Equilibrium distributions in thermodynamical traffic gas

We derive the exact formula for thermal-equilibrium spacing distribution of one-dimensional particle gas with repulsive potential V(r)=r^(-a) (a>0) depending on the distance r between the neighboring particles. The calculated distribution (for a=1) is successfully compared with the highway-traffic clearance distributions, which provides a detailed view of changes in microscopical structure of traffic sample depending on traffic density. In addition to that, the observed correspondence is a strong support of studies applying the equilibrium statistical physics to traffic modelling.Comment: 5 pages, 6 figures, changed content, added reference

Modern Erosion Rates and Loss of Coastal Features and Sites, Beaufort Sea Coastline, Alaska

This study presents modern erosion rate measurements based upon vertical aerial photography captured in 1955, 1979, and 2002 for a 100 km segment of the Beaufort Sea coastline. Annual erosion rates from 1955 to 2002 averaged 5.6 m a-1. However, mean erosion rates increased from 5.0 m a-1 in 1955–79 to 6.2 m a-1 in 1979–2002. Furthermore, from the first period to the second, erosion rates increased at 60% (598) of the 992 sites analyzed, decreased at 31% (307), and changed less than ± 30 cm at 9% (87). Historical observations and quantitative studies over the past 175 years allowed us to place our erosion rate measurements into a longer-term context. Several of the coastal features along this stretch of coastline received Western place names during the Dease and Simpson expedition in 1837, and the majority of those features had been lost by the early 1900s as a result of coastline erosion, suggesting that erosion has been active over at least the historical record. Incorporation of historical and modern observations also allowed us to detect the loss of both cultural and historical sites and modern infrastructure. U.S. Geological Survey topographic maps reveal a number of known cultural and historical sites, as well as sites with modern infrastructure constructed as recently as the 1950s, that had disappeared by the early 2000s as a result of coastal erosion. We were also able to identify sites that are currently being threatened by an encroaching coastline. Our modern erosion rate measurements can potentially be used to predict when a historical site or modern infrastructure will be affected if such erosion rates persist.Cette étude présente les mesures de taux d’érosion contemporains établies en fonction de photographies aériennes verticales prises en 1955, en 1979 et en 2002 sur un segment de 100 km du littoral de la mer de Beaufort. Entre 1955 et 2002, les taux d’érosion annuels ont atteint 5,6 m a-1 en moyenne. Cependant, les taux d’érosion moyens se sont accrus pour passer de 5,0 m a-1 pendant les années 1955- 1979 à 6,2 m a-1 dans les années 1979 - 2002. Par ailleurs, de la première période à la deuxième période, les taux d’érosion ont augmenté à 60 % (598) des 992 sites analysés, ont diminué dans le cas de 31 % (307) des sites, et changé de moins de ± 30 cm à 9 % (87) des sites. Les observations historiques et les études quantitatives recueillies au cours des 175 dernières années nous ont permis de placer nos mesures des taux d’érosion dans un contexte à plus long terme. Plusieurs des caractéristiques côtières le long de cette étendue du littoral ont reçu des noms d’endroits typiques de l’Ouest dans le cadre de l’expédition de Dease et Simpson en 1837, et la majorité de ces caractéristiques avaient disparu vers le début des années 1900 en raison de l’érosion côtière. Cela laisse donc entendre que l’érosion s’est à tout le moins manifestée pendant la période visée par les données historiques. Grâce à l’utilisation d’observations historiques et d’observations contemporaines, nous avons pu déceler la perte de sites culturels et historiques de même que d’infrastructures modernes. Les cartes topographiques de l’U.S. Geological Survey révèlent un certain nombre de sites culturels et historiques connus, ainsi que des sites dotés d’infrastructures modernes datant des années 1950, sites et infrastructures qui avaient disparu vers le début des années 2000 en raison de l’érosion côtière. Nous avons également été en mesure de cerner des sites qui sont présentement menacés par un littoral qui empiète sur le terrain. Nos mesures des taux d’érosion contemporains pourraient éventuellement servir à déterminer à quel moment un site historique ou une infrastructure moderne sera touché advenant que des taux d’érosion similaires persistent

The Urban Heat Island in Winter at Barrow, Alaska

The village of Barrow, Alaska, is the northernmost settlement in the USA and the largest native community in the Arctic. The population has grown from about 300 residents in 1900 to more than 4600 in 2000. In recent decades, a general increase of mean annual and mean winter air temperature has been recorded near the centre of the village, and a concurrent trend of progressively earlier snowmelt in the village has been documented. Satellite observations and data from a nearby climate observatory indicate a corresponding but much weaker snowmelt trend in the surrounding regions of relatively undisturbed tundra. Because the region is underlain by ice-rich permafrost, there is concern that early snowmelt will increase the thickness of the thawed layer in summer and threaten the structural stability of roads, buildings, and pipelines. Here, we demonstrate the existence of a strong urban heat island (UHI) during winter. Data loggers (54) were installed in the ∼150 km2 study area to monitor hourly air and soil temperature, and daily spatial averages were calculated using the six or seven warmest and coldest sites. During winter (December 2001–March 2002), the urban area averaged 2.2 °C warmer than the hinterland. The strength of the UHI increased as the wind velocity decreased, reaching an average value of 3.2 °C under calm (s−1) conditions and maximum single-day magnitude of 6 °C. UHI magnitude generally increased with decreasing air temperature in winter, reflecting the input of anthropogenic heat to maintain interior building temperatures. On a daily basis, the UHI reached its peak intensity in the late evening and early morning. There was a strong positive relation between monthly UHI magnitude and natural gas production/use. Integrated over the period September–May, there was a 9% reduction in accumulated freezing degree days in the urban area. The evidence suggests that urbanization has contributed to early snowmelt in the village

Advancing Landscape Change Research through the Incorporation of Iñupiaq Knowledge

Indigenous knowledge is a valuable but under-used source of information relevant to landscape change research. We interviewed Iñupiat elders, hunters, and other knowledge-holders in the villages of Barrow and Atqasuk on the western Arctic Coastal Plain of northern Alaska to gain further insight into the processes governing the ubiquitous lakes and the dynamics of landscape change in this region of continuous permafrost. The interviews provided a suite of information related to lakes and associated drained lake basins, as well as knowledge on landforms, environmental change, human events, and other phenomena. We were able to corroborate many observations independently and verify the timing of several large and significant lake drainage events using either aerial photography or remotely sensed time series. Data collected have been incorporated into a geodatabase to develop a multi-layer Geographic Information System that will be useful for local and scientific communities. This research demonstrates that indigenous knowledge can reveal a new understanding of landscape changes on the Arctic Coastal Plain in general and on lake processes in particular. We advocate ongoing, community-oriented research throughout the Arctic as a means of assessing and responding to the consequences of rapid environmental change.Les connaissances indigènes représentent une source d’information à la fois précieuse et sous-utilisée en matière de recherche sur les changements caractérisant le paysage. Nous avons interviewé des aînés de la nation Iñupiat, de même que des chasseurs et des personnes qui possèdent des connaissances dans les villages de Barrow et d’Atqasuk sur la plaine côtière occidentale de l’Arctique du nord de l’Alaska afin de mieux comprendre les processus qui gouvernent les lacs ubiquistes et la dynamique du changement de paysage dans cette région au pergélisol permanent. Les entrevues nous ont permis de recueillir une série de renseignements se rapportant aux lacs et aux bassins lacustres asséchés connexes de même que des connaissances sur les reliefs, le changement environnemental, les événements humains et d’autres phénomènes. Nous avons réussi à corroborer de nombreuses observations de manière indépendante et à vérifier le moment auquel plusieurs grands et importants événements d’assèchement lacustre se sont produits et ce, à l’aide de photographies aériennes ou de séries chronologiques télédétectées. Les données ainsi recueillies ont été intégrées à une banque de données cartographiques afin de permettre l’élaboration d’un système d’information géographique multicouche qui sera utile aux communautés locales et scientifiques. Cette recherche démontre que les connaissances indigènes peuvent aider à mieux comprendre les changements de paysage sur la plaine côtière de l’Arctique en général, et les processus lacustres en particulier. Nous favorisons donc la réalisation de recherches permanentes et axées sur la communauté dans l’Arctique pour évaluer les conséquences du changement environnemental rapide et les façons d’y réagir

Scenarios as the basis for assessment of mitigation and adaptation

The possibilities and need for adaptation and mitigation depends on uncertain future developments with respect to socio-economic factors and the climate system. Scenarios are used to explore the impacts of different strategies under uncertainty. In this chapter, some scenarios are presented that are used in the ADAM project for this purpose. One scenario explores developments with no mitigation, and thus with high temperature increase and high reliance on adaptation (leading to 4oC increase by 2100 compared to pre-industrial levels). A second scenario explores an ambitious mitigation strategy (leading to 2oC increase by 2100 compared to pre-industrial levels). In the latter scenario, stringent mitigation strategies effectively reduces the risks of climate change, but based on uncertainties in the climate system a temperature increase of 3oC or more cannot be excluded. The analysis shows that, in many cases, adaptation and mitigation are not trade-offs but supplements. For example, the number of people exposed to increased water resource stress due to climate change can be substantially reduced in the mitigation scenario, but even then adaptation will be required for the remaining large numbers of people exposed to increased stress. Another example is sea level rise, for which adaptation is more cost-effective than mitigation, but mitigation can help reduce damages and the cost of adaptation. For agriculture, finally, only the scenario based on a combination of adaptation and mitigation is able to avoid serious climate change impacts

The Prelude to the Deep Minimum between Solar Cycles 23 and 24: Interplanetary Scintillation Signatures in the Inner Heliosphere

Extensive interplanetary scintillation (IPS) observations at 327 MHz obtained between 1983 and 2009 clearly show a steady and significant drop in the turbulence levels in the entire inner heliosphere starting from around ~1995. We believe that this large-scale IPS signature, in the inner heliosphere, coupled with the fact that solar polar fields have also been declining since ~1995, provide a consistent result showing that the buildup to the deepest minimum in 100 years actually began more than a decade earlier.Comment: 9 pages, 4 figures, accepted for publication in Geophysical Research Letters on 28 September 201

Global coastal wetland change under sea-level rise and related stresses: The DIVA Wetland Change Model

The Dynamic Interactive Vulnerability Assessment Wetland Change Model (DIVA_WCM) comprises a dataset of contemporary global coastal wetland stocks (estimated at 756 × 10^3 km^2 (in 2011)), mapped to a one-dimensional global database, and a model of the macro-scale controls on wetland response to sea-level rise. Three key drivers of wetland response to sea-level rise are considered: 1) rate of sea-level rise relative to tidal range; 2) lateral accommodation space; and 3) sediment supply. The model is tuned by expert knowledge, parameterised with quantitative data where possible, and validated against mapping associated with two large-scale mangrove and saltmarsh vulnerability studies. It is applied across 12,148 coastal segments (mean length 85 km) to the year 2100. The model provides better-informed macro-scale projections of likely patterns of future coastal wetland losses across a range of sea-level rise scenarios and varying assumptions about the construction of coastal dikes to prevent sea flooding (as dikes limit lateral accommodation space and cause coastal squeeze). With 50 cm of sea-level rise by 2100, the model predicts a loss of 46–59% of global coastal wetland stocks. A global coastal wetland loss of 78% is estimated under high sea-level rise (110 cm by 2100) accompanied by maximum dike construction. The primary driver for high vulnerability of coastal wetlands to sea-level rise is coastal squeeze, a consequence of long-term coastal protection strategies. Under low sea-level rise (29 cm by 2100) losses do not exceed ca. 50% of the total stock, even for the same adverse dike construction assumptions. The model results confirm that the widespread paradigm that wetlands subject to a micro-tidal regime are likely to be more vulnerable to loss than macro-tidal environments. Countering these potential losses will require both climate mitigation (a global response) to minimise sea-level rise and maximisation of accommodation space and sediment supply (a regional response) on low-lying coasts.The authors gratefully acknowledge funding from the European Union under contract number EVK2-2000-22024. They thank all their partners in the DINAS-COAST project Dynamic and Interactive Assessment of National, Regional and Global Vulnerability of Coastal Zones to Climate Change and Sea-level rise. We are grateful to staff at UNEP-WCMC for generous access to evolving databases on global coastal wetland extent: Jon Hutton, Hannah Thomas, Jan-Willem van Bochove, Simon Blyth and Chris McOwen. Current wetland databases held at WCMC build upon the pioneering efforts of Mark Spalding and Carmen Lacambra.This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.gloplacha.2015.12.01

Flat-H Redundant Frangible Joint Design Evolution 2018: Feasibility Study Conclusions

This paper reports results of an investigation into developing a single failure tolerant pyrotechnic linear separation system which features completely redundant explosive trains suitable for human spaceflight. It is a follow up to Flat-H Redundant Frangible Joint Design Evolution 2017 and Flat-H Redundant Frangible Joint Evolution. The paper chronicles the history of the redundant frangible joint development program including testing, analysis, and design improvements from 2014 to the present culminating in a successful proof-of-concept prototype. The paper describes work done to address debris control and containment of combustion products. A performance optimization strategy is presented along with optimization results. Additionally a novel containment manifold design is presented with test results

Rapid Saline Permafrost Thaw Below a Shallow Thermokarst Lake in Arctic Alaska

Permafrost warming and degradation is well documented across the Arctic. However, observation- and model-based studies typically consider thaw to occur at 0°C, neglecting the widespread occurrence of saline permafrost in coastal plain regions. In this study, we document rapid saline permafrost thaw below a shallow arctic lake. Over the 15-year period, the lakebed subsided by 0.6 m as ice-rich, saline permafrost thawed. Repeat transient electromagnetic measurements show that near-surface bulk sediment electrical conductivity increased by 198% between 2016 and 2022. Analysis of wintertime Synthetic Aperture Radar satellite imagery indicates a transition from a bedfast to a floating ice lake with brackish water due to saline permafrost thaw. The regime shift likely contributed to the 65% increase in thermokarst lake lateral expansion rates. Our results indicate that thawing saline permafrost may be contributing to an increase in landscape change rates in the Arctic faster than anticipated