Nitrogen Availability Decreases the Severity of Snow Storm Damage in a Temperate Forest

Storms are among the greatest natural disturbances in temperate forests, and increased nitrogen (N) availability is thought to increase storm damage. However, the extent to which N availability increases damage from snowfall is less clear. To test how N availability might affect the susceptibility of trees to snow damage in a temperate forest, we took advantage of an opportunistic storm and surveyed damage in fertilized and unfertilized stands, and across a native N availability gradient. In response to a severe, early season snow storm—a consequence of Superstorm Sandy—the percentages of both basal area and stems damaged were lower in a fertilized watershed than in an unfertilized watershed. Across the native N availability gradient, the percentage of basal area damaged by snow decreased with higher soil N. The effects of N availability on damage were also affected by tree species. Our results suggest that N availability decreases damage from snow storms, contrary to our hypotheses drawn from broader studies. Understanding the relation between storm damage and N availability is important, considering the global increase in N deposition, and since severe storms are likely to become more prevalent with climate change.

Field Evaluation of Different Pre-Wetting Ratios for Sustainable Salting

This research presents the findings from a field study aimed at comparing the performance of different pre-wet (PW) ratios of salt for their impacts on snow melting performance/friction of road surfaces. The research was motivated by the question of whether or not better snow melting performance can be achieved by using higher PW ratios. Field tests were conducted on three sections of a provincial highway, located in Western Ontario in the winter season of 2016/2017 under three PW ratios, 5% (current practice), 10%, and 20%. Promelt Mag 22 (22% magnesium chloride, MgCl2, concentration) was used for pre-wetting. Based on a comprehensive statistical analysis of the field testing data, it was found that salt pre-wetted at 20% improved friction levels by approximately 12% while reducing the salt usage by 19% and sand by 35% when compared with usages at a PW ratio of 5%. Examination of images collected during snow storms showed that sections treated with salts with higher PW ratios generally had lower snow coverage.

Snow patches of the Lagonaky highlands (Western Caucasus)

The article presents results of investigation of snowfields on the Lagonaky plateau: conditions of their formation, distribution and dynamics. Snow patches are the most characteristic elements of the high-mountain landscapes of the Lagonaky plateau. In warm seasons, they are widely distributed on local flat-topped ridges of the Lagonaky: Abadzeshsh Murzikao, Kamennoe and others, as well as on the mountain masses Fisht, Pshehasu, Oshten, and Nagoychuk. Morphological and climatic conditions of the Lagonaky Highlands are unique and favorable for formation of snow patches and long preservation of them during the spring-summer periods. These conditions are high mountain ridges with flat tops, negative karst forms of the relief as well as a favorable wind regime with long winter snow storms and heavy snowfalls. Snow patches result from snow transport and accumulation after strong snow-drift on the leeward slopes. The avalanche snow patches arise when avalanches release from steep and long slopes of the above mountain ranges. Permanent snow patches are usually formed at the same places, and duration of their existence depends on sizes and a degree of shading. At the same time, even relatively small snow patches (100–200 thousand m3) can be preserved if they are located in narrow fissures (for example, the area of the Maly Fisht Glacier). In the last 3–5 years, the permanent snow patches melt completely, which is probably a result of small amount of solid precipitation during the cold season and the relatively high air temperatures in the warm time (standard deviation is 0.8–1.0 °C above the normal).

Near-surface snow particle dynamics from particle tracking velocimetry and turbulence measurements during alpine blowing snow storms

Many blowing snow conceptual and predictive models have been based on simplified two-phase flow dynamics derived from time-averaged observations of bulk flow conditions in blowing snow storms. Measurements from the first outdoor application of particle tracking velocimetry (PTV) of near-surface blowing snow yield new information on mechanisms for blowing snow initiation, entrainment, and rebound, whilst also confirming some findings from wind tunnel observations. Blowing snow particle movement is influenced by complex surface flow dynamics, including saltation development from creep that has not previously been measured for snow. Comparisons with 3-D atmospheric turbulence measurements show that blowing snow particle motion immediately above the snow surface responds strongly to high-frequency turbulent motions. Momentum exchange from wind to the dense near-surface particle-laden flow appears significant and makes an important contribution to blowing snow mass flux and saltation initiation dynamics. The more complete and accurate description of near-surface snow particle motions observable using PTV may prove useful for improving blowing snow model realism and accuracy.

The new antiquarianism?

Christopher Witmore (2014: 215) recently observed that “things go on perturbing one another when humans cease to be part of the picture. A former house may be transformed through relations with bacteria, hedgehogs, water, compaction”; and if the materials that archaeologists confront are material memories (cf. Olivier 2011) from which a past is to be recalled in the future, then The kind of memory that things hold often tells us little of whether materials strewn across an abandonment level resulted from the reuse of a structure as a sheepfold, a series of exceptional snow storms, the collapse of a roof made of olive wood after many years of exposure to the weather (rapports between microbes, fungi, water and wood), the cumulative labors of generations of badgers, children playing a game in a ruin, or the probing roots of oak trees (Witmore 2014: 215). In other words, the things that archaeologists confront bear the memories of their own formation without the necessity of a human presence, and the traditional and often exclusive priority given to a human agency in the making of those things and in giving them meaning is simply misplaced. Things get on “just fine” without the benefit of human intervention and interpretation (Witmore 2014: 217). Should archaeology therefore allow that it is not a discipline concerned with excavating the indications of the various past human labours that once acted upon things, and should it eschew the demand to “look beyond the pot, the awl or a stone enclosure for explanations concerning the reasons for their existence” (Witmore 2014: 204)? Consequently, is archaeology now a matter of following the things themselves to wherever they might lead—what Witmore characterises as the New Materialisms—and if so, are we now to practise archaeology “not as the study of the human past through its material remains, but as the discipline of things” (Witmore 2014: 203)?

Glaciers in equilibrium, McMurdo Dry Valleys, Antarctica

ABSTRACTThe McMurdo Dry Valleys are a cold, dry polar desert and the alpine glaciers therein exhibit small annual and seasonal mass balances, often <±0.06 m w.e. Typically, winter is the accumulation season, but significant snow storms can occur any time of year occasionally making summer the accumulation season. The yearly equilibrium line altitude is poorly correlated with mass balance because the elevation gradient of mass balance on each glacier can change dramatically from year to year. Most likely, winds redistribute the light snowfall disrupting the normal gradient of increasing mass balance with elevation. Reconstructed cumulative mass balance shows that the glaciers have lost <2 m w.e. over the past half century and area changes show minimal retreat. In most cases these changes are less than the uncertainty and the glaciers are considered in equilibrium. Since 2000, however, the glaciers have lost mass despite relatively stable summer air temperatures suggesting a different mechanism in play. Whether this trend is a harbinger of future changes or a temporary excursion is unclear.