Helle Astrid Kjær
Associate Professor
Physics of Ice, Climate and Earth
Tagensvej 16
2200 København N.
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Determination of 129I in Arctic snow by a novel analytical approach using IC-ICP-SFMS
Ezerinskis, Z., Spolaor, A., Kirchgeorg, T., Cozzi, G., Vallelonga, P., Kjær, Helle Astrid, Sapolaite, J., Barbante, C. & Druteikiene, R., 10 Jan 2014, In: Journal of Analytical Atomic Spectrometry. 29, 10, p. 1827-1834Research output: Contribution to journal › Journal article › Research › peer-review
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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
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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
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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
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A novel method for the detection of acidity in ice cores
Kjær, Helle Astrid, Vallelonga, P. T. & Svensson, Anders, 27 Apr 2014, European Geosciences Union General Assembly 2014, 16, 27 April – 02 May 2014. European Geosciences Union ed. Vienna, Austria, 1526Research output: Chapter in Book/Report/Conference proceeding › Article in proceedings › Research › peer-review
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A portable lightweight in situ analysis (LISA) box for ice and snow analysis
Kjær, Helle Astrid, Lolk Hauge, L., Simonsen, M., Yoldi, Zuriñe, Koldtoft, Iben, Hörhold, M., Freitag, J., Kipfstuhl, S., Svensson, Anders & Vallelonga, P., 2021, In: Cryosphere. 15, 8, p. 3719-3730Research output: Contribution to journal › Journal article › Research › peer-review
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Antarctic evidence for an abrupt northward shift of the Southern Hemisphere westerlies at 32 ka BP
Venugopal, A. U., Bertler, N. A. N., Severinghaus, J. P., Brook, E. J., Cortese, G., Lee, J. E., Blunier, Thomas, Mayewski, P. A., Kjær, Helle Astrid, Carter, L., Weber, M. E., Levy, R. H., Pyne, R. L. & Vandergoes, M. J., 5 Sep 2023, In: Nature Communications. 14, 1, 8 p., 5432.Research output: Contribution to journal › Journal article › Research › peer-review
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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
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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., Kjær, Helle Astrid, Curran, M. A. J., Moy, A. D., Schoenhardt, A., Blechschmidt, A. -., Burrows, J. P., Plane, J. M. C. & Barbante, C., 10 Jan 2014, In: Atmospheric Chemistry and Physics. 14, 18, p. 9613-9622Research output: Contribution to journal › Journal article › Research › peer-review
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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
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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
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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
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Continuous Chemistry in Ice Cores: Phosphorus, pH and the Photolysis of Humic Like Substances
Kjær, Helle Astrid, 2014, The Niels Bohr Institute, Faculty of Science, University of Copenhagen.Research output: Book/Report › Ph.D. thesis › Research
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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
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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
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El Niño-Southern Oscillation signal in a new East Antarctic ice core, Mount Brown South
Crockart, C. K., Vance, T. R., Fraser, A. D., Abram, N. J., Criscitiello, A. S., Curran, M. A. J., Favier, V., Gallant, A. J. E., Kittel, C., Kjær, Helle Astrid, Klekociuk, A. R., Jong, L. M., Moy, A. D., Plummer, C. T., Vallelonga, P. T., Wille, J. & Zhang, L., 9 Sep 2021, In: Climate of the Past. 17, 5, p. 1795-1818 24 p.Research output: Contribution to journal › Journal article › Research › peer-review
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Duration of Greenland Stadial 22 and ice-gas Δage from counting of annual layers in Greenland NGRIP ice core
Vallelonga, P. T., Bertagna, G., Blunier, Thomas, Kjær, Helle Astrid, Popp, T. J., Rasmussen, Sune Olander, Steffensen, Jørgen Peder, Stowasser, C., Svensson, Anders, Warming, E., Winstrup, M., Bigler, M. & Kipfstuhl, S., 20 Nov 2012, In: Climate of the Past. 8, 6, p. 1839-1847 8 p.Research output: Contribution to journal › Journal article › Research › peer-review
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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. 2970-2989Research output: Contribution to journal › Journal article › Research › peer-review
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On the occurrence of annual layers in Dome Fuji ice core early Holocene ice
Svensson, Anders, Fujita, S., Bigler, M., Braun, M., Dallmayr, R., Gkinis, Vasileios, Goto-Azuma, K., Hirabayashi, M., Kawamura, K., Kipfstuhl, S., Kjær, Helle Astrid, Popp, T., Simonsen, M., Steffensen, Jørgen Peder, Vallelonga, P. & Vinther, Bo Møllesøe, 2015, In: Climate of the Past. 11, 9, p. 1127-1137Research output: Contribution to journal › Journal article › Research › peer-review
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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
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Melt in the Greenland EastGRIP ice core reveals Holocene warm events
Westhoff, Julien, Sinnl, Giulia, Svensson, Anders, Freitag, J., Kjær, Helle Astrid, Vallelonga, P. T., Vinther, Bo Møllesøe, Kipfstuhl, S., Dahl-Jensen, Dorthe & Weikusat, I., 10 May 2022, In: Climate of the Past. 18, 5, p. 1011-1034 24 p.Research output: Contribution to journal › Journal article › Research › peer-review
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Canadian forest fires, Icelandic volcanoes and increased local dust observed in six shallow Greenland firn cores
Kjær, Helle Astrid, Zens, P., Black, S., Lund, K. H., Svensson, Anders & Vallelonga, P., 10 Oct 2022, In: Climate of the Past. 18, 10, p. 2211-2230 20 p.Research output: Contribution to journal › Journal article › Research › peer-review
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Sea-ice reconstructions from bromine and iodine in ice cores
Vallelonga, P., Maffezzoli, N., Saiz-Lopez, A., Scoto, F., Kjær, Helle Astrid & Spolaor, A., 1 Oct 2021, In: Quaternary Science Reviews. 269, 41 p., 107133.Research output: Contribution to journal › Review › Research › peer-review
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Sea ice in the northern North Atlantic through the Holocene: Evidence from ice cores and marine sediment records
Maffezzoli, N., Risebrobakken, B., Miles, M. W., Vallelonga, P., Berben, S. M. P., Scoto, F., Edwards, R., Kjær, Helle Astrid, Sadatzki, H., Saiz-Lopez, A., Turetta, C., Barbante, C., Vinther, Bo Møllesøe & Spolaor, A., 3 Nov 2021, In: Quaternary Science Reviews. 273, 17 p., 107249.Research output: Contribution to journal › Journal article › Research › peer-review
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Five thousand years of fire history in the high North Atlantic region: natural variability and ancient human forcing
Segato, D., Villoslada Hidalgo, M. D. C., Edwards, R., Barbaro, E., Vallelonga, P., Kjær, Helle Astrid, Simonsen, M., Vinther, Bo Møllesøe, Maffezzoli, N., Zangrando, R., Turetta, C., Battistel, D., Vesteinsson, O., Barbante, C. & Spolaor, A., 20 Jul 2021, In: Climate of the Past. 17, 4, p. 1533-1545 13 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
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174
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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
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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