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12 results on '"Pedersen, Rasmus Anker"'

1. Sammenligning af klimafaktorer udarbejdet af Spildevandskomiteen og Klimaatlas og anbefaling af praksis for dimensionering og analyse af afløbssystemer

Author

Gregersen, Ida Bülow, Arnbjerg-Nielsen, Karsten, and Pedersen, Rasmus Anker

Abstract

Dette fælles notat fra Spildevandskomiteen (SVK) og DMI sammenligner og forklarer forskellene på de klimafaktorer for ekstremnedbør, der findes i SVKs Skrift 30 og DMIs Klimaatlas. Samlet set, anbefales det fortsat at benytte de branchespecifikke anbefalinger fra SVKs skrifter i forbindelse med dimensionering af afløbssystemer. Sammenligningen af klimafaktorerne viser, at SVKs nuværende anbefalinger i rimelig grad repræsenterer de nye udledningsscenarier fra Klimaatlas. På lokal skala kan der være mindre forskelle mellem Klimaatlas og SVKs Skrift 30; klimafaktorerne i SVKs anbefalinger er landsdækkende tal baseret på en samlet ekspertvurdering på tværs af udledningsscenarier og modelusikkerheder. Landsdækkende tal anbefales også for lokale projekter. DMI og Spildevandskomiteen vil løbende sikre at det bedst mulige videnskabelige grundlag for klimatilpasning indarbejdes i praksis, og resultaterne fra Klimaatlas vil blive inddraget i en kommende opdatering af klimatilpasningsscenarierne fra Spildevandskomiteen.

Published
2021

2. Evaluation of extreme precipitation over the Nordic region using a convection-permitting regional climate model

Author

Toivonen, Erika, primary, Belušić, Danijel, additional, Thomassen, Emma Dybro, additional, Berg, Peter, additional, Christensen, Ole Bøssing, additional, Dobler, Andreas, additional, Dyrrdal, Anita Verpe, additional, Haugen, Jan Erik, additional, Jylhä, Kirsti, additional, Kjellström, Erik, additional, Landgren, Oskar, additional, Lind, Petter, additional, Lindstedt, David, additional, Matte, Dominic, additional, Mäkelä, Antti, additional, Olsson, Jonas, additional, Pedersen, Rasmus Anker, additional, Wang, Fuxing, additional, and Yang, Wei, additional

Published
2020
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6. Modelling Interglacial Climate:Investigating the Mechanisms of a Warming Climate

Author

Pedersen, Rasmus Anker and Pedersen, Rasmus Anker

Abstract

Past warm climate states could potentially provide information on future global warming. The past warming was driven by changed insolation rather than an increased greenhouse effect, and thus the warm climate states are expected to be different. Nonetheless, the response of the climate system involves some of the same mechanisms in the two climate states. This thesis aims to investigate these mechanisms through climate model experiments. This two-part study has a special focus on the Arctic region, and the main paleoclimate experiments are supplemented by idealized experiments detailing the impact of a changing sea ice cover. The first part focusses on the last interglacial climate (125,000 years before present) which was characterized by substantial warming at high northern latitudes due to an increased insolation during summer. The simulations reveal that the oceanic changes dominate the response at high northern latitudes, while the direct insolation impact is more dominant in the tropics. On Greenland, the simulated warming is low compared to the ice core reconstructions. Surface mass balance calculations indicate that the oceanic conditions favor increased accumulation in the southeast, while the insolation appears to be the dominant cause of the expected ice sheet reduction. The second part explores the atmospheric sensitivity to the location of sea ice loss. Three investigated sea ice scenarios with ice loss in different regions all exhibit substantial near-surface warming, with maximum warming occurring in winter. The three scenarios all affect the climate beyond the Arctic, especially the mid-latitude circulation which is sensitive to the location of the ice loss. Together, the results presented in this thesis illustrate that the changes in the Arctic sea ice cover are important for shaping both past and future warm climate states. Nonetheless, the last interglacial is not an ideal analogue for future climate changes, as the chan

Published
2016

10. How does sea ice influence δ18O of Arctic precipitation?

Author

Faber, Anne-Katrine, Vinther, Bo Møllesøe, Sjolte, Jesper, and Pedersen, Rasmus Anker

Subjects
METEOROLOGICAL precipitation, ATMOSPHERE, SEA surface positioning
Abstract

This study investigates how variations in Arctic sea ice and sea surface conditions influence δ18O of present-day Arctic precipitation. This is done using the model isoCAM3, an isotope-equipped version of the National Center for Atmospheric Research Community Atmosphere Model version 3. Four sensitivity experiments and one control simulation are performed with prescribed sea surface temperature (SST) and sea ice. Each of the four experiments simulates the atmospheric and isotopic response to Arctic oceanic conditions for selected years after the beginning of the satellite era in 1979. Changes in sea ice extent and SSTs have different impacts in Greenland and the rest of the Arctic. The simulated changes in central Arctic sea ice do not influence δ18O of Greenland precipitation, only anomalies of Baffin Bay sea ice. However, this does not exclude the fact that simulations based on other sea ice and sea surface temperature distributions might yield changes in the δ18O of precipitation in Greenland. For the Arctic, δ18O of precipitation and water vapour is sensitive to local changes in sea ice and sea surface temperature and the changes in water vapour are surface based. Reduced sea ice extent yields more enriched isotope values, whereas increased sea ice extent yields more depleted isotope values. The distribution of the sea ice and sea surface conditions is found to be essential for the spatial distribution of the simulated changes in δ18O. [ABSTRACT FROM AUTHOR]

Published
2017
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12. How does sea ice influence δ18O of Arctic precipitation?

Author

Faber, Anne-Katrine, Vinther, Bo Møllesøe, Sjolte, Jesper, and Pedersen, Rasmus Anker

Abstract

This study investigates how variations in Arctic sea ice cover influence δ18O of present day Arctic precipitation. This is done using the model isoCAM3, an isotope-equipped version of the National Center for Atmospheric Research Community Atmosphere Model version. Four sensitivity experiments and one control simulation are performed with prescribed SST and sea ice. Each of the four experiments simulates the atmospheric and isotopic response to Arctic oceanic conditions for selected years after the beginning of the satellite era in 1979. Results show that δ18O of precipitation is sensitive to local changes of sea ice concentration. Reduced sea ice extent yields more enriched isotope values while increased sea ice extent yields more depleted isotope values. The distribution of the sea ice cover is essential for the spatial distribution of the simulated changes in δ18O. The experiments of this study show no changes of δ18O for central Greenland. However, this does not exclude that simulations based on other sea ice distributions might yield changes in Greenland δ18O. [ABSTRACT FROM AUTHOR]

Published
2016
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