bluuebunny/crossref_metadata_2025_split huggingface dataset:
Parameterization of the Annual Surface Temperature and Mass Balance of Antarctica
Authors: Fortuin J.P.F. , Oerlemans J. 
Published: September 2017

This study entails the parameterization, by means of a linear multiple-regression analysis, of the annual surface temperature and mass balance of Antarctica. The analysis was performed for the entire ice cap as well as for three separate regions: ice shelves (elevation less than 200 m), the interior (elevation above 1500 m), and the escarpment region in between. It was found that temperature can be parameterized very well in terms of elevation and latitude. The latitudinal gradient on the ice shelves can be explained by the super-adiabatic lapse rate along the surface and latitudinal temperature gradient in the interior, assuming adiabatic descent of air in the inversion layer from the interior region towards the coast and an axisymmetric spreading over the ice shelves. The surface mass balance can be parameterized reliably only in the interior, where it has a strong positive correlation with the saturation vapour pressure of the free atmosphere, and a significant correlation with the shape of the dome. The convex shape of the dome contributes to the mass balance by inducing subsidence of the relatively moist air of the free atmosphere into the inversion layer. This results in precipitation, as radiative cooling in the inversion exceeds adiabatic warming. An estimate is made of the annual horizontal and vertical advective velocities in the free atmosphere above the interior, based on regression results and a physical analysis of the precipitation processes in this region.A temperature sensitivity analysis was performed for the current mass-balance distribution. For a 1 K. rise in surface temperature, the regression estimate of the increase in accumulation on the grounded ice sheet is equivalent to a rate of sea-level lowering of 0.2 mm a−1. This is about 30% less than estimates based on the current mass balance perturbated by the increase in saturation vapour pressure of the free atmosphere.
A 1400-Year Oxygen Isotope History from the Ross Sea Area, Antarctica
Authors: Grootes P.M. , Stuiver M. , Saling T.L. , Mayewski P.A. , Spencer M.J. , Alley R.B. , Jenssen D. 
Published: September 2017

Four ice cores from the Ross Sea drainage, Antarctica, show patterns of δ18O variations on a time scale of decades to centuries over the last 1400 years without change in the long-term average δ18O. Century scale δ18O fluctuations in the two cores drilled in the Ross Ice Shelf at Station J-9 (82°23′S, 168°38′W, elevation 60 m) are highly correlated (P < 2 × 10−4). The long isotope record (>30 000 a) of the 1978 J-9 core thus represents local conditions over at least 102 m and on time scales of 100 years and longer.Regional correlations between the J-9 δ18O records and those from Ridge BC (82°54′S, 136°40′W, elevation 509 m) and the Dominion Range (85°15′S, 166°10′E, elevation 2700 m) are barely significant (P ≈ 0.05 for J-9 '76 and Dominion Range, 580 to 1400 years ago) or absent. The failure to find clear regional isotope trends related to climate fluctuations may reflect the finding that between 1957 and 1982 the area was in the transition zone between areas with opposite temperature trends, and showed little or no temperature change. The fact that the records nevertheless show significant δ18O fluctuations highlights the need to base regional climate reconstructions on a regional suite of ice-core records.
An Apparent One-Year Lag Relationship of Heavy Snow Years Between Eurasia and North America
Authors: Iwasaki Tomohiko 
Published: September 2017

The purpose of this study is to investigate the interannual variability of winter snow cover in the northern hemisphere, using the satellite-derived monthly snow cover data (NOAA/NESDIS) from 1967 to 1987. An empirical orthogonal function (EOF) analysis is made to see the typical pattern of snow cover variations during winter. EOF1, which represents about 40% of the total variance, shows concurrent snow cover patterns between Eurasia and North America. EOF2, which represents over 20% of the total variance, shows a negatively correlated pattern between the eastern and western parts of the continent in Eurasia and North America.We examined time series of mean snow cover for key regions of the northern hemisphere to investigate variations depicted in the EOF patterns in more detail. We selected two key regions which represent continental-scale snow variation. One is the eastern part of Eurasia and the other is the western part of North America. The time series of the two key regions show an apparent one-year lag relationship of heavy snow cover years; winters with extensive snow cover over Eurasia tend to be followed by extensive snow cover over North America during the succeeding winters.
Asynchronous Coupling of Ice-Sheet and Atmospheric Forcing Models
Authors: Pollard David , Muszynski Isabelle , Schneider Stephen H. , Thompson Starley L. 
Published: September 2017

Asynchronous coupling schemes between ice sheet and atmospheric forcing models are evaluated for use in long-term ice-age simulations. In these schemes the ice sheet and atmospheric forcing are run together for short synchronous periods (Ts), alternating with longer asynchronous periods (TA) during which the ice sheet is run with atmospheric information extrapolated from the previous synchronous period(s). Two simple ice-sheet models are used that predict ice thickness as a function of latitude, and the atmosphere is represented by a prescribed pattern of net annual accumulation minus ablation. The pattern is shifted vertically to represent long-term orbital variations, stochastic inter-annual weather variability and ice-sheet albedo feedback.Several asynchronous schemes are evaluated by comparing results with those from fully synchronous runs. The best overall results are obtained using a scheme in which the forcing during each asynchronous period is linearly extrapolated from its means in the previous two synchronous periods. Differences from the synchronous results are caused primarily by poor sampling of the stochastic forcing component, which exaggerates the stochastic ice-sheet fluctuations. We examine how these errors depend on Ts and TA, and outline implications for GCM ice-age simulations.
Albedo of Young and First-Year Antarctic Sea Ice
Authors: Brandt Richard , Allison Ian , Warren Stephen 
Published: September 2017

Reflection of solar radiation was studied in the seasonal sea-ice zone off East Antarctica on a cruise of the Australian Antarctic Expedition, October-December 1988. Spectral and total albedos were measured for grease ice, nilas, young grey ice, grey-white ice, snow-covered ice, and open water. Spectral measurements covered the region 400–1000 nm wavelength. For ice too thin to support our weight, the radiometers were mounted at the end of a 1.5 m rod extended out the door of a helicopter or from a basket hung from the ship's crane, using a positioning and leveling rack. Corrections had to be applied to the downward radiation flux because the helicopter or the crane was in the field of view of the cosine-collector.The fractional coverage of each of the ice types (and open water) was estimated hourly for the region near the ship, as well as the thickness of each ice type, and the snow thickness. Observations were carried out continuously during the four weeks the ship was in the ice, supplemented by occasional helicopter surveys covering larger areas. These observations, together with the radiation measurements, make possible the computation of area-average albedo for the East Antarctic sea-ice zone in spring.
Velocity Patterns and Elevations On Ice Stream B
Authors: Jackson M. , Whillans I.M. 
Published: September 2017

All of the West Antarctic ice sheet draining into the Ross Ice Shelf lies on bedrock which is below sea level. This is thought to make it especially senstitive to rapid decay which could be triggered by an increase in atmospheric CO2 levels, ice stream B, one of the main outlets of the West Antarctic Ice Sheet, is thinning, possibly in response to changes in climate. However, Ice Stream C, its neighbor, is thickening.One of the most effective ways to study ice streams is by repeat aerial photogrammetry. Thousands of velocity values and elevations are available for Ice Stream B using this technique. Two sections of the ice stream have repeat photogrammetry with control. Maps of elevations, velocity components and velocity gradients have been produced following the methods of Brecher (1986).The area considered here is a 40 by 30 km block across a part of the ice stream. The maps show that most of the increase in longitudinal velocity occurs within about 6 km of the ice-stream margin and reaches a maximum of 460 m a-1 in the center of the stream. Strain rates in the shear margins reach 0.12 a-;1 and are an order of magnitude less in the main body of the stream.The elevation maps show ridges and troughs. These features appear to be related to transverse velocities.
Hydrodynamic Model Of Glaciers and Ice Sheets Interacted With Ocean
Authors: Mazo V.L. 
Published: September 2017

Tidewater glaciers and large ice sheets, e.g. the Antarctic ice sheet and a late-Würm Arctic ice sheet, are complex but single dynamic systems composed of terrestrial, marine and floating parts. Morphology and dynamics of the different parts are different. The terrestrial parts are convex and their dynamics are controlled by shear stress only (the longitudinal stress is zero); the floating parts are concave and their dynamics are controlled by longitudinal stress only (the shear stress is zero). To connect the different parts we should consider transitional zones where shear and longitudinal stresses are comparable.To describe glacier and ice-sheet dynamics, longwave approximation of the first order is used. In this approximation it is impossible to connect terrestrial and floating parts dynamically, only morphologically and kinematically. It means that the first-order longwave approximation is not sufficient.If the transitional zone between the terrestrial and floating parts is long in comparison to ice thickness (in hydrodynamics the term “weak” is used) we can do the next step in the longwave approximation to describe the single dynamical system consisting of the terrestrial and floating parts and the weak transitional zones (ice streams). It is a purely hydrodynamical approach to the problem without ad hoc hypothesis.The presented model is a non-stationary three-dimensional hydrodynamic model of glaciers and ice sheets interacted with ocean, involving the conditions of ice continuity and dynamic equilibrium, ice rheology, and boundary conditions on the free surface (dynamic and kinematic) and on the bed (ice freezing or sliding). Longwave approximation is used to reduce the three-dimensional model to a two-dimensional one. The latter consists of (1) evolution equations for grounded and floating parts and weak transitional zones; (2) boundary conditions on the fronts (e.g. the conditions of calving); (3) equations governing the junctions of the parts (the most important junction is the grounded line) with the conditions connecting the evolution equations.
Recent Terminus Behavior Of North Cascade Glaciers, Washington, Related To Climatic Sensitivity
Authors: Pelto Mauri S. 
Published: September 2017

Since 1977 ablation-season temperature has been 1.1°C above the 1930–80 mean and winter precipitation has been 14% below the 1930–80 mean. In order to identify the effect of this climatic fluctuation on North Cascade glaciers, the North Cascade Glacier-Climate Project has monitored the terminus behavior of 107 glaciers between 1983 and 1988.The 107 glaciers examined represent six climate sensitivity groups. Each group has a different sensitivity to the four primary climatic parameters: (1) ablation-season temperature, (2) accumulation-season precipitation, (3) summer cloud cover and (4) freezing levels during May and October precipitation events. A glacier’s sensitivity to each climatic parameter is determined by its geographic location and topographic position. Each sensitivity type has specific geographic and topographic characteristics, such as degree of radiational shading, orientation, altitude with respect to the local glaciation threshold, accumulation sources, and distance from the Cascade Crest. Accumulation sources are direct snowfall, wind drifting and avalanching.Of the 107 glaciers examined, 91 had retreated significantly between 1983 and 1988 and three had advanced. Correlation of retreat rate and climatic sensitivity type indicates that the higher a glacier’s winter balance, the smaller the retreat rate. High-altitude accumulation zones, multiple accumulation sources and a northward orientation are all associated with higher winter balances. Retreat was greatest for glaciers with poor radiational shading, and only direct snowfall accumulation. Retreat rate was slowest for glaciers with multiple accumulation sources and a northward orientation, though not necessarily good radiational shading. Retreat rate increased with distance east of the Cascade Crest and retreat rate was high for low-altitude glaciers.
Detecting Global Change In The Arctic
Authors: Weller Gunter 
Published: September 2017

Numerical models have predicted global temperature increases due to rising atmospheric CO2 levels, which should be detectable by now, but have not yet been identified in an unambiguous manner. This detection is complicated by inadequate data and by the fact that climate can be changed by factors other than CO2 increases. A systematic monitoring strategy is therefore needed to assess global change. In the Arctic, cryospheric parameters, including sea ice, snow cover, glaciers and permafrost are sensitive indicators of climate change and their monitoring by satellites and surface observations is of particular interest. Sea ice and snow cover are perhaps the most important of these parameters. They respond quickly to climate change, and in turn directly affect the climate through feedback processes; major changes in ice and snow extent and thickness can be expected as a consequence of climate change. Glaciers also respond to climatic variability by changes in their mass balance which can be monitored. Melting glaciers raise the level of the world ocean, and the glaciers of the sub-Arctic, particularly in the Alaskan coastal mountains, have been major contributors to the observed sea-level rise of about 20–30 cm over the last century. Past temperature changes are recorded in glacier ice and permafrost and techniques are now available to reconstruct past climates from these sources.The numerical models of the CO2 greenhouse effect show the polar regions to be affected most strongly by greenhouse warming, and sea ice, snow, glaciers and permafrost should be good indicators of such a global change. The known responses and sensitivities of cryospheric parameters to climate change are reviewed, and a monitoring strategy is suggested. The Alaska SAR Facility, utilizing synthetic aperture radar from several spacecraft scheduled for launch in the 1990s, will be a key facility for collecting and analyzing climate-related satellite data. Its monitoring capabilities are briefly reviewed.
Soluble Impurities In Ice Core D-1 Of Dunde Ice Cap, China, Over The Last 500 Years
Authors: Xiaoling Wu , Jingsona Liu , Qinzhou Yang 
Published: September 2017

This paper gives the preliminary results of 26 trace element measurements of ice cores from Dunde Ice Cap, China. The chemical composition of soluble impurities along ice core D-1 covering the last 500 years B P., is reported and interpreted in terms of atmospheric contributions. The dust content in ice cores of Dunde Ice Cap is 36 times higher than in Byrd Station, Antarctica. Variations of soluble elements such as Ca, Mg, Κ and Na, in Dunde Ice cores are very sensitive to climatic and environmental changes. The 25 trace elements in ice core D-1 (K, Na, Ca, Mg, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Al, Sr, Ti, V, Zn, As, Ba, Β, Li, Ρ, S, Sn) were measured. Cationicions arranged in order of content are as follows: Ca > Na > Mg > Κ > Αl > Fe > Ζn > Cu > Μn > Pb > Cr > Ni > Co > Cd etc. The content of soluble impurities has typical terrestrial features. Rock-forming elements such as Ca, Mg, Κ, Na, Si, Al, and Fe make up 99% in the core samples.Particular attention is given to the possible impact of the so-called “pre-Industrial Revolution period” and man’s influence on the atmospheric chemistry. The spectral analysis of time series for the variation of each of the 26 contributions show a 92 year cycle that is present in the variation of all 26 ions with depth. Short-term variations, such as 23, 31, 48, 81 year cycles, are also discussed. The ice-core research program has been supported by the Chinese National Foundation of Natural Science under Grant DO125-4860011.
Effect Of Eurasian Snow Cover On Summer Climate Of The Northern Hemisphere: A GCM Study
Authors: Yasunari Tetsuzo , Kitoh Akio , Tokioka Tatsushi 
Published: September 2017

Observational studies have shown that Eurasian snow-cover anomalies during winter-through-spring seasons have a great effect on anomalies in atmospheric circulation and climate in the following summer season through snow albedo feedback (Hahn and Shukla, 1976; Dey and Bhanu Kumar, 1987). Morinaga and Yasunari (1987) have revealed that large-scale snow-cover extent over central Asia in late winter, which particularly has a great effect on the circulation over Eurasia in the following season, is closely related to the Eurasian pattern circulation (Wallace and Gutzler, 1981) in the beginning of winter.Some atmospheric general circulation models (GCM) have suggested that not only the albedo effect of the snow cover but also the snow-hydrological process are important in producing the atmospheric anomalies in the following seasons (Yeh and others, 1984; Barnett and others, 1988).However, more quantitative evaluations of these effects have not yet been examined. For example, it is not clear to what extent atmospheric anomalies are explained solely by snow-cover anomalies. Spatial and seasonal dependencies of these effects are supposed to be very large. Relative importance of snow cover over Tibetan Plateau should also be examined, particularly relevant to Asian summer monsoon anomalies. Moreover, these effects seem to be very sensitive to parameterizations of these physical processes (Yamazaki, 1988).This study focuses on these problems by using some versions of GCMs of the Meteorological Research Institute. The results include the evaluation of total snow-cover feedbacks as part of internal dynamics of climatic change from 12-year GCM integration, and of the effect of anomalous snow cover over Eurasia in late winter on land surface conditions and atmospheric circulations in the succeeding seasons.
Climatic Shift of the Equilibrium Line: Kuhn's Concept Applied to the Greenland Ice Cap
Authors: Ambach Walter 
Published: September 2017

The shift of the equilibrium line in response to climatic disturbances is calculated for the International Glaciological Greenland Expedition (EGIG) profile of the Greenland Ice Cap. Data of heat balance studies carried out during EGIG 1959 and EGIG 1967 are used according to Kuhn’s algorithm. The following parameters are applied; the heat transfer coefficient of the sensible heat flux; the effective emissivity of the atmosphere for long wave downward radiation; a factor relating net radiation to cloudiness; the duration of the ablation season; the altitudinal temperature gradient; the altitudinal accumulation gradient.The altitudinal shift of the equilibrium line results for the EGIG profile + 77m/°C and -4 m per 1/10 cloudiness with 35d of ablation. Changes in heat balance by formation of superimposed ice are taken into account.
Snow avalanche runout from two Canadian mountain ranges
Authors: Nixon D.J. , Mcclung D. M. 
Published: September 2017

Field measurements on maximum runout from two different mountain ranges in Canada are presented and compared: the Coast Mountains in British Columbia and the Rocky Mountains. We include a statistical analysis of topographic terrain parameters such as starting zone catchment area, horizontal reach, vertical drop and relevant slope angles. Following McClung and Mears (1991), we derived a dimensionless parameter which is a measure of runout for each avalanche and we found that the runout ratios (defined below) for a given mountain range obey a Gumbel distribution consistent with previous results. In addition, we found that the runout ratios for both mountain ranges have a length-scale dependence which is potentially very important for land-use planning procedures: the mean value of the runout ratio decreases significantly as the horizontal reach increases. Together with data from other mountain ranges, our results show that path length effects will have to be incorporated when using statistical prediction methods for engineering zoning purposes.The runout ratio is defined as the quotient of two lengths, Δx/Xβ, where Δ is the horizontal distance from the 10° point to the maximum runout position, and Xβ is the horizontal distance from the start position to the point where slope angle first declines to 10°.
A computer database for falling snowflakes
Authors: Muramoto Ken-ichiro , Matsuura Kohki , Harimaya Toshio , Endoh Tatsuo 
Published: September 2017

A computer-based measurement system for characteristics of snowfall is described. To measure the size and velocity of falling snowflakes quantitatively, images of snowflakes were input to an image processor and the primary data were analyzed in real time. In this process, maximum diameter in a horizontal plane and falling velocity were recorded in previously set intervals, then stored on a disk. Since a lot of data were obtained during a full winter season, data had to be processed to make up a database after an experiment. Using this database, the data of the distribution of size and velocity of snowflakes can be retrieved at anytime.We observed snowflakes during winter months of 1986-92 in Sapporo and Toyama, which are located near the north east and middle of the Japan Sea coast respectively. The data indicate that the average size of snowflakes in Toyama was larger than that in Sapporo, while the number concentration of snowflakes in Sapporo was rather higher. The fall velocity tends to increase with increasing size of snowflakes, as observed in both areas.