Identifying uncertainties in Arctic climate change projections   总被引：2，自引：2，他引：0  

Daniel L. R. Hodson  Sarah P. E. Keeley  Alex West  Jeff Ridley  Ed Hawkins  Helene T. Hewitt 《Climate Dynamics》2013,40(11-12):2849-2865

Wide ranging climate changes are expected in the Arctic by the end of the 21st century, but projections of the size of these changes vary widely across current global climate models. This variation represents a large source of uncertainty in our understanding of the evolution of Arctic climate. Here we systematically quantify and assess the model uncertainty in Arctic climate changes in two CO₂ doubling experiments: a multimodel ensemble (CMIP3) and an ensemble constructed using a single model (HadCM3) with multiple parameter perturbations (THC-QUMP). These two ensembles allow us to assess the contribution that both structural and parameter variations across models make to the total uncertainty and to begin to attribute sources of uncertainty in projected changes. We find that parameter uncertainty is an major source of uncertainty in certain aspects of Arctic climate. But also that uncertainties in the mean climate state in the 20th century, most notably in the northward Atlantic ocean heat transport and Arctic sea ice volume, are a significant source of uncertainty for projections of future Arctic change. We suggest that better observational constraints on these quantities will lead to significant improvements in the precision of projections of future Arctic climate change.  相似文献   

The developing circulation patterns on a β-plane obtained in the case of an initial basic flow varying sinusoidally with latitude     

Dr. A. Huss 《Meteorology and Atmospheric Physics》1966,15(3-4):265-279

Summary Circulation patterns were obtained from a two-level quasigeostrophic model and an initial state characterized by a sinusoidal latitudinal variation of the zonal flow. The results were compared to a similar numerical experiment with an initial constant zonal flow.

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Zusammenfassung Aus einem quasi-geostrophischen Zweischichtenmodell und einem Anfangszustand, der durch eine sinusförmige Breitenvariation des zonalen Grundstroms gegeben war, wurden die Charakteristiken der großräumigen Zirkulation errechnet. Die Resultate wurden mit denen eines ähnlichen numerischen Experiments verglichen, das mit einem konstanten Grundstrom in den Anfangsbedingungen arbeitete.

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Résumé On calcule les caractéristiques de la circulation macrospatiale. Pour cela, on part d'un modèle quasi-géostrophique à deux couches et d'un état initial donné par un courant zonal de base dont les variations en latitude ont une forme sinusoïdale. Les résultats de ce calcul sont comparés à ceux d'une expérience numérique semblable, mais basée sur un courant initial constant.

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With 7 Figures

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The research in this report has been sponsored by the Air Force Cambridge Research Laboratories under Grant AF EOAR 63-108 through the European Office of Aerospace Research (OAR), United States Air Force.  相似文献   

The 2dF Galaxy Redshift Survey: galaxy clustering per spectral type     

Darren S. Madgwick  Ed Hawkins  Ofer Lahav  Steve Maddox  Peder Norberg  John A. Peacock  Ivan K. Baldry  Carlton M. Baugh  Joss Bland-Hawthorn  Terry Bridges  Russell Cannon  Shaun Cole  Matthew Colless  Chris Collins  Warrick Couch  Gavin Dalton  Roberto De Propris  Simon P. Driver  George Efstathiou  Richard S. Ellis  Carlos S. Frenk  Karl Glazebrook  Carole Jackson  Ian Lewis  Stuart Lumsden  Bruce A. Peterson  Will Sutherland  Keith Taylor 《Monthly notices of the Royal Astronomical Society》2003,344(3):847-856

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Ultracompact HII regions: the impact of newly formed massive stars on their environment     

Ed Churchwell 《Astronomy and Astrophysics Review》1990,2(2):79-123

Summary Ultracompact (UC)HII regions are manifestations of newly formed massive stars that are still embedded in their natal molecular cloud. They are among the brightest and most luminous single objects in the Galaxy at far infrared and radio wavelengths. Recent high spatial resolution studies, particularly at radio wavelengths, have greatly contributed to our understanding of these dynamic objects and the impact they have on their environment. A summary is given of our current understanding of the physical properties, morphologies, dynamics, number and distribution in the Galaxy, and molecular environments of UCHII regions. Recent models of the circumnebular dust imply that the graphite/silicate abundance ratio is about half that of dust in the diffuse interstellar medium. The dust cocoons are large, cool, and optically thick shortward of a few microns. There are apparently between 1700 and 3000 UCHII regions in the Galaxy. This represents 10–20% of the total O star population. There are too many UCHII regions (just counting those studied with the VLA) to be consistent with the short dynamical lifetimes of this very compact stage of evolution. Both the morphologies and the large number can be understood if UC HII regions are bow shocks. Models of stellar wind supported bow shocks are discussed and consequences for the dynamics and morphologies of the ionized and molecular gas are explored.  相似文献   

Laser ablation ICP-MS screening of corals for diagenetically affected areas applied to Tahiti corals from the last deglaciation     

Ed C. Hathorne  Thomas Felis  Alex Thomas 《Geochimica et cosmochimica acta》2011,75(6):1490-1506

Fossil corals are unique archives of past seasonal climate variability, providing vital information about seasonal climate phenomena such as ENSO and monsoons. However, submarine diagenetic processes can potentially obscure the original climate signals and lead to false interpretations. Here we demonstrate the potential of laser ablation ICP-MS to rapidly detect secondary aragonite precipitates in fossil Porites colonies recovered by Integrated Ocean Drilling Program (IODP) Expedition 310 from submerged deglacial reefs off Tahiti. High resolution (100 μm) measurements of coralline B/Ca, Mg/Ca, S/Ca, and U/Ca ratios are used to distinguish areas of pristine skeleton from those afflicted with secondary aragonite. Measurements of coralline Sr/Ca, U/Ca and oxygen isotope ratios, from areas identified as pristine, reveal that the seasonal range of sea surface temperature in the tropical south Pacific during the last deglaciation (14.7 and 11 ka) was similar to that of today.  相似文献   

Challenges and lessons from a wetland LiDAR project: a case study of the Okefenokee Swamp,Georgia, USA     

L. Shea Rose  Jared Ogle  Ed Beute  Jon Indridason  Jacob D. Hall 《国际地球制图》2013,28(3):210-226

Airborne LiDAR (Light Detection and Ranging) provides opportunities to generate high-quality digital elevation models (DEMs) even in wetland environments. Our project, performed over the Okefenokee Swamp in Georgia during the spring of 2010, shows that several, distinctive factors must be considered to ensure successful wetland LiDAR projects. Some of the challenges include selecting optimal flight times in accordance with weather variability and water levels, having effective and quality control protocols, applying and developing filtering and interpolation algorithms, breaklines in swamps and accounting for data striping and noise. While some of these issues are faced in any airborne LiDAR acquisition, many of these require special consideration in a low-slope wetland environment with water saturated soils, widespread shallow water, and sediments and extensive vegetation. An examination of these issues and how they were handled will help in ensuring the success of future LiDAR acquisitions and, in particular, will advance knowledge of producing quality DEMs in wetland environments.  相似文献   

Dartmoor's overlooked glacial legacy     

David J.A. Evans  Stephan Harrison  Andreas Vieli  Ed Anderson 《Geology Today》2012,28(6):224-229

Traditionally regarded as a relict permafrost and periglacial landscape that lay beyond the limits of Pleistocene glaciation, the granite uplands of northern Dartmoor in south‐west England in fact contain geomorphological evidence for the former existence of a plateau ice cap, making the area the location of the southernmost independent glacier mass in the British Isles. In addition to weakly U‐shaped valleys, the most prominent evidence comprises arcuate and linear bouldery ridges and hummocky valley floor drift, which are interpreted as latero‐frontal moraines deposited by the outlet glacier lobes of a plateau ice cap. Inset sequences of these depositional landforms, in association with meltwater channels, demarcate the receding margins of the glacier lobes. A numerical model of ice cap development shows that a predominantly thin plateau icefield type glaciation is required in order to produce significant ice flow into surrounding valleys. The highest and most extensive plateau areas were occupied by ice for the longest cumulative period of time throughout the Pleistocene, thereby explaining: (1) the lack of tors in such areas as the product of ‘average’ glacial conditions preferentially removing tors or dampening their production rates, (2) the survival of high relief tors during glaciation if they occupied summits too narrow to develop thick and erosive glacier ice, and (3) the survival of subdued tors in areas glaciated less regularly during the Pleistocene.  相似文献   

The Eagle,Nebraska Enstatite Chondrite (EL6)     

Edward J. Olsen  Glenn I Huss  Eugene Jarosewich 《Meteoritics & planetary science》1988,23(4):379-380

Abstract— The Eagle enstatite chondrite (presently 9.2 kg) was an observed fall in October 1946. It was not recovered until the spring of 1947 and was allowed to remain out-of-doors until 1984. The meteorite appears relatively unweathered, although the absence of oldhamite and the depletion of calcium indicates it has suffered chemical weathering during its 37 years of exposure. Its bulk composition classifies it as an EL6. Its lack of chondrules or remnants of chondrules place it among the most recrystallized of enstatite chondrites. It contains unusual rounded black inclusions, up to 1 cm, composed of the same minerals as the host, but of significantly finer grain size. We conclude Eagle is a post-metamorphic breccia, the breccia inclusions having been rounded by abrasion during regolith processing.  相似文献   

Extinct Be in Type A calcium-aluminum-rich inclusions from CV chondrites     

Glenn J. MacPherson  Gary R. Huss 《Geochimica et cosmochimica acta》2003,67(17):3165-3179

We have found clear evidence of live ¹⁰Be in five normal Type A Calcium-aluminum-rich inclusions (CAIs), one normal Type B CAI, and one FUN Type A CAI, all from CV3 chondrites. The (¹⁰Be/⁹Be)₀ ratios range from ∼0.36 × 10^-3 to ∼0.77 × 10^-3 and are similar to those found by previous workers. The (¹⁰Be/⁹Be)₀ ratios do not correlate in a temporal fashion with (²⁶Al/²⁷Al)₀, suggesting that ¹⁰Be and ²⁶Al were produced by different mechanisms. An examination of possible sources for the short-lived radionuclides indicates that production of ¹⁰Be was almost certainly by particle irradiation, possibly within the solar system, and was probably accompanied by significant production of ⁴¹Ca and ⁵³Mn. In contrast, all of the ⁶⁰Fe, most of the ²⁶Al, and some of the ⁵³Mn were probably produced in stars and were imported into the solar system within presolar dust grains.  相似文献   

DISCUSSION OF "An Economical Approach to Determining the Extent of Ground-Water Contamination and Formulating a Contaminant Removal Plan", by Kiyoshi W. Mido, January-February issue, v. 19, no. 1, pp. 41–47     

David S. Ward  Ed Tang 《Ground water》1981,19(5):552-553

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