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121.
Supergranulation is one of the most visible length scales of solar convection and has been studied extensively by local helioseismology. We use synthetic data computed with the Seismic Propagation through Active Regions and Convection (SPARC) code to test regularized-least squares (RLS) inversions of helioseismic-holography measurements for a supergranulation-like flow. The code simulates the acoustic wavefield by solving the linearized three-dimensional Euler equations in Cartesian geometry. We model a single supergranulation cell with a simple, axisymmetric, mass-conserving flow. The use of simulated data provides an opportunity for direct evaluation of the accuracy of measurement and inversion techniques. The RLS technique applied to helioseismic-holography measurements is generally successful in reproducing the structure of the horizontal-flow field of the model supergranule cell. The errors are significant in horizontal-flow inversions near the top and bottom of the computational domain as well as in vertical-flow inversions throughout the domain. We show that the errors in the vertical velocity are due largely to cross talk from the horizontal velocity. 相似文献
122.
A GIS FOR THE ANTARCTIC SPECIALLY MANAGED AREA OF ADMIRALTY BAY,KING GEORGE ISLAND,ANTARCTICA 总被引:1,自引:0,他引:1
Jefferson Cardia Sim“非汉字符号”es F.A.Ferron Matthias Braun J.Arigony Neto F.E.Aquino 《地球空间信息科学学报》2001,4(2):8-14
1 IntroductionKingGeorgeIsland’s (KGI)ecosystemshavebeensubjectedtovarioustypesofexploitationandobjectofseveralscientificexpeditions,sinceitwasdiscoveredjustafterthefirstsightingofAntarctilandbyWilliamSmithin1 81 9.KGIwasnamedaf tertheBritishkingofthattime … 相似文献
123.
[35]Braun M,Rau F.Using a multi_year data archive of ERS SAR imagery for the monitoring of firn line positions and ablation patterns on the King George Island ice cap (Antarctica).The Workshop of EARSeL Special Interest Group:Remote Sensing of Land Ice and Snow.Dresden,2000(published on CD_Rom in 2001)
[36]Rau F,Braun M,Friedrich M,et al.Radar glacier zones and its boundaries as indicators of glacier mass balance and climatic variability.The Workshop of EARSeL Special Interest Group:Remote Sensing of Land Ice and Snow.Dresden,2000(published on CD_Rom in 2001)
[1]Bahr D B.Global distribution of glacier properties:A stochastic scaling paradigm.Water Resource Research,1997,33(7):1 669~1 679
[2]Bahr D B,Meier M F.Snow patch and glacier size distributions.Water Resource Research,2000,36(2):495~501
[3]Braun M,Schneider C.Characteristics of summer energy balance on the west coast of the Antarctic Peninsula.Annals of Glaciology,2000,31:179~183
[4]Braun M,Rau F,Saurer H,et al.The development of radar glacier zones on the King George Island Ice Cap (Antarctica) during the Austral summer 1996~1997 as observed in ERS_2 SAR data.Annals of Glaciology,2000,31:357~363
[5]Calvet J,Corbera J,Furada G.Variacion del frente glaciar en Bahia Sur y Punta Siddons entre 1956 y 1991,Isla Livingston,Islas Shetland del Sur.In: López_Martinez,J.: Geología de la Antártida Occidental.III Congreso Geológico de Espana y VIII Congreso Latinoamericano de Geología,Salamanca,Espana,1992.283~292
[6]Doake C S M,Vaughan D G.Rapid disintegration of the Wordie Ice Shelf in response to atmospheric warming.Nature,1991,350(6 316):328~330
[7]Doake C S M,Corr H F J,Rott H,et al.Break_up and conditions for stability of the northern Larsen Ice Shelf,Antarctica.Nature,1998,391:778~780
[8]Fox A J,Cooper A P R.Climate_change indicators from archival aerial photography of the Antarctic Peninsula.Annals of Glaciology,1998,27:636~642
[9]Harangozo S A,Colwell S R,King J C.An analysis of a 34_year air temperature record from Fossil Bluff (71° S,68° W),Antarctica.Antarctic Science,1997,9(3):355~363
[10]Hulbe C L.Recent changes to Antarctic Peninsula ice shelves: what lessons have been learned? Natural Science,1997,1(6)
[11]Jones P D.Antarctic temperatures over the present century——a study of the early expedition record.Journal of Climate,1990,3:1 193~1 203
[12]Kieffer H and 41 others.New eyes from the skye measure glaciers and ice sheets.EOS,2000,81(24):265,270~271
[13]King J C.Recent climate variability in the vicinity of the Antarctic Peninsula.International Journal of Climatology,1994,14:357~369
[14]King J C,Harangozo S A.Climate change in the western Antarctic Peninsula since 1945: observations and possible causes.Annals of Glaciology,1998,27:571~575
[15]Klser H,Arntz W E.RASCAL (RESEARCH on Antarctic Shallow Coastal and Litoral systems).Untersuchungen zur Struktur und Dynamik eines antarktischen Küstenjosystems.Polarforschung,1994,64(1):27~41
[16]Klser H,Ferreyra G,Schloss I,et al.Hydrography of Potter Cove,a small fjord_like inlet in King George Island,South Shetands.Estuarine,Coastal and Shelf Science,1994,38:523~537
[17]Lucchitta B K,Rosanova C E.Retreat of northern margins of George VI and Wilkins Ice Shelves,Antarctic Peninsula.Annals of Glaciology,1998,27:41~46
[18]Morris E M.Surface ablation rates on Moraine Corrie Glacier,Antarctica.Global and Planetary Change,1999,22:221~231
[19]Park B K,Chang S K,Yoon H I,et al.Recent retreat of ice cliffs,King George Island,South Shetland Islands,Antarctic Peninsula.Annals of Glaciology,1998,27:633~635
[20]Rakusa_Suszczewski S.The maritime Antarctic coastal ecosystem of Admiralty Bay.Department of Antarctic Biology,Polish Academy of Sciences,Warsaw,1993.216
[21]Rakusa_Suszczewski S.The hydrography of Admiralty Bay and its inlets,coves and lagoons (King George Island,Antarctica).Polish Polar Research,1995,16(1/2):61~70
[22]Rau F,Braun M,Saurer H,et al.Multi_year snow cover dynamics on the Antarctic Peninsula using SAR imagery.Polarforschung,2000,67(1/2):27~40
[23]Rott H,Skvarca P,Nagler T.Rapid Collapse of northern Larsen Ice Shelf,Antarctica.Science,1996,271:788~792
[24]Rott H,Rack W,Nagler T,et al.Climatically induced retreat and collapse of northern Larsen Ice Shelf,Antarctic Peninsula.Annals of Glaciology,1998,27:86~92
[25]Skvarca P,Rack W,Rott H,et al.Evidence of recent climatic warming on the eastern Antarctic Penisnula.Annals of Glaciology,1998,27:628~932
[26]Simes J C,Bremer U F,Aquino F E,et al.Morphology and variations of glacial drainage basins in the King George Island ice field,Antarctica.Annals of Glaciology,1999,29:220~224
[27]Smith A M,Vaughan D G,Doake C S M,et al.Surface lowering of the ice ramp at Rothera Point,Antarctic Peninsula,in response to regional climate change.Annals of Glaciology,1998,27:113~118
[28]Smith R C,Stammerjohn S E,Baker K S.Surface air temperature variations in the western Antarctic Peninsula region.Antarctic Research Series,1996,70:105~121
[29]Splettstoesser J.Antarctic Global Warming? Nature,1992,355(6 360):503
[30]Stark P.Climatic warming in the central Antarctic Peninsula area.Weather,1994,49(6):215~220
[31]Turner J,Colwel S R,Harangozo S.Variability of precipitation over the coastal western Antarctic Peninsula from synoptic observations.Journal of Geophysical Research,1997,102(D12):13 999~14 007
[32]Warren C R.Iceberg calving and the glaciomarine record.Progress in Physical Geography,1992,16(3):253~282
[33]Wunderle S.Die Schneedeckendynamik der Antarkische Halbinsel und ihre Erfassung mit aktiven und passiven Fernerkundungsverfahren.Freiburger Geographische Hefte,1996,48:172
[34]Braun M,Saurer H,Vogt S,Simes J C,et al.The influence of large_scale atmospheric circulation on surface energy balance on the ice cap of King George Island.International Journal of Climatology,2001,21(1):21~36 相似文献
124.
The light noble gases He, Ne and Ar have been measured in the iron meteorites Dongling, Nantan and Ningbo. Dongling and Ningbo
show a deficit of cosmic-ray that produced3He of ca. 30% and 10%, respectively, which is argued to be caused by the loss of3H (tritium) from the meteoroids during the time of their exposure to the cosmic radiation. Nantan has the lowest content of
noble gases as yet reported for any iron meteorite. Cosmogenic3He and38Ar are only about 1/5000 of those in Dongling which has particularly interesting implications if the two meteorites belong
to the same fall[2]. In addition, Nantan contains nonspallogenic4He which we believe to be of radiogenic origin. This radiogenic4He, together with a U-content of 2.6×10−11 g/g[20] yields a4He retention age close to the cosmic-ray exposure age of Dongling. If Dongling and Nantan were part of the same meteoroid[2], this result would indicate that He retention in the meteoroid age were 4,500 Ma, a U-content of less than 7.2×10−13 g/g is required to explain the non-cosmogenic4He present. An upper limit to the number of transuranium or superheavy-element atoms which have decayed by α-emission in Nantan
since onset of He retention is 2×1010 per gram. 相似文献
125.
Daily ozone soundings over Switzerland in the winter of 1979 showed, at the end of January some extremely high values of the ozone mixing ration around the 10 mb level-9 to 10 ppm compared with a climatological mean of 6 ppm. At the same time, the temperature and ozone mixing ratio was measured by the LIMS experiment (Limb Infrared Monitor of the Stratosphere) on Nimbus 7. The single LIMS ozone profiles, as well as the LIMS 10 mb ozone maps, also showed extreme ozone maxima. Ozone transport was investigated by trajectory computations based on the LIMS geopotential height fields. Displacements and deformations of air parcel chains in 48 h were used to construct ozone maps, using the distribution on a previous day. The correspondence of such kinematically-constructed ozone maps using the actual LIMS maps is striking. This method is, thus, a strong indication of the self-consistency of the different LIMS products (ozone, temperature, geopotential) and explains the unusual ozone observations. 相似文献
126.
Duane D. Braun 《地球表面变化过程与地形》1985,10(6):639-642
Abrahams' comment relates meander length to channel cross-section shape and recurrence interval so that meander length can be both directly and inversely proportional to rock resistance. This reply notes that either meander length is directly proportional to rock resistance or it is not; one cannot have it both ways. Many Appalachian Valley and Ridge bedrock meanders are shown to be the same size as alluvial meanders, and appear to be somewhat underfit. A hypothesis is proposed where modest discharge increases may have accelerated bedrock meander cutting although present streams remain capable of slowly cutting the meanders. 相似文献
127.
Eckart Braun 《Contributions to Mineralogy and Petrology》1974,46(4):301-327
Zusammenfassung In einem Profil ansteigender Metamorphose werden im Stavanger-Gebiet/SW-Norwegen zwei Gesteinstypen, repräsentiert durch 17 Meta-Arkosen und Quarz-Feldspat-Gneise, sowie 19 metamorphe Tuffe und Tuffite, modellhaft auf ihre Saussuritparagenesen hin analysiert.Mikroskopische und mikroanalytische Untersuchungen zeigen eine weitestgehende Eduktabhängigkeit der Saussuritparagenesen. In calcitarmen granitoiden Edukten bilden sich schon im sehr schwach-metamorphen Stadium folgende mit Ab-reichem Plagioklas koexistierende Saussuritmineralien: 4 An-reicher Plagioklas+K-Feldspat+4 Eisenhydroxid + H2O 2 Fe(III)Al2-Epidot+Muskovit+Hämatit+2 Quarz. In calcitführenden Meta-Arkosen gewinnt die Mineralreaktion: An-Plagioklas+K-Feldspat+2 Eisenhydroxid+CO2Calcit+Muskovit+ Hämatit+Quarz an Bedeutung. Im reduzierenden geochemischen Milieu der Meta-Tuffe und -Tuffite tritt in diesem metamorphen Bereich als charakteristische Neubildung Biotit neben Muskovit auf. Auch in den calcitreichen tuffitischen Proben koexistieren die Saussuritkomponenten Calcit, Muskovit, Hämatit, Quarz und Biotit.Die mikroanalytisch untersuchten Saussuritmineralien Plagioklas und Epidot zeigen anhand von annähernd 800 chemischen Vollanalysen in der Entwicklung ihrer Chemismen während der Metamorphose für beide Sedimente gleiche Trends. Im niedrigtemperierten Bildungsstadium der Saussurite können die An-Gehalte der Feldspäte in Abhängigkeit vom Edukt und aufgrund unterschiedlich intensiver Rekristallisation der Sedimente relativ stark schwanken. Die Epidote sind je nach primärem Fe(III)-Angebot mehr oder weniger eisenreich. In Richtung ansteigender Metamorphose stellen sich in den Epidoten beim Übergang zu oligoklasführenden Paragenesen maximale Fe(III)-Gehalte ein, die in Form eines rhythmischen Zonarbaus die wechselnden
-Bedingungen im Verlauf der Metamorphose widerspiegeln. Bereits hier setzt der retrograde Saussuritisierungsprozeß ein: es reagieren Fe(III)Al2-Epidot, Muskovit, Quarz, Hämatit und Albit/Oligoklas zu anorthitreicherem Plagioklas, Biotit und Wasser. Zusätzlich bildet sich durch die Zersetzung des Al-reichen Epidots Mikroklin.Die Untersuchung zur Wechselbeziehung zwischen dem Eisengehalt des Eduktes und dem der Epidote ergibt, daß die Fe(III)-Einbaurate der Epidote in keiner Weise von den Fe(III)-Konzentrationen der Meta-Sedimente beeinflußt wird, vielmehr können eduktspezifische Intervalle für die Eisenanreicherung der Epidote nachgewiesen werden.
Herrn Prof. Dr. G. Müller, Clausthal, danke ich für viele anregende Diskussionen sowie für die kritische Durchsicht des Manuskriptes.
Mein Dank gilt auch Herrn Dr. A. Schneider, Geochemisches Institut der Universität Göttingen, der mir freundlicherweise das Rucklidge-Korrekturprogramm für Silikatanalysen zur Verfügung stellte. Zu danken habe ich auch Herrn Dr. F. Wurm, Geologisches Landesamt Baden-Württemberg, für sein großzügiges Entgegenkommen und die tatkräftige Unterstützung bei der ergänzenden Probennahme im Gebiet der nordwestlichen Inseln des Boknfjords.
Der Deutschen Forschungsgemeinschaft schulde ich Dank für die finanzielle Unterstützung dieser Arbeit. 相似文献
Electron microprobe investigations of saussurites dependent on metamorphic stage and geochemical environment
In a profile of ascending metamorphism, the saussuritic parageneses of two characteristic rock types, 17 acid meta-arkoses and 19 basic meta-tuffs and meta-tuffites, were investigated by microscopical and microanalytical methods.Microscopic studies reveal that the specific saussurite mineral association is dependent on the petrographic substratum. In very low stage metamorphism, granitic rocks show the following saussurite minerals coexisting with albite-rich plagioclase: 4 An-rich plagioclase+K-feldspar +4 ironhydroxide+H2O2 Fe (III) Al2-epidote + muscovite + hematite + 2 quartz. Phyllitic and calciferous meta-arkoses exhibit predominantly the following saussurite reaction: An-plagioclase + K-feldspar + 2 ironhydroxide + CO2 calcite + muscovite + hematite + quartz. In the reducing environment of the meta-tuffs and meta-tuffites, biotite is formed in addition to muscovite.The changing chemical composition of the saussurite minerals (plagioclase and epidote) at different stages of metamorphism was determined by 800 quantitative electron microprobe analyses. The changes found in both rock types are nearly the same. During low metamorphic stage, the An-content of the plagioclases depends on the substratum and the variable intensity of recrystallization. The Fe-content of the epidotes is dependent on the amount of iron available.The epidotes are enriched in Fe toward the transition to oligoclase-bearing parageneses. These Fe-contents cause rhythmical zoning, representing varying conditions during metamorphism. With increasing metamorphic grade the retrograde process of saussuritization is initiated. The reactants are Fe (III) Al2-epidote, muscovite, quartz, hematite, and albite/ oligoclase. The decomposition of these minerals leads to An-rich plagioclase, biotite, microcline, and H2O.
Herrn Prof. Dr. G. Müller, Clausthal, danke ich für viele anregende Diskussionen sowie für die kritische Durchsicht des Manuskriptes.
Mein Dank gilt auch Herrn Dr. A. Schneider, Geochemisches Institut der Universität Göttingen, der mir freundlicherweise das Rucklidge-Korrekturprogramm für Silikatanalysen zur Verfügung stellte. Zu danken habe ich auch Herrn Dr. F. Wurm, Geologisches Landesamt Baden-Württemberg, für sein großzügiges Entgegenkommen und die tatkräftige Unterstützung bei der ergänzenden Probennahme im Gebiet der nordwestlichen Inseln des Boknfjords.
Der Deutschen Forschungsgemeinschaft schulde ich Dank für die finanzielle Unterstützung dieser Arbeit. 相似文献
128.
– Durch Experimente erzielte Anreicherungsfaktoren für Quecksilber in Karpfen bestätigen, daß eine Rüekrechnung von gemessenen Quecksilberkonzentrationen im Fisch auf solche im Wasser mit Hilfe der Faktoren nicht ohne weiteres möglich ist; – dagegen zeichnet sich ab, daß ein Vergleich verschiedener quecksilberhaltiger Fischorgane gewisse Rückschlüsse auf die vorangegangene Art (chronisch oder akut) der Quecksilber-belastung ermöglicht; – die Höhe der Quecksilberaufnahme der Karpfenkiemen bei akut-toxischer Quecksilberkonzentration im Wasser hing von der Queckeilberbelastung der Karpfen ab. Ebenso wurde biervon die Manifestationszeit beeinflußt 相似文献
129.
We investigate the production of26Al during hydrogen burning and its ejection by massive single and binary stars. Effects of convection and rotation are studied. We discuss the importance of RSGs, LBVs and WR stars to the total Galactic26Al production, and the detection probability of the26Al decay in individual objects as P Cygni, Velorum and Carinae. 相似文献
130.