Eolian sediment transport during dust storms: Slims River Valley, Yukon Territory

1978 ◽  
Vol 15 (7) ◽  
pp. 1069-1084 ◽  
Author(s):  
W. G. Nickling
Keyword(s):  
Sediment Transport ◽  
Shear Velocity ◽  
Yukon Territory ◽  
River Valley ◽  
Dust Storms ◽  
Atmospheric Conditions ◽  
Creep Flow ◽  
Air Turbulence ◽  
Surface Creep ◽  
Individual Grains

The amount of sediment transported by wind in surface creep, saltation, and suspension was measured during 15 dust storms in the Slims River Valley, Yukon Territory. Results of the investigation showed that the quantity of sediment transported in creep and saltation varied approximately with the cube of shear velocity, which supports theoretical and empirical models presented by other investigators. The suspended sediment flow rate, however, seemed to be more directly controlled by the degree of air turbulence than by shear velocity. The total sediment transport rate was also shown to be directly affected by the surface moisture content and the presence of soluble salts at or near the surface. Both these factors tend to stabilize the surface by holding individual grains in place. Although eolian sediment transport is common in the Slims River Valley, high saltation–creep flow rates and major dust storms appear to be associated with a distinct set of atmospheric conditions, which are best developed on warm clear days following periods of heavy or extended rainfall.

The Spatial and Temporal Probability of Dust Storm Activity in Chryse, One of the Tentative Landing Areas of Tianwen-1 Mission

2020 ◽  
Author(s):  
Bo Li ◽  
Jiang Zhang ◽  
Zongyu Yue ◽  
Peiwen Yao ◽  
Chenfan Li ◽  
...  
Keyword(s):  
Dust Storm ◽  
Dust Storms ◽  
The Arctic ◽  
Atmospheric Conditions ◽  
Polar Ice ◽  
Storm Activity ◽  
Mars Atmosphere ◽  
Ice Cap ◽  
Activity Frequency ◽  
Temporal And Spatial

Abstract Dust storms, observed in all seasons, are among the most momentous Mars atmosphere activities. The Entry-Descent-Landing (EDL) activity of a Martian landing mission is influenced by local atmospheric conditions, especially the dust storm activity probability. It is of great significance to know well the dust storm situation that China's first Mars mission (Tianwen-1) may encounter in EDL season in the Chryse area, one of the tentative landing areas. Firstly, based on four Martian years’ Mars Orbiter Camera (MOC) Mars Daily Global Maps (MDGMs), 1172 dust storms were identified within Chryse’s 1600 km radius ring with their shape parameters extracted, including center, range and area. Secondly, the daily mean dust storm probability was calculated binned by 1° of solar longitude in the Chryse area during EDL season. Dust storm activity frequency was closely interrelated with the seasonal ebb and flow of the arctic polar ice cap, consequently, most of dust storms occurring in either the cap’s grow or the recession. The dust storm activity in the Chryse area mainly came from the northern polar cap region, Acidalia and Chryse, with some contribution from the southern hemisphere (Argyre and Bosprous) northward. Thirdly, we divided the Chryse area into many square grids of 0.5° and computed the average occurrence probability of dust storm in each grid during EDL season. The dust storm activity probability in space was also in-homogeneous, low in the west and south but high in the east and north, which was mainly affected by three factors: topography, the origin and the path of dust storm sequence. Based on Empirical orthogonal function (EOF) analysis, of the storms in the Chryse area we’ve discovered, 40.5% are cap-edge storms in the northern hemisphere and 17.5% are textured dust storms. Finally, according to the temporal and spatial probability of dust storm activity in the Chryse area during EDL season, we held that the preferred landing time of the Tianwen-1 mission in 2021 was in Ls=18°-65° and three preferred landing areas were selected with low dust storm probability.

scholarly journals Pleistocene Geology of the South-West Yukon Territory, Canada

1965 ◽  
Vol 5 (40) ◽  
pp. 385-397 ◽  
Author(s):  
Daniel B. Krinsley
Keyword(s):  
Yukon Territory ◽  
River Valley ◽  
The South ◽  
North West ◽  
White River ◽  
North East ◽  
South West ◽  
M 12

Abstract A morainal sequence in south-west Yukon Territory, Canada, records at least four major, successively less extensive glaciations from ice fields in the St. Elias Mountains south of the glaciated area. The Nisling Moraine flanks the Klondike Plateau in a belt t km. wide to an altitude of 1,040 m., 12 km. north-east of Snag. The northernmost lobe of this moraine terminates at the junction of the Donjek and White Rivers, 120 km, from the nearest source of ice, Klutlan Glacier. 11 km. north-east of Snag, the prominent front of the Donjek Moraine lies 180 m. below the front of the Nisling Moraine. The northernmost lobe of the Donjek Moraine terminates 106 km. north of Klutlan Glacier and occupies the lower courses of canyons cut into the Nisling Moraine. The front of the Snag Moraine crosses the White River valley 210 m. below the front of the Donjek Moraine and 96 km. north of Klutlan Glacier. The Tchawsahmon Moraine, 38 km. north-west of Klutlan Glacier. consists of a series of concentric ridges, the oldest of which impounded Tchawsahmon Lake. Provisional correlations suggest that the Nisling Moraine is pre-Illinoian; the Donjek, Illinoian; the Snag, pre-classical Wisconsin; and the Tchawsahmon, classical Wisconsin.

scholarly journals Pleistocene Geology of the South-West Yukon Territory, Canada

1965 ◽  
Vol 5 (40) ◽  
pp. 385-397 ◽  
Author(s):  
Daniel B. Krinsley
Keyword(s):  
Yukon Territory ◽  
River Valley ◽  
The South ◽  
North West ◽  
White River ◽  
North East ◽  
South West ◽  
M 12

AbstractA morainal sequence in south-west Yukon Territory, Canada, records at least four major, successively less extensive glaciations from ice fields in the St. Elias Mountains south of the glaciated area.The Nisling Moraine flanks the Klondike Plateau in a belt t km. wide to an altitude of 1,040 m., 12 km. north-east of Snag. The northernmost lobe of this moraine terminates at the junction of the Donjek and White Rivers, 120 km, from the nearest source of ice, Klutlan Glacier. 11 km. north-east of Snag, the prominent front of the Donjek Moraine lies 180 m. below the front of the Nisling Moraine. The northernmost lobe of the Donjek Moraine terminates 106 km. north of Klutlan Glacier and occupies the lower courses of canyons cut into the Nisling Moraine. The front of the Snag Moraine crosses the White River valley 210 m. below the front of the Donjek Moraine and 96 km. north of Klutlan Glacier. The Tchawsahmon Moraine, 38 km. north-west of Klutlan Glacier. consists of a series of concentric ridges, the oldest of which impounded Tchawsahmon Lake.Provisional correlations suggest that the Nisling Moraine is pre-Illinoian; the Donjek, Illinoian; the Snag, pre-classical Wisconsin; and the Tchawsahmon, classical Wisconsin.

scholarly journals First Records of the Northern Long-eared Bat, Myotis septentrionalis, in the Yukon Territory

2006 ◽  
Vol 120 (1) ◽  
pp. 39 ◽  
Author(s):  
Thomas S. Jung ◽  
Brian G. Slough ◽  
David W. Nagorsen ◽  
Tanya A. Dewey ◽  
Todd Powell
Keyword(s):  
Population Structure ◽  
North America ◽  
Adult Male ◽  
Yukon Territory ◽  
River Valley ◽  
Myotis Septentrionalis ◽  
Northwestern North America

Three adult male Northern Long-eared Bats, Myotis septentrionalis, were captured in mist nets in July 2004 in the LaBiche River Valley, southeastern Yukon. These are the first records of M. septentrionalis in the Yukon. Further survey work is needed to delineate the extent of the range and population structure of this and other species of bats in northwestern North America.

Holocene Glacial and Tree-Line Variations in the White River Valley and Skolai Pass, Alaska and Yukon Territory

1977 ◽  
Vol 7 (1) ◽  
pp. 63-111 ◽  
Author(s):  
George H. Denton ◽  
Wibjörn Karlén
Keyword(s):  
20Th Century ◽  
Little Ice Age ◽  
Yukon Territory ◽  
Summer Temperature ◽  
River Valley ◽  
Ice Age ◽  
The Arctic ◽  
Tree Line ◽  
White River ◽  
Glacier Recession

Complex glacier and tree-line fluctuations in the White River valley on the northern flank of the St. Elias and Wrangell Mountains in southern Alaska and Yukon Territory are recognized by detailed moraine maps and drift stratigraphy, and are dated by dendrochronology, lichenometry,14C ages, and stratigraphic relations of drift to the eastern (123014C yr BP) and northern (198014C yr BP) lobes of the White River Ash. The results show two major intervals of expansion, one concurrent with the well-known and widespread Little Ice Age and the other dated between 2900 and 210014C yr BP, with a culmination about 2600 and 280014C yr BP. Here, the ages of Little Ice Age moraines suggest fluctuating glacier expansion between ad 1500 and the early 20th century. Much of the 20th century has experienced glacier recession, but probably it would be premature to declare the Little Ice Age over. The complex moraine systems of the older expansion interval lie immediately downvalley from Little Ice Age moraines, suggesting that the two expansion intervals represent similar events in the Holocene, and hence that the Little Ice Age is not unique. Another very short-lived advance occurred about 1230 to 105014C yr BP. Spruce immigrated into the valley to a minimum altitude of 3500 ft (1067 m), about 600 ft (183 m) below the current spruce tree line of 4100 ft (1250 m), at least by 802014C yr BP. Subsequent intervals of high tree line were in accord with glacier recession; in fact, several spruce-wood deposits above current tree line occur bedded between Holocene tills. High deposits of fossil wood range up to 76 m above present tree line and are dated at about 5250, 3600 to 3000, and 2100 to 123014C yr BP. St. Elias glacial and tree-line fluctuations, which probably are controlled predominantly by summer temperature and by length of the growing and ablation seasons, correlate closely with a detailed Holocene tree-ring curve from California, suggesting a degree of synchronism of Holocene summer-temperature changes between the two areas. This synchronism is strengthened by comparison with the glacier record from British Columbia and Mt. Rainier. Likewise, broad synchronism of Holocene events exists across the Arctic between the St. Elias Mountains and Swedish Lappland. Finally, two sequences from the Southern Hemisphere show similar records, in so far as dating allows. Hence, we believe that a preliminary case can be made for broad synchronism of Holocene climatic fluctuations in several regions, although further data are needed and several areas, particularly Colorado and Baffin Island, show major differences in the regional pattern.

The ice-nucleating efficacy of glacial dust from the Copper River, Alaska

2020 ◽  
Author(s):  
Sarah Barr ◽  
Bethany Wyld ◽  
Natalie Ratcliffe ◽  
Jim McQuaid ◽  
Benjamin Murray
Keyword(s):  
Dust Emission ◽  
Particle Size Analysis ◽  
River Valley ◽  
Dust Storms ◽  
Radiative Properties ◽  
Size Analysis ◽  
Climate Projections ◽  
High Latitudes ◽  
Near Surface ◽  
Field Campaign

<p>Ice nucleating particles (INPs) play an important role in the climate system by influencing cloud radiative properties, cloud lifetime and precipitation. An understanding of the interaction between INPs and clouds is needed in order to improve the accuracy of both climate projections and short term weather forecasts. In the high latitudes the influence of mid and low latitude sources of INPs (such as potassium feldspar from desert dust) is reduced and local sources could be important for ice nucleation. However, there is a scarcity of field observations and many dust sources which could be important sources of INPs have not been quantified. The south coast of Alaska, in particular the Copper River valley in the Valdez-Cordova region, is one such area where there are regular dust storms. These can clearly be seen from satellite imagery, which provides information on the frequency and extent of these outbreaks. In order to investigate the potential importance of the Copper River valley as a source of INPs we undertook a field campaign to collect samples in October 2019. During this campaign size segregated aerosol samples from the near surface (1.5  metre) were collected on to polycarbonate filter substrates using a multistage cascade impactor with 5 size categories in the range <0.25 μm to >2.5 μm. We collected samples during 7 dust emission events over a 10 day period. In addition, samples of dry sediment were collected from the surface. We used the University of Leeds Microlitre Nucleation by Immersed Particle Instrument (μL-NIPI) to quantify the ice nucleating ability of these samples. We also used laser diffraction particle size analysis to determine the surface area of particles to allow the subsequent calculation of ice active surface site density (n<sub>s</sub>). In addition, surface samples were separated in order to isolate the atmospherically relevant fraction (<10 μm) and used to determine the chemical composition of the dust using x-ray diffraction. This, combined with further work such as heat testing, will be used to identify what controls the ice nucleating efficacy in this dust and if there is an active biological contribution.  We will present the results from the field campaign and subsequent analysis. These results show high ice nucleating activity of the samples, comparable to glacial dust from other regions, and highlight the importance of glacial dust as a source of INPs in the high latitudes.</p>

scholarly journals Robustness Analysis of Model Parameters for Sediment Transport Equation Development

2019 ◽  
Vol 12 ◽  
pp. 1-17
Author(s):  
Nadiatul Adilah Ahmad Abdul Ghani ◽  
Junaidah Ariffin ◽  
Duratul Ain Tholibon
Keyword(s):  
Sediment Transport ◽  
Transport Equation ◽  
Polynomial Regression ◽  
Robustness Analysis ◽  
Shear Velocity ◽  
Model Parameters ◽  
Evolutionary Polynomial Regression ◽  
Sediment Transport Equation ◽  
Sediment Data ◽  
Influential Parameters

Robustness analysis of model parameters for sediment transport equation development is carried out using 256 hydraulics and sediment data from twelve Malaysian rivers. The model parameters used in the analyses include parameters in equations by Ackers-White, Brownlie, Engelund-Hansen, Graf, Molinas-Wu, Karim-Kennedy, Yang, Ariffin and Sinnakaudan. Seven parameters in five parameter classes were initially tested. Robustness of the model parameters was measured on the statistical relations through Evolutionary Polynomial Regression (EPR) technique and further examined using the discrepancy ratio of the predicted versus the measured values. Results from analyses suggest  (ratio of shear velocity to flow velocity) and  (ratio of hydraulic radius to mean sediment diameter) to be the most significant and influential parameters for the development of sediment transport equation.

scholarly journals Technical Note: Minerals in dust productive soils – impacts and global distribution

2011 ◽  
Vol 11 (9) ◽  
pp. 26009-26034 ◽  
Author(s):  
S. Nickovic ◽  
A. Vukovic ◽  
M. Vujadinovic ◽  
V. Djurdjevic ◽  
G. Pejanovic
Keyword(s):  
High Resolution ◽  
Mineral Composition ◽  
Atmospheric Transport ◽  
Dust Emission ◽  
Technical Note ◽  
Dust Storms ◽  
Dust Particles ◽  
Atmospheric Conditions ◽  
Airborne Dust ◽  
Aerosol Process

Abstract. Dust storms and associated mineral aerosol transport are mainly driven by meso and synoptic scale atmospheric processes. It is therefore essential that the dust aerosol process and background atmospheric conditions that drive the dust emission and atmospheric transport be represented with sufficiently well resolved spatial and temporal features. Effects of airborne dust interactions with the environment are determent by the mineral composition of dust particles. Fractions of various minerals in the aerosol are determined by the mineral composition of arid soils, therefore high-resolution specification of mineral and physical properties of dust sources is needed as well. Most current dust atmospheric models simulate/predict the evolution of dust concentration but in most cases they do not consider fractions of minerals in dust. Accumulated knowledge on impacts of mineral composition in dust on weather and climate processes emphasizes the importance of considering minerals in modelling systems. Following such needs, in this study we developed a global dataset on mineral composition of potentially dust productive soils. In our study (a) we mapped mineral data into a high-resolution 30-s grid, (b) we included mineral carrying soil types in dust productive regions that were not considered in previous studies, and (c) included phosphorus having in mind their importance for terrestrial and marine nutrition processes.

Controls on sediment transport in semi-alluvial boulder-bed streams—implications for restoration of spawning gravel

2020 ◽  
Author(s):  
Lina Polvi
Keyword(s):  
Shear Stress ◽  
Sediment Transport ◽  
Critical Shear Stress ◽  
Field Research ◽  
Tracer Experiment ◽  
Transport Processes ◽  
Mountain Streams ◽  
Northern Fennoscandia ◽  
Transport Distance ◽  
Individual Grains

<p>Many streams in northern Fennoscandia are considered semi-alluvial in that they contain abundant coarse sediment (cobbles and boulders) deposited during continental glaciation in the form of moraines, eskers, and erratics. These streams contain sensitive trout and salmon populations, and restoration efforts (after channelization from over a century of timber-floating) strive to re-create essential habitat and spawning beds. However, little is known about controls on sediment transport processes in boulder-bed streams that can affect both channel evolution and restoration of spawning gravel. Prior flume and field research of boulder-bed channels in mountainous areas show that boulder protrusion and proximity can alter critical shear stress; however, in contrast to mountain streams, boulder-bed channels in northern Fennoscandia have relatively low bed slopes (S<sub>0</sub>: 0.5-6%) and low-magnitude flow regimes (buffered by upstream lakes).</p><p>In order to determine controls on gravel and cobble sediment transport in semi-alluvial boulder-bed streams, a sediment tracer experiment was conducted in the Vindel River catchment in northern Sweden. Approximately 1500 tracer clasts (b-axis: 2.5-15 cm), with imbedded RFID tags, were placed in five stream reaches (121-556 per reach) with a range of channel slopes (S<sub>0</sub>: ~2-6%), boulder densities, and degrees of protrusion. The geometry of each tracer clast (a-, b-, and c-axes) was quantified, and the location of each tracer clast was surveyed with a total station in the summers of 2017, 2018, and 2019. Both the morphologic setting (e.g., step, pool, riffle, backwater, directly above/below boulder) and constrainment class (e.g., unconstrained, shielded, imbricated, buried) were classified for each tracer at each survey occasion. There was a 80-90% recovery rate of tracer clasts; despite several reaches experiencing >Q<sub>50</sub> snowmelt flood, the median transport distance for D<sub>10</sub>- to D<sub>50 </sub>clasts was ~0.1 m. Preliminary analyses showed large variation in particle-size thresholds for entrainment and relationships with transport distance within and among reaches. There was no clear relationship between local bed slope or calculated bankfull shear stress and transport distance. Differences in entrainment and transport distances among reaches was controlled by boulder density and protrusion, which likely increase grain resistance and thus critical shear stress, reducing sediment transport (as shown by previous studies in boulder-bed mountain streams). Factors negatively affecting sediment transport include shielding, proximity to boulders, and certain morphologic settings (e.g., backwaters and pools). Variability was too high to allow confident prediction of entrainment of individual grains; however, based on these results and observations, some general guidelines for stream restoration of spawning gravel in semi-alluvial boulder-bed channels are presented.      </p>

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