ranges, as well as their inter-annual differences. This is showcased with the contrasting snow depths between 2017 and 2018 in the US Sierra Nevada and European Alps. With Sentinel-1 continuity ensured until 2030 and likely beyond, these findings lay a foundation for quantifying the long-term vulnerability of mountain snow-water resources to climate change.

While the processes controlling pore closure are broadly understood, the physical mechanisms driving the associated elemental fractionation remains ambiguous. Previous studies have shown that the pore closure process leads to a depletion in small-sized molecules (e.g. H2 , O2 , Ar, Ne, He) in ice core bubbles relative to larger-sized molecules like N2. This size-dependent fractionation, identified using ice core δ(O2/N2) records, exhibits a clear anti-correlation with local summer solstice insolation, making δ(O2/N2) a valuable ice core dating tool. Mechanisms controlling this relationship are attributed to the physical properties of deep firn. In this study, we compile δ(O2/N2) records from 15 polar ice cores and show a new additional link between δ(O2/N2) and local surface temperature and/or accumulation rate. Using the Crocus snowpack model, we perform sensitivity tests to identify the response of near-surface snow properties to changes in insolation intensity, accumulation rate, and air temperature. These tests support a mechanism linked to firn grain size, such that the larger the grain size for a given density, the stronger the pore closure fractionation and, hence, the lower the δ(O2/N2) values archived in the ice. Based on both snowpack model outputs and data compilation, our findings suggest that local accumulation rate and temperature should be considered when interpreting δ(O2/N2) as a local insolation proxy. [ABSTRACT FROM AUTHOR]

Accurate snow cover modeling is a high-stakes issue for mountain regions. Alpine snow evolution and spatial variability result from a multitude of complex processes including interactions between wind and snow. The SnowPappus blowing snow model was designed to add blowing snow modeling capabilities to the SURFEX/Crocus simulation system for applications across large spatial and temporal extents. This paper presents the first spatialized evaluation of this simulation system over a 902 km 2 domain in the French Alps. Here we compare snow cover simulations to the spatial distribution of snow height obtained from Pléiades satellites stereo imagery and to snow melt-out dates from Sentinel-2 and Landsat 8 time series over three snow seasons. We analyzed the sensitivity of the simulations to three different precipitation datasets and two horizontal resolutions. The evaluations are presented as a function of elevation and landform types. The results show that the SnowPappus model forced with high-resolution wind fields enhances the snow cover spatial variability at high elevations allowing a better agreement between observed and simulated spatial distributions above 2500 m and near peaks and ridges. Model improvements are not obvious at low to medium altitudes where precipitation errors are the prevailing uncertainty. Our study illustrates the necessity to consider error contributions from blowing snow, precipitation forcings, and unresolved subgrid variability for robust evaluations of spatialized snow simulations. Despite the significant effect of the unresolved spatial scales of snow transport, 250 m horizontal-resolution snow simulations using SnowPappus are found to be a promising avenue for large-scale modeling of alpine snowpacks. [ABSTRACT FROM AUTHOR]

Human centromeres are defined by chromatin containing the histone H3 variant CENP-A assembled onto repetitive alphoid DNA sequences. By inducing rapid, complete degradation of endogenous CENP-A, we now demonstrate that once the first steps of centromere assembly have been completed in G1/S, continued CENP-A binding is not required for maintaining kinetochore attachment to centromeres or for centromere function in the next mitosis. Degradation of CENP-A prior to kinetochore assembly is found to block deposition of CENP-C and CENP-N, but not CENP-T, thereby producing defective kinetochores and failure of chromosome segregation. Without the continuing presence of CENP-A, CENP-B binding to alphoid DNA sequences becomes essential to preserve anchoring of CENP-C and the kinetochore to each centromere. Thus, there is a reciprocal interdependency of CENP-A chromatin and the underlying repetitive centromere DNA sequences bound by CENP-B in the maintenance of human chromosome segregation.

Waxy skinned berry fruits contain essential nutrients and play an important role in human health and nutrition. However, these fruits encounter two major problems; firstly, they are extremely perishable in nature that limits their consumption throughout the year and to address this bottleneck, osmotic dehydration (OD) can be an efficient way which brings the second problem associated with berries. The waxy skin of some valuable berries acts like a barrier and reduces the mass transfer (MT) during OD. The restricted MT during OD can be improved by applying pretreatments, accelerators during OD as well as optimizing OD parameters. Therefore, this review is first of its kind aims to provide a comprehensive discussion on the concept of OD, pretreatments and processing parameters associated with the improved MT in the waxy skinned berries. In terms of maintaining the sensory attributes, innovative non-thermal pretreatments are found better than classical thermal, mechanical, and chemical/enzymatic pretreatments. Moreover, factors affecting the MT rate and efficiency of OD processes, along with mathematical and computational models to optimize OD of waxy skinned berries are given. The advantages of OD processes on the quality of the products, in terms of bioactive compounds, texture, sensory properties, and color, were additionally summarized. The novelty of this review lies in its exclusive focus on the OD of berry fruits with a waxy layer on their surface and the strategies to ease off the process. [ABSTRACT FROM AUTHOR]