What are glacier surges?

1969 ◽  
Vol 6 (4) ◽  
pp. 807-817 ◽  
Author(s):  
Mark F. Meier ◽  
Austin Post
Keyword(s):  
Active Phase ◽  
High Flow ◽  
Type I ◽  
Western North America ◽  
Ice Flow ◽  
Flow Rates ◽  
Glacier Surges ◽  
Longitudinal Profiles ◽  
Fast Flow ◽  
Very High

A total of 204 surging glaciers has been identified in western North America. These glaciers surge repeatedly and probably with uniform periods (from about 15 to greater than 100 years). Ice flow rates during the active phase may range from about 150 m/year to > 6 km/year, and horizontal displacements may range from < 1 to > 11 km. Ice reservoir and ice receiving areas can be defined for surging glaciers, and the reservoir area does not necessarily coincide with the accumulation area. Glaciers of all shapes, sizes, and longitudinal profiles can surge, and no unusual "ice dams" or bedrock constrictions are evident. Surges occur in many different climatic, tectonic, and geologic environments, but only in certain limited areas (mainly in the Alaska, eastern Wrangell, and St. Elias mountains). Three types of surging glaciers are defined: (I) large to moderate-sized glaciers with large displacements and very fast flow, (II) large to moderate glaciers with moderate displacements and flow rates, and (III) small glaciers with small displacements and moderate to fast flow rates. All three types involve an inherent instability which is self-triggered at regular intervals, but with Type I surges an additional (unknown) mechanism produces the very high flow rates.

scholarly journals Parameters Affecting Efficiency of Centrifugal Pump - A Review

2021 ◽  
pp. 49-58
Author(s):  
Shivani Kaustubh Chitale ◽  
Pranjal Nitin Jadhav ◽  
Snehal Suresh Dhoble ◽  
Dr. Mr. Satyajeet Deshmukh
Keyword(s):  
Centrifugal Pump ◽  
Driving Force ◽  
Electrical Energy ◽  
High Flow ◽  
Liquid Viscosity ◽  
Flow Rates ◽  
Pressure Concentration ◽  
Process Fluid ◽  
Very High ◽  
Selection Of

The pump is used as one of the most significant components in chemical industry so without its existence process may not be completed, because for any fluid to flow, initial driving force is required and it is fulfilled by the pump by consuming electrical energy and converting it to pressure energy. So, the selection of pump is very important in every field of section, depending on the property of process fluid. The Centrifugal pump is most demanding nowadays because it has simple design, less maintenance, can handle large quantities of fluids, and provides very high flow rates. The Centrifugal pump has mainly two components rotating components and stationary components. Shaft and impeller (open, semi-enclosed, and fully-enclosed) comes under the category of rotating components and casing (Volute, Vortex, and circular) comes under stationary components. Various parameters of process fluid like liquid viscosity, temperature, specific gravity, vapor pressure, concentration, shear sensitive and abrasive or non-abrasive, MOC, pump environment, pressure, flow rate, etc. are calculated to gain the desired efficiency and prevent a problem like cavitation if not properly handled. In this paper, a single-stage centrifugal pump is reviewed and studied how to increase performance and efficiency of centrifugal pump.

scholarly journals The initiation of glacier surging at Fridtjovbreen, Svalbard

2003 ◽  
Vol 36 ◽  
pp. 110-116 ◽  
Author(s):  
Tavi Murray ◽  
Adrian Luckman ◽  
Tazio Strozzi ◽  
Anne-Marie Nuttall
Keyword(s):  
Flow Direction ◽  
Three Dimensional ◽  
Surface Dynamics ◽  
Ice Flow ◽  
Deceleration Phase ◽  
Digital Elevation ◽  
Glacier Surges ◽  
Satellite Radar ◽  
Glacier Velocity ◽  
Fast Flow

AbstractGlacier surges in Svalbard have long durations and multi-year terminations, but much less is known regarding surge initiation in the archipelago. Fridtjovbreen, a 12 km long glacier in central Spitsbergen, advanced ∼ 2.8 km during a surge in the 1990s at a maximum rate of ∼ 4. 2 m d–1 . Differential dual-azimuth satellite radar interferometry (SRI) is used to produce ten snapshots of three-dimensional surface dynamics and four digital elevation models covering the period October 1991–October 1997. The glacier velocity rose slowly and uniformly until June 1995. It then increased dramatically to a measured maximum of ∼ 2.5 m d–1 during February and May 1996, and by October 1997 it had dropped. We attempt to evaluate errors in the calculated velocities. Systematic errors are evaluated using the apparent displacement of bedrock, ∼0.03 m d–1 . Errors arise from assumptions during processing, for example that ice-flow direction does not change during the surge. Two independent measurements using dual-azimuth processing show the mean absolute change in flow direction was ∼1.2°. This study covers fast-flow initiation and peak flow, but not the deceleration phase. The SRI observations show a progressive acceleration phase to the surge, with no evidence of a surge front propagating down-glacier.

scholarly journals Location of two glacier surges in West Greenland

1984 ◽  
Vol 120 ◽  
pp. 100-104
Author(s):  
A Weidick
Keyword(s):  
Ice Sheet ◽  
High Flow ◽  
The Other ◽  
Diagnostic Features ◽  
Flow Rates ◽  
Reservoir Area ◽  
West Greenland ◽  
Glacier Surges ◽  
Short Time ◽  
Rapid Transfer

The registration of West Greenland glaciers was completed in 1983. Around 5000 local glaciers and lobes from the Inland lce have been located. Indications of surging behaviour have been noted at a restricted number of these, and the two localities with the best documentation and most peculiar features are described below. One is an example of a 'periodic surge', while the other is essentiaIly a 'permanent surge'. The main characteristic of glacier surges is a rapid transfer of large volumes of ice from a reservoir area (usually to the snout), so that velocities are 10 to 100 times those of normal glaciers. Rates of movement of surging glaciers usually reach 1 m or more per day (Paterson, 1981). The strong movement leaves diagnostic features on the glacier surfaee in the form of chaotic crevassing or looped moraines. Local glaciers ean only provide enough ice to maintain high flow rates for a short time, and the catastrophic advances of such 'periodic surges' are often repeated with reported intervals of 20-100 years. Since some of the outlets from the Greenland Inland lce move permanently with high velocities the concept of surging has been extended to cover these cases as well, but as 'permanent surges' (Hughes, 1978; Weertman, 1983). The ice sheet here provides sufficient ice for the permanent maintenance of high flow rates.

Immobilization of reactive dyes on several matrices that allow high and very high flow-rates to be used

1990 ◽  
Vol 510 ◽  
pp. 165-175 ◽  
Author(s):  
Etienne Algiman ◽  
Yolande Kroviarski ◽  
Sylvie Cochet ◽  
Youne Lie Kong Sing ◽  
Daniel Muller ◽  
...  
Keyword(s):  
Reactive Dyes ◽  
High Flow ◽  
Flow Rates ◽  
Very High

Monitoring Effects of Catchment Management Practices on Phosphorus Loads into the Eutrophic Peel-Harvey Estuary, Western Australia

1986 ◽  
Vol 18 (4-5) ◽  
pp. 53-61 ◽  
Author(s):  
P. B. Birch ◽  
G. G. Forbes ◽  
N. J. Schofield
Keyword(s):  
Management Practices ◽  
Major Change ◽  
High Flow ◽  
Catchment Management ◽  
Flow Rates ◽  
Early Results ◽  
Phosphorus Loads ◽  
Time Of Year ◽  
High Runoff

Early results from monitoring runoff suggest that the programme to reduce application of superphosphate to farmlands in surrounding catchments has been successful in reducing input of phosphorus to the eutrophic Peel-Harvey estuary. In the estuary this phosphorus fertilizes algae which grow in abundance and accumulate and pollute once clean beaches. The success of the programme has been judged from application of an empirical statistical model, which was derived from 6 years of data from the Harvey Estuary catchment prior to a major change in fertilizer practices in 1984. The model relates concentration of phosphorus with rate of flow and time of year. High phosphorus concentrations were associated with high flow rates and with flows early in the high runoff season (May-July). The model predicted that the distribution of flows in 1984 should have resulted in a flow-weighted concentration of phosphorus near the long-term average; the observed concentration was 25% below the long-term average. This means that the amount of phosphorus discharged into the Harvey Estuary could have been about 2 5% less than expected from the volume of runoff which occurred. However several more years of data are required to confirm this trend.

scholarly journals ‘Tanned’ gelatin spheres and granules for exclusion chromatography

1968 ◽  
Vol 108 (4) ◽  
pp. 641-646 ◽  
Author(s):  
A. Polson ◽  
W. Katz
Keyword(s):  
Molecular Weight ◽  
Polyethylene Glycol ◽  
High Molecular Weight ◽  
Weight Fraction ◽  
High Flow ◽  
High Molecular Weight Fraction ◽  
Flow Rates ◽  
Protein Molecules ◽  
Exclusion Chromatography

1. The preparation of tanned gelatin spheres and granules from high-molecular-weight gelatin is described. This material is comparatively hard, giving high flow rates, is insoluble in water at temperatures between 0° and 100° and is resistant to digestion by trypsin and chymotrypsin. The high-molecular-weight fraction of gelatin was prepared by precipitation with polyethylene glycol, and the spheres and granules prepared from this fraction were hardened and insolubilized by tanning with either formalin or chromium salts or both. 2. The spheres and granules were used successfully for the separation of protein molecules and other protein-aceous materials ranging in molecular weight from 200 to greater than 6000000. This gel exclusion material has several properties superior to those of other products used for similar purposes. Further, it was noticed that the porosity of the spheres differed considerably from that of the granules.

scholarly journals Dilation of subglacial sediment governs incipient surge motion in glaciers with deformable beds

2020 ◽  
Vol 476 (2238) ◽  
pp. 20200033 ◽  
Author(s):  
B. M. Minchew ◽  
C. R. Meyer
Keyword(s):  
Pore Water ◽  
Flow Model ◽  
Pore Water Pressure ◽  
Water Pressure ◽  
Slip Rate ◽  
Effective Pressure ◽  
Ice Flow ◽  
History Of ◽  
Glacier Surges ◽  
Geographical Clustering

Glacier surges are quasi-periodic episodes of rapid ice flow that arise from increases in slip rate at the ice–bed interface. The mechanisms that trigger and sustain surges are not well understood. Here, we develop a new model of incipient surge motion for glaciers underlain by sediments to explore how surges may arise from slip instabilities within a thin layer of saturated, deforming subglacial till. Our model represents the evolution of internal friction, porosity and pore water pressure within the till as functions of the rate and history of shear deformation, and couples the till mechanics to a simple ice-flow model. Changes in pore water pressure govern incipient surge motion, with less permeable till facilitating surging because dilation-driven reductions in pore water pressure slow the rate at which till tends towards a new steady state, thereby allowing time for the glacier to thin dynamically. The reduction of overburden (and thus effective) pressure at the bed caused by dynamic thinning of the glacier sustains surge acceleration in our model. The need for changes in both the hydromechanical properties of the till and the thickness of the glacier creates restrictive conditions for surge motion that are consistent with the rarity of surge-type glaciers and their geographical clustering.

scholarly journals Evaluation of a Humidified Nasal High-Flow Oxygen System, Using Oxygraphy, Capnography and Measurement of Upper Airway Pressures

2011 ◽  
Vol 39 (6) ◽  
pp. 1103-1110 ◽  
Author(s):  
J. E. Ritchie ◽  
A. B. Williams ◽  
C. Gerard ◽  
H. Hockey
Keyword(s):  
Healthy Volunteers ◽  
Airway Pressure ◽  
Gas Flow ◽  
Air Entrainment ◽  
High Flow ◽  
Positive Pressure ◽  
Mean Airway Pressure ◽  
Flow Rates ◽  
Oxygen Fraction ◽  
Airway Pressures

In this study, we evaluated the performance of a humidified nasal high-flow system (Optiflow™, Fisher and Paykel Healthcare) by measuring delivered FiO2 and airway pressures. Oxygraphy, capnography and measurement of airway pressures were performed through a hypopharyngeal catheter in healthy volunteers receiving Optiflow™ humidified nasal high flow therapy at rest and with exercise. The study was conducted in a non-clinical experimental setting. Ten healthy volunteers completed the study after giving informed written consent. Participants received a delivered oxygen fraction of 0.60 with gas flow rates of 10, 20, 30, 40 and 50 l/minute in random order. FiO2, FEO2, FECO2 and airway pressures were measured. Calculation of FiO2 from FEO2 and FECO2 was later performed. Calculated FiO2 approached 0.60 as gas flow rates increased above 30 l/minute during nose breathing at rest. High peak inspiratory flow rates with exercise were associated with increased air entrainment. Hypopharyngeal pressure increased with increasing delivered gas flow rate. At 50 l/minute the system delivered a mean airway pressure of up to 7.1 cmH2O. We believe that the high gas flow rates delivered by this system enable an accurate inspired oxygen fraction to be delivered. The positive mean airway pressure created by the high flow increases the efficacy of this system and may serve as a bridge to formal positive pressure systems.

scholarly journals The duration of the active phase on surge-type glaciers: contrasts between Svalbard and other regions

1991 ◽  
Vol 37 (127) ◽  
pp. 388-400 ◽  
Author(s):  
Julian A. Dowdeswell ◽  
Gordon S. Hamilton ◽  
Jon Ove Hagen
Keyword(s):  
Time Series ◽  
North America ◽  
Active Phase ◽  
Aerial Photographs ◽  
Polar Ice ◽  
Phase Duration ◽  
Field Surveys ◽  
The World ◽  
Glacier Surges ◽  
Fast Motion

AbstractMany glaciers in Svalbard and in other glacierized areas of the world are known to surge. However, the time series of observations required to assess the duration of fast motion is very restricted. Data on active-phase duration in Svalbard come from aerial photographs, satellite imagery, field surveys and airborne reconnaissance. Evidence on surge duration is available for eight Svalbard ice masses varying from 3 to 1250 km2. Worldwide, active-phase duration is recorded for less than 50 glaciers. Few observations are available on high polar ice masses. The duration of the active phase is significantly longer for Svalbard glaciers than for surge-type glaciers in other areas from which data are available. In Svalbard, the active phase may last from 3 to 10 years. By contrast, a surge duration of 1–2 years is more typical of ice masses in northwest North America, Iceland and the Pamirs. Ice velocities during the protracted active phase on Svalbard glaciers are considerably lower than those for many surge-type glaciers in these other regions. Mass is transferred down-glacier more slowly but over a considerably longer period. Svalbard surge-type glaciers do not exhibit the very abrupt termination of the active phase, over periods of a few days, observed for several Alaskan glaciers. The duration of the active phase in Svalbard is not dependent on parameters related to glacier size. The quiescent phase is also relatively long (50–500 years) for Svalbard ice masses. Detailed field monitoring of changing basal conditions through the surge cycle is required from surge-type glaciers in Svalbard in order to explain the significantly longer length of the active phase for glaciers in the archipelago, which may also typify other high polar ice masses. The finding that surge behaviour, in the form of active-phase duration, shows systematic differences between different regions and their environments has important implications for understanding the processes responsible for glacier surges.

Thermal Hydraulic, Exergy and Exergy-Economic Analysis of Micro Heat Sinks at High Flow Rates

2010 ◽  
Author(s):  
Mehmed Rafet O¨zdemir ◽  
Ali Kos¸ar ◽  
Orc¸un Demir ◽  
Cemre O¨zenel ◽  
Og˘uzhan Bahc¸ivan
Keyword(s):  
High Flow ◽  
Heat Sinks ◽  
Flow Rates ◽  
Geometrical Properties ◽  
Pin Fin ◽  
Fluidic Devices ◽  
System Flow ◽  
Reaction Chambers ◽  
Heat And Fluid Flow ◽  
Microchannel Device

Recently, micro/nanofabrication technology has been used to develop a number of microfluidic systems. With its integration to microfluidic devices, microchannels and micro scale pin fin heat sinks find applications in many areas such as drug delivery and propulsion in biochemical reaction chambers and micro mixing. Many research efforts have been performed to reveal thermal and hydrodynamic performances of microchannel based micro fluidic devices. In the current study, it is aimed to extend the knowledge on this field by investigating heat and fluid flow in micro heat sinks at high flow rates. Moreover, thermodynamic and thermo-economic aspects were also considered. De-ionized water was used as the coolant in the system. Flow rates were measured over pressures of 20–80 psi. A serpentine heater was deposited at the back of the micro pin fin devices to enable the delivery of heat to these devices. Two micro-pin fin devices each having different geometrical properties (Circular based and Hydrofoil based) were used in this study. In addition, the performances (thermal-hydraulic, exergy, exergo-economic) were also experimentally obtained for a plain microchannel device. Thermal resistances, exergy efficiencies and thermo-economic parameters were obtained from the devices and their performances were assessed.

Sign in / Sign up

Export Citation Format

Share Document