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151. The MOSAiC ice floe: sediment-laden survivor from the Siberian shelf

Author

Krumpen, Thomas, primary, Birrien, Florent, additional, Kauker, Frank, additional, Rackow, Thomas, additional, von Albedyll, Luisa, additional, Angelopoulos, Michael, additional, Belter, H. Jakob, additional, Bessonov, Vadlimir, additional, Damm, Ellen, additional, Dethloff, Klaus, additional, Haapala, Jari, additional, Haas, Christian, additional, Hendricks, Stefan, additional, Hoelemann, Jens, additional, Hoppmann, Mario, additional, Kaleschke, Lars, additional, Karcher, Michael, additional, Kolabutin, nikolai, additional, Lenz, Josefine, additional, Morgenstern, Anne, additional, Nicolaus, Marcel, additional, Nixdorf, Uwe, additional, Petrovsky, Tomash, additional, Rabe, Benjamin, additional, Rabenstein, Lasse, additional, Rex, Markus, additional, Ricker, Robert, additional, Rohde, Jan, additional, Shimanchuk, Egor, additional, Singha, Suman, additional, Smolyanitsky, Vasily, additional, Sokolov, Vladimir, additional, Stanton, Tim, additional, Timofeeva, Anna, additional, and Tsamados, Michel, additional

Published
2020
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155. 13-years of sea ice draft observations in the Laptev Sea from moored ADCPS and ULSs: changes, variability and comparison to Earth Observation data

Author

Belter, H. Jakob, Krumpen, Thomas, Janout, Markus A., Ricker, Robert, Hendricks, Stefan, and Haas, Christian

Abstract

Moored upward-looking Acoustic Doppler Current Profilers (ADCPs) can be used to observe sea ice draft. While previous studies relied on the availability of auxiliary pressure sensors to measure the instrument depth of the ADCP, we present an adaptive approach that infers instrument depth from the ADCPs default bottom track (BT) mode measurements of error velocity and range. We demonstrate that this method can be used to obtain daily mean sea ice draft time series with an estimated uncertainty of 0.1 m. The ADCP-derived ice draft time series are validated with data from adjacent Upward-Looking Sonar (ULS) moorings in the Laptev Sea. This new approach provides a low-cost opportunity to derive daily mean ice draft time series accessing existing ADCP data. Applying this method to ADCP data from the sparsely-sampled Laptev Sea allows an extension of mooring-based in situ ice draft measurements from 2 to about 13 years. The Laptev Sea is an important region for net ice production and a major contributor to the Transpolar Drift System. Recent studies show that sea ice area and volume exports from the Laptev Sea are increasing. This increased export accelerates summer sea ice retreat in the Laptev Sea and has far-reaching consequences for the entire Arctic sea ice balance. The newly acquired Laptev Sea ice draft data archive is used to analyse seasonal and interannual changes in sea ice thickness from 2003 to 2016. In addition, it provides unique data for the comparison with sea ice thickness data records derived from ENVISAT, CryoSat-2 and SMOS satellite measurements in an area where large-scale validation data sets are currently unavailable.

Published
2019

156. Ice Thickness and Deformation in the 2018 Greenland Polynya - How much did deformation contribute to sea ice thickness change in the North Greenland Polynya?

Author

von Albedyll, Luisa, Haas, Christian, Hollands, Thomas, Dierking, Wolfgang, Krumpen, Thomas, Hendricks, Stefan, Rohde, Jan, and Kauker, Frank

Subjects
human activities
Abstract

In February and March 2018 a unique polynya of open water had opened in the Wandel Sea north of Greenland due to unusually strong southerly winds. The polynya subsequently refroze and the area of the growing young ice strongly decreased by ice convergence due to northerly winds, constituting a natural, well-constrained, full-scale ice deformation experiment. We have carried out an airborne electromagnetic ice thickness survey of the young ice one month after the polynya began to close. It showed a thickness distribution with a modal ice thickness of 1 m and mean thickness of 2 m, representative of the contributions of thermodynamic and dynamic growth in the one month since the ice had begun to grow. We used time series of Sentinel 1 SAR images to back-track the surveyed young ice to its location of initial formation. Results showed that the area of young ice approximately halved between the time of its formation and the time of the ice thickness survey. This is in good qualitative agreement with the result of the thickness survey, showing that its mean thickness was twice its modal thickness, i.e. mean ice thickness doubled while the region's area halved. These results and the SAR observed deformation processes provide valuable information for improving representation of ice rheology and thickness redistribution in sea ice models.

Published
2019

157. Snow depth on Arctic sea ice derived from airborne radar measurements

Author

Jutila, Arttu, Ricker, Robert, Hendricks, Stefan, Paden, John, King, Joshua, Polashenski, Chris, Lange, Benjamin, Michel, Christine, and Haas, Christian

Abstract

The snow layer on sea ice has high importance for polar climate as it affects heat, radiation, and fresh-water budgets. Additionally, snow loading is a critical parameter for the sea-ice freeboard-to-thickness conversion for satellite radar and laser altimeters. Despite its importance, there is a lack of snow observations spanning different spatial and temporal scales, thus introducing a significant source of uncertainty to altimetric sea-ice thickness retrievals. The ultra-wideband microwave radar (UWBM) Snow Radar, a 2–18 GHz airborne frequency-modulated continuous-wave (FMCW) radar developed by the Center for Remote Sensing of Ice Sheets (CReSIS) at the University of Kansas, can accurately detect the air/snow and snow/ice interfaces to measure snow thickness. Since 2009, an airborne Snow Radar has been operated onboard NASA’s Operation IceBridge (OIB) campaigns. In 2017, the UWBM Snow Radar was operated for the first time on an Alfred Wegener Institute (AWI) research aircraft, together with an airborne laser scanner for surface topography and freeboard measurements and an electromagnetic induction sounding instrument (EM Bird) to measure total ice thickness. The AWI airborne surveys operate at a low survey altitude (60 m a.g.l.) and slow aircraft speed, enabling fine-resolution mapping of the snow layer. Furthermore, the unique instrument setup on board the AWI research aircraft and the concurrent measurements of snow freeboard, total sea-ice thickness and snow depth allow us to directly investigate the freeboard-to-thickness conversion on regional scales for the first time. Here, we evaluate the performance of the radar installation and present radar-derived snow depth retrieved with a wavelet technique from recent airborne campaigns, PAMARCMiP2017 and IceBird winter 2019, over Arctic sea ice in the Greenland, Lincoln, Beaufort and Chukchi Seas and the central Arctic Ocean in March–April of the respective years.

Published
2019

158. State of the Climate in 2018

Author

Ades, M., Adler, R., Aldeco, Laura S., Alejandra, G., Alfaro, Eric J., Aliaga-Nestares, Vannia, Allan, Richard P., Allan, Rob, Alves, Lincoln M., Amador, Jorge A., Andersen, J. K., Anderson, John, Arndt, Derek S., Arosio, C., Arrigo, Kevin, Azorin-Molina, César, Bardin, M. Yu, Barichivich, Jonathan, Barreira, Sandra, Baxter, Stephen, Beck, H. E., Becker, Andreas, Bell, Gerald D., Bellouin, Nicolas, Belmont, M., Benedetti, Angela, Benedict, Imme, Bernhard, G. H., Berrisford, Paul, Berry, David I., Bettio, Lynette, Bhatt, U. S., Biskaborn, B. K., Bissolli, Peter, Bjella, Kevin L., Bjerke, J. K., Blake, Eric S., Blenkinsop, Stephen, Blunden, Jessica, Bock, Olivier, Bosilovich, Michael G., Boucher, Olivier, Box, J. E., Boyer, Tim, Braathen, Geir, Bringas, Francis G., Bromwich, David H., Brown, Alrick, Brown, R., Brown, Timothy J., Buehler, S. A., Cáceres, Luis, Calderón, Blanca, Camargo, Suzana J., Campbell, Jayaka D., Campos Diaz, Diego A., Cappelen, J., Carrea, Laura, Carrier, Seth B., Carter, Brendan R., Castro, Anabel Y., Cetinic, Ivona, Chambers, Don P., Chen, Lin, Cheng, Lijing, Cheng, Vincent Y.S., Christiansen, Hanne H., Christy, John R., Chung, E. S., Claus, Federico, Clem, Kyle R., Coelho, Caio A.S., Coldewey-Egbers, Melanie, Colwell, Steve, Cooper, Owen R., Cosca, Cathy, Covey, Curt, Coy, Lawrence, Dávila, Cristina P., Davis, Sean M., de Eyto, Elvira, de Jeu, Richard A.M., De Laat, Jos, Decharme, B., Degasperi, Curtis L., Degenstein, Doug, Demircan, Mesut, Derksen, C., Dhurmea, K. R., Di Girolamo, Larry, Diamond, Howard J., Diaz, Eliecer, Diniz, Fransisco A., Dlugokencky, Ed J., Dohan, Kathleen, Dokulil, Martin T., Dolman, A. Johannes, Domingues, Catia M., Domingues, Ricardo, Donat, Markus G., Dorigo, Wouter A., Drozdov, D. S., Druckenmiller, Matthew L., Dunn, Robert J.H., Durre, Imke, Dutton, Geoff S., Elkharrim, M., Elkins, James W., Epstein, H. E., Espinoza, Jhan C., Famiglietti, James S., Farrell, Sinead L., Fausto, R. S., Feely, Richard A., Feng, Z., Fenimore, Chris, Fettweis, X., Fioletov, Vitali E., Flemming, Johannes, Fogt, Ryan L., Forbes, B. C., Foster, Michael J., Francis, S. D., Franz, Bryan A., Frey, Richard A., Frith, Stacey M., Froidevaux, Lucien, Ganter, Catherine, Garforth, J., Gerland, Sebastian, Gilson, John, Gleason, Karin, Gobron, Nadine, Goetz, S., Goldenberg, Stanley B., Goni, Gustavo, Gray, Alison, Grooß, Jens Uwe, Gruber, Alexander, Gu, Guojun, Guard, Charles Chip P., Gupta, S. K., Gutiérrez, Dimitri, Haas, Christian, Hagos, S., Hahn, Sebastian, Haimberger, Leo, Hall, Brad D., Halpert, Michael S., Hamlington, Benjamin D., Hanna, E., Hanssen-Bauer, I., Harris, Ian, Hazeleger, Wilco, He, Q., Heidinger, Andrew K., Heim, Richard R., Hemming, D. L., Hendricks, Stefan, Hernández, Rafael, Hersbach, H. E., Hidalgo, Hugo G., Ho, Shu Peng Ben, Holmes, R. M., Hu, Chuanmin, Huang, Boyin, Hubbard, Katherine, Hubert, Daan, Hurst, Dale F., Ialongo, Iolanda, Ijampy, J. A., Inness, Antje, Isaac, Victor, Isaksen, K., Ishii, Masayoshi, Jeffries, Martin O., Jevrejeva, Svetlana, Jia, G., Jiménez, C., Jin, Xiangze, John, Viju, Johnsen, Bjørn, Johnson, Gregory C., Johnson, Kenneth S., Johnson, Bryan, Jones, Philip D., Jumaux, Guillaume, Kabidi, Khadija, Kaiser, J. W., Karaköylü, Erdem M., Karlsen, S. R., Karnauskas, Mandy, Kato, Seiji, Kazemi, A. Fazl, Kelble, Christopher, Keller, Linda M., Kennedy, John, Kholodov, A. L., Khoshkam, Mahbobeh, Kidd, R., Killick, Rachel, Kim, Hyungjun, Kim, S. J., King, A. D., King, Brian A., Kipling, Z., Klotzbach, Philip J., Knaff, John A., Korhonen, Johanna, Korshunova, Natalia N., Kramarova, Natalya A., Kratz, D. P., Kruger, Andries, Kruk, Michael C., Krumpen, Thomas, Labbé, L., Ladd, C., Lakatos, Mónika, Lakkala, Kaisa, Lander, Mark A., Landschützer, Peter, Landsea, Chris W., Lareau, Neil P., Lavado-Casimiro, Waldo, Lazzara, Matthew A., Lee, T. C., Leuliette, Eric, L’heureux, Michelle, Li, Bailing, Li, Tim, Lieser, Jan L., Lim, J. Y., Lin, I. I., Liu, Hongxing, Locarnini, Ricardo, Loeb, Norman G., Long, Craig S., López, Luis A., Lorrey, Andrew M., Loyola, Diego, Lumpkin, Rick, Luo, Jing Jia, Luojus, K., Lyman, John M., Malkova, G. V., Manney, Gloria L., Marchenko, S. S., Marengo, José A., Marin, Dora, Marquardt Collow, Allison B., Marra, John J., Marszelewski, Wlodzimierz, Martens, B., Martínez-Güingla, Rodney, Massom, Robert A., May, Linda, Mayer, Michael, Mazloff, Matthew, McBride, Charlotte, McCabe, M., McClelland, J. W., McEvoy, Daniel J., McGree, Simon, McVicar, Tim R., Mears, Carl A., Meier, Walt, Meijers, Andrew, Mekonnen, Ademe, Mengistu Tsidu, G., Menzel, W. Paul, Merchant, Christopher J., Meredith, Michael P., Merrifield, Mark A., Miller, Ben, Miralles, Diego G., Misevicius, Noelia, Mitchum, Gary T., Mochizuki, Y., Monselesan, Didier, Montzka, Stephen A., Mora, Natali, Morice, Colin, Mosquera-Vásquez, Kobi, Mostafa, Awatif E., Mote, T., Mudryk, L., Mühle, Jens, Mullan, A. Brett, Müller, Rolf, Myneni, R., Nash, Eric R., Nauslar, Nicholas J., Nerem, R. Steven, Newman, Paul A., Nicolas, Julien P., Nieto, Juan José, Noetzli, Jeannette, Osborn, Tim J., Osborne, Emily, Overland, J., Oyunjargal, Lamjav, Park, T., Pasch, Richard J., Pascual Ramírez, Reynaldo, Pastor Saavedra, Maria Asuncion, Paterson, Andrew M., Pearce, Petra R., Pelto, Mauri S., Perovich, Don, Petropavlovskikh, Irina, Pezza, Alexandre B., Phillips, C., Phillips, David, Phoenix, G., Pinty, Bernard, Pitts, Michael, Po-Chedley, S., Polashenski, Chris, Preimesberger, W., Purkey, Sarah G., Quispe, Nelson, Rajeevan, Madhavan, Rakotoarimalala, C. L., Ramos, Andrea M., Ramos, Isabel, Randel, W., Raynolds, M. K., Reagan, James, Reid, Phillip, Reimer, Christoph, Rémy, Samuel, Revadekar, Jayashree V., Richardson, A. D., Richter-Menge, Jacqueline, Ricker, Robert, Ripaldi, A., Robinson, David A., Rodell, Matthew, Rodriguez Camino, Ernesto, Romanovsky, Vladimir E., Ronchail, Josyane, Rosenlof, Karen H., Rösner, Benajamin, Roth, Chris, Rozanov, A., Rusak, James A., Rustemeier, Elke, Rutishäuser, T., Sallée, Jean Baptiste, Sánchez-Lugo, Ahira, Santee, Michelle L., Sawaengphokhai, P., Sayouri, Amal, Scambos, Ted A., Scanlon, T., Scardilli, Alvaro S., Schenzinger, Verena, Schladow, S. Geoffey, Schmid, Claudia, Schmid, Martin, Schoeneich, P., Schreck, Carl J., Selkirk, H. B., Sensoy, Serhat, Shi, Lei, Shiklomanov, A. I., Shiklomanov, Nikolai I., Shimpo, A., Shuman, Christopher A., Siegel, David A., Sima, Fatou, Simmons, Adrian J., Smeets, C. J.P.P., Smith, Adam, Smith, Sharon L., Soden, B., Sofieva, Viktoria, Sparks, T. H., Spence, Jacqueline, Spencer, R. G.M., Spillane, Sandra, Srivastava, A. K., Stabeno, P. J., Stackhouse, Paul W., Stammerjohn, Sharon, Stanitski, Diane M., Steinbrecht, Wolfgang, Stella, José L., Stengel, M., Stephenson, Tannecia S., Strahan, Susan E., Streeter, Casey, Streletskiy, Dimitri A., Sun-Mack, Sunny, Suslova, A., Sutton, Adrienne J., Swart, Sebastiann, Sweet, William, Takahashi, Kenneth S., Tank, S. E., Taylor, Michael A., Tedesco, M., Thackeray, S. J., Thompson, Philip R., Timbal, Bertrand, Timmermans, M. L., Tobin, Skie, Tømmervik, H., Tourpali, Kleareti, Trachte, Katja, Tretiakov, M., Trewin, Blair C., Triñanes, Joaquin A., Trotman, Adrian R., Tschudi, Mark, Tye, Mari R., van As, D., van de Wal, R. S.W., van der A, Ronald J., van der Schalie, Robin, van der Schrier, Gerard, van der Werf, Guido R., van Heerwaarden, Chiel, Van Meerbeeck, Cedric J., Verburg, Piet, Vieira, G., Vincent, Lucie A., Vömel, Holger, Vose, Russell S., Walker, D. A., Walsh, J. E., Wang, Bin, Wang, Hui, Wang, Lei, Wang, M., Wang, Mengqiu, Wang, Ray, Wang, Sheng Hung, Wanninkhof, Rik, Watanabe, Shohei, Weber, Mark, Webster, Melinda, Weerts, Albrecht, Weller, Robert A., Westberry, Toby K., Weyhenmeyer, Gesa A., Widlansky, Matthew J., Wijffels, Susan E., Wilber, Anne C., Wild, Jeanette D., Willett, Kate M., Wong, Takmeng, Wood, E. F., Woolway, R. Iestyn, Xue, Yan, Yin, Xungang, Yu, Lisan, Zambrano, Eduardo, Zeyaeyan, Sadegh, Zhang, Huai Min, Zhang, Peiqun, Zhao, Guanguo, Zhao, Lin, Zhou, Xinjia, Zhu, Zhiwei, Ziemke, Jerry R., Ziese, Markus, Andersen, Andrea, Griffin, Jessicca, Hammer, Gregory, Love-Brotak, S. Elizabeth, Misch, Deborah J., Riddle, Deborah B., Veasey, Sara W., Processus et interactions de fine échelle océanique (PROTEO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Océan et variabilité du climat (VARCLIM), Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU), Berry, David, Jevrejeva, Svetlana, King, Brian, and Domingues, Catia

Subjects
Surface (mathematics), Atmospheric Science, Materials science, 010504 meteorology & atmospheric sciences, 0207 environmental engineering, Mineralogy, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], 02 engineering and technology, 01 natural sciences, ComputingMethodologies_DOCUMENTANDTEXTPROCESSING, SDG 13 - Climate Action, SDG 14 - Life Below Water, 020701 environmental engineering, GeneralLiterature_REFERENCE(e.g.,dictionaries,encyclopedias,glossaries), ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

In 2018, the dominant greenhouse gases released into Earth's atmosphere-carbon dioxide, methane, and nitrous oxide-continued their increase. The annual global average carbon dioxide concentration at Earth's surface was 407.4 ± 0.1 ppm, the highest in the modern instrumental record and in ice core records dating back 800 000 years. Combined, greenhouse gases and several halogenated gases contribute just over 3 W m−2 to radiative forcing and represent a nearly 43% increase since 1990. Carbon dioxide is responsible for about 65% of this radiative forcing. With a weak La Niña in early 2018 transitioning to a weak El Niño by the year's end, the global surface (land and ocean) temperature was the fourth highest on record, with only 2015 through 2017 being warmer. Several European countries reported record high annual temperatures. There were also more high, and fewer low, temperature extremes than in nearly all of the 68-year extremes record. Madagascar recorded a record daily temperature of 40.5°C in Morondava in March, while South Korea set its record high of 41.0°C in August in Hongcheon. Nawabshah, Pakistan, recorded its highest temperature of 50.2°C, which may be a new daily world record for April. Globally, the annual lower troposphere temperature was third to seventh highest, depending on the dataset analyzed. The lower stratospheric temperature was approximately fifth lowest. The 2018 Arctic land surface temperature was 1.2°C above the 1981-2010 average, tying for third highest in the 118-year record, following 2016 and 2017. June's Arctic snow cover extent was almost half of what it was 35 years ago. Across Greenland, however, regional summer temperatures were generally below or near average. Additionally, a satellite survey of 47 glaciers in Greenland indicated a net increase in area for the first time since records began in 1999. Increasing permafrost temperatures were reported at most observation sites in the Arctic, with the overall increase of 0.1°-0.2°C between 2017 and 2018 being comparable to the highest rate of warming ever observed in the region. On 17 March, Arctic sea ice extent marked the second smallest annual maximum in the 38-year record, larger than only 2017. The minimum extent in 2018 was reached on 19 September and again on 23 September, tying 2008 and 2010 for the sixth lowest extent on record. The 23 September date tied 1997 as the latest sea ice minimum date on record. First-year ice now dominates the ice cover, comprising 77% of the March 2018 ice pack compared to 55% during the 1980s. Because thinner, younger ice is more vulnerable to melting out in summer, this shift in sea ice age has contributed to the decreasing trend in minimum ice extent. Regionally, Bering Sea ice extent was at record lows for almost the entire 2017/18 ice season. For the Antarctic continent as a whole, 2018 was warmer than average. On the highest points of the Antarctic Plateau, the automatic weather station Relay (74°S) broke or tied six monthly temperature records throughout the year, with August breaking its record by nearly 8°C. However, cool conditions in the western Bellingshausen Sea and Amundsen Sea sector contributed to a low melt season overall for 2017/18. High SSTs contributed to low summer sea ice extent in the Ross and Weddell Seas in 2018, underpinning the second lowest Antarctic summer minimum sea ice extent on record. Despite conducive conditions for its formation, the ozone hole at its maximum extent in September was near the 2000-18 mean, likely due to an ongoing slow decline in stratospheric chlorine monoxide concentration. Across the oceans, globally averaged SST decreased slightly since the record El Niño year of 2016 but was still far above the climatological mean. On average, SST is increasing at a rate of 0.10° ± 0.01°C decade−1 since 1950. The warming appeared largest in the tropical Indian Ocean and smallest in the North Pacific. The deeper ocean continues to warm year after year. For the seventh consecutive year, global annual mean sea level became the highest in the 26-year record, rising to 81 mm above the 1993 average. As anticipated in a warming climate, the hydrological cycle over the ocean is accelerating: dry regions are becoming drier and wet regions rainier. Closer to the equator, 95 named tropical storms were observed during 2018, well above the 1981-2010 average of 82. Eleven tropical cyclones reached Saffir-Simpson scale Category 5 intensity. North Atlantic Major Hurricane Michael's landfall intensity of 140 kt was the fourth strongest for any continental U.S. hurricane landfall in the 168-year record. Michael caused more than 30 fatalities and $25 billion (U.S. dollars) in damages. In the western North Pacific, Super Typhoon Mangkhut led to 160 fatalities and $6 billion (U.S. dollars) in damages across the Philippines, Hong Kong, Macau, mainland China, Guam, and the Northern Mariana Islands. Tropical Storm Son-Tinh was responsible for 170 fatalities in Vietnam and Laos. Nearly all the islands of Micronesia experienced at least moderate impacts from various tropical cyclones. Across land, many areas around the globe received copious precipitation, notable at different time scales. Rodrigues and Réunion Island near southern Africa each reported their third wettest year on record. In Hawaii, 1262 mm precipitation at Waipā Gardens (Kauai) on 14-15 April set a new U.S. record for 24-h precipitation. In Brazil, the city of Belo Horizonte received nearly 75 mm of rain in just 20 minutes, nearly half its monthly average. Globally, fire activity during 2018 was the lowest since the start of the record in 1997, with a combined burned area of about 500 million hectares. This reinforced the long-term downward trend in fire emissions driven by changes in land use in frequently burning savannas. However, wildfires burned 3.5 million hectares across the United States, well above the 2000-10 average of 2.7 million hectares. Combined, U.S. wildfire damages for the 2017 and 2018 wildfire seasons exceeded $40 billion (U.S. dollars).

Published
2019

159. Second Data Science Symposium at AWI

Author

Pfeiffenberger, Hans, Frickenhaus, Stephan, Nerger, Lars, Piepenburg, Dieter, Niehoff, Barbara, Lange, Stephan, Behrendt, Axel, Pfalz, Gregor, Koppe, Roland, Fischer, Philipp, Mieruch-Schnülle, Sebastian, Wittig, Rolf, Leefmann, Tim, Hendricks, Stefan, Helm, Veit, Hoppema, Mario, Buttigieg, Pier Luigi, Klockmann, Marlene, Emeis, Kay-Christian, Rath, Willi, and Wölfl, Anne-Cathrin

Abstract

The second Data Science Symposium at AWI gathered several data science related talks from AWI, GEOMAR and HZG.

Published
2018

160. Copernicus Marine Service Ocean State Report, Issue 3 Introduction

Author

von Schuckmann, Karina, Le Traon, Pierre-Yves, Smith, Neville, Pascual, Ananda, Djavidnia, Samuel, Gattuso, Jean-Pierre, Gregoire, Marilaure, Nolan, Glenn, Aaboe, Signe, Aguiar, Eva, Alvarez Fanjul, Enrique, Alvera-Azcarate, Aida, Aouf, Lotfi, Barciela, Rosa, Behrens, Arno, Rivas, Maria Belmonte, Ismail, Sana Ben, Bentamy, Abderrahim, Borgini, Mireno, Brando, Vittorio E., Bensoussan, Nathaniel, Blauw, Anouk, Bryere, Philippe, Nardelli, Bruno Buongiorno, Caballero, Ainhoa, Yumruktepe, Veli Caglar, Cebrian, Emma, Chiggiato, Jacopo, Clementi, Emanuela, Corgnati, Lorenzo, de Alfonso, Marta, de Pascual Collar, Alvaro, Deshayes, Julie, Di Lorenzo, Emanuele, Dominici, Jean-Marie, Dupouy, Cecile, Drevillon, Marie, Echevin, Vincent, Eleveld, Marieke, Enserink, Lisette, Garcia Sotillo, Marcos, Garnesson, Philippe, Garrabou, Joaquim, Garric, Gilles, Gasparin, Florent, Gayer, Gerhard, Gohin, Francis, Grandi, Alessandro, Griffa, Annalisa, Gourrion, Jerome, Hendricks, Stefan, Heuze, Celine, Holland, Elisabeth, Iovino, Doroteaciro, Juza, Melanie, Kersting, Diego Kurt, Kipson, Silvija, Kizilkaya, Zafer, Korres, Gerasimos, Kouts, Mariliis, Lagemaa, Priidik, Lavergne, Thomas, Lavigne, Heloise, Ledoux, Jean-Baptiste, Legeais, Jean-Francois, Lehodey, Patrick, Linares, Cristina, Liu, Ye, Mader, Julien, Maljutenko, Ilja, Mangin, Antoine, Manso-Narvarte, Ivan, Mantovani, Carlo, Markager, Stiig, Mason, Evan, Mignot, Alexandre, Menna, Milena, Monier, Maeva, Mourre, Baptiste, Muller, Malte, Nielsen, Jacob Woge, Notarstefano, Giulio, Ocana, Oscar, Patti, Bernardo, Payne, Mark R., Peirache, Marion, Pardo, Silvia, Perez Gomez, Begona, Pisano, Andrea, Perruche, Coralie, Peterson, K. Andrew, Pujol, Marie-Isabelle, Raudsepp, Urmas, Ravdas, Michalis, Raj, Roshin P., Renshaw, Richard, Reyes, Emma, Ricker, Robert, Rubio, Anna, Sammartino, Michela, Santoleri, Rosalia, Sathyendranath, Shubha, Schroeder, Katrin, She, Jun, Sparnocchia, Stefania, Staneva, Joanna, Stoffelen, Ad, Szekely, Tanguy, Tilstone, Gavin H., Tinker, Jonathan, Tintore, Joaquin, Tranchant, Benoit, Uiboupin, Rivo, Van der Zande, Dimitry, Wood, Richard, Zabala, Mikel, Zacharioudaki, Anna, Zuberer, Frederic, Zuo, Hao, von Schuckmann, Karina, Le Traon, Pierre-Yves, Smith, Neville, Pascual, Ananda, Djavidnia, Samuel, Gattuso, Jean-Pierre, Gregoire, Marilaure, Nolan, Glenn, Aaboe, Signe, Aguiar, Eva, Alvarez Fanjul, Enrique, Alvera-Azcarate, Aida, Aouf, Lotfi, Barciela, Rosa, Behrens, Arno, Rivas, Maria Belmonte, Ismail, Sana Ben, Bentamy, Abderrahim, Borgini, Mireno, Brando, Vittorio E., Bensoussan, Nathaniel, Blauw, Anouk, Bryere, Philippe, Nardelli, Bruno Buongiorno, Caballero, Ainhoa, Yumruktepe, Veli Caglar, Cebrian, Emma, Chiggiato, Jacopo, Clementi, Emanuela, Corgnati, Lorenzo, de Alfonso, Marta, de Pascual Collar, Alvaro, Deshayes, Julie, Di Lorenzo, Emanuele, Dominici, Jean-Marie, Dupouy, Cecile, Drevillon, Marie, Echevin, Vincent, Eleveld, Marieke, Enserink, Lisette, Garcia Sotillo, Marcos, Garnesson, Philippe, Garrabou, Joaquim, Garric, Gilles, Gasparin, Florent, Gayer, Gerhard, Gohin, Francis, Grandi, Alessandro, Griffa, Annalisa, Gourrion, Jerome, Hendricks, Stefan, Heuze, Celine, Holland, Elisabeth, Iovino, Doroteaciro, Juza, Melanie, Kersting, Diego Kurt, Kipson, Silvija, Kizilkaya, Zafer, Korres, Gerasimos, Kouts, Mariliis, Lagemaa, Priidik, Lavergne, Thomas, Lavigne, Heloise, Ledoux, Jean-Baptiste, Legeais, Jean-Francois, Lehodey, Patrick, Linares, Cristina, Liu, Ye, Mader, Julien, Maljutenko, Ilja, Mangin, Antoine, Manso-Narvarte, Ivan, Mantovani, Carlo, Markager, Stiig, Mason, Evan, Mignot, Alexandre, Menna, Milena, Monier, Maeva, Mourre, Baptiste, Muller, Malte, Nielsen, Jacob Woge, Notarstefano, Giulio, Ocana, Oscar, Patti, Bernardo, Payne, Mark R., Peirache, Marion, Pardo, Silvia, Perez Gomez, Begona, Pisano, Andrea, Perruche, Coralie, Peterson, K. Andrew, Pujol, Marie-Isabelle, Raudsepp, Urmas, Ravdas, Michalis, Raj, Roshin P., Renshaw, Richard, Reyes, Emma, Ricker, Robert, Rubio, Anna, Sammartino, Michela, Santoleri, Rosalia, Sathyendranath, Shubha, Schroeder, Katrin, She, Jun, Sparnocchia, Stefania, Staneva, Joanna, Stoffelen, Ad, Szekely, Tanguy, Tilstone, Gavin H., Tinker, Jonathan, Tintore, Joaquin, Tranchant, Benoit, Uiboupin, Rivo, Van der Zande, Dimitry, Wood, Richard, Zabala, Mikel, Zacharioudaki, Anna, Zuberer, Frederic, and Zuo, Hao

Published
2019
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161. Retrieving Sea Level and Freeboard in the Arctic: A Review of Current Radar Altimetry Methodologies and Future Perspectives

Author

Quartly, Graham D., Rinne, Eero, Passaro, Marcello, Andersen, Ole B., Dinardo, Salvatore, Fleury, Sara, Guillot, Amandine, Hendricks, Stefan, Kurekin, Andrey A., Müller, Felix L., Ricker, Robert, Skourup, Henriette, Tsamados, Michel, Quartly, Graham D., Rinne, Eero, Passaro, Marcello, Andersen, Ole B., Dinardo, Salvatore, Fleury, Sara, Guillot, Amandine, Hendricks, Stefan, Kurekin, Andrey A., Müller, Felix L., Ricker, Robert, Skourup, Henriette, and Tsamados, Michel

Published
2019

162. Copernicus Marine Service Ocean State Report, Issue 3

Author

von Schuckmann, Karina, Le Traon, Pierre-Yves, Smith, Neville, Pascual, Ananda, Djavidnia, Samuel, Gattuso, Jean-Pierre, Grégoire, Marilaure, Nolan, Glenn, Aaboe, Signe, Aguiar, Eva, Álvarez Fanjul, Enrique, Alvera-Azcárate, Aida, Aouf, Lotfi, Barciela, Rosa, Behrens, Arno, Belmonte Rivas, Maria, Ben Ismail, Sana, Bentamy, Abderrahim, Borgini, Mireno, Brando, Vittorio E., Bensoussan, Nathaniel, Blauw, Anouk, Bryère, Philippe, Buongiorno Nardelli, Bruno, Caballero, Ainhoa, Çağlar Yumruktepe, Veli, Cebrian, Emma, Chiggiato, Jacopo, Clementi, Emanuela, Corgnati, Lorenzo, de Alfonso, Marta, de Pascual Collar, Álvaro, Deshayes, Julie, Di Lorenzo, Emanuele, Dominici, Jean-Marie, Dupouy, Cécile, Drévillon, Marie, Echevin, Vincent, Eleveld, Marieke, Enserink, Lisette, García Sotillo, Marcos, Garnesson, Philippe, Garrabou, Joaquim, Garric, Gilles, Gasparin, Florent, Gayer, Gerhard, Gohin, Francis, Grandi, Alessandro, Griffa, Annalisa, Gourrion, Jérôme, Hendricks, Stefan, Heuzé, Céline, Holland, Elisabeth, Iovino, Doroteaciro, Juza, Mélanie, Kurt Kersting, Diego, Kipson, Silvija, Kizilkaya, Zafer, Korres, Gerasimos, Kõuts, Mariliis, Lagemaa, Priidik, Lavergne, Thomas, Lavigne, Heloise, Ledoux, Jean-Baptiste, Legeais, Jean-François, Lehodey, Patrick, Linares, Cristina, Liu, Ye, Mader, Julien, Maljutenko, Ilja, Mangin, Antoine, Manso-Narvarte, Ivan, Mantovani, Carlo, Markager, Stiig, Mason, Evan, Mignot, Alexandre, Menna, Milena, Monier, Maeva, Mourre, Baptiste, Müller, Malte, Nielsen, Jacob Woge, Notarstefano, Giulio, Ocaña, Oscar, Patti, Bernardo, Payne, Mark R., Peirache, Marion, Pardo, Silvia, Pérez Gómez, Begoña, Pisano, Andrea, Perruche, Coralie, Peterson, K. Andrew, Pujol, Marie-Isabelle, Raudsepp, Urmas, Ravdas, Michalis, Raj, Roshin P., Renshaw, Richard, Reyes, Emma, Ricker, Robert, Rubio, Anna, Sammartino, Michela, Santoleri, Rosalia, Sathyendranath, Shubha, Schroeder, Katrin, She, Jun, Sparnocchia, Stefania, Staneva, Joanna, Stoffelen, Ad, Szekely, Tanguy, Tilstone, Gavin H., Tinker, Jonathan, Tintoré, Joaquín, Tranchant, Benoît, Uiboupin, Rivo, Van der Zande, Dimitry, Wood, Richard, Woge Nielsen, Jacob, Zabala, Mikel, Zacharioudaki, Anna, Zuberer, Frédéric, Zuo, Hao, von Schuckmann, Karina, Le Traon, Pierre-Yves, Smith, Neville, Pascual, Ananda, Djavidnia, Samuel, Gattuso, Jean-Pierre, Grégoire, Marilaure, Nolan, Glenn, Aaboe, Signe, Aguiar, Eva, Álvarez Fanjul, Enrique, Alvera-Azcárate, Aida, Aouf, Lotfi, Barciela, Rosa, Behrens, Arno, Belmonte Rivas, Maria, Ben Ismail, Sana, Bentamy, Abderrahim, Borgini, Mireno, Brando, Vittorio E., Bensoussan, Nathaniel, Blauw, Anouk, Bryère, Philippe, Buongiorno Nardelli, Bruno, Caballero, Ainhoa, Çağlar Yumruktepe, Veli, Cebrian, Emma, Chiggiato, Jacopo, Clementi, Emanuela, Corgnati, Lorenzo, de Alfonso, Marta, de Pascual Collar, Álvaro, Deshayes, Julie, Di Lorenzo, Emanuele, Dominici, Jean-Marie, Dupouy, Cécile, Drévillon, Marie, Echevin, Vincent, Eleveld, Marieke, Enserink, Lisette, García Sotillo, Marcos, Garnesson, Philippe, Garrabou, Joaquim, Garric, Gilles, Gasparin, Florent, Gayer, Gerhard, Gohin, Francis, Grandi, Alessandro, Griffa, Annalisa, Gourrion, Jérôme, Hendricks, Stefan, Heuzé, Céline, Holland, Elisabeth, Iovino, Doroteaciro, Juza, Mélanie, Kurt Kersting, Diego, Kipson, Silvija, Kizilkaya, Zafer, Korres, Gerasimos, Kõuts, Mariliis, Lagemaa, Priidik, Lavergne, Thomas, Lavigne, Heloise, Ledoux, Jean-Baptiste, Legeais, Jean-François, Lehodey, Patrick, Linares, Cristina, Liu, Ye, Mader, Julien, Maljutenko, Ilja, Mangin, Antoine, Manso-Narvarte, Ivan, Mantovani, Carlo, Markager, Stiig, Mason, Evan, Mignot, Alexandre, Menna, Milena, Monier, Maeva, Mourre, Baptiste, Müller, Malte, Nielsen, Jacob Woge, Notarstefano, Giulio, Ocaña, Oscar, Patti, Bernardo, Payne, Mark R., Peirache, Marion, Pardo, Silvia, Pérez Gómez, Begoña, Pisano, Andrea, Perruche, Coralie, Peterson, K. Andrew, Pujol, Marie-Isabelle, Raudsepp, Urmas, Ravdas, Michalis, Raj, Roshin P., Renshaw, Richard, Reyes, Emma, Ricker, Robert, Rubio, Anna, Sammartino, Michela, Santoleri, Rosalia, Sathyendranath, Shubha, Schroeder, Katrin, She, Jun, Sparnocchia, Stefania, Staneva, Joanna, Stoffelen, Ad, Szekely, Tanguy, Tilstone, Gavin H., Tinker, Jonathan, Tintoré, Joaquín, Tranchant, Benoît, Uiboupin, Rivo, Van der Zande, Dimitry, Wood, Richard, Woge Nielsen, Jacob, Zabala, Mikel, Zacharioudaki, Anna, Zuberer, Frédéric, and Zuo, Hao

Published
2019

163. Product User Guide & Algorithm Specification: AWI CryoSat-2 Sea Ice Thickness (version 2.2)

Author

Hendricks, Stefan, Ricker, Robert, Hendricks, Stefan, and Ricker, Robert

Abstract

This document provides an overview of all aspects of the CryoSat-2 Arctic sea-ice thickness data product (version 2.2) generated at the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research (AWI). It contains information on a) primary and auxiliary data sets used in the processing, b)description of the algorithm used deriving geophysical information along orbit segments and on space-time grids, c)t echnical specifications of the product files, d) data access and e) known Issues of the data record

Published
2019

164. IceBird 2019 Winter: ICESat-2 Validation Data Acquisition Report

Author

Hendricks, Stefan, Ricker, Robert, Jutila, Arttu, Hendricks, Stefan, Ricker, Robert, and Jutila, Arttu

Abstract

This technical report provides information on validation activities of ICESat-2 sea ice products in April 2019 by airborne observations within the IceBird aircraft campaign series of the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research. The airborne data acquisition includes direct observations of snow freeboard, snow depth on sea ice and sea-ice thickness by a set of sensors. The following sections specify the extent of airborne data collocated with an ICESat-2 orbit, the specification of the sensors and the file format of the validation data.

Published
2019

165. Arctic warming interrupts the Transpolar Drift and affects long-range transport of sea ice and ice-rafted matter

Author

Krumpen, Thomas, Belter, Jakob, Boetius, Antje, Damm, Ellen, Haas, Christian, Hendricks, Stefan, Nicolaus, Marcel, Noethig, Eva-Maria, Paul, Stephan, Peeken, Ilka, Ricker, Robert, Stein, Rüdiger, Krumpen, Thomas, Belter, Jakob, Boetius, Antje, Damm, Ellen, Haas, Christian, Hendricks, Stefan, Nicolaus, Marcel, Noethig, Eva-Maria, Paul, Stephan, Peeken, Ilka, Ricker, Robert, and Stein, Rüdiger

Abstract

Sea ice is an important transport vehicle for gaseous, dissolved and particulate matter in the Arctic Ocean. Due to the recently observed acceleration in sea ice drift, it has been assumed that more matter is advected by the Transpolar Drift from shallow shelf waters to the central Arctic Ocean and beyond. However, this study provides first evidence that intensified melt in the marginal zones of the Arctic Ocean interrupts the transarctic conveyor belt and has led to a reduction of the survival rates of sea ice exported from the shallow Siberian shelves (−15% per decade). As a consequence, less and less ice formed in shallow water areas (<30 m) has reached Fram Strait (−17% per decade), and more ice and ice-rafted material is released in the northern Laptev Sea and central Arctic Ocean. Decreasing survival rates of first-year ice are visible all along the Russian shelves, but significant only in the Kara Sea, East Siberian Sea and western Laptev Sea. Identified changes affect biogeochemical fluxes and ecological processes in the central Arctic: A reduced long-range transport of sea ice alters transport and redistribution of climate relevant gases, and increases accumulation of sediments and contaminates in the central Arctic Ocean, with consequences for primary production, and the biodiversity of the Arctic Ocean.

Published
2019

166. IceBird - A Pan-Arctic Airborne Sea Ice Observation System

Author

Hendricks, Stefan, Haas, Christian, Krumpen, Thomas, Herber, Andreas, Birnbaum, Gerit, Ricker, Robert, Jutila, Arttu, Hendricks, Stefan, Haas, Christian, Krumpen, Thomas, Herber, Andreas, Birnbaum, Gerit, Ricker, Robert, and Jutila, Arttu

Published
2019

167. Evidence for an Increasing Role of Ocean Heat in Arctic Winter Sea Ice Growth.

Author

Ricker, Robert, Kauker, Frank, Schweiger, Axel, Hendricks, Stefan, Zhang, Jinlun, and Paul, Stephan

Subjects
SEA ice, OCEAN temperature, ATMOSPHERIC temperature, WINTER, HEAT flux, OCEAN
Abstract

We investigate how sea ice decline in summer and warmer ocean and surface temperatures in winter affect sea ice growth in the Arctic. Sea ice volume changes are estimated from satellite observations during winter from 2002 to 2019 and are partitioned into thermodynamic growth and dynamic volume change. Both components are compared with validated sea ice–ocean models forced by reanalysis data to extend observations back to 1980 and to understand the mechanisms that cause the observed trends and variability. We find that a negative feedback driven by the increasing sea ice retreat in summer yields increasing thermodynamic ice growth during winter in the Arctic marginal seas eastward from the Laptev Sea to the Beaufort Sea. However, in the Barents and Kara Seas, this feedback seems to be overpowered by the impact of increasing oceanic heat flux and air temperatures, resulting in negative trends in thermodynamic ice growth of −2 km3 month−1 yr−1 on average over 2002–19 as derived from satellite observations. [ABSTRACT FROM AUTHOR]

Published
2021
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169. Recent achievements in sea ice thickness derived from radar altimetry

Author

Ricker, Robert, Hendricks, Stefan, Paul, Stephan, Kaleschke, Lars, and Tian-Kunze, Xiangshan

Abstract

The retrieval of Arctic sea ice thickness is one of the major objectives of the European CryoSat-2 radar altimeter mission and the 7-year long period of operation has produced an unprecedented record of monthly sea ice thickness information. We present CryoSat-2 results that show changes and variability of Arctic sea ice for the period 2010 to 2018. CryoSat-2, however, was designed to observe thick perennial sea ice, while retrieving thin seasonal sea ice accurately is more challenging. We have therefore developed a method of completing and improving Arctic sea ice thickness information by merging complementary satellite retrievals. The European SMOS satellite can detect thin sea ice, whereas its companion CryoSat-2 lacks sensitivity. Using these satellite missions together overcomes several issues of single-mission retrievals and provides a more accurate and comprehensive view on the state of Arctic sea-ice thickness at higher temporal resolution. Nevertheless, stand-alone CryoSat-2 observations can be used as reference data for the exploitation of older radar altimetry data sets over sea ice. In order to observe trends in sea ice thickness, it is required to minimize inter-mission biases between subsequent satellite missions. A climate data record of sea ice thickness derived from satellite radar altimetry has been developed for both hemispheres, based on the 15-year (2002-2017) monthly retrievals from Envisat and CryoSat-2 and calibrated in the 2010-2012 overlap period.

Published
2018

170. CryoSat Ice Baseline-D Validation and Evolutions

Author

Meloni, Marco, primary, Bouffard, Jerome, additional, Parrinello, Tommaso, additional, Dawson, Geoffrey, additional, Garnier, Florent, additional, Helm, Veit, additional, Di Bella, Alessandro, additional, Hendricks, Stefan, additional, Ricker, Robert, additional, Webb, Erica, additional, Wright, Ben, additional, Nielsen, Karina, additional, Lee, Sanggyun, additional, Passaro, Marcello, additional, Scagliola, Michele, additional, Bjerregaard Simonsen, Sebastian, additional, Sandberg Sørensen, Louise, additional, Brockley, David, additional, Baker, Steven, additional, Fleury, Sara, additional, Bamber, Jonathan, additional, Maestri, Luca, additional, Skourup, Henriette, additional, Forsberg, René, additional, and Mizzi, Loretta, additional

Published
2019
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171. Copernicus Marine Service Ocean State Report, Issue 3

Author

von Schuckmann, Karina, primary, Le Traon, Pierre-Yves, additional, Smith, Neville, additional, Pascual, Ananda, additional, Djavidnia, Samuel, additional, Gattuso, Jean-Pierre, additional, Grégoire, Marilaure, additional, Nolan, Glenn, additional, Aaboe, Signe, additional, Aguiar, Eva, additional, Álvarez Fanjul, Enrique, additional, Alvera-Azcárate, Aida, additional, Aouf, Lotfi, additional, Barciela, Rosa, additional, Behrens, Arno, additional, Belmonte Rivas, Maria, additional, Ben Ismail, Sana, additional, Bentamy, Abderrahim, additional, Borgini, Mireno, additional, Brando, Vittorio E., additional, Bensoussan, Nathaniel, additional, Blauw, Anouk, additional, Bryère, Philippe, additional, Buongiorno Nardelli, Bruno, additional, Caballero, Ainhoa, additional, Çağlar Yumruktepe, Veli, additional, Cebrian, Emma, additional, Chiggiato, Jacopo, additional, Clementi, Emanuela, additional, Corgnati, Lorenzo, additional, de Alfonso, Marta, additional, de Pascual Collar, Álvaro, additional, Deshayes, Julie, additional, Di Lorenzo, Emanuele, additional, Dominici, Jean-Marie, additional, Dupouy, Cécile, additional, Drévillon, Marie, additional, Echevin, Vincent, additional, Eleveld, Marieke, additional, Enserink, Lisette, additional, García Sotillo, Marcos, additional, Garnesson, Philippe, additional, Garrabou, Joaquim, additional, Garric, Gilles, additional, Gasparin, Florent, additional, Gayer, Gerhard, additional, Gohin, Francis, additional, Grandi, Alessandro, additional, Griffa, Annalisa, additional, Gourrion, Jérôme, additional, Hendricks, Stefan, additional, Heuzé, Céline, additional, Holland, Elisabeth, additional, Iovino, Doroteaciro, additional, Juza, Mélanie, additional, Kurt Kersting, Diego, additional, Kipson, Silvija, additional, Kizilkaya, Zafer, additional, Korres, Gerasimos, additional, Kõuts, Mariliis, additional, Lagemaa, Priidik, additional, Lavergne, Thomas, additional, Lavigne, Heloise, additional, Ledoux, Jean-Baptiste, additional, Legeais, Jean-François, additional, Lehodey, Patrick, additional, Linares, Cristina, additional, Liu, Ye, additional, Mader, Julien, additional, Maljutenko, Ilja, additional, Mangin, Antoine, additional, Manso-Narvarte, Ivan, additional, Mantovani, Carlo, additional, Markager, Stiig, additional, Mason, Evan, additional, Mignot, Alexandre, additional, Menna, Milena, additional, Monier, Maeva, additional, Mourre, Baptiste, additional, Müller, Malte, additional, Nielsen, Jacob Woge, additional, Notarstefano, Giulio, additional, Ocaña, Oscar, additional, Patti, Bernardo, additional, Payne, Mark R., additional, Peirache, Marion, additional, Pardo, Silvia, additional, Pérez Gómez, Begoña, additional, Pisano, Andrea, additional, Perruche, Coralie, additional, Peterson, K. Andrew, additional, Pujol, Marie-Isabelle, additional, Raudsepp, Urmas, additional, Ravdas, Michalis, additional, Raj, Roshin P., additional, Renshaw, Richard, additional, Reyes, Emma, additional, Ricker, Robert, additional, Rubio, Anna, additional, Sammartino, Michela, additional, Santoleri, Rosalia, additional, Sathyendranath, Shubha, additional, Schroeder, Katrin, additional, She, Jun, additional, Sparnocchia, Stefania, additional, Staneva, Joanna, additional, Stoffelen, Ad, additional, Szekely, Tanguy, additional, Tilstone, Gavin H., additional, Tinker, Jonathan, additional, Tintoré, Joaquín, additional, Tranchant, Benoît, additional, Uiboupin, Rivo, additional, Van der Zande, Dimitry, additional, von Schuckmann, Karina, additional, Wood, Richard, additional, Woge Nielsen, Jacob, additional, Zabala, Mikel, additional, Zacharioudaki, Anna, additional, Zuberer, Frédéric, additional, and Zuo, Hao, additional

Published
2019
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173. Retrieving Sea Level and Freeboard in the Arctic: A Review of Current Radar Altimetry Methodologies and Future Perspectives

Author

Quartly, Graham D., primary, Rinne, Eero, additional, Passaro, Marcello, additional, Andersen, Ole B., additional, Dinardo, Salvatore, additional, Fleury, Sara, additional, Guillot, Amandine, additional, Hendricks, Stefan, additional, Kurekin, Andrey A., additional, Müller, Felix L., additional, Ricker, Robert, additional, Skourup, Henriette, additional, and Tsamados, Michel, additional

Published
2019
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174. Arctic warming interrupts the Transpolar Drift and affects long-range transport of sea ice and ice-rafted matter

Author

Krumpen, Thomas, primary, Belter, H. Jakob, additional, Boetius, Antje, additional, Damm, Ellen, additional, Haas, Christian, additional, Hendricks, Stefan, additional, Nicolaus, Marcel, additional, Nöthig, Eva-Maria, additional, Paul, Stephan, additional, Peeken, Ilka, additional, Ricker, Robert, additional, and Stein, Rüdiger, additional

Published
2019
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176. Sea ice thickness derived from radar altimetry: achievements and future plans

Author

Ricker, Robert, Hendricks, Stefan, Paul, Stephan, Kaleschke, Lars, and Tian-Kunze, Xiangshan

Abstract

The retrieval of Arctic sea ice thickness is one of the major objectives of the European CryoSat-2 radar altimeter mission and the 7-year long period of operation has produced an unprecedented record of monthly sea ice thickness information. We present CryoSat-2 results that show changes and variability of Arctic sea ice from the winter season 2010/2011 until fall 2017. CryoSat-2, however, was designed to observe thick perennial sea ice, while an accurate retrieval of thin seasonal sea ice is more challenging. We have therefore developed a method of completing and improving Arctic sea ice thickness information within the ESA SMOS+ Sea Ice project by merging CryoSat-2 and SMOS sea ice thickness retrievals. Using these satellite missions together overcomes several issues of single-mission retrievals and provides a more accurate and comprehensive view on the state of Arctic sea-ice thickness at higher temporal resolution. However, stand-alone CryoSat-2 observations can be used as reference data for the exploitation of older pulse-limited radar altimetry data sets over sea ice. In order to observe trends in sea ice thickness, it is required to minimize inter-mission biases between subsequent satellite missions. Within the ESA Climate Change Initiative (CCI) on Sea Ice, a climate data record of sea ice thickness derived from satellite radar altimetry has been developed for both hemispheres, based on the 15-year (2002-2017) monthly retrievals from Envisat and CryoSat-2 and calibrated in the 2010-2012 overlap period. The next step in promoting the utilization of sea ice thickness information from radar altimetry is to provide products by a service that meets the requirements for climate applications and operational systems. This task will be pursued within a Copernicus Climate Change Service project (C3S). This framework also aims to include additional sensors such as onboard Sentinel-3 and we will show first results of Sentinel-3 Arctic sea-ice thickness. These developments are the base for preserving the continuity of the sea ice thickness data record and the transformation from research oriented products into an operational service.

Published
2017

178. Arctic Mission Benefit Analysis: impact of sea ice thickness, freeboard, and snow depth products on sea ice forecast performance

Author

Kaminski, Thomas, Kauker, Frank, Toudal Pedersen, Leif, Voßbeck, Michael, Haak, Helmuth, Niederdrenk, Laura, Hendricks, Stefan, Ricker, Robert, Karcher, Michael, Eicken, Hajo, Gråbak, Ola, Kaminski, Thomas, Kauker, Frank, Toudal Pedersen, Leif, Voßbeck, Michael, Haak, Helmuth, Niederdrenk, Laura, Hendricks, Stefan, Ricker, Robert, Karcher, Michael, Eicken, Hajo, and Gråbak, Ola

Abstract

Assimilation of remote-sensing products of sea ice thickness (SIT) into sea ice–ocean models has been shown to improve the quality of sea ice forecasts. Key open questions are whether assimilation of lower-level data products such as radar freeboard (RFB) can further improve model performance and what performance gains can be achieved through joint assimilation of these data products in combination with a snow depth product. The Arctic Mission Benefit Analysis system was developed to address this type of question. Using the quantitative network design (QND) approach, the system can evaluate, in a mathematically rigorous fashion, the observational constraints imposed by individual and groups of data products. We demonstrate the approach by presenting assessments of the observation impact (added value) of different Earth observation (EO) products in terms of the uncertainty reduction in a 4-week forecast of sea ice volume (SIV) and snow volume (SNV) for three regions along the Northern Sea Route in May 2015 using a coupled model of the sea ice–ocean system, specifically the Max Planck Institute Ocean Model. We assess seven satellite products: three real products and four hypothetical products. The real products are monthly SIT, sea ice freeboard (SIFB), and RFB, all derived from CryoSat-2 by the Alfred Wegener Institute. These are complemented by two hypothetical monthly laser freeboard (LFB) products with low and high accuracy, as well as two hypothetical monthly snow depth products with low and high accuracy. On the basis of the per-pixel uncertainty ranges provided with the CryoSat-2 SIT, SIFB, and RFB products, the SIT and RFB achieve a much better performance for SIV than the SIFB product. For SNV, the performance of SIT is only low, the performance of SIFB is higher and the performance of RFB is yet higher. A hypothetical LFB product with low accuracy (20cm uncertainty) falls between SIFB and RFB in performance for both SIV and SNV. A reduction in the uncertaint

Published
2018

180. Empirical parametrization of Envisat freeboard retrieval of Arctic and Antarctic sea ice based on CryoSat-2: progress in the ESA Climate Change Initiative

Author

Paul, Stephan, Hendricks, Stefan, Ricker, Robert, Kern, Stefan, Rinne, Eero, Paul, Stephan, Hendricks, Stefan, Ricker, Robert, Kern, Stefan, and Rinne, Eero

Abstract

In order to derive long-term changes in sea-ice volume, a multi-decadal sea-ice thickness record is required. CryoSat-2 has showcased the potential of radar altimetry for sea-ice mass-balance estimation over the recent years. However, precursor altimetry missions such as Environmental Satellite (Envisat) have not been exploited to the same extent so far. Combining both missions to acquire a decadal sea-ice volume data set requires a method to overcome the discrepancies due to different footprint sizes from either pulse-limited or beam-sharpened radar echoes. In this study, we implemented an inter-mission-consistent surface-type classification scheme for both hemispheres, based on the waveform pulse peakiness, leading-edge width, and surface backscatter. In order to achieve a consistent retracking procedure, we adapted the threshold first-maximum retracker algorithm, previously used only for CryoSat-2, to develop an adaptive retracker threshold that depends on waveform characteristics. With our method, we produce a global and consistent freeboard data set for CryoSat-2 and Envisat. This novel data set features a maximum monthly difference in the mission-overlap period of 2.2cm (2.7cm) for the Arctic (Antarctic) based on all gridded values with spatial resolution of 25 km × 25 km and 50 km × 50 km for the Arctic and Antarctic, respectively.

Published
2018

181. Ice and snow thickness variability and change in the high Arctic Ocean observed by in-situ measurements

Author

Haas, Christian, Beckers, Justin, King, Josh, Silis, Arvids, Stroeve, Julienne, Wilkinson, Jeremy, Notenboom, Bernice, Schweiger, Axel, and Hendricks, Stefan

Subjects
education, human activities
Abstract

In April 2017, we collected unique, extensive in situ data of sea ice and snow thickness. At 10 sampling sites, located under a CryoSat-2 overpass, between Ellesmere Island and 87.1°N mean and modal total ice thicknesses ranged between 2 to 3.4 m and 1.8 to 2.9 m, respectively. Coincident snow thicknesses ranged between 0.3 to 0.47 m (mean) and 0.1 to 0.5 m (mode). The profile spanned the complete multiyear ice zone in the Lincoln Sea, into the first-year ice zone farther north. Complementary snow thickness measurements near the North Pole showed a mean thickness of 0.31 m. Compared with scarce measurements from other years, multiyear ice was up to 0.75 m thinner than in 2004, but not significantly different from 2011 and 2014. We found excellent agreement with a commonly used snow climatology and with published long-term ice thinning rates. There was reasonable agreement with CryoSat-2 thickness retrievals.

Published
2017

182. Biogeochemical impact of snow cover and cyclonic intrusions on the winter Weddell Sea ice pack

Author

Tison, Jean-Louis, Schwegmann, S., Dieckmann, Gerhard S., Rintala, Janne-Markus, Meyer, H., Moreau, Sébastien, Vancoppenolle, Martin, Nomura, Daiki, Engberg, S., Blomster, J., Hendricks, Stefan, Uhlig, C., Luhtanen, A.-M., De Jong, J., Janssens, Jan, Carnat, Gauthier, Zhou, J., Delille, Bruno, Environmental Sciences, Jaanika Blomster / Principal Investigator, Life Science Education, Biosciences, Elina Roine / Principal Investigator, General Microbiology, Structure of the Viral Universe, Tvärminne Zoological Station, Marine Ecosystems Research Group, Teachers' Academy, Laboratoire de Glaciologie, Université libre de Bruxelles (ULB), Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), Helsingin yliopisto = Helsingfors universitet = University of Helsinki, Institute for Marine and Antarctic Studies [Hobart] (IMAS), University of Tasmania [Hobart, Australia] (UTAS), Faculty of Fisheries Sciences [Hakodate], Hokkaido University [Sapporo, Japan], Finnish Environment Institute (SYKE), Laboratoire de Glaciologie [Bruxelles], Université de Liège, Australian Research Council's Special Research Initiative for Antarctic Gateway Partnership . Grant Number: SR140300001JSPS KAKENHI . Grant Numbers: 12J04175 , 17H04715, European Project: 262922,EC:FP7:SPA,FP7-SPACE-2010-1,SIDARUS(2011), Institute for Marine and Antarctic Studies [Horbat] (IMAS), Nucleus for European Modeling of the Ocean (NEMO R&D ), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Muséum national d'Histoire naturelle (MNHN)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), University of Helsinki, Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-École polytechnique (X)-Centre National d'Études Spatiales [Toulouse] (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-Institut de Recherche pour le Développement (IRD)-Muséum national d'Histoire naturelle (MNHN)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)

Subjects
1171 Geosciences, Weddell Sea, PHYSICAL-PROPERTIES, [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph], SEASONAL-VARIATIONS, winter, sea ice, MCMURDO SOUND, CO2 EXCHANGE, ANTARCTICA, MODEL, CARBON, biogeochemistry, MASS-BALANCE, ISOTOPIC COMPOSITION, SOUTHERN-OCEAN
Abstract

International audience; Sea ice is a dynamic biogeochemical reactor and a double interface actively interacting with both the atmosphere and the ocean. However, proper understanding of its annual impact on exchanges, and therefore potentially on the climate, notably suffer from the paucity of autumnal and winter data sets. Here we present the results of physical and biogeochemical investigations on winter Antarctic pack ice in the Weddell Sea (R. V. Polarstern AWECS cruise, June–August 2013) which are compared with those from two similar studies conducted in the area in 1986 and 1992. The winter 2013 was characterized by a warm sea ice cover due to the combined effects of deep snow and frequent warm cyclones events penetrating southward from the open Southern Ocean. These conditions were favorable to high ice permeability and cyclic events of brine movements within the sea ice cover (brine tubes), favoring relatively high chlorophyll‐a (Chl‐a) concentrations. We discuss the timing of this algal activity showing that arguments can be presented in favor of continued activity during the winter due to the specific physical conditions. Large‐scale sea ice model simulations also suggest a context of increasingly deep snow, warm ice, and large brine fractions across the three observational years, despite the fact that the model is forced with a snowfall climatology. This lends support to the claim that more severe Antarctic sea ice conditions, characterized by a longer ice season, thicker, and more concentrated ice are sufficient to increase the snow depth and, somehow counterintuitively, to warm the ice.

Published
2017

185. Arctic Mission Benefit Analysis: impact of sea ice thickness, freeboard, and snow depth products on sea ice forecast performance

Author

Kaminski, Thomas, primary, Kauker, Frank, additional, Toudal Pedersen, Leif, additional, Voßbeck, Michael, additional, Haak, Helmuth, additional, Niederdrenk, Laura, additional, Hendricks, Stefan, additional, Ricker, Robert, additional, Karcher, Michael, additional, Eicken, Hajo, additional, and Gråbak, Ola, additional

Published
2018
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187. Review of Radar Altimetry Techniques over the Arctic Ocean: Recent Progress and Future Opportunities for Sea Level and Sea Ice Research

Author

Quartly, Graham D., primary, Rinne, Eero, additional, Passaro, Marcello, additional, Andersen, Ole B., additional, Dinardo, Salvatore, additional, Fleury, Sara, additional, Guerreiro, Kevin, additional, Guillot, Amandine, additional, Hendricks, Stefan, additional, Kurekin, Andrey A., additional, Müller, Felix L., additional, Ricker, Robert, additional, Skourup, Henriette, additional, and Tsamados, Michel, additional

Published
2018
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190. SMOS-derived Antarctic thin sea ice thickness: data description and validation in the Weddell Sea.

Author

Kaleschke, Lars, Tian-Kunze, Xiangshan, Hendricks, Stefan, and Ricker, Robert

Subjects
*SEAWATER salinity, *SPHERICAL projection, *ROOT-mean-squares, *BRIGHTNESS temperature, *ANTARCTIC ice, *SEA ice
Abstract

Accurate satellite measurements of the thickness of Antarctic sea ice are urgently needed but pose a particular challenge. The Antarctic data presented here were produced using a method to derive the sea ice thickness from 1.4 GHz brightness temperatures previously developed for the Arctic, with only modified auxiliary data. The ability to observe the thickness of thin sea ice using this method is limited to cold conditions, meaning it is only reasonable during the freezing period, typically March to October. The Soil Moisture and Ocean Salinity (SMOS) level-3 sea ice thickness product contains estimates of the sea ice thickness and its uncertainty up to a thickness of about 1 m. The sea ice thickness is provided as a daily average on a polar stereographic projection grid with a sample resolution of 12.5 km , while the SMOS brightness temperature data used have a footprint size of about 35–40 km in diameter. Data from SMOS have been available since 2010, and the mission's operation has been extended to continue until at least the end of 2025. Here we compare two versions of the SMOS Antarctic sea ice thickness product which are based on different level-1 input data (v3.2 based on SMOS L1C v620 and v3.3 based on SMOS L1C 724). A validation is performed to generate a first baseline reference for future improvements of the retrieval algorithm and synergies with other sensors. Sea ice thickness measurements to validate the SMOS product are particularly rare in Antarctica, especially during the winter season and for the valid range of thicknesses. From the available validation measurements, we selected datasets from the Weddell Sea that have varying degrees of representativeness: Helicopter-based EM Bird (HEM), Surface and Under-Ice Trawl (SUIT), and stationary Upward-Looking Sonars (ULS). While the helicopter can measure hundreds of kilometres, SUIT's use is limited to distances of a few kilometres and thus only captures a small fraction of an SMOS footprint. Compared to SMOS, the ULS are point measurements and multi-year time series are necessary to enable a statistically representative comparison. Only four of the ULS moorings have a temporal overlap with SMOS in the year 2010. Based on selected averaged HEM flights and monthly ULS climatologies, we find a small mean difference (bias) of less than 10 cm and a root mean square deviation of about 20 cm with a correlation coefficient R > 0.9 for the valid sea ice thickness range between 0 and about 1 m. The SMOS sea ice thickness showed an underestimate of about 40 cm with respect to the less representative SUIT validation data in the marginal ice zone. Compared with sea ice thickness outside the valid range, we find that SMOS strongly underestimates the real values, which underlines the need for combination with other sensors such as altimeters. In summary, the overall validity of the SMOS sea ice thickness for thin sea ice up to a thickness of about 1 m has been demonstrated through validation with multiple datasets. To ensure the quality of the SMOS product, an independent regional sea ice extent index was used for control. We found that the new version, v3.3, is slightly improved in terms of completeness, indicating fewer missing data. However, it is worth noting that the general characteristics of both datasets are very similar, also with the same limitations. Archived data are available in the PANGAEA repository at https://doi.org/10.1594/PANGAEA.934732 and operationally at https://doi.org/10.57780/sm1-5ebe10b. [ABSTRACT FROM AUTHOR]

Published
2024
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191. Satellite-observed drop of Arctic sea ice growth in winter 2015-2016

Author

Ricker, Robert, Hendricks, Stefan, Girard-ardhuin, Fanny, Kaleschke, Lars, Lique, Camille, Tian-kunze, Xiangshan, Nicolaus, Marcel, Krumpen, Thomas, Ricker, Robert, Hendricks, Stefan, Girard-ardhuin, Fanny, Kaleschke, Lars, Lique, Camille, Tian-kunze, Xiangshan, Nicolaus, Marcel, and Krumpen, Thomas

Abstract

An anomalous warm winter 2015–2016 lead to the lowest winter ice extent and highlights the sensitivity of the Arctic sea ice. Here we use the 6 year record of an improved sea ice thickness product retrieved from data fusion of CryoSat-2 radar altimetry and Soil Moisture and Ocean Salinity radiometry measurements to examine the impact of recent temperature trend on the Arctic ice mass balance. Between November 2015 and March 2016, we find a consistent drop of cumulative freezing degree days across the Arctic, with a negative peak anomaly of about 1000 degree days in the Barents Sea, coinciding with an Arctic-wide average thinning of 10 cm in March with respect to the 6 year average. In particular, the loss of ice volume is associated with a significant decline of March first-year ice volume by 13%. This reveals that due to the loss of multiyear ice during previous years, the Arctic ice cover becomes more sensitive to climate anomalies.

Published
2017
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192. A weekly Arctic sea-ice thickness data record from merged CryoSat-2 and SMOS satellite data

Author

Ricker, Robert, Hendricks, Stefan, Kaleschke, Lars, Tian-kunze, Xiangshan, King, Jennifer, Haas, Christian, Ricker, Robert, Hendricks, Stefan, Kaleschke, Lars, Tian-kunze, Xiangshan, King, Jennifer, and Haas, Christian

Abstract

Sea-ice thickness on a global scale is derived from different satellite sensors using independent retrieval methods. Due to the sensor and orbit characteristics, such satellite retrievals differ in spatial and temporal resolution as well as in the sensitivity to certain sea-ice types and thickness ranges. Satellite altimeters, such as CryoSat-2 (CS2), sense the height of the ice surface above the sea level, which can be converted into sea-ice thickness. Relative uncertainties associated with this method are large over thin ice regimes. Another retrieval method is based on the evaluation of surface brightness temperature (TB) in L-band microwave frequencies (1.4 GHz) with a thickness-dependent emission model, as measured by the Soil Moisture and Ocean Salinity (SMOS) satellite. While the radiometer-based method looses sensitivity for thick sea ice (> 1 m), relative uncertainties over thin ice are significantly smaller than for the altimetry-based retrievals. In addition, the SMOS product provides global sea-ice coverage on a daily basis unlike the altimeter data. This study presents the first merged product of complementary weekly Arctic sea-ice thickness data records from the CS2 altimeter and SMOS radiometer. We use two merging approaches: a weighted mean (WM) and an optimal interpolation (OI) scheme. While the weighted mean leaves gaps between CS2 orbits, OI is used to produce weekly Arctic-wide sea-ice thickness fields. The benefit of the data merging is shown by a comparison with airborne electromagnetic (AEM) induction sounding measurements. When compared to airborne thickness data in the Barents Sea, the merged product has a root mean square deviation (RMSD) of about 0.7m less than the CS2 product and therefore demonstrates the capability to enhance the CS2 product in thin ice regimes. However, in mixed first-year (FYI) and multiyear (MYI) ice regimes as in the Beaufort Sea, the CS2 retrieval shows the lowest bias.

Published
2017
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193. CS2SMOS User Guide v3.0

Author

Ricker, Robert, Hendricks, Stefan, Kaleschke, Lars, Tian-Kunze, Xiangshan, Ricker, Robert, Hendricks, Stefan, Kaleschke, Lars, and Tian-Kunze, Xiangshan

Published
2017

194. Airborne and ground based atmospheric and sea ice measurements - A contribution to MOSAiC

Author

Birnbaum, Gerit, Lüpkes, Christof, Hartmann, Jörg, Schmithüsen, Holger, Loose, Bernd, Hendricks, Stefan, Haas, Christian, Herber, Andreas, Dierking, Wolfgang, Birnbaum, Gerit, Lüpkes, Christof, Hartmann, Jörg, Schmithüsen, Holger, Loose, Bernd, Hendricks, Stefan, Haas, Christian, Herber, Andreas, and Dierking, Wolfgang

Published
2017

195. Sea-ice thickness from field measurements in the northwestern Barents Sea

Author

King, Jennifer, Spreen, Gunnar, Gerland, Sebastian, Haas, Christian, Hendricks, Stefan, Kaleschke, Lars, Wang, Caixin, King, Jennifer, Spreen, Gunnar, Gerland, Sebastian, Haas, Christian, Hendricks, Stefan, Kaleschke, Lars, and Wang, Caixin

Abstract

The Barents Sea is one of the fastest changing regions of the Arctic, and has experienced the strongest decline in winter-time sea-ice area in the Arctic, at -23 +/- 4% per decade. Sea-ice thickness in the Barents Sea is not well studied. We present two previously unpublished helicopter-borne electromagnetic (HEM) ice thickness measurements from the northwestern Barents Sea acquired in March 2003 and 2014. The HEM data are compared to ice thickness calculated from ice draft measured by ULS deployed between 1994 and 1996. These data show that ice thickness varies greatly from year to year; influenced by the thermodynamic and dynamic processes that govern local formation vs long-range advection. In a year with a large inflow of sea-ice from the Arctic Basin, the Barents Sea ice cover is dominated by thick multiyear ice; as was the case in 2003 and 1995. In a year with an ice cover that was mainly grown in situ, the ice will be thin and mechanically unstable; as was the case in 2014. The HEM data allow us to explore the spatial and temporal variability in ice thickness. In 2003 the dominant ice class was more than 2 years old; and modal sea-ice thickness varied regionally from 0.6 to 1.4 m, with the thinner ice being either first-year ice, or multiyear ice which had come into contact with warm Atlantic water. In 2014 the ice cover was predominantly locally grown ice less than 1 month old (regional modes of 0.5–0.8 m). These two situations represent two extremes of a range of possible ice thickness distributions that can present very different conditions for shipping traffic; or have a different impact on heat transport from ocean to atmosphere.

Published
2017

196. Biogeochemical Impact of Snow Cover and Cyclonic Intrusions on the Winter Weddell Sea Ice Pack

Author

Tison, J.-L., Schwegmann, S., Dieckmann, G.S., Rintala, J.-M., Meyer, H., Moreau, S., Vancoppenolle, M., Nomura, D., Enberg, S., Blomster, L. J., Hendricks, Stefan, Uhlig, C., Luhtanen, A.-M., de Jong, J., Janssens, J., Carnat, G., Zhou, J., Delille, B., Tison, J.-L., Schwegmann, S., Dieckmann, G.S., Rintala, J.-M., Meyer, H., Moreau, S., Vancoppenolle, M., Nomura, D., Enberg, S., Blomster, L. J., Hendricks, Stefan, Uhlig, C., Luhtanen, A.-M., de Jong, J., Janssens, J., Carnat, G., Zhou, J., and Delille, B.

Abstract

Sea ice is a dynamic biogeochemical reactor and a double interface actively interacting with both the atmosphere and the ocean. However, proper understanding of its annual impact on exchanges, and therefore potentially on the climate, notably suffer from the paucity of autumnal and winter data sets. Here we present the results of physical and biogeochemical investigations on winter Antarctic pack ice in the Weddell Sea (R. V. Polarstern AWECS cruise, June–August 2013) which are compared with those from two similar studies conducted in the area in 1986 and 1992. The winter 2013 was characterized by a warm sea ice cover due to the combined effects of deep snow and frequent warm cyclones events penetrating southward from the open Southern Ocean. These conditions were favorable to high ice permeability and cyclic events of brine movements within the sea ice cover (brine tubes), favoring relatively high chlorophyll-a (Chl-a) concentrations. We discuss the timing of this algal activity showing that arguments can be presented in favor of continued activity during the winter due to the specific physical conditions. Large-scale sea ice model simulations also suggest a context of increasingly deep snow, warm ice, and large brine fractions across the three observational years, despite the fact that the model is forced with a snowfall climatology. This lends support to the claim that more severe Antarctic sea ice conditions, characterized by a longer ice season, thicker, and more concentrated ice are sufficient to increase the snow depth and, somehow counterintuitively, to warm the ice.

Published
2017

197. An Assessment of State-of-the-Art Mean Sea Surface and Geoid Models of the Arctic Ocean: Implications for Sea Ice Freeboard Retrieval

Author

Skourup, Henriette, Farell, Sinead, Hendricks, Stefan, Ricker, Robert, Armitage, Thomas, Ridout, Andy, Andersen, Ole B., Haas, Christian, Baker, Steve, Skourup, Henriette, Farell, Sinead, Hendricks, Stefan, Ricker, Robert, Armitage, Thomas, Ridout, Andy, Andersen, Ole B., Haas, Christian, and Baker, Steve

Abstract

State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors in a given model in the high frequency domain, primarily due to unresolved gravity features, can result in errors in the estimated along-track freeboard. These errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multi-sensor oceanographic time-series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL13/04, DTU15/13/10) and a commonly used GGM (EGM2008). We describe errors due to unresolved gravity features, inter-satellite biases, and remaining satellite orbit errors, and their impact on the derivation of sea ice freeboard. The latest MSS models, incorporating CryoSat-2 sea surface height measurements, show improved definition of gravity features, such as the Gakkel Ridge. The standard deviation between models ranges 0.03-0.25 m. The impact of remaining MSS/GGM errors on freeboard retrieval can reach several decimeters in parts of the Arctic. While the maximum observed freeboard difference found in the central Arctic was 0.59 m (UCL13 MSS minus EGM2008 GGM), the standard deviation in freeboard differences is 0.03-0.06 m.

Published
2017

198. Brief communication: Antarctic sea ice gain does not compensate for increased solar absorption from Arctic ice loss

Author

Katlein, Christian, Hendricks, Stefan, Key, Jeffrey, Katlein, Christian, Hendricks, Stefan, and Key, Jeffrey

Abstract

Here we show on the basis of the new consistent long-term observational dataset APP-x, that the observed increase of sea ice extent in the Antarctic cannot compensate for the loss of Arctic sea ice in terms of the shortwave radiation budget in the polar oceans poleward of 50° latitude. The observations show, that apart from retreating sea-ice additional effects like albedo changes and especially changing cloud coverage lead to a total increase of solar shortwave energy deposited into the polar oceans despite of the marginal increase in Antarctic winter sea ice extent.

Published
2017

199. Snow depth and air temperature on sea ice derived from autonomous Snow Buoy measurements

Author

Nicolaus, Marcel, Arndt, Stefanie, Hendricks, Stefan, Heygster, Georg, Hoppmann, Mario, Huntemann, Marcus, Katlein, Christian, Langevin, Danielle, Rossmann, Leonard, and König-Langlo, Gert

Abstract

More observations of snow depth on sea ice are urgently needed for various applications in polar and climate research. Large-scale and seasonal snow depth products are required for many in-situ, remote sensing, and numerical modelling applications. We developed a new buoy type to obtain time series of snow depth and air temperature on Arctic and Antarctic sea ice. The buoy is based on four sonic ranging sensors, and transmits the data via Iridium satellites. The buoy concept and design are based on low unit costs and easy deployment. Snow buoys proved to be most valuable when co-deployed with other buoy types. Near real time data sharing into international networks for a large user community: GTS, buoy programs.

Published
2016

200. data.seaiceportal.de - Open Data Portal for Sea Ice Climate Data

Author

Nicolaus, Marcel, Asseng, Jölund, Bartsch, Annekathrin, Bräuer, Benny, Fritzsch, Bernadette, Grosfeld, Klaus, Huntemann, Marcus, Hendricks, Stefan, Hiller, Wolfgang, Heygster, Georg, Krumpen, Thomas, Melsheimer, Christian, Ricker, Robert, Treffeisen, Renate, and Weigelt, Marietta

Abstract

There is an increasing public interest in sea ice information from both Polar Regions, which requires up-to-date background information and data sets at different levels for various target groups. In order to serve this interest and need, seaiceportal.de (originally: meereisportal.de) was developed as a comprehensive German knowledge platform on sea ice and its snow cover in the Arctic and Antarctic. It was launched in April 2013. Since then, the content and selection of data sets increased and the data portal received increasing attention, also from the international science community. Meanwhile, we are providing near-real time and archive data of many key parameters of sea ice and its snow cover. The data sets result from measurements acquired by various platforms as well as numerical simulations. Satellite observations of sea ice concentration, freeboard, thickness and drift are available as gridded data sets. Sea ice and snow temperatures and thickness as well as atmospheric parameters are available from autonomous platforms (buoys). Additional ship observations, ice station measurements, and mooring time series are compiled as data collections over the last decade. In parallel, we are continuously extending our meta-data and uncertainty information for all data sets. In addition to the data portal, seaiceportal.de provides general comprehensive background information on sea ice and snow as well as expert statements on recent observations and developments. This content is mostly in German in order to complement the various existing international sites for the German speaking public. We will present the portal, its content and function, but we are also asking for direct user feedback.

Published
2016

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