Description: Previous studies show accelerations of West Antarctic glaciers, implying that basal melt rates of these glaciers were previously small and increased in the middle of the 20th century. This enhanced melting is a likely source of the observed Ross Sea (RS) freshening, but its long-term impact on the Southern Ocean hydrography has not been well investigated. Here, we conduct coupled sea ice-ice shelf-ocean simulations with different levels of ice shelf melting from West Antarctic glaciers. Freshening of RS shelf and bottom water is simulated with enhanced West Antarctic ice shelf melting, while no significant changes in shelf water properties are simulated when West Antarctic ice shelf melting is small. We further show that the freshening caused by glacial meltwater from ice shelves in the Amundsen and Bellingshausen seas can propagate further downstream along the East Antarctic coast into the Weddell Sea. The freshening signal propagates onto the RS continental shelf within a year of model simulation, while it takes roughly 5-10 and 10-15 years to propagate into the region off Cape Darnley and into the Weddell Sea, respectively. This advection of freshening modulates the shelf water properties and possibly impacts the production of Antarctic Bottom Water if the enhanced melting of West Antarctic ice shelves continues for a longer period.

Description: Remote sensing of night light emissions in the visible band offers a unique opportunity to directly observe human activity from space. This has allowed a host of applications including mapping urban areas, estimating population and GDP, monitoring disasters and conflicts. More recently, remotely sensed night lights data have found use in understanding the environmental impacts of light emissions (light pollution), including their impacts on human health. In this review, we outline the historical development of night-time optical sensors up to the current state of the art sensors, highlight various applications of night light data, discuss the special challenges associated with remote sensing of night lights with a focus on the limitations of current sensors, and provide an outlook for the future of remote sensing of night lights. While the paper mainly focuses on space borne remote sensing, ground based sensing of night-time brightness for studies on astronomical and ecological light pollution, as well as for calibration and validation of space borne data, are also discussed. Although the development of night light sensors lags behind day-time sensors, we demonstrate that the field is in a stage of rapid development. The worldwide transition to LED lights poses a particular challenge for remote sensing of night lights, and strongly highlights the need for a new generation of space borne night lights instruments. This work shows that future sensors are needed to monitor temporal changes during the night (for example from a geostationary platform or constellation of satellites), and to better understand the angular patterns of light emission (roughly analogous to the BRDF in daylight sensing). Perhaps most importantly, we make the case that higher spatial resolution and multispectral sensors covering the range from blue to NIR are needed to more effectively identify lighting technologies, map urban functions, and monitor energy use.

Description: The Yedoma region is unique in the permafrost region of the Northern Hemisphere and is characterized by a particularly high ground ice content in the sediment. These frozen deposits store a large amount of carbon and thus have the potential to influence the global climate. Especially the upper layers are susceptible to thaw processes, as they are exposed to increasingly rising mean annual air temperatures. The Northeastern Siberian Yedoma domain is of particular interest in this study. The morphology of ground ice is highly variable and the exact abundance and distribution is still unknown in large parts of Siberia. For an accurate overview of the distribution of intrasedimentary ground ice content, data from 26 sites in Northeastern Siberia were examined. The data were taken from data repositories (e.g., PANGAEA), expedition reports, scientific papers etc. and has been synthesized in a template in Excel. Of relevance was the absolute ice content (wt%) at different depths. Five depth classes were investigated: depth class 1: 0-0.99m; depth class 2: 1-1.99m; depth class 3: 2-2.99m; depth class 4: 3-24.99m; depth class 5: 25-65m. Using the mean absolute ice content for each depth class, ArcGIS was used to create a map for the distribution of ice content. R was applied to represent the ground ice content distribution at the different depths. Furthermore, the focus was on other parameters such as stratigraphy, total organic carbon content and landscape types, which were also examined with respect to the absolute ice content. The ice content is distributed very heterogeneously in Northeastern Siberia, averaging between 30 and 60 wt% over all depths. In large parts of the study area, the ice content in the upper three meters is with 40 to 65 wt% much higher than in the deeper sediment layers. In the depths of 3-65m, the ice content ranges from 20 to 50 wt%. Investigations of the age classes showed that the mean absolute ice content in thermokarst deposits (MIS 1) is with 48.60 wt% higher than in older sedimentary units. The TOC content also decreases significantly with depth. The Yedoma sediment composition and depositional regimes are highly variable. Even on a small scale, large differences in ice content could be observed. With the given data basis, no concrete statements about the vertical and horizontal ice content could be made for the whole study area. The model created in this study can be applied to model the absolute ground ice content based on the TOC content. Assessing the nature and content of ground ice in the upper layers in Northeastern Siberia is fundamental to environmental assessment and important for quantifying carbon fluxes and understanding permafrost response to climate change.