Helle Astrid Kjær

Helle Astrid Kjær

Associate Professor


  1. 2020
  2. 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 conferenceConference abstract for conferenceResearchpeer-review

  3. 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 journalJournal articlepeer-review

  4. 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 journalJournal articlepeer-review

  5. 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 journalJournal articlepeer-review

  6. 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 journalJournal articlepeer-review

  7. 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, Parrenin, F., Buizert, C., McConnell, J. R., Severi, M., Mulvaney, R. & Bigler, M., 19 Aug 2020, In: Climate of the Past. 16, p. 1565-1580 15 p.

    Research output: Contribution to journalJournal articlepeer-review

  8. 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, Parrenin, F., Buizert, C., McConnell, J. R., Severi, M., Mulvaney, R. & Bigler, M., 6 Apr 2020, 32 p. Copernicus/EGU.

    Research output: Other contributionResearch

  9. 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 contributionResearch

  10. 2019
  11. 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. 2019-2030

    Research output: Contribution to journalJournal articlepeer-review

  12. 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. 2031-2051

    Research output: Contribution to journalJournal articlepeer-review

  13. 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 journalJournal articlepeer-review

  14. 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, Neff, P. D., Pyne, R. L., Simonsen, M. F., Svensson, Anders, Tuohy, A., Waddington, E. D. & Wheatley, S., 10 Apr 2019, In: Climate of the Past. 15, 2, p. 751-779 29 p.

    Research output: Contribution to journalJournal articlepeer-review

  15. 2018
  16. 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, Dadic, R., Kjær, Helle Astrid, Kurbatov, A., Zhang, D., Waddington, E. D., Baccolo, G., Beers, T., Brightley, H. J., Carter, L., Clemens-Sewall, D., Ciobanu, V. G., Delmonte, B., Eling, L., Ellis, A., Ganesh, S., Golledge, N. R., Haines, S., Handley, M., Hawley, R. L., Hogan, C. M., Johnson, K. M., Korotkikh, E., Lowry, D. P., Mandeno, D., McKay, R. M., Menking, J. A., Naish, T. R., Noerling, C., Simonsen, M. & Wang, S., 21 Feb 2018, In: Climate of the Past. 14, 2, p. 193-214

    Research output: Contribution to journalJournal articlepeer-review

  17. 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 journalJournal articlepeer-review

  18. 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, Audette, Y., Bertrand, I., Beyhaut, E., Boitt, G., Bradshaw, N., Brearley, C. A., Bruulsema, T. W., Cozzolino, V., Duran, P. C., Mora, M. L., de Menezes, A. B., Dodd, R. J., Dunfield, K., Engl, C., Frazao, J. J., Jimenez, J. L. G., Harrison, A. F., Hou, E. Q., Johnes, P. J., Kaiser, K., Kjær, Helle Astrid, Klumpp, E., Lamb, A. L., Macintosh, K. A., Nelson, L. A., Tibbett, M., Wallander, H., Wang, L., Wasaki, J. & Haygarth, P. M., Jun 2018, In: Plant and Soil. 427, 1-2, SI, p. 209-211

    Research output: Contribution to journalJournal articlepeer-review

  19. 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 proceedingBook chapterEducation

  20. 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. 1-11

    Research output: Contribution to journalJournal articlepeer-review

  21. 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, Winstrup, M., Wegner, A., Twarloh, B., Wolff, K., Schmidt, K., Goto-Azuma, K., Kuramoto, T., Hirabayashi, M., Uetake, J., Zheng, J., Bourgeois, J., Fisher, D., Zhiheng, D., Xiao, C., Legrand, M., Spolaor, A., Gabrieli, J., Barbante, C., Kang, J. -., Hur, S. D., Hong, S. B., Hwang, H. J., Hong, S., Hansson, M., Iizuka, Y., Oyabu, I., Muscheler, R., Adolphi, F., Maselli, O. & McConnell, J., 16 Apr 2018, In: Nature Communications. 9, 1476.

    Research output: Contribution to journalJournal articlepeer-review

  22. 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. 601-608

    Research output: Contribution to journalJournal articlepeer-review

  23. 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 journalJournal articlepeer-review

  24. 2017
  25. 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, Dadic, R., Kjær, Helle Astrid, Kurbatov, A., Zhang, D., Waddington, E. D., Baccolo, G., Beers, T., Brightley, H. J., Carter, L., Clemens-Sewall, D., Ciobanu, V. G., Delmonte, B., Eling, L., Ellis, A. A., Ganesh, S., Golledge, N. R., Haines, S. A., Handley, M., Hawley, R. L., Hogan, C. M., Johnson, K. M., Korotkikh, E., Lowry, D. P., Mandeno, D., McKay, R. M., Menking, J. A., Naish, T. R., Noerling, C., Ollive, A., Orsi, A., Proemse, B. C., Pyne, A. R., Pyne, R. L., Renwick, J., Scherer, R. P., Semper, S., Simonsen, M., Sneed, S. B., Steig, E. J., Tuohy, A., Venugopal, A. U., Valero-Delgado, F., Venkatesh, J., Wang, F., Wang, S., Winski, D. A., Winton, V. H. L., Whiteford, A., Xiao, C., Yang, J. & Zhang, X., 1 Aug 2017, In: Climate of the Past Discussions. 31 p.

    Research output: Contribution to journalJournal articlepeer-review

  26. 2016
  27. 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. 11-20

    Research output: Contribution to journalJournal articlepeer-review

  28. 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. 10485-10493

    Research output: Contribution to journalJournal articlepeer-review

  29. 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 journalJournal articlepeer-review

  30. 2015
  31. Published

    The summer 2012 Greenland heat wave: In situ and remote sensing observations of water vapor isotopic composition during an atmospheric river event

    Bonne, J., Steen-Larsen, H. C., Risi, C., Werner, M., Sodemann, H., Lacour, J., Fettweis, X., Cesana, G., Delmotte, M., Cattani, O., Vallelonga, P. T., Kjær, Helle Astrid, Clerbaux, C., Svienbjörndóttir, Á. E. & Masson-Delmotte, V., 1 Apr 2015, In: Journal of Geophysical Research: Biogeosciences. 120, 7, p. 2970-2989

    Research output: Contribution to journalJournal articlepeer-review

ID: 33355865