Subsurface Temperature Properties for Three Types of Permeable Pavements in Cold Weather Climates and Implications for Deicer Reduction

Permeable pavement has been shown to be an effective urban stormwater management tool although much is still unknown about freeze-thaw responses and the implications for deicer reduction in cold weather climates. Temperature data from the subsurface of three permeable pavement types—interlocking concrete pavers (PICP), concrete (PC), and asphalt (PA)—were collected over a seven-year period and evaluated. Temperature profiles of all pavements indicate favorable conditions to allow infiltration during winter rain and melting events, with subsurface temperatures remaining above freezing even when air temperatures were below freezing. Data show that PICP surpassed PC and PA with fewer days below freezing, higher temperatures on melt days, slower freeze and faster thaw times, and less penetration of freezing temperatures at depth.

Quantifying seasonal cornice dynamics using a terrestrial laser scanner in Svalbard, Norway

Snow cornices develop along mountain ridges, edges of plateaus, and marked inflections in topography throughout regions with seasonal and permanent snow cover. Despite the recognized hazard posed by cornices in mountainous locations, limited modern research on cornice dynamics exists and accurately forecasting cornice failure continues to be problematic. Cornice failures and associated cornice fall avalanches comprise a majority of observed avalanche activity and endanger human life and infrastructure annually near Longyearbyen in central Svalbard, Norway. In this work, we monitored the seasonal development of the cornices along the plateaus near Longyearbyen with a terrestrial laser scanner (TLS) during the 2016/2017 and 2017/2018 winter seasons. The spatial resolution at which we acquired snow surface data with TLS enabled us to observe and quantify changes to the cornice systems in detail not previously achieved. We focused primarily on the evolution and failure of the lower cornice surfaces where accessibility has precluded previous research. We measured cornice accretion rates in excess of 10 mm hr−1 during several accretion events coinciding with winter storms. We observed five cornice fall avalanche events following periods of cornice accretion and one event following a warm period with mid-winter rain. The results of our investigation provide quantitative reinforcement to existing conceptual models of cornice dynamics and illustrate cornice response to specific meteorological events. Our results demonstrate the utility of TLS for monitoring cornice processes and as a viable method for quantitative cornice studies in this and other locations where cornices are of scientific or operational interest.

How Things Happen for the Sake of Something: The Dialectical Strategy of Aristotle, Physics 2.8

I offer a fresh interpretation of the dialectical strategy of Physics 2.8’s arguments that things in nature happen for the sake of something. Whereas many recent interpreters have concluded that these arguments inevitably beg the question against Aristotle’s opponents, I argue that they constitute a careful attempt to build common ground with an opponent who rejects Aristotle’s basic worldview. This common ground, first articulated in the famous Winter Rain Argument, takes the form of an intriguing pattern of reasoning: that natural proceedings that happen in a given manner always or for the most part do not do so by chance.

Western Mediterranean hydro-climatic consequences of Holocene ice-rafted debris (Bond) events

Gerard C. Bond established a Holocene series of North Atlantic ice-rafted debris events based on quartz and haematite-stained grains recovered from subpolar North Atlantic marine cores. These so-called “Bond events” document nine large-scale and multi-centennial North Atlantic cooling phases that might be linked to a reduced thermohaline circulation. Regardless of the high prominence of the Holocene North Atlantic ice-rafted debris record, there are critical scientific comments on the study: the Holocene Bond curve has not yet been replicated in other marine archives of the North Atlantic and there exist only very few palaeoclimatic studies that indicate all individual Bond events in their own record. Therefore, evidence of consistent hydro-climatic teleconnections between the subpolar North Atlantic and distant regions is not clear. In this context, the Western Mediterranean region presents key hydro-climatic sites for the reconstruction of a teleconnection with the subpolar North Atlantic. In particular, variability in Western Mediterranean winter precipitation might be the result of atmosphere–ocean coupled processes in the outer-tropical North Atlantic realm. Based on an improved Holocene δ18O record from Lake Sidi Ali (Middle Atlas, Morocco), we correlate Western Mediterranean precipitation anomalies with North Atlantic Bond events to identify a probable teleconnection between Western Mediterranean winter rains and subpolar North Atlantic cooling phases. Our data show a noticeable similarity between Western Mediterranean winter rain minima and Bond events during the Early Holocene and an opposite pattern during the Late Holocene. There is evidence of an enduring hydro-climatic change in the overall Atlantic atmosphere–ocean system and the response to external forcing during the Middle Holocene. Regarding a potential climatic anomaly around 4.2 ka (Bond event 3) in the Western Mediterranean, a centennial-scale winter rain maximum is generally in-phase with the overall pattern of alternating “wet and cool” and “dry and warm” intervals during the last 5000 years.

The Role of Winter Rain in the Glacial System on Svalbard

Rapid Arctic warming results in increased winter rain frequencies, which may impact glacial systems. In this paper, we discuss climatology and precipitation form trends, followed by examining the influence of winter rainfall (Oct‒May) on both the mass balance and dynamics of Hansbreen (Svalbard). We used data from the Hornsund meteorological station (01003 WMO), in addition to the original meteorological and glaciological data from three measurement points on Hansbreen. Precipitation phases were identified based on records of weather phenomena and used—along with information on lapse rate—to estimate the occurrence and altitudinal extent of winter rainfall over the glacier. We found an increase in the frequency of winter rain in Hornsund, and that these events impact both glacier mass balance and glacier dynamics. However, the latter varied depending on the degree of snow cover and drainage systems development. In early winter, given the initial, thin snow cover and an inefficient drainage system, rainfall increased glacier velocity. Full-season winter rainfall on well-developed snow was effectively stored in the glacier, contributing on average to 9% of the winter accumulation.

Seed yield and subsequent emergence pattern of subterranean clover cultivars in response to summer rain

At Lincoln University, Canterbury, seven subterranean cultivars rated in Australia as having different levels of ‘hardseedeness’ were established. Monocultures were sown in autumn and allowed to grow and set seed. Seed yields ranged from 340 to 1050 kg/ha. Heavy rain in early January 2016 resulted in a “false strike” of ≤ 4.0% of seeds during the subsequent dry February. A second emergence event in March also resulted in a “false strike” with a further 7 to 15% of total seeds lost. However, cultivars established >1000 seedlings/m2 after early winter rain, which is considered adequate for future persistence. Emergence was consistent with Australian hardseededness rankings. Cultivars with hardseed ranks <4 may be more suitable for dryland systems in New Zealand due to their early emergence and the ability to exploit the late summer and autumn rains.

Soil carbon and nitrogen responses to snow removal and concrete frost in a northern coniferous forest

Climate change in northeastern North America is resulting in warmer winters with reduced snow accumulation. Soils under a thin snowpack are more likely to experience freeze–thaw cycles, disrupting carbon (C) and nitrogen (N) transformations. We conducted a 2 year snow removal experiment in Maine to study the effects of soil freezing on soil C and N processes. O horizon soils were sampled during winter and spring of 2015 and 2016, and they were analyzed for labile inorganic N and water-extractable organic carbon (WEOC) concentrations, specific ultraviolet absorbance (SUVA254), and potential net N mineralization. The winter of 2015 was cold and snowy, whereas 2016 was warm with a shallow, short-term snowpack. Snow removal caused the soils to freeze, but winter rain-on-soil events in 2015 resulted in the formation of concrete frost, as opposed to granular frost in 2016. Concrete frost increased soil ammonium (NH4+-N) and WEOC concentrations and decreased SUVA254, which we attribute to microbial cell lysis. In contrast, granular frost did not alter soil nutrient concentrations, reflecting limited microbial distress. Our study demonstrates that moisture content influences the intensity of soil freezing, highlighting the importance of snowpack depth and winter rain events in regulating winter and spring biogeochemical processes and nutrient availability.