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11.
Collins Glacier Retreat Process and Regional Climatic Variations,King George Island,Antarctica
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Carolina Lorenz Simoes Katia Kellem da Rosa Fabiane Fernanda Czapela Rosemary Vieira Jefferson Cardia Simoes 《Geographical review》2015,105(4):462-471
This paper investigates the recent climatic variability and changes in snow line and ice front position in Collins Glacier, King George Island, South Shetland Islands, Antarctic Peninsula. This region has recorded one of the largest temperature increases in the past fifty years and has been demonstrated to be highly sensitive to climate changes. To monitor recent changes (1983–2006), we determined the fluctuations of the terminus and snow line of the glacier via remote sensing data and field observation in the summer of 2013. We conclude that the Collins Glacier has responded slowly to regional climate changes (decades or even centuries), as glacial responses to climatic events do not depend solely on one environmental variable. The glacier presented more retreat and elevation of the snow line in the north sector. The retreat data are correlated with the mean monthly temperature and annual number of days of melting‐degree variations. 相似文献
12.
Keller P. Nicolini Katia C. Lombardi Wido H. Schreiner Irineu Mazzaro Fernando Wypych Antonio S. Mangrich 《Mineralogy and Petrology》2009,97(1-2):139-144
We report on a paramagnetic anisotropy study of three layered phyllosilicates. The mineral samples were characterized through X-ray powder diffraction (XRPD), X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR). Based on EPR measurements of samples oriented parallel or perpendicular to the magnetic field lines, we show how the substitutional iron is transformed from Fe(II) (biotite) into Fe(III) (muscovite and kaolinite) species and from axial Fe(III) coordination sites (muscovite) to rhombic (kaolinite) sites in response to weathering. 相似文献
13.
A new multi‐proxy investigation of Late Quaternary palaeoenvironments along the north‐western Barents Sea (Storfjorden Trough Mouth Fan)
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14.
Abstract Surface soil texture controls many important ecological, hydrological, and geomorphic processes in arid regions and is therefore important from a land-management perspective. Soil survey efforts have traditionally fulfilled this need, but they are constrained by the size, remoteness, and inaccessibility of many arid regions, which renders simple field measurements prohibitively expensive. This article compares several different predictive soil-mapping techniques with a sparse data set in order to develop surficial soil texture maps. Our results suggest that data collected at the landscape scale can be used as input to predictive soil-mapping techniques to create maps of soil texture at higher fidelity and a fraction of the cost than would be required using traditional methods. 相似文献
15.
Katia Ganda Jesús Falcón-Barroso Reynier F. Peletier Michele Cappellari Eric Emsellem Richard M. McDermid P. Tim de Zeeuw C. Marcella Carollo 《Monthly notices of the Royal Astronomical Society》2006,367(1):46-78
We present the stellar and gas kinematics of a sample of 18 nearby late-type spiral galaxies (Hubble types ranging from Sb to Sd), observed with the integral-field spectrograph SAURON at the 4.2-m William Herschel Telescope. SAURON covers the spectral range 4800–5380 Å, allowing us to measure the Hβ, Fe, Mg b absorption features and the emission in the Hβ line and the [O iii ]λλ4959, 5007 Å and [N i ]λλ5198, 5200 Å doublets over a 33 × 41-arcsec2 field of view. The maps cover the nuclear region of these late-type galaxies and in all cases include the entire bulge. In many cases the stellar kinematics suggests the presence of a cold inner region, as visible from a central drop in the stellar velocity dispersion. The ionized gas is almost ubiquitous and behaves in a complicated fashion: the gas velocity fields often display more features than the stellar ones, including wiggles in the zero-velocity lines, irregular distributions, ring-like structures. The line ratio [O iii ]/Hβ often takes on low values over most of the field, probably indicating a wide-spread star formation. 相似文献
16.
Katia M. Ferrière 《Astrophysics and Space Science》2001,277(1-2):247-257
We present the basic characteristics of a rotating magnetosphere. More specifically, we describe its overall equilibrium state,
explain the ‘subcorotation’ phenomenon resulting from plasma production or from outward transport, discuss the conditions
under which a magnetospheric system is driven unstable, and comment on the nature of the unstable motions, with emphasis on
the interchange motions believed to be responsible for the outward plasma transport.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Improving governability is an important objective in many fisheries and coastal areas. However, it may be difficult to modify the factors influencing this. Specifically, enhancing the capacity of user groups and civil society to cope with the tasks involved in co-governance situations may constitute a challenge, although the advantages in factors such as legitimacy and adaptability to local situations may reward the efforts. This paper attempts to analyze the process of transformation of on-foot shellfish gathering in Galicia, an activity that has traditionally been developed mainly by women in a regime similar to an open access regime. However, in recent decades this situation has changed, and nowadays many areas where this activity flourishes are in a situation of active co-governance, with a type of license system. Shellfisher organizations plan and control the exploitation with the support of the government, even using seeding techniques to regenerate areas that were previously degraded. Over the last decade, they have avoided overexploitation and have managed the marketing of the shellfish much better than ever before. We emphasize in the article that the role of the administration in this process has been decisive, investing in training and improving the organizations and the social dimension of the activity through different strategies. The empowerment of women has been an essential element in this process, which has also enhanced social valuation of the activity. This case may exemplify the possibilities open for progress in potential co-governing situations. 相似文献
18.
Stefano Calcaterra Claudio Cesi Caterina Di Maio Piera Gambino Katia Merli Margherita Vallario Roberto Vassallo 《Natural Hazards》2012,61(1):257-266
This paper reports experimental data on surface and deep displacements evaluated by means of GPS stations and inclinometers
in two rototranslational deep landslides in a clayey slope of the Italian Southern Apennines. The displacements of the landslides
cause continuous damage to buildings and infrastructures. To study these phenomena and control their effects, the local public
administration provided financial support for a geotechnical investigation that started in 2004. Laboratory tests, in situ
pore pressure and inclinometer measurements were carried out. In July 2006, systems of fixed-in-place inclinometer probes
with continuous data acquisition were installed in two of the eleven guide casings, in correspondence to the slip surfaces
detected by previous periodical measurements. In the meanwhile, a GPS network was installed, consisting in six permanent stations
and ten non-permanent ones. Among the latter, five were installed on the top of five inclinometer casings. The experimental
results show that, in the case under study, the surface displacements evaluated by means of the GPS stations are consistent
with the surface displacements evaluated by means of the inclinometer measurements. This implies mutual data validation, availability
of considerable amount of continuous data, as well as monitoring continuity when, for some reason, one of the instruments
goes out of use. 相似文献
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20.
In a context of increased demand for food and of climate change, the water consumptions associated with the agricultural practice of irrigation focuses attention. In order to analyze the global influence of irrigation on the water cycle, the land surface model ORCHIDEE is coupled to the GCM LMDZ to simulate the impact of irrigation on climate. A 30-year simulation which takes into account irrigation is compared with a simulation which does not. Differences are usually not significant on average over all land surfaces but hydrological variables are significantly affected by irrigation over some of the main irrigated river basins. Significant impacts over the Mississippi river basin are shown to be contrasted between eastern and western regions. An increase in summer precipitation is simulated over the arid western region in association with enhanced evapotranspiration whereas a decrease in precipitation occurs over the wet eastern part of the basin. Over the Indian peninsula where irrigation is high during winter and spring, a delay of 6?days is found for the mean monsoon onset date when irrigation is activated, leading to a significant decrease in precipitation during May to July. Moreover, the higher decrease occurs in June when the water requirements by crops are maximum, exacerbating water scarcity in this region. A significant cooling of the land surfaces occurs during the period of high irrigation leading to a decrease of the land-sea heat contrast in June, which delays the monsoon onset. 相似文献