WWW.ABSTRACT.XLIBX.INFO
FREE ELECTRONIC LIBRARY - Abstract, dissertation, book
 
<< HOME
CONTACTS



Pages:     | 1 |   ...   | 3 | 4 || 6 | 7 |   ...   | 24 |

«Changing Polar Regions 25th International Congress on Polar Research March 17-22, 2013, Hamburg, Germany German Society for Polar Research Edited by ...»

-- [ Page 5 ] --

Wenngleich die gemessenene Temperaturzunahme sehr gering ist, führt die "Changing Polar Regions" - 25th International Congress on Polar Research 2013 vertikale Erstreckung über nahezu die gesamte Wassersäule zur Speicherung von signifikanten Wärmemengen, da die Wärmekapazität des Meerwassers um etwa einen Faktor 4000 höher ist, als die der Atmosphäre. Somit kann die Erhöhung der mittleren Wassertemperatur um 0,01°C über die gesamte Wassersäule der Weltozeane die mögliche Erwärmung der Atmosphäre um 1°C reduzieren. Da der Südliche Ozean etwa 13% der Erdoberfläche einnimmt, würde dadurch ein erheblicher Teil der durch den erhöhten Treibhauseffekt gewonnenen Wärme nicht zur Erwärmung der Atmosphäre sondern des Ozeans beitragen und damit das Weddellmeer zum Tor des Wärmespeichers über längere Zeiträume machen. Der zirkumpolare Charakter des Südlichen Ozeans erlaubt, dass die Wärmespeicherung über den Zeitraum von Jahrzehnten ein nahezu globales Volumen erfassen kann.

Wenn diese Wärmemenge nicht vom Ozean aufgenommen worden wäre, wo sie über 3900 m Tiefe zur Erwärmung von 0,04 K geführt hat, hätte sie in der der darüber liegenden Atmosphäre eine Erwärmung von etwa 1°C über 24 Jahre bewirkt, bzw. hat die zu erwartende Erwärmung um etwa diesen Betrag gedämpft. Wie Johnson und Purkey (2012) an Hand des WOCE-Datensatzes zeigen, ist die Erwärmung nicht auf den Südlichen Ozean beschränkt, sondern breitet sich entlang des Ausstroms von AABW in die nördlichen Becken aus und ist daher langfristig von globaler Bedeutung.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 ICE MATTERS. ARCTIC AND ANTARCTIC UNDER-ICE

COMMUNITIES LINKING SEA ICE WITH THE PELAGIC FOOD WEB

–  –  –

In both Polar Regions, sea ice environments are undergoing rapid environmental change. Because sea ice constitutes an important habitat for numerous species, as well as an important carbon source during critical periods of the year, these changes impact significantly on ecosystem functioning, biodiversity, species distribution and population sizes, including commercially exploited fish stocks. Species dwelling at the ice-water interface (e.g. Antarctic krill and Arctic cod) play a key role in this context as trophic carbon transmitters from the sea ice into pelagic food webs, and ultimately to the deep sea benthos. Quantifying under-ice communities was hampered in the past by the inaccessibility of the ice underside to conventional sampling gear. Using a new under-ice trawl, it could be shown that Antarctic krill concentrates under sea ice almost year-round, and that krill dwelling under ice are significantly under-estimated by pelagic nets and sonars. An Arctic expedition in 2012 using the same sampling gear brought evidence of a vivid under-ice community even in the biologically poor-considered central Arctic Ocean. Using a bioenvironmental sensor array during under-ice fishing enabled fine-scale characterization of sea ice habitat properties as a basis for statistical modeling of under-ice species distribution. During the talk, past results from under-ice fishing in the Southern Ocean will be summarized, and complemented by preliminary results from the Arctic Ocean to elucidate similarities and differences of polar under-ice communities in both hemispheres.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 DAS KLIMA DER EURASISCHEN ARKTIS IN DEN LETZTEN 2000

JAHREN - ERGEBNISSE EINER EISKERNSTUDIE VON

SEWERNAJA SEMLJA

–  –  –

Die Arktis ist eine Schlüsselregion des globalen Klimasystems und wird von der gegenwärtigen Erwärmung mehr beeinflusst als andere Regionen. Die Kenntnis natürlicher Klimaschwankungen der Vergangenheit ist für die Einschätzung heutiger Klimaveränderungen und für verlässliche Prognosen erforderlich. Repräsentative meteorologische Beobachtungen liegen in den meisten Regionen der Arktis erst seit ca. 1900 vor. Klimarekonstruktionen früherer Epochen beruhen hauptsächlich auf Untersuchungen von Eis- und Sedimentkernen oder Baumjahresringen die sogenannte Stellvertreterdaten (proxy data) liefern.

Vorgestellt werden die Variationen des Sauerstoffisotopenverhältnisses18O/16Ound ausgewählter Hauptionenwährend der letzten 2000 Jahre in einem 724 m langen Eiskern, gebohrt im Zentrum der Eiskappe Akademii Nauk (Sewernaja Semlja, Russische Arktis). Der Vergleich mit der längsten verfügbaren meteorologischen Temperaturmessreihe der Region (Vardø, Nord-Norwegen) zeigt, dass die δ18O Daten von AkademiiNaukals proxies der Temperatur gut geeignet sind und damit eine Rekonstruktion mittlerer Jahrestemperaturen möglich machen. Kritisch ist dabei die Datierung des Eiskerns, die nicht durch übliche Fließmodelle möglich ist. Die Eiskappe hat sich, zumindest in dem hier untersuchten Zentralteil, nicht im dynamischen Gleichgewicht befunden, was aus der Tiefenlage von vulkanischen Horizonten bekannten Alters abzulesen ist.

Gute Übereinstimmung zeigen die δ18O Reihen von Akademii Nauk und Austfonna (Svalbard) wobei die letztere nur 800 Jahre zurück reicht. Typisch für beide Zeitreihen sind ein absolutes Temperaturminimum um 1800 und eine Erwärmung im frühen 20. Jahrhundert, die auf Svalbard, Sewernaja Semlja und in Nord-Norwegen in 2 Phasen verlief, was in anderen arktischen Regionen so nicht beobachtet wurde.





Die Sauerstoffdaten von Akademii Nauk spiegeln regionale Besonderheiten wieder und weichen zum Teil erheblich von Rekonstruktionen der oberflächennahen Lufttemperatur der Gesamtarktis ab. Ein mittelalterliches Klimaoptimum und der Beginn der Kleinen Eiszeit treten in der δ18O Reihe von Akademii Nauk nicht deutlich hervor.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 PRE-GLACIAL TO GLACIAL SEDIMENTATION OF THE AMUNDSEN

SEA EMBAYMENT SHELF, WEST ANTARCTICA, FROM SEISMIC

SURVEYING

–  –  –

Studies of the sedimentary architecture and characteristics of Antarctic shelves provide clues of past ice sheet advance-retreat cycles and help improve constraints for paleo-ice dynamic models since early glacial periods. A first seismostratigraphic analysis of the Amundsen Sea Embayment shelf and slope of West Antarctica reveals insights into the structural architecture of the continental shelf and slope and shows stages of sediment deposition, erosion and transport history from pre-glacial times to early glaciation and to the last glacial periods. The shelf geometry consists of a large pre- and syn-rift basin in the middle shelf region between outcropping basement of the inner shelf and basement ridge and highs of the outer shelf. A middle shelf sub-basin exists which can be associated with motion along an early West Antarctic Rift System branch. At least 4 km of pre-glacial strata has been eroded from the present inner shelf and coastal hinterland since the onset of glaciation by ice sheet advances. Parts of the eroded sediments deposited as a progradational wedge extending the outer shelf by 25 to 65 km oceanward of the preglacial shelf-break. Comparing the observed seismic characteristics with that of other Antarctic shelf sequences, we assign an Early Cretaceous age for bottom sedimentary unit ASS-1, a Late Cretaceous to Oligocene age for unit ASS-2, an Early to Mid-Miocene age for unit ASS-3, a Mid-Miocene age for unit ASS-4, a Late Miocene to Early Pliocene age for unit ASS-5, and a Pliocene to Pleistocene age for the top unit ASS-6. The survival of buried grounding zone wedges in the upper part of unit ASS-5 of the outer shelf is consistent with the onset of a long warming phase and a retreated ice sheet in the early Pliocene as observed for the Ross Sea shelf and predicted by paleo-ice sheet models. Our data also reveal that the paleo-paths of central Pine Island Trough system have remained in stationary positions across the middle and outer shelf since early glacial advances. This study and its stratigraphic constraints will serve as a basis for future drilling operations required for an improved understanding of processes and mechanisms leading to West Antarctic Ice Sheet retreats as presently observed in high rate for the Amundsen Sea Embayment.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 PALEO-DYNAMICS OF THE WEST ANTARCTIC ICE SHEET FROM

PROCESSES OBSERVED ALONG THE PACIFIC MARGIN

–  –  –

Data from sparsely existing drill information and numerical model simulations suggest that the West Antarctic Ice Sheet (WAIS) has behaved in a highly dynamic fashion in response to climatic variations. The analyses of drill cores from the Ross Sea shelf, for instance, infer that the WAIS underwent partial or full collapses in Pliocene times, and possible in the Miocene, when atmospheric carbon dioxide and temperature levels reached and exceeded those predicted for the next centuries. The collection of substantial seismic and other geophysical data as well as sediment cores along the West Antarctic margin from the Ross Sea to the Amundsen and Bellingshausen Sea in the recent years allows a first quantitative comparison of glacially influenced sedimentary transport and deposition processes from shelves to the continental rise of the southernmost Pacific. Sediment drift deposits of the continental rise document stages of particular dynamic bottom-currents and associated sedimentary transport activities. Drifts in the Ross Sea deep-sea record support an inferred Oligocene WAIS expansion to the outer shelf. Observations from the Amundsen Sea indicate bottom-current activity and hence a cold climate for the late Paleogene in an area, which today lies under the influence of Antarctic Bottom Water originating in the Ross Sea. The generation of drift bodies is accompanied by the occurrence of mass transport deposits leading to the identification of a phase of strong ice sheet expansion (15-4 Ma), which was followed by less material input during the last 4 m.y.

due to a change in ice regime from wet-based to dry-based.

A first seismostratigraphic analysis of the Amundsen Sea Embayment shelf reveals insights into the structural architecture and shows stages of sediment deposition, erosion and transport history from pre-glacial times to early glaciation and to the last glacial periods. At least 4 km of pre-glacial strata has been eroded from the present inner shelf and coastal hinterland since the onset of glaciation by ice sheet advances.

The survival of buried grounding zone wedges in the upper part of the outer shelf is consistent with the onset of a long warming phase and a retreated ice sheet in the early Pliocene as observed for the Ross Sea shelf and predicted by paleo-ice sheet models. These studies and their stratigraphic constraints will serve as a basis for future drilling operations required for an improved understanding of processes leading to West Antarctic Ice Sheet retreats mechanisms.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 COASTAL POLYNYAS IN THE SOUTHWESTERN WEDDELL SEA:

INFLUENCE ON HEAT FLUX AND SEA ICE FORMATION

–  –  –

Coastal polynyas open where the sea ice is driven away from the coastline, usually by strong off-shore winds. The resulting reduction in ice cover enables very strong heat fluxes to the atmosphere throughout the winter months and results in exceptionally high freezing rates. Therefore coastal polynyas have often been referred to as ‘ice factories’.

We investigate the coastal polynyas in the southwestern Weddell Sea with the Finite Element Sea ice-Ocean Model (FESOM) which is a coupled system of a primitiveequation, hydrostatic ocean model and a dynamic-thermodynamic sea ice model.

The global, unstructured grid features a horizontal resolution of up to 3 km along the southwestern Weddell Sea coastline and 37 depth levels of which 6 are within the uppermost 100 m. The model was initialized on 01.01.1980 with data from the Polar Hydrographic Climatology and run using boundary conditions from the NCEP/NCAR Reanalysis. The period 1990-2009 is used for analysis.

During the average winter season (May-September) we find coastal polynyas covering 9000 km2, with a mean heat flux of 370 W/m2 to the atmosphere (thereof 61% sensible, 24% latent, 16% longwave and -1.5% shortwave). 50 W/m2 are supplied by cooling the water column and the remainder induces a sea ice production of 9 cm/d (in total 1·1011 m3/season). However, momentary values can differ far from the mean and interannual variability is strong. The robustness of our results was tested using different forcing data sets and while locally strong variations appear, the large-scale results are consistent.

"Changing Polar Regions" - 25th International Congress on Polar Research 2013 DENSE SHELF WATER FORMATION IN THE SOUTHWESTERN

WEDDELL SEA AND THE ROLE OF COASTAL POLYNYAS

–  –  –

For the formation of Antarctic Bottom Water, for which the Weddell Sea is considered a major source region, the salinity-enriched dense shelf water is a necessary ingredient. Dense shelf water is produced during winter on the Antarctic continental shelves by cooling and brine-rejection in the sea ice formation process. Coastal polynyas – due to their reduced ice cover – feature high freezing rates and thus are of great influence on the dense shelf water production.

We investigate processes in the southwestern Weddell Sea with the Finite Element Sea-ice Ocean Model (FESOM), a combination of a primitive-equation, hydrostatic ocean model and a dynamic-thermodynamic sea ice model. We use a global, unstructured grid that features a horizontal resolution of up to 3 km along the southwestern Weddell Sea coastline and 37 depth levels with increasing resolution toward the surface. The model was initialized on 01/01/1980 with data from the Polar Hydrographic Climatology and forced with daily NCEP/NCAR Reanalysis data.

The analysis of the years 1990-2009 gives 2.5 kg m-2d-1 as a mean seasonal (MaySeptember) salt input from sea ice formation (9 cm d-1) in the southwestern Weddell Sea polynyas. Therefore a seasonal increase of 0.3 psu occurs in the bottom salinity at the Ronne Ice Shelf front and 5·104 km3 of dense shelf water are produced.



Pages:     | 1 |   ...   | 3 | 4 || 6 | 7 |   ...   | 24 |


Similar works:

«3-001 MØDET ONSDAG, DEN 25. SEPTEMBER 2002 SITZUNG AM MITTWOCH, 25. SEPTEMBER 2002 ΣΥΝΕ∆ΡΙΑΣΗ ΤΗΣ ΤΕΤΑΡΤΗΣ 25 ΣΕΠΤΕΜΒΡΙΟΥ 2002 SITTING OF WEDNESDAY, 25 SEPTEMBER 2002 SESIÓN DEL MIÉRCOLES, 25 DE SEPTIEMBRE DE 2002 SÉANCE DU MERCREDI 25 SEPTEMBRE 2002 SEDUTA DI MERCOLEDI' 25 SETTEMBRE 2002 VERGADERING VAN WOENSDAG 25 SEPTEMBER 2002 SESSÃO DE QUARTA-FEIRA, 25 DE SETEMBRO DE 2002 ISTUNTO KESKIVIIKKONA 25. SYYSKUUTA 2002 SAMMANTRÄDET ONSDAG, DEN 25 SEPTEMBER...»

«OCTOBER 2015 Whyalla Vintage & Classic Car Club Inc. PO BOX 2288, WHYALLA NORRIE, SA, 5608 Email address; whyallavccc@hotmail.com. Website; Whyallavcc.com Singapore Street Cars A couple of the many Lamborghinis' seen on the streets of Singapore. All the wealthy “lads” come out to play particularly during the run up to the Formula 1 held in September. Also “common” are the latest from Bentley, Jaguar, Mercedes, Ferrari, McLaren and Porsche, as well as the top of the line from Audi and...»

«PRINT April 2016 Wimborne Minster Parish Magazine No. 356 At the Minster Sunday services 8.00 am Holy Communion 9.45 am Parish Eucharist 11.15 am Informal Communion (1st Sunday in month) Matins (2nd Sunday in month) Informal Service (3rd Sunday in month) 12.00 noon Holy Communion (2nd Sunday in month) 6.30 pm Evensong Weekday services Tuesday 8.00 am Holy Communion (Trinity Chapel) Thursday 9.30 am Holy Communion (Trinity Chapel) Friday 11.00 am Holy Communion at St Margaret’s Saturday 9.15...»

«Publié dans Bulletin VALS-ASLA (Association suisse de linguistique appliquée) 83-2, 33-52, 2006 qui doit être utilisée pour toute référence à ce travail Orthographe, légitimation et construction des publics: débats idéologiques et linguistiques autour de la récente réforme de l’orthographe allemande1 Sally JOHNSON Department of Linguistics and Phonetics, School of Modern Languages and Cultures, University of Leeds, UK-Leeds LS2 9JT; s.a.johnson@leeds.ac.uk When the recent reform...»

«PÁZMÁNY PÉTER KATOLIKUS EGYETEM, HITTUDOMÁNYI KAR Krisztus követése az önkiüresítésben és a fölmagasztalásban A Filippi levél, mint egységes teológiai koncepció Doktori disszertáció Témavezető: Dr. Tarjányi Béla professzor Szerző: Harmai Gábor BUDAPEST, 2004 -2Tartalomjegyzék 1. BEVEZETÉS 2. A FILIPPI LEVÉLRŐL ÁLTALÁBAN 2.1 MÓDSZERTANI MEGJEGYZÉSEK 2.2 A LEVÉL KELETKEZÉSÉNEK KÖRÜLMÉNYEI 2.2.1 A levél szerzője 2.2.2 A levél címzettjei 2.2.3 A levél...»

«    The Use of the Anecdote in the Critical Study of Aboriginal Literature A Project submitted to the College of Graduate Studies and Research in Partial Fulfillment of the Requirements for the Degree of Masters of Arts in the Department of English University of Saskatchewan Saskatoon By Robyn Moore Copyright, Robyn Moore, November 2009. All Rights Reserved.     PERMISSION TO USE In presenting this thesis/dissertation in partial fulfillment of the requirements for a Postgraduate degree from...»

«DAS NEULIBERTÄRE MANIFEST Samuel Edward Konkin III Samuel Edward Konkin III -2Das Neulibertäre Manifest 1. Auflage: Anarchosamisdat Press – 1980 2. Auflage: KoPubCo – 1983 3. (Gedenk-)Auflage: Foundation for Social Justice – 28. März 2004 4. (25. Jubiläums-)Auflage: KoPubCo – 2006 Deutsche Übersetzung – Januar 2007 -3Samuel Edward Konkin III Widmung Für Chris R. Tame, der mir sagte, „Du sollst nicht das Richtige herausfinden, Du sollst es aufschreiben!“ Danksagungen vor...»

«TransmissionCode 2007 – Anhang D2 Teil 2 TransmissionCode 2007 Anhang D2 Teil 2 Anforderungen für die Umsetzung des SRL-Poolkonzepts zwischen ÜNB und Anbietern Anbieteranforderungen SRL-Poolkonzept November 2009 © Forum Netztechnik/Netzbetrieb im VDE (FNN) Bismarckstr. 33, 10625 Berlin Telefon: + 49 (0) 30 3838687 0 Fax: + 49 (0) 30 3838687 7 E-Mail: fnn@vde.com www.vde.com/fnn Internet: © Forum Netztechnik/Netzbetrieb im VDE (FNN) November 2009 Seite 1 von 47 TransmissionCode 2007 –...»

«Positive Vibes Entertainment – 701-A South Military Highway, Virginia Beach, VA 23464 757-248-3820 Positive Vibes Wedding Accessories Professional D.J. & Emcee Services Office (757)248-3820, Fax 1-757-941-7152 Use All Numbers, E-Mail: info@positivevibes.net www.positivevibes.net //_ _To: The staff of Positive Vibes Inc.From: Peace and Blessings, Hopefully this information packet will be helpful in the preparations for your function. This packet will provide all our basic information and our...»

«Application Number: 2012/1472 Location: Severn Trent Water PLC, Stoke Lane, Stoke Bardolph NOTE: This map is provided only for purposes of site location and should not be read as an up to date representation of the area around the site. Reproduced with the permission of the Controller of H.M.S.O. Crown Copyright License No. LA 100021248 Unauthorised reproduction infringes Crown copyright and may lead to prosecution of civil proceedings Report to Planning Committee Application Number: 2012/1472...»

«RFP CONTRACTOR City of Rialto Purchasing Division Purchasing Manager: William Jernigan Phone: (909) 820-2570 Fax: (909) 820-2600 Email: procurement@rialtoca.gov REQUEST FOR PROPOSAL #15-048 Auto Body Repair Services Closing Date: January 15, 2015, 4:00 P.M. RFP Number: 15-048 Due Date: January 15, 2015 Time: 4:00 P.M. Project: Auto Body Repair Services The prospective supplier shall submit a fully executed sealed proposal, to be received no later than 4:00 P.M., January 15, 2015. Sealed...»

«G C/43/4 Rev. ORIGINAL: englisch DATUM: 22. Oktober 2009 INTERNATIONALER VERBAND ZUM SCHUTZ VON PFLANZENZÜCHTUNGEN GENF DER RAT Dreiundvierzigste ordentliche Tagung Genf, 22. Oktober 2009 PROGRAMM UND HAUSHALTSPLAN FÜR DIE RECHNUNGSPERIODE 2010-2011 vom Rat angenommen 1. Auf seiner dreiundvierzigsten ordentlichen Tagung am 22. Oktober 2009 in Genf prüfte der Rat das Dokument C/43/4 „Entwurf eines Programms und Haushaltsplans für die Rechnungsperiode 2010-2011“ und billigte: a) die in...»





 
<<  HOME   |    CONTACTS
2016 www.abstract.xlibx.info - Free e-library - Abstract, dissertation, book

Materials of this site are available for review, all rights belong to their respective owners.
If you do not agree with the fact that your material is placed on this site, please, email us, we will within 1-2 business days delete him.