Helle Astrid Kjær

Helle Astrid Kjær

Assistant professor


  1. 2019
  2. Published

    East Greenland ice core dust record reveals timing of Greenland ice sheet advance and retreat. / Simonsen, Marius Folden; Baccolo, Giovanni; Blunier, Thomas; Borunda, Alejandra; Delmonte, Barbara; Frei, Robert; Goldstein, Steven ; Grinsted, Aslak; Kjær, Helle Astrid; Sowers, Todd A.; Svensson, Anders; Vinther, Bo Møllesøe; Vladimirova, Diana; Winckler, Gisela; Winstrup, Mai; Vallelonga, Paul Travis.

    In: Nature Communications, Vol. 10, 4494, 03.10.2019.

    Research output: Contribution to journalJournal articleResearchpeer-review

  3. Published

    A 2700-year annual timescale and accumulation history for an ice core from Roosevelt Island, West Antarctica. / Winstrup, Mai; Vallelonga, Paul; Kjaer, Helle A.; Fudge, Tyler J.; Lee, James E.; Riis, Marie H.; Edwards, Ross; Bertler, Nancy A. N.; Blunier, Thomas; Brook, Ed J.; Buizert, Christo; Ciobanu, Gabriela; Conway, Howard; Dahl-Jensen, Dorthe; Ellis, Aja; Emanuelsson, B. Daniel; Hindmarsh, Richard C. A.; Keller, Elizabeth D.; Kurbatov, Andrei V.; Mayewski, Paul A.; Neff, Peter D.; Pyne, Rebecca L.; Simonsen, Marius F.; Svensson, Anders; Tuohy, Andrea; Waddington, Edwin D.; Wheatley, Sarah.

    In: Climate of the Past, Vol. 15, No. 2, 10.04.2019, p. 751-779.

    Research output: Contribution to journalJournal articleResearchpeer-review

  4. 2018
  5. Published

    Afslørende kemi i Grønlands og Antarktis' iskerner. / Svensson, Anders; Kjær, Helle Astrid.

    In: Dansk Kemi, Vol. 9, 01.06.2018, p. 18-21.

    Research output: Contribution to journalJournal articleResearchpeer-review

  6. 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.; 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. Gonzalez; Harrison, A. F.; Hou, E. Q.; Johnes, P. J.; Kaiser, K.; Kjaer, H. A.; Klumpp, E.; Lamb, A. L.; Macintosh, K. A.; Nelson, L. A.; Tibbett, M.; Wallander, H.; Wang, L.; Wasaki, J.; Haygarth, P. M.

    In: Plant and Soil, Vol. 427, No. 1-2, SI, 06.2018, p. 209-211.

    Research output: Contribution to journalJournal articleResearchpeer-review

  7. Published

    Laboratory supervision of MSc projects -Qualitative interviews, thematic analysis, and recommendations for the supervisor. / Kjær, Helle Astrid.

    Improving University Science Teaching and Learning Pedagogical Projects 2018. Vol. 12 Institut for Naturfagenes Didaktik. ed. København, Danmark : Københavns Universitet, 2018. p. 91-105 (Improving University Science Teaching and Learning - Pedagogical Projects).

    Research output: Chapter in Book/Report/Conference proceedingBook chapterEducation

  8. Published

    Particle shape accounts for instrumental discrepancy in ice core dust size distributions. / Simonsen, Marius Folden; Cremonesi, Llorenc; Baccolo, Giovanni; Bosch, Samuel; Delmonte, Barbara; Erhardt, Tobias; Kjaer, Helle Astrid; Potenza, Marco; Svensson, Anders; Vallelonga, Paul.

    In: Climate of the Past, Vol. 14, No. 5, 03.05.2018, p. 601-608.

    Research output: Contribution to journalJournal articleResearchpeer-review

  9. 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.; 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. -H.; 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.

    In: Nature Communications, Vol. 9, 1476, 16.04.2018.

    Research output: Contribution to journalJournal articleResearchpeer-review

  10. Published

    Rapid increase in atmospheric iodine levels in the North Atlantic since the mid-20th century. / Cuevas, Carlos A.; Maffezzoli, Niccolo; Corella, Juan Pablo; Spolaor, Andrea; Vallelonga, Paul Travis; Kjær, Helle Astrid; Simonsen, Marius Folden; Winstrup, Mai; Vinther, Bo Møllesøe; Horvat, Christopher; Fernandez, Rafael P.; Kinnison, Douglas; Lamarque, Jean-Francois; Barbante, Carlo; Saiz-Lopez, Alfonso.

    In: Nature Communications, Vol. 9, 1452, 13.04.2018.

    Research output: Contribution to journalJournal articleResearchpeer-review

  11. Published

    A novel approach to process brittle ice for continuous flow analysis of stable water isotopes. / Pyne, Rebecca L.; Keller, Elizabith D.; Canessa, Silvia; Bertler, Nancy A.; Pyne, Alex R.; Pyne, Alex R.; Mandeno, Darcy; Vallelonga, Paul Travis; Semper, Stefanie; Kjær, Helle Astrid; Hutchison, Ed; Baisden, W. Troy.

    In: Journal of Glaciology, Vol. 64, No. 243, 16.03.2018, p. 1-11.

    Research output: Contribution to journalJournal articleResearchpeer-review

  12. Published

    The Ross Sea Dipole - temperature, snow accumulation and sea ice variability in the Ross Sea region, Antarctica, over the past 2700 years. / Bertler, Nancy A. N.; Conway, Howard; Dahl-Jensen, Dorthe; Emanuelsson, Daniel B.; Winstrup, Mai; Vallelonga, Paul T.; Lee, James E.; Brook, Ed J.; Severinghaus, Jeffrey P.; Fudge, Taylor J.; Keller, Elizabeth D.; Baisden, W. Troy; Hindmarsh, Richard C. A.; Neff, Peter D.; Blunier, Thomas; Edwards, Ross; Mayewski, Paul A.; Kipfstuhl, Sepp; Buizert, Christo; Canessa, Silvia; Dadic, Ruzica; Kjaer, Helle A.; Kurbatov, Andrei; Zhang, Dongqi; Waddington, Edwin D.; Baccolo, Giovanni; Beers, Thomas; Brightley, Hannah J.; Carter, Lionel; Clemens-Sewall, David; Ciobanu, Viorela G.; Delmonte, Barbara; Eling, Lukas; Ellis, Aja; Ganesh, Shruthi; Golledge, Nicholas R.; Haines, Skylar; Handley, Michael; Hawley, Robert L.; Hogan, Chad M.; Johnson, Katelyn M.; Korotkikh, Elena; Lowry, Daniel P.; Mandeno, Darcy; McKay, Robert M.; Menking, James A.; Naish, Timothy R.; Noerling, Caroline; Simonsen, Marius; Wang, Shimeng.

    In: Climate of the Past, Vol. 14, No. 2, 21.02.2018, p. 193-214.

    Research output: Contribution to journalJournal articleResearchpeer-review

  13. 2016
  14. Published

    An Optical Dye Method for Continuous Determination of Acidity in Ice Cores. / Kjær, Helle Astrid; Vallelonga, Paul Travis; Svensson, Anders; Kristensen, Magnus Elleskov; Tibuleac, Catalin; Winstrup, Mai; Kipfstuhl, Seep.

    In: Environmental Science & Technology, Vol. 50, No. 19, 01.09.2016, p. 10485-10493.

    Research output: Contribution to journalJournal articleResearchpeer-review

  15. Published

    A High-Resolution Continuous Flow Analysis System for Polar Ice Cores. / Dallmayr, Remi; Goto-Azuma, Kumiko; Kjær, Helle Astrid; Azuma, Nobuhiko; Takata, Morimasa; Schüpbach, Simon; Hirabayashi, Motohiro.

    In: Bulletin of Glaciological Research, Vol. 34, 2016, p. 11-20.

    Research output: Contribution to journalJournal articleResearchpeer-review

  16. Published

    Ice core evidence for a 20th century increase in surface mass balance in coastal Dronning Maud Land, East Antarctica. / Philippe, Morgane; Tison, Jean-Louis; Fjosne, Karen; Hubbard, Bryn; Kjær, Helle Astrid; Lenaerts, Jan T. M.; Drews, Reinhard; Sheldon, Simon Geoffrey; De Bondt, Kevin; Claeys, Philippe; Pattyn, Frank.

    In: Cryosphere, Vol. 10, No. 5, 2016, p. 2501-2516.

    Research output: Contribution to journalJournal articleResearchpeer-review

  17. 2015
  18. Published

    Greenland ice cores constrain glacial atmospheric fluxes of phosphorus. / Kjær, Helle Astrid; Dallmayr, Remi; Gabrieli, Jacopo; Goto-Azuma, K.; Hirabayashi, M.; Svensson, Anders; Vallelonga, Paul Travis.

    In: Journal of Geophysical Research: Earth Surface, Vol. 120, No. 20, 29.10.2015.

    Research output: Contribution to journalJournal articleResearchpeer-review

  19. Published

    Greenland 2012 melt event effects on CryoSat-2 radar altimetry. / Nilsson, Johan; Vallelonga, Paul; Simonsen, Sebastian B.; Sorensen, Louise Sandberg; Forsberg, Rene; Dahl-Jensen, Dorthe; Hirabayashi, Motohiro; Goto-Azuma, Kumiko; Hvidberg, Christine S.; Kjaer, Helle A.; Satow, Kazuhide.

    In: Geophysical Research Letters (Online), Vol. 42, No. 10, 28.05.2015, p. 3919-3926.

    Research output: Contribution to journalJournal articleResearchpeer-review

  20. Published

    The summer 2012 Greenland heat wave : In situ and remote sensing observations of water vapor isotopic composition during an atmospheric river event. / Bonne, Jean-Louis; Steen-Larsen, Hans Christian; Risi, Camille; Werner, Martin; Sodemann, Harald; Lacour, Jean-Lionel; Fettweis, Xavier; Cesana, Grégory; Delmotte, Marc; Cattani, Olivier; Vallelonga, Paul Travis; Kjær, Helle Astrid; Clerbaux, Cathy; Svienbjörndóttir, Árny Erla; Masson-Delmotte, Valérie.

    In: Journal of Geophysical Research: Earth Surface, Vol. 120, No. 7, 01.04.2015, p. 2970-2989.

    Research output: Contribution to journalJournal articleResearchpeer-review

  21. Published

    On the occurrence of annual layers in Dome Fuji ice core early Holocene ice. / Svensson, A.; Fujita, S.; Bigler, M.; Braun, M.; Dallmayr, R.; Gkinis, V.; Goto-Azuma, K.; Hirabayashi, M.; Kawamura, K.; Kipfstuhl, S.; Kjaer, H. A.; Popp, T.; Simonsen, M.; Steffensen, J. P.; Vallelonga, P.; Vinther, B. M.

    In: Climate of the Past, Vol. 11, No. 9, 2015, p. 1127-1137.

    Research output: Contribution to journalJournal articleResearchpeer-review

  22. 2014
  23. Published

    A novel method for the detection of acidity in ice cores. / Kjær, Helle Astrid; Vallelonga, Paul Travis; Svensson, Anders.

    European Geosciences Union General Assembly 2014, 16, 27 April – 02 May 2014. European Geosciences Union. ed. Vienna, Austria, 2014. 1526.

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

  24. Published

    Constraining Glacial input of phosphorus to the oceans based on Greenland ice core evidence. / Kjær, Helle Astrid; Gotto-Azuma, Kumiko; Dallmayr, R.; Hirabayashi, M.; Vallelonga, Paul Travis; Svensson, Anders.

    European Geosciences Union General Assembly 2014, 16, 27 April – 02 May 2014. European Geosciences Union. ed. Vienna, Austria, 2014. 1524.

    Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review

  25. Published

    Determination of 129I in Arctic snow by a novel analytical approach using IC-ICP-SFMS. / Ezerinskis, Zilvinas; Spolaor, Andrea; Kirchgeorg, Torben; Cozzi, Giulio; Vallelonga, Paul; Kjaer, Helle A.; Sapolaite, Justina; Barbante, Carlo; Druteikiene, Ruta.

    In: Journal of Analytical Atomic Spectrometry, Vol. 29, No. 10, 10.01.2014, p. 1827-1834.

    Research output: Contribution to journalJournal articleResearchpeer-review

  26. Published

    Initial results from geophysical surveys and shallow coring of the Northeast Greenland Ice Stream (NEGIS). / Vallelonga, Paul Travis; Christianson, K.; Alley, R.B.; Anandakrishnan, S.; Dahl-Jensen, Dorthe; Gkinis, Vasileios; Holme, Christian Terkelsen; Jacobel, R.w.; Karlsson, Nanna Bjørnholt; Keisling, B.A.; Kipfstuhl, S.; Kjær, Helle Astrid; Kristensen, Magnus Elleskov; Muto, A.; Peters, L.E.; Popp, Trevor James; Riverman, K.L.; Svensson, Anders; Tibuleac, Catalin; Vinther, Bo Møllesøe; Weng, Y; Winstrup, Mai.

    In: The Cryosphere Discussions, Vol. 8, 10.01.2014, p. 1275-1287.

    Research output: Contribution to journalJournal articleResearchpeer-review

  27. Published

    Seasonality of halogen deposition in polar snow and ice. / Spolaor, A.; Vallelonga, P.; Gabrieli, J.; Martma, T.; Bjorkman, M. P.; Isaksson, E.; Cozzi, G.; Turetta, C.; Kjaer, H. A.; Curran, M. A. J.; Moy, A. D.; Schoenhardt, A.; Blechschmidt, A. -M.; Burrows, J. P.; Plane, J. M. C.; Barbante, C.

    In: Atmospheric Chemistry and Physics, Vol. 14, No. 18, 10.01.2014, p. 9613-9622.

    Research output: Contribution to journalJournal articleResearchpeer-review

  28. Published

    Continuous Chemistry in Ice Cores : Phosphorus, pH and the Photolysis of Humic Like Substances. / Kjær, Helle Astrid.

    The Niels Bohr Institute, Faculty of Science, University of Copenhagen, 2014.

    Research output: Book/ReportPh.D. thesisResearch

  29. 2013
  30. Published

    Continuous Flow Analysis Method for Determination of Dissolved Reactive Phosphorus in Ice Cores. / Kjær, Helle Astrid; Vallelonga, Paul Travis; Svensson, Anders; Elleskov L. Kristensen, Magnus; Tibuleac, Catalin; Bigler, Matthias.

    In: Environmental Science & Technology (Washington), Vol. 47, No. 21, 05.11.2013, p. 12325-12332.

    Research output: Contribution to journalJournal articleResearchpeer-review

  31. Published

    Eemian interglacial reconstructed from a Greenland folded ice core. / Dahl-Jensen, Dorthe; Albert, M. R.; Aldahan, A.; Azuma, N.; Balslev-Clausen, David Morten; Baumgartner, M.; Berggren, A.-M.; Bigler, M.; Binder, Thomas; Blunier, Thomas; Bourgeois, J.C.; Brook, E.J.; Buchardt, Susanne Lilja; Buizert, Christo; Capron, E.; Chappellaz, J.; Chung, J.; Clausen, Henrik Brink; Cvijanovic, Ivana; Davies, S.M.; Ditlevsen, Peter; Eicher, O.; Fischer, H.; Fisher, D. A.; Fleet, L.G.; Gfeller, G.; Gkinis, Vasileios; Gogineni, S.; Goto-Azuma, K.; Grinsted, Aslak; Gudlaugsdottir, H.; Guillevic, Myriam; Hansen, S. B.; Hansson, M.; Hirabayashi, M.; Hong, S.; Hur, S.D.; Huybrechts, P.; Hvidberg, Christine Schøtt; Iizuka, Y.; Jenk, Theo Manuel; Johnsen, Sigfus Johann; Jones, T.R.; Jouzel, J.; Karlsson, Nanna Bjørnholt; Kawamura, K.; Keegan, K.; Kettner, Ernesto; Kipfstuhl, S.; Kjær, Helle Astrid; Koutnik, M.; Kuramoto, T.; Köhler, P.; Laepple, T.; Landais, A.; Langen, Peter Lang; Larsen, Lars Berg; Leuenberger, D.; Leuenberger, M.; Leuschen, C.; Li, J.; Lipenkov, V.; Martinerie, P.; Maselli, O. J.; Masson-Delmotte, V.; McConnell, J. R.; Miller, H.; Mini, O.; Miyamoto, A.; Montagnat-Rentier, M.; Mulvaney, R.; Muscheler, R.; Orsi, A.J.; Paden, J.; Panton, Christian; Pattyn, F.; Petit, J.-R.; Pol, K.; Popp, Trevor James; Possnert, G.; Prié, F.; Prokopiou, M.; Quiquet, A.; Rasmussen, Sune Olander; Raynaud, D.; Ren, J.; Reutenauer, Corentin; Ritz, C.; Röckmann, T.; Rosen, J.L.; Rubino, Mauro; Rybak, O.; Samyn, D.; Sapart, C.J.; Schilt, A.; Schmidt, Astrid Mariah Zelma; Schwander, J.; Schüpbach, S.; Seierstad, Inger Kathrine; Severinghaus, J. P.; Sheldon, S.; Simonsen, Sebastian Bjerregaard; Sjolte, Jesper; Solgaard, Anne Munck; Sowers, T.; Sperlich, Peter; Steen-Larsen, Hans Christian; Steffen, K.; Steffensen, Jørgen Peder; Steinhage, D.; Stocker, T.F.; Stowasser, Christopher; Sturevik, A.S.; Sturges, W.T.; Sveinbjörnsdottir, A.; Svensson, Anders; Tison, J.-L.; Uetake, J.; Vallelonga, Paul Travis; Van De Wal, R.S.W.; Van Der Wel, G.; Vaughn, B.H.; Vinther, Bo Møllesøe; Waddington, E.; Wegner, A.; Weikusat, I.; White, J. W. C.; Wilhelms, F.; Winstrup, Mai; Witrant, E.; Wolff, E.W.; Xiao, C.; Zheng, Jin.

    In: Nature, Vol. 493, No. 7433, 24.01.2013, p. 489-494.

    Research output: Contribution to journalJournal articleResearchpeer-review

  32. 2012
  33. Published

    Duration of Greenland Stadial 22 and ice-gas Δage from counting of annual layers in Greenland NGRIP ice core. / Vallelonga, Paul Travis; Bertagna, G.; Blunier, Thomas; Kjær, Helle Astrid; Popp, Trevor James; Rasmussen, Sune Olander; Steffensen, Jørgen Peder; Stowasser, Christopher; Svensson, Anders; Warming, E.; Winstrup, Mai; Bigler, Matthias; Kipfstuhl, S.

    In: Climate of the Past, Vol. 8, No. 6, 20.11.2012, p. 1839-1847.

    Research output: Contribution to journalJournal articleResearchpeer-review

  34. 2011
  35. Published

    Iskerner-et indblik i fortidens klimaforandringer. / Kjær, Helle Astrid; Balslev-Clausen, David.

    Aspekter af dansk kemi i det 20. og 21. århundrede. 1. ed. København : Kemi Forlaget, 2011. p. 65-70.

    Research output: Chapter in Book/Report/Conference proceedingBook chapterCommunication

  36. 2009
  37. Assessment of the temperature, precipitation and snow in the RCM HIRHAM4 at 25 km resolution : Danish Climate Centre Report 09-08. / Kjær, Helle Astrid.

    Assessment of the temperature, precipitation and snow in the RCM HIRHAM4 at 25 km resolution: Danish Climate Centre Report 09-08. Danmarks Meterologiske Institut (DMI), 2009.

    Research output: Chapter in Book/Report/Conference proceedingReport chapterResearch

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