Helle Astrid Kjær
Associate Professor
Physics of Ice, Climate and Earth
Tagensvej 16
2200 København N.
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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
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Greenland 2012 melt event effects on CryoSat-2 radar altimetry
Nilsson, J., Vallelonga, P., Simonsen, S. B., Sorensen, L. S., Forsberg, R., Dahl-Jensen, Dorthe, Hirabayashi, M., Goto-Azuma, K., Hvidberg, Christine Schøtt, Kjær, Helle Astrid & Satow, K., 28 May 2015, In: Geophysical Research Letters (Online). 42, 10, p. 3919-3926Research output: Contribution to journal › Journal article › Research › peer-review
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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
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Nanoplastics measurements in Northern and Southern polar ice
Materic, D., Kjær, Helle Astrid, Vallelonga, P., Tison, J., Rockmann, T. & Holzinger, R., 15 May 2022, In: Environmental Research. 208, 9 p., 112741.Research output: Contribution to journal › Journal article › Research › peer-review
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Accelerating ice flow at the onset of the Northeast Greenland Ice Stream
Grinsted, Aslak, Hvidberg, Christine Schøtt, Lilien, D. A., Rathmann, Nicholas Mossor, Karlsson, N. B., Gerber, T., Kjær, Helle Astrid, Vallelonga, P. & Dahl-Jensen, Dorthe, 23 Sep 2022, In: Nature Communications. 13, 1, 4 p., 5589.Research output: Contribution to journal › Journal article › Research › peer-review
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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
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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
Assessment of the temperature, precipitation and snow in the RCM HIRHAM4 at 25 km resolution: Danish Climate Centre Report 09-08
Kjær, Helle Astrid, 2009, 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)Research output: Chapter in Book/Report/Conference proceeding › Report chapter › Research
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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
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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
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Constraining Glacial input of phosphorus to the oceans based on Greenland ice core evidence
Kjær, Helle Astrid, Gotto-Azuma, K., Dallmayr, R., Hirabayashi, M., 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, 1524Research output: Chapter in Book/Report/Conference proceeding › Article in proceedings › Research › peer-review
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Magnitude, frequency and climate forcing of global volcanism during the last glacial period as seen in Greenland and Antarctic ice cores (60–9 ka)
Lin, Jiamei, Svensson, Anders, Hvidberg, Christine Schøtt, Lohmann, Johannes Jakob, Kristiansen, S., Dahl-Jensen, Dorthe, Steffensen, Jørgen Peder, Rasmussen, Sune Olander, Cook, Eliza, Kjær, Helle Astrid, Vinther, Bo Møllesøe, Fischer, H., Stocker, T., Sigl, M., Bigler, M., Severi, M., Traversi, R. & Mulvaney, R., 9 Aug 2021, 45 p. Copernicus/EGU.Research output: Other contribution › Research
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Eemian interglacial reconstructed from a Greenland folded ice core
Dahl-Jensen, D., Albert, M. R., Aldahan, A., Azuma, N., Balslev-Clausen, D. M., Baumgartner, M., Berggren, A-M., Bigler, M., Binder, T., Blunier, T., Bourgeois, J. C., Brook, E. J., Buchardt, S. L., Buizert, C., Capron, E., Chappellaz, J., Chung, J., Clausen, H. B., Cvijanovic, I., Davies, S. M. & 113 others, , 24 Jan 2013, In: Nature. 493, 7433, p. 489-494 6 p.Research output: Contribution to journal › Journal article › Research › peer-review
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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
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High-resolution aerosol concentration data from the Greenland NorthGRIP and NEEM deep ice cores
Erhardt, T., Bigler, M., Federer, U., Gfeller, G., Leuenberger, D., Stowasser, O., Rothlisberger, R., Schupbach, S., Ruth, U., Twarloh, B., Wegner, A., Goto-Azuma, K., Kuramoto, T., Kjaer, H. A., Vallelonga, P. T., Siggaard-Andersen, M-L., Hansson, M. E., Benton, A. K., Fleet, L. G., Mulvaney, R. & 4 others, , 16 Mar 2022, In: Earth System Science Data. 14, 3, p. 1215-1231 17 p.Research output: Contribution to journal › Journal article › Research › peer-review
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Role of mineral dust in the nitrate preservation during the glacial period: Insights from the RICE ice core
Venugopal, A. U., Bertler, N. A. N., Pyne, R. L., Kjær, Helle Astrid, Winton, V. H. L., Mayewski, P. A. & Cortese, G., 1 Feb 2022, In: Global and Planetary Change. 209, 10 p., 103745.Research output: Contribution to journal › Journal article › Research › peer-review
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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
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An Age Scale for the First Shallow (Sub-)Antarctic Ice Core from Young Island, Northwest Ross Sea
Moser, D. E., Jackson, S., Kjær, Helle Astrid, Markle, B., Ngoumtsa, E., Pedro, J. B., Segato, D., Spolaor, A., Tetzner, D., Vallelonga, P. & Thomas, E. R., Sep 2021, In: Geosciences. 11, 9, 18 p., 368.Research output: Contribution to journal › Journal article › Research › peer-review
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Continuous flow analysis of the Mount Brown South ice core
Harlan, Meg, Kjær, Helle Astrid, Vance, T., Vallelonga, P., Gkinis, Vasileios, Blunier, Thomas, Svensson, Anders, Moy, A., Plummer, C., Jackson, S., Peensoo, K. & Campo, A. D., 9 Apr 2021, 1 p. Copernicus/EGU.Research output: Other contribution › Research
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Sea ice fluctuations in the Baffin Bay and the Labrador Sea during glacial abrupt climate changes
Scoto, F., Sadatzki, H., Maffezzoli, N., Barbante, C., Gagliardi, A., Varin, C., Vallelonga, P., Gkinis, Vasileios, Dahl-Jensen, Dorthe, Kjær, Helle Astrid, Burgay, F., Saiz-Lopez, A., Stein, R. & Spolaor, A., 1 Nov 2022, In: Proceedings of the National Academy of Sciences of the United States of America. 119, 44, 9 p., 2203468119.Research output: Contribution to journal › Journal article › Research › peer-review
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Climate changes modulated the history of Arctic iodine during the Last Glacial Cycle
Corella, J. P., Maffezzoli, N., Spolaor, A., Vallelonga, P., Cuevas, C. A., Scoto, F., Müller, J., Vinther, Bo Møllesøe, Kjær, Helle Astrid, Cozzi, G., Edwards, R., Barbante, C. & Saiz-Lopez, A., 2022, In: Nature Communications. 13, 88.Research output: Contribution to journal › Journal article › Research › peer-review
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Iskerner-et indblik i fortidens klimaforandringer
Kjær, Helle Astrid & Balslev-Clausen, D., 2 Apr 2011, Aspekter af dansk kemi i det 20. og 21. århundrede. 1 ed. København: Kemi Forlaget, p. 65-70 5 p.Research output: Chapter in Book/Report/Conference proceeding › Book chapter › Communication
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Greenland ice cores constrain glacial atmospheric fluxes of phosphorus
Kjær, Helle Astrid, Dallmayr, R., Gabrieli, J., Goto-Azuma, K., Hirabayashi, M., Svensson, Anders & Vallelonga, P. T., 29 Oct 2015, In: Journal of Geophysical Research: Biogeosciences. 120, 20Research output: Contribution to journal › Journal article › Research › peer-review
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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
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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
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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177
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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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138
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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