bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thinning and retreat of Glaciar Upsala, and an estimate of annual ablation changes in southern Patagonia
Authors: Naruse Renji , Skvarca Pedro , Takeuchi Yukari 
Published: February 2017

Glaciar Upsala, a freshwater calving glacier in southern Patagonia, has been retreating since 1978, and after a drastic recession of about 700 m a−1 in 1994 the retreat seems to have stopped in 1995. A large ice-thinning rate of 11 m a−1 was obtained between 1990 and 1993, by surveying surface elevations near the terminus of Glaciar Upsala. In 1993–94, the thinning was estimated at about 20 m a−1 near the lateral margin. Some possible causes of the thinning behavior are considered.
In the ablation area of Glaciar Perito Moreno, 50 km south of Glaciar Upsala, ablation rates were measured during 110 d in summer 1993–94, and air temperature was continuously recorded throughout 1994. Using a degree-day method with temperature data at the nearest meteorological station, Calafate, annual ablation during the last 30 years was estimated to fluctuate from about 12 ± 2 to 16 ± 2 m a−1 in ice thickness, with a mean of 14 ± 2 m a−1. Thus, the temperature anomaly alone cannot elucidate the thinning of 11 m a−1 at Glaciar Upsala. As a possible mechanism of the ice-thinning, it is suggested that the considerable retreat due to calving may have resulted in reduction of longitudinal compressive stress exerted from bedrock rises and islands near the glacier front, causing a considerable decrease in the emergence flow. Thus, the ice may have thinned at a rate close to the annual ablation rate.
Modelling of Last Glacial Maximum ice sheets using different accumulation parameterizations
Authors: Fabre Adeline , Ritz Catherine , Ramstein Gilles 
Published: February 2017

We use a three-dimensional thermomechanical ice-sheet model, previously tested on the Greenland ice sheet, to reconstruct Last Glacial Maximum (LGM) ice sheets. We compare the effects on the results of the ice-sheet model of three different accumulation parameterization schemes. In the first and second schemes, LGM precipitation is computed from the present precipitation, taking and not taking into account moisture transport. In the third scheme, LGM precipitation and surface temperatures are computed using outputs of an atmospheric global circulation model (AGCM), treated in anomaly mode.
Results are compared to the last reconstruction of the Northern Hemisphere ice sheets (Peltier, 1994), computed using global rebound rates in a visco-elastic model of the Earth’s crust. The first two accumulation parameterizations do not give satisfactory reconstructions of the LGM ice sheets, since they are unable to compute realistic LGM climatic conditions. The third method gives very satisfactory results, which leads us to conclude that the best way to obtain realistic LGM climatic conditions is to use AGCM outputs.
Numerical modelling of the historic front variation and the future behaviour of the Pasterze glacier, Austria
Authors: Zuo Z. , Oerlemans J. 
Published: February 2017

An ice-flow model is used to simulate the front variations of the Pasterze glacier, Austria. The model deals explicitly with the ice flux from sub-streams and tributaries to the main ice stream. The dynamic calibration method adopted successfully calibrates the ice-flow model under a non-steady-state condition. Despite the complexity of the glacier geometry, the ice dynamics of the Pasterze are adequately simulated.
Results of the sensitivity experiments suggest that the Pasterze glacier has been in a non-steady state most of the time and has a response time of 34–50 years.
Projections of the behaviour of the Pasterze in the next 100 years are made under various climate scenarios. Results suggest that the Pasterze will undergo a substantial retreat if there is future warming. The glacier is likely to retreat 2–5 km by the year 2100. The ice volume could be reduced by 24–63% by the end of the 21st century.
Volumetric variations of Glacier de Sarennes, French Alps, during the last two centuries
Authors: Valla François , Piedallu Christian 
Published: February 2017

Glacier de Sarennes, located in the heart of the French Alps, has been observed closely since 1906 and regularly measured (snow accumulation, ablation and mass balance) since 1948. Several publications have stemmed from this research, such as the 1906 and 1958 glaciological maps and the 1981 and 1991 photogrammetric analyses. In 1992, a field radar campaign determined the ice thickness and allowed the drawing of the bedrock map with reasonable accuracy. The Little Ice Age stage was reconstructed with the bedrock tracks, in 1995.
The above-mentioned documents were digitized, and the computer program Arc-Info permitted the calculation of the successive volume stages occupied by the glacier from 1850 to 1991. Cross-sections and slope profiles illustrate the evolution of the thickness of Glacier de Sarennes during the last 150 years. All of these results, consistent with the variation of the mass balance observed or estimated, show the main conclusion: compared with today, the glacier was about four times more voluminous 90 years ago (i.e. it has lost three-quarters of its ice volume) and five times bigger one and a half centuries ago.
Passive microwave measurements of tundra and taiga snow covers in Alaska, U.S.A.
Authors: Sturm Matthew , Grenfell Thomas C. , Perovich Donald K. 
Published: February 2017

The microwave emissivity of two snow covers was measured in Alaska in March, 1990. Observations were made on taiga snow near Fairbanks that was 0.83 m thick with a 0.55 m thick basal layer of depth hoar. Other measurements were made on the tundra snow cover at Imnaviat Creek north of the Brooks Range which was 0.27 to 0.64 m thick and consisted of two or more wind slabs overlying a depth hoar layer 0.14 to 0.26 m thick. Density, crystal structure, and grain size were similar in tundra and taiga depth hoar layers.Emissivity was measured at 18.7 and 37 GHz using radiometers mounted on a 1.5 m tall bipod. Measurements were made on undisturbed snow, and then several snow layers were removed and additional measurements were made. This sequence was repeated until all snow had been removed. Effective emissivity values for the full snow depth ranged from 0.6 (37 GHz, H-pol) to 0.95 (18.7 GHz, V-pol) and were similar for both taiga and tundra snow covers. For both snow covers, there was a marked reduction in the effective emissivity (eeff) from that of the underlying ground with a maximum reduction of about 30%. All of the reduction was found to occur within the depth hoar layer. Maximum reduction in eeffcould be caused by a depth hoar layer 0.3 m thick. Overlying wind slab or new snow were nearly “invisible”, increasing the effective emissivity only by a small amount due to self-emittance. Thus, it was difficult to distinguish the two different snow covers on the basis of their emissivity, since both contained 0.3 m of depth hoar or more.
Determination of a melt-onset date for Arctic sea-ice regions using passive-microwave data
Authors: Anderson Mark R. 
Published: February 2017

Although the formation and melt of sea ice are primarily functions of the annual radiation cycle, atmospheric sensible-heat forcing does serve to delay or advance the timing of such events. Additionally, if atmospheric conditions in the Arctic were to vary due to climate change it may have significant influence on ice conditions. Therefore, this paper investigates a methodology to determine melt-onset dale distribution, both spatially and temporally, in the Arctic Ocean and surrounding sea-ice covered regions.Melt determination is made by a threshold technique using the spectral signatures of the horizontal brightness temperatures (19 GHz horizontal channel minus the 37 GHz horizontal channel) obtained from the Special Sensor Microwave Imager (SSM/I) passive-microwave sensor. Passive-microwave observations are used to identify melt because of the large increase in emissivity that occurs when liquid water is present. Emissivity variations are observed in the brightness temperatures due to the different scattering, absorption and penetration depths of the snowpack from the available satellite channels during melt. Monitoring the variations in the brightness temperatures allows the determination of melt-onset dates.Analysis of daily brightness temperature data allows spatial variations in the date of the snow inch onset for sea ice to be detected. Since the data are gridded on a daily basis, a climatology of daily melt-onset dates can be produced for the Arctic region. From this climatology, progression of melt can be obtained and compared inter-annually.
Empirical model for snowdrift distribution in avalanche-starting zones
Authors: Mases M. , Buisson L. , Frey W. , Martí G. 
Published: February 2017

Field data from Stillberg (Switzerland), provided by SFISAR, have been analysed in order to understand the spatial distribution of snow transported by wind in avalanche-starting zones. The results have been used to develop a new empirical model for snowdrift distribution. This model constitutes the “snow-wind module” of the knowledge-based computer system called ELSA.The model is based on an empirical parameter called the wind or “aeolien” coefficient. It represents the relation between two snow heights at a given place: the snow accumulated at the end of a wind period (or wind episode) and the snow available for transport at the beginning of the wind period. The wind coefficient has been established using field data from the Stillberg site.
Snow-accumulation rates and isotopic content (2H,3H) of near-surface firn from the Filchner-Ronne Ice Shelf, Antarctica
Authors: Graf W. , Moser H. , Reinwarth O. , Kipfstuhl J. , Oerter H. , Minikin A. , Wagenbach D. 
Published: February 2017

The accumulation and distribution of the2H content of near-surface layers in the eastern part of the Ronne Ice Shelf were determined from 16 firn cores drilled to about 10 m depth during the Filchner IIIa and IV campaigns in 1990 and 1992, respectively. The cores were dated stratigraphically by seasonal δ2H variations in the firn. In addition,3H and high-resolution chemical profiles were used to assist in dating. Both the accumulation rate and the stable-isotope content decrease with increasing distance from the ice edge: the δ2H values range from about 195‰ at the ice edge to -25‰ at BAS sites 5 and 6, south of Henry Ice Rise, and the accumulation rates from about 210 to 90 kgm-2a-1. The δ2H values of the near-surface firn and the 10 m firn temperatures (Θ) at individual sites are very well correlated: dδ2H/dΘ = (10.3 ± 0.6)‰K-1; r = 0.97.The δ2H profiles of the two ice cores BI3 and BI5 drilled in 1990 and 1992 to 215 and 320 m depth, respectively, reflect the gradual depletion in2H in the firn upstream of the drill sites. Comparison with the surface data indicates that the ice above 142 m in core BIS and above 137 m in core BI3 was deposited on the ice shelf, whereas the deeper ice, down to 152.8 m depth, most probably originated from the margin of the Antarctic ice sheet.
Spatial and seasonal variations of the snow chemistry at the central Filchner-Ronne Ice Shelf, Antarctica
Authors: Minikin Andreas , Wagenbach Dietmar , Graf Wolfgang , Kipfstuhl Josef 
Published: February 2017

The chemical stratigraphy of the surface firn of the central Filchner- Ronne Ice Shelf was determined in conjunction with stable isotopes from shallow firn cores and snow-pit samples collected at 1.1 widely distributed sites, and covering a time period of at least 20 years. The chemical analysis included ECM profiling and the determination of chloride, non-sea-salt (nss) sulphate, methanesulphonate (MSA), nitrate and, partly, sodium and bromide. Throughout the investigated area, winter time nss sulphate levels are found to be substantially negative, indicating that the sulphate to sodium ratio in airborne sea-salt particles is depleted by a factor of 5, approximately, in relation to the bulk sea-water ratio. While winter firn layers appear to be marked by episodic events of large sea-salt inputs, pronounced annual cycles with maxima in summer firn layers are commonly observed for the ECM signal and for nss sulphate, nitrate and MSA at all sites. For MSA, however, this phase relation is almost reversed for depths greater than 3-4m.The mean impurity levels consistently are strongly depleted with increasing distance from the ice edge by about 30% / 100 km for sea salt, 25% / 100 km for MSA and only 10%/ 100 km for nss sulphate. However, no substantial trend is observed for nitrate. It is concluded, therefore, that the sea-salt and the biogenic sulphur compounds deposited on the Filchner-Ronne Ice Shelf mainly originate from the adjacent Weddell Sea.Further important implications of the continental effects are: (a) an atmospheric residence time of nss sulphate apparently exceeding that of MSA probably due to the supplementary sulphate production on the ice shelf from biogenic SO2, and (b) a substantial limitation of the potential of deep ice cores already drilled on the Filchner- Ronne Ice Shelf in extracting reliable net temporal changes of sea-salt and biogenic sulphur species.
The oceanic environment beneath the northwest Ronne Ice Shelf, Antarctica
Authors: Robinson Allan , Makinson Keith , Nicholls Keith 
Published: February 2017

Oceanographic data have been obtained from beneath the Ronne Ice Shelf at a site on the southeastern side of a sea-floor trough, the Ronne Depression. The data consist of 5 d of conductivity temperature depth (CTD) profiling and a long-term temperature record from a thermistor cable. The water column was found to be composed of two layers: a cold buoyant layer of lce Shelf Water (ISW) overlying a layer of unmodified Western Shelf Water (WSW).
A change in the water column was observed on the last day of profiling, the WSW layer thinning, a cold intrusion appearing directly above the WSW and the ISW becoming colder. In addition, on three profiles the ISW cooled further and increased in salinity, becoming apparently statically unstable. The temperature record from the thermistor cable confirms that the ISW layer occasionally becomes colder. with greater variation in temperature than seen on the CTD profiles. These low temperatures and high salinities arc interpreted as indicating that water containing ice crystals in suspension has been advected beneath the site.
Researches in Space Flight Technology
Authors: Silverstein Abe 
Published: February 2017

The Forty-Ninth Wilbur Wright Memorial Lecture, “Researches in Space Flight Technology,” was given by Dr. Abe Silverstein, B.S., F.R.Ae.S., F.I.A.S., Director of Space Flight Programs, N.A.S.A., before a large and distinguished audience in the Lecture Theatre, 4 Hamilton Place, on 12th September 1961. Air Marshal Sir Owen Jones, K.B.E., C.B., A.F.C, B.A., D.I.C., F.R.Ae.S., M.I.Mech.E., R.A.F.(retd.), President of the Society, presided. The Lecture was given during the Eighth Anglo-American Aeronautical Conference, and the President was accompanied on the platform by Dr. H. Guyford Stever, President of the Institute of the Aerospace Sciences, and Head of the Mechanical Engineering Department at the Massachusetts Institute of Technology, and Air Commodore W. P. Gouin, R.C.A.F., a member of the Directing Staff of the National Defence College, Canada, and President of the Canadian Aeronautical Institute.As has become the custom, before the Lecture was delivered, the President presented the awards made by the Council for 1961 for outstanding contributions to aeronautics. The list of awards presented on this occasion was published in the June 1961 Journal (p. XXVII).Introducing the Lecturer, the President reminded the audience that the first Wilbur Wright Memorial Lecture was given in 1913 by Horace Darwin. The list of Lecturers, as they would see in their programmes, contained the names of eminent scientists and engineers from America and from this country. They had with them on this occasion a number of those who had given the lecture, among them their very distinguished visitor, Dr. von Kármán.This lecture had been given alternately by a lecturer from this country and one from the United States, with one exception. On one occasion it had been given by the late Professor Ludwig Prandtl—a name well-known to them all.Now Dr. Abe Silverstein was to give the 49th Wilbur Wright Memorial Lecture and had chosen as his subject “Researches in Space Flight Technology.” Dr. Silverstein was Director of Space Flight Programs at the National Aeronautics and Space Administration headquarters in Washington. Before the N.A.S.A. was established on 1st October 1958, Dr. Silverstein had been Associate Director of the Lewis Flight Propulsion Laboratory, Cleveland, a research centre of the National Advisory Committee for Aeronautics, which formed a nucleus of the N.A.S.A. Dr. Silverstein joined the N.A.C.A. in 1929 and spent much time at the Langley Aeronautical Laboratory on wind tunnel design and high speed research until he was transferred to the Lewis Laboratory in 1943 to direct research at the Altitude Wind Tunnel. He had done pioneering work on large scale ram-jet engines and on the supersonic wind tunnels at Lewis.
Bird Flight and The Aeroplane
Authors: Wilding J. 
Published: February 2017

If man's desire to fly was not totally inspired by the flight of birds at least his early attempts at heavier-than-air flight were a direct imitation of birds. To the earliest known aviators two features seemed indispensable in any flying machine, wings that flapped, and wings covered with feathers. The former at least seems reasonable, but no attempt was made to discover the purpose of feathering a bird's wing and feathers were used simply to give the flying contraption the appearance of a bird. As we shall see later these factors probably delayed the advent of sustained flight—not necessarily powered—by many years.Imagination has always, in the past, attributed the bird with greater powers than it really possessed. Many early flying machines were designed as chariots borne by as few as six doves—powerful indeed! Its powers to soar so high that it became lost to sight gave it the status of a semi-deity, from which came the mariner's faith in the albatross, perhaps.
The Development of Tailless Aircraft and Flying Wings
Authors: Bishop W. 
Published: February 2017

The tailless aircraft configuration is relatively rare in the field of aircraft design and for many years was regarded as a “freak” design. It is intended to trace the development of tailless and flying wing aircraft and to outline the major problems in control and stability.First it is necessary to arrive at an arbitrary definition of the term tailless aircraft. Later an attempt will be made to classify the different tailless types in detail, but for the moment it is sufficient to regard a tailless aircraft as “an aircraft having no auxiliary horizontal stabilising plane, deriving lift and controlling moment solely from the main plane.” This definition, as it stands, includes what are often termed flying wing aircraft.
Aspects of the Determination of the Strength of Materials
Authors: Mardles E. W. J. 
Published: February 2017

Some aspects of the determination of the strength of materials formed the subject of two meetings held jointly with the British Rheologists’ Club (President, Prof. E. N. da C. Andrade) and the Royal Aircraft Establishment in the Assembly Hall, Farnborough, on the 16th June, 1945, and with the Royal Aeronautical Society in the library at 4, Hamilton Place, on the 19th February, 1946, under the chairmanship of Sir Ben Lockspeiser.At the Farnborough meeting three papers were read, namely, “The investigation of failures in wood by microscopical examination” by M. C. Pryor and A. Rayne; “The effect of duration of loading on the strength of brittle materials” by C. Gurney; and “Application of statistical methods to mechanical test results” by B. Chalmers and E. R. W. Jones. At the London meeting Prof. N. F. Mott of Bristol University spoke on the “Griffith theory of cracks in solids and recent developments of this theory, with application to brittle fracture in glass and in metals.”
The Helicopter—Has It a Future?
Authors: Robertson F. H. 
Published: February 2017

It is always difficult and sometimes dangerous to estimate future trends and events. Nevertheless, it is a most satisfactory outlet for one's imagination and it is, to some extent, necessary unless we are to abandon all attempts at shaping our own future.Before trying to forecast the future of the helicopter, I feel that I must define what I mean by a helicopter. Resort to the English Dictionary does not help greatly; as is so often the case, it has been left behind by progress.A helicopter is described as “a flying machine that should rise vertically by airscrews revolving horizontally.” Derivation from the Greek, helix—a spiral, and pteron—a wing. This definition indicates that every aeroplane having a thrust loading of less than one is a helicopter, unless it is propelled by rockets, ramjets or pulse jets!The dictionary definition of an aeroplane is “ a flying machine heavier than air using planes.”
Commonsense and Aeronautics
Authors: Tizard H. T. 
Published: February 2017

Before beginning the main subject of my lecture, the Society may perhaps wish me to refer to some of the outstanding events of the year.The honour of the first flight round the world has fallen to the countrymen of Wilbur and Orville Wright, and well have they deserved it. We can realise to the full the courage, endurance and skill that they brought to their task; and we can share to the full the disappointment of those of their own party, and of their friendly French and British competitors, who had the misfortune to fall by the way.The flights round Australia, though less spectacular, and covering less distance, are perhaps equally worthy of recognition. With practically no organisation, complete reliance had to be placed on the aircraft and engines, as well as on the pilots; there, was no possibility of effecting any but quite minor replacements.
Royal Aero Club Light Aeroplane Competitions
Authors: Buchanan J. S. 
Published: February 2017

I am indebted to the Air Ministry for permission to use the material contained in the various official reports dealing with this subject, and I wish to say that the views expressed in this paper are my own personal views and do not in any way represent the official view of the Air Ministry, nor indicate the policy to be pursued.I am also indebted to the makers of the aircraft for supplying information in such detail and for permission to make use of this information.
Gliders: Their History and Uses
Authors: Sayers W. H. 
Published: February 2017

Just a month or two more than twenty years ago, Orville Wright made the. first flight on a power-driven man-carrying aeroplane. This original Wright biplane was very far from being the first serious attempt to produce a man-carrying aeroplane, and it is not unfair to say that the machine itself was in its essential principles, and in respect to the skill and ingenuity displayed in its design and construction, no revolutionary advance upon certain previous machines which had been designed for the same end.As a matter of fact, the machine, including engine, was designed and built in little more than a year, and regarded purely as an engineering structure it was considerably cruder than certain earlier aeroplanes which never succeeded in flying. The explanation of the Wrights’ success in this matter is, I think, to be found in the fact that they had learnt to fly before they attempted to build an aeroplane rather than in any remarkable qualities possessed by the aeroplane which they produced.