Helle Astrid Kjær
Associate Professor
Physics of Ice, Climate and Earth
Tagensvej 16
2200 København N.
- 2021
- Published
Melt in the Greenland EastGRIP ice core reveals Holocene warming events
Westhoff, Julien, Sinnl, Giulia, Svensson, Anders, Freitag, J., Kjær, Helle Astrid, Vallelonga, P., Vinther, Bo Møllesøe, Kipfstuhl, S., Dahl-Jensen, Dorthe & Weikusat, I., 16 Jul 2021, 36 p. Copernicus/EGU.Research output: Other contribution › Research
- 2020
- Published
New data from the 40 year old Dye3 core
Blunier, Thomas, Venkatesh, J., Soestmeyer, D. A., Liisberg, J. B., Rhodes, R., Menking, J. A., Severinghaus, J. P., Harlan, Meg, Kjær, Helle Astrid & Vallelonga, P., 23 Mar 2020. 1 p.Research output: Contribution to conference › Conference abstract for conference › Research › peer-review
- Published
Surface velocity of the Northeast Greenland Ice Stream (NEGIS): assessment of interior velocities derived from satellite data by GPS
Hvidberg, Christine Schøtt, Grinsted, Aslak, Dahl-Jensen, Dorthe, Khan, S. A., Kusk, A., Andersen, Jonas Kvist, Neckel, N., Solgaard, Anne Munck, Karlsson, N. B., Kjær, Helle Astrid & Vallelonga, P., 22 Oct 2020, In: Cryosphere. 14, 10, p. 3487-3502 16 p.Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Past perspectives on the present era of abrupt Arctic climate change
Jansen, E., Christensen, Jens Hesselbjerg, Dokken, T., Nisancioglu, K. H., Vinther, Bo Møllesøe, Capron, E., Guo, C., Jensen, M. F., Langen, P. L., Pedersen, R. A., Yang, S., Bentsen, M., Kjær, Helle Astrid, Sadatzki, H., Sessford, E. & Stendel, M., 1 Aug 2020, In: Nature climate change. 10, 8, p. 714-721 8 p.Research output: Contribution to journal › Journal article › Research › peer-review
- Published
A first chronology for the East Greenland Ice-core Project (EGRIP) over the Holocene and last glacial termination
Mojtabavi, S., Wilhelms, F., Cook, Eliza, Siwan M., D., Sinnl, Giulia, Skov Jensen, M., Dahl-Jensen, Dorthe, Svensson, Anders, Vinther, Bo Møllesøe, Kipfstuhl, S., Gwydion, J., Karlsson, N. B., Henrique Faria, S., Gkinis, Vasileios, Kjær, Helle Astrid, Erhardt, T., Berben, S. M. P., Nisancioglu, K. H., Koldtoft, Iben & Rasmussen, Sune Olander, 27 Sep 2020, In: Climate of the Past. 16, 6, p. 2359-2380 21 p.Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Rapid reductions and millennial-scale variability in Nordic Seas sea ice cover during abrupt glacial climate changes
Sadatzki, H., Maffezzoli, N., Dokken, T. M., Simon, M. H., Berben, S. M. P., Fahl, K., Kjær, Helle Astrid, Spolaor, A., Stein, R., Vallelonga, P., Vinther, Bo Møllesøe & Jansen, E., 24 Nov 2020, In: Proceedings of the National Academy of Sciences of the United States of America. 117, 47, p. 29478-29486 9 p.Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Bipolar volcanic synchronization of abrupt climate change in Greenland and Antarctic ice cores during the last glacial period
Svensson, A., Dahl-Jensen, D., Steffensen, J. P., Blunier, T., Rasmussen, S. O., Vinther, B. M., Vallelonga, P. T., Capron, E., Gkinis, V., Cook, E., Kjær, H. A., Muscheler, R., Kipfstuhl, S., Wilhelms, F., Stocker, T. F., Fischer, H., Adolphi, F., Erhardt, T., Sigl, M., Landais, A. & 6 others, , 19 Aug 2020, In: Climate of the Past. 16, p. 1565-1580 15 p.Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Supplementary material to "Bipolar volcanic synchronization of abrupt climate change in Greenland and Antarctic ice cores during the last glacial period"
Svensson, A., Dahl-Jensen, D., Steffensen, J. P., Blunier, T., Rasmussen, S. O., Vinther, B. M., Vallelonga, P., Capron, E., Gkinis, V., Cook, E., Kjær, H. A., Muscheler, R., Kipfstuhl, S., Wilhelms, F., Stocker, T. F., Fischer, H., Adolphi, F., Erhardt, T., Sigl, M., Landais, A. & 6 others, , 6 Apr 2020, 32 p. Copernicus/EGU.Research output: Other contribution › Research
- Published
Assessing surface-exposed old ice along the Greenland Ice Sheet margin as an analogue for the Northern Polar Layered Deposits on Mars
Yoldi, Zuriñe, Hvidberg, Christine Schøtt, Svensson, Anders, Vallelonga, P. T. & Kjær, Helle Astrid, 8 Oct 2020, 3 p. Göttingen, Germany : Europlanet Science Congress.Research output: Other contribution › Research
- 2019
- Published
Holocene atmospheric iodine evolution over the North Atlantic
Corella, J. P., Maffezzoli, N., Cuevas, C. A., Vallelonga, P., Spolaor, A., Cozzi, G., Muller, J., Vinther, Bo Møllesøe, Barbante, C., Kjær, Helle Astrid, Edwards, R. & Saiz-Lopez, A., 18 Dec 2019, In: Climate of the Past. 15, 6, p. 2019-2030Research output: Contribution to journal › Journal article › Research › peer-review
- Published
A 120 000-year record of sea ice in the North Atlantic?
Maffezzoli, N., Vallelonga, P., Edwards, R., Saiz-Lopez, A., Turetta, C., Kjær, Helle Astrid, Barbante, C., Vinther, Bo Møllesøe & Spolaor, A., 19 Dec 2019, In: Climate of the Past. 15, 6, p. 2031-2051Research output: Contribution to journal › Journal article › Research › peer-review
- Published
East Greenland ice core dust record reveals timing of Greenland ice sheet advance and retreat.
Simonsen, M. F., Baccolo, G., Blunier, Thomas, Borunda, A., Delmonte, B., Frei, Robert, Goldstein, S., Grinsted, Aslak, Kjær, Helle Astrid, Sowers, T., Svensson, Anders, Vinther, Bo Møllesøe, Vladimirova, D., Winckler, G., Winstrup, M. & Vallelonga, P., 3 Oct 2019, In: Nature Communications. 10, 8 p., 4494.Research output: Contribution to journal › Journal article › Research › peer-review
- Published
A 2700-year annual timescale and accumulation history for an ice core from Roosevelt Island, West Antarctica
Winstrup, M., Vallelonga, P., Kjaer, H. A., Fudge, T. J., Lee, J. E., Riis, M. H., Edwards, R., Bertler, N. A. N., Blunier, T., Brook, E. J., Buizert, C., Ciobanu, G., Conway, H., Dahl-Jensen, D., Ellis, A., Emanuelsson, B. D., Hindmarsh, R. C. A., Keller, E. D., Kurbatov, A. V., Mayewski, P. A. & 7 others, , 10 Apr 2019, In: Climate of the Past. 15, 2, p. 751-779 29 p.Research output: Contribution to journal › Journal article › Research › peer-review
- 2018
- Published
The Ross Sea Dipole - temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years
Bertler, N. A. N., Conway, H., Dahl-Jensen, D., Emanuelsson, D. B., Winstrup, M., Vallelonga, P. T., Lee, J. E., Brook, E. J., Severinghaus, J. P., Fudge, T. J., Keller, E. D., Baisden, W. T., Hindmarsh, R. C. A., Neff, P. D., Blunier, T., Edwards, R., Mayewski, P. A., Kipfstuhl, S., Buizert, C., Canessa, S. & 30 others, , 21 Feb 2018, In: Climate of the Past. 14, 2, p. 193-214Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Rapid increase in atmospheric iodine levels in the North Atlantic since the mid-20th century
Cuevas, C. A., Maffezzoli, N., Corella, J. P., Spolaor, A., Vallelonga, P. T., Kjær, Helle Astrid, Simonsen, M. F., Winstrup, M., Vinther, Bo Møllesøe, Horvat, C., Fernandez, R. P., Kinnison, D., Lamarque, J., Barbante, C. & Saiz-Lopez, A., 1 Dec 2018, In: Nature Communications. 9, 1452.Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Organic phosphorus in the terrestrial environment: a perspective on the state of the art and future priorities
George, T. S., Giles, C. D., Menezes-Blackburn, D., Condron, L. M., Gama-Rodrigues, A. C., Jaisi, D., Lang, F., Neal, A. L., Stutter, M. I., Almeida, D. S., Bol, R., Cabugao, K. G., Celi, L., Cotner, J. B., Krueger, J., Plassard, C., Rosling, A., Darch, T., Fraser, T., Tamburini, F. & 30 others, , Jun 2018, In: Plant and Soil. 427, 1-2, SI, p. 209-211Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Laboratory supervision of MSc projects -Qualitative interviews, thematic analysis, and recommendations for the supervisor
Kjær, Helle Astrid, 23 May 2018, Improving University Science Teaching and Learning Pedagogical Projects 2018. Institut for Naturfagenes Didaktik ed. København, Danmark: Københavns Universitet, Vol. 12. p. 91-105 (Improving University Science Teaching and Learning - Pedagogical Projects).Research output: Chapter in Book/Report/Conference proceeding › Book chapter › Education
- Published
A novel approach to process brittle ice for continuous flow analysis of stable water isotopes
Pyne, R. L., Keller, E. D., Canessa, S., Bertler, N. A., Pyne, A. R., Pyne, A. R., Mandeno, D., Vallelonga, P. T., Semper, S., Kjær, Helle Astrid, Hutchison, E. & Baisden, W. T., 16 Mar 2018, In: Journal of Glaciology. 64, 243, p. 1-11Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene
Schupbach, S., Fischer, H., Bigler, M., Erhardt, T., Gfeller, G., Leuenberger, D., Mini, O., Mulvaney, R., Abram, N. J., Fleet, L., Frey, M. M., Thomas, E., Svensson, A., Dahl-Jensen, D., Kettner, E., Kjaer, H., Seierstad, I., Steffensen, J. P., Rasmussen, S. O., Vallelonga, P. & 30 others, , 16 Apr 2018, In: Nature Communications. 9, 1476.Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Particle shape accounts for instrumental discrepancy in ice core dust size distributions
Simonsen, M. F., Cremonesi, L., Baccolo, G., Bosch, S., Delmonte, B., Erhardt, T., Kjær, Helle Astrid, Potenza, M., Svensson, Anders & Vallelonga, P., 3 May 2018, In: Climate of the Past. 14, 5, p. 601-608Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Afslørende kemi i Grønlands og Antarktis' iskerner
Svensson, Anders & Kjær, Helle Astrid, 1 Jun 2018, In: Dansk Kemi. 9, p. 18-21 3 p.Research output: Contribution to journal › Journal article › Research › peer-review
- 2017
- Published
The Ross Sea Dipole – Temperature, Snow Accumulation and Sea Ice Variability in the Ross Sea Region, Antarctica, over the Past 2,700 Years
Bertler, N. A. N., Conway, H., Dahl-Jensen, D., Emanuelsson, D. B., Winstrup, M., Vallelonga, P. T., Lee, J. E., Brook, E. J., Severinghaus, J. P., Fudge, T. J., Keller, E. D., Baisden, W. T., Hindmarsh, R. C. A., Neff, P. D., Blunier, T., Edwards, R., Mayewski, P. A., Kipfstuhl, S., Buizert, C., Canessa, S. & 51 others, , 1 Aug 2017, In: Climate of the Past Discussions. 31 p.Research output: Contribution to journal › Journal article › Research › peer-review
- 2016
- Published
A High-Resolution Continuous Flow Analysis System for Polar Ice Cores
Dallmayr, R., Goto-Azuma, K., Kjær, Helle Astrid, Azuma, N., Takata, M., Schüpbach, S. & Hirabayashi, M., 2016, In: Bulletin of Glaciological Research. 34, p. 11-20Research output: Contribution to journal › Journal article › Research › peer-review
- Published
An Optical Dye Method for Continuous Determination of Acidity in Ice Cores
Kjær, Helle Astrid, Vallelonga, P. T., Svensson, Anders, Kristensen, M. E., Tibuleac, C., Winstrup, M. & Kipfstuhl, S., 1 Sep 2016, In: Environmental Science & Technology. 50, 19, p. 10485-10493Research output: Contribution to journal › Journal article › Research › peer-review
- Published
Ice core evidence for a 20th century increase in surface mass balance in coastal Dronning Maud Land, East Antarctica
Philippe, M., Tison, J., Fjosne, K., Hubbard, B., Kjær, Helle Astrid, Lenaerts, J. T. M., Drews, R., Sheldon, S. G., De Bondt, K., Claeys, P. & Pattyn, F., 2016, In: Cryosphere. 10, 5, p. 2501-2516 16 p.Research output: Contribution to journal › Journal article › Research › peer-review
ID: 33355865
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On the occurrence of annual layers in Dome Fuji ice core early Holocene ice
Research output: Contribution to journal › Journal article › Research › peer-review
Published -
176
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Greenland records of aerosol source and atmospheric lifetime changes from the Eemian to the Holocene
Research output: Contribution to journal › Journal article › Research › peer-review
Published -
137
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Rapid increase in atmospheric iodine levels in the North Atlantic since the mid-20th century
Research output: Contribution to journal › Journal article › Research › peer-review
Published