排序方式: 共有21条查询结果,搜索用时 265 毫秒
1.
2.
3.
Holocene climate variability 总被引:17,自引:0,他引:17
4.
Holocene hydrological cycle changes in the Southern Hemisphere documented in East Antarctic deuterium excess records 总被引:1,自引:0,他引:1
F. Vimeux V. Masson J. Jouzel J. R. Petit E. J. Steig M. Stievenard R. Vaikmae J. W. C. White 《Climate Dynamics》2001,17(7):503-513
Four Holocene-long East Antarctic deuterium excess records are used to study past changes of the hydrological cycle in the
Southern Hemisphere. We combine simple and complex isotopic models to quantify the relationships between Antarctic deuterium
excess fluctuations and the sea surface temperature (SST) integrated over the moisture source areas for Antarctic snow. The
common deuterium excess increasing trend during the first half of the Holocene is therefore interpreted in terms of a warming
of the average ocean moisture source regions over this time. Available Southern Hemisphere SST records exhibit opposite trends
at low latitudes (warming) and at high latitudes (cooling) during the Holocene. The agreement between the Antarctic deuterium
excess and low-latitude SST trends supports the idea that the tropics dominate in providing moisture for Antarctic precipitation.
The opposite trends in SSTs at low and high latitudes can potentially be explained by the decreasing obliquity during the
Holocene inducing opposite trends in the local mean annual insolation between low and high latitudes. It also implies an increased
latitudinal insolation gradient that in turn can maintain a stronger atmospheric circulation transporting more tropical moisture
to Antarctica. This mechanism is supported by results from a mid-Holocene climate simulation performed using a coupled ocean-atmosphere
model.
Received: 7 July 1999 / Accepted: 21 July 2000 相似文献
5.
6.
Pieter M Grootes Eric J Steig Minze Stuiver Edwin D Waddington David L Morse Marie-Jose Nadeau 《Quaternary Research》2001,56(3)
The 18O/16O profile of a 554-m long ice core through Taylor Dome, Antarctica, shows the climate variability of the last glacial–interglacial cycle in detail and extends at least another full cycle. Taylor Dome shares the main features of the Vostok record, including the early climatic optimum with later cool phase of the last interglacial period in Antarctica. Taylor Dome δ18O fluctuations are more abrupt and larger than those at Vostok and Byrd Station, although still less pronounced than those of the Greenland GISP2 and GRIP records. The influence of the Atlantic thermohaline circulation on regional ocean heat transport explains the partly “North Atlantic” character of this Antarctic record. Under full glacial climate (marine isotope stage 4, late stage 3, and stage 2), this marine influence diminished and Taylor Dome became more like Vostok. Varying degrees of marine influence produce climate heterogeneity within Antarctica, which may account for conflicting evidence regarding the relative phasing of Northern and Southern Hemisphere climate change. 相似文献
7.
8.
John B. Reid Jr. Eric Steig Wilfred B. Bryan 《Contributions to Mineralogy and Petrology》1989,101(3):318-325
Basalt petrologists disagree as to whether the commonly used projection, forsterite-diopside-silica, in the system CMAS (CaO-MgO-Al2O3-SiO2), can adequately resolve differences in basaltic glass compositions for purposes of petrogenetic modelling. Here, we suggest than an analogous plot, the aluminium-factor diagram (ALFE) of Nesbitt and Cramer (1981), has greater diagnostic value than Fo-Di-Sil. A plot of molar (Al2O2-CaO-Na2O-K2O)/(FeO + MgO) vs FeO/(FeO + MgO), it produces more coherent patterns both for experimental basalt glasses, and for natural lavas. It is, like Fo-Di-Sil, a projection through plagioclase, but has the advantage that it monitors changes in Fe/(Fe + Mg) in melts and associated crystalline phases, and is particularly useful in assessing the timing of clinopyroxene crystallization in a suite of lavas. The diagram owes its greater resolving power to the fact that the computation of its coordinates is less sensitive to analytical uncertainty than for Fo-Di-Sil. In the latter diagram, normative quartz is calculated as a residual and thus manifests the uncertainties in all the major elements. 相似文献
9.
Eric J. Steig 《GeoJournal》2007,70(1):5-9
The portrayal of the science of climate change in An Inconvenient Truth is largely correct. Some aspects of the film, such as the discussion of Hurricane Katrina, oversimplify the complex factors involved, while others conflate global warming with other environmental changes that may not be related. However it is not in question that continuing emissions of greenhouse gases by human activities will cause greater climate change in the future, and that the impacts of such change are likely to be negative. The chief message of the film—that this fact places important moral and ethical choices before society—is therefore an accurate one. 相似文献
10.
Valrie Masson Franoise Vimeux Jean Jouzel Vin Morgan Marc Delmotte Philippe Ciais Claus Hammer Sigfus Johnsen Vladimir Ya. Lipenkov E. Mosley-Thompson Jean-Robert Petit Eric J. Steig Michel Stievenard Rein Vaikmae 《Quaternary Research》2000,54(3):348
A comparison is made of the Holocene records obtained from water isotope measurements along 11 ice cores from coastal and central sites in east Antarctica (Vostok, Dome B, Plateau Remote, Komsomolskaia, Dome C, Taylor Dome, Dominion Range, D47, KM105, and Law Dome) and west Antarctica (Byrd), with temporal resolution from 20 to 50 yr. The long-term trends possibly reflect local ice sheet elevation fluctuations superimposed on common climatic fluctuations. All the records confirm the widespread Antarctic early Holocene optimum between 11,500 and 9000 yr; in the Ross Sea sector, a secondary optimum is identified between 7000 and 5000 yr, whereas all eastern Antarctic sites show a late optimum between 6000 and 3000 yr. Superimposed on the long time trend, all the records exhibit 9 aperiodic millennial-scale oscillations. Climatic optima show a reduced pacing between warm events (typically 800 yr), whereas cooler periods are associated with less-frequent warm events (pacing >1200 yr). 相似文献