Blar i forfatter "Ricker, Robert"

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    • Different mechanisms of Arctic first-year sea-ice ridge consolidation observed during the MOSAiC expedition 

      Salganik, Evgenii; Lange, Benjamin; Itkin, Polona; Divine, Dmitry; Katlein, Christian; Nicolaus, Marcel; Hoppmann, Mario; Neckel, Niklas; Ricker, Robert; Høyland, Knut Vilhelm; Granskog, Mats (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-22)
      Sea-ice ridges constitute a large fraction of the ice volume in the Arctic Ocean, yet we know little about the evolution of these ice masses. Here we examine the thermal and morphological evolution of an Arctic firstyear sea-ice ridge, from its formation to advanced melt. Initially the mean keel depth was 5.6 m and mean sail height was 0.7 m. The initial rubble macroporosity (fraction of seawater ...

    • Overview of the MOSAiC expedition: Snow and sea ice 

      Marcel, Nicolaus; Perovich, Donald; Spreen, Gunnar; Granskog, Mats; Divine, Dmitry; Gerland, Sebastian; Gradinger, Rolf Rudolf; Høyland, Knut Vilhelm; Salganik, Evgenii; Albedyll, Luisa von; Angelopoulos, Michael; Anhaus, Philipp; Arndt, Stefanie; Belter, H. Jakob; Bessonov, Vladimir; Birnbaum, Gerit; Brauchle, Jörg; Calmer, Radiance; Cardellach, Estel; Cheng, Bin; Clemens-Sewall, David; Dadic, Ruzica; Damm, Ellen; de Boer, Gijs; Demir, Oguz; Dethloff, Klaus; Fong, Allison A.; Fons, Steven; Frey, Markus M.; Fuchs, Niels; Gabarro, Carolina; Goessling, Helge F.; Haapala, Jari; Haas, Christian; Hamilton, Jonathan; Hannula, Henna-Reetta; Hendricks, Stefan; Herber, Andreas; Heuze´, Céline; Hoppmann, Mario; Huntemann, Marcus; Hutchings, Jennifer K.; Kaleschke, Lars; Katlein, Christian; Kolabutin, Nikolai; Krampe, Daniela; Savstrup Kristensen, Steen; Krumpen, Thomas; Kurtz, Nathan; Lampert, Astrid; Lange, Benjamin Allen; Lei, Ruibo; Light, Bonnie; Linhardt, Felix; Liston, Glen E.; Loose, Brice; Macfarlane, Amy R.; Mahmud, Mallik; Matero, Ilkka O.; Maus, Sönke; Morgenstern, Anne; Naderpour, Reza; Nandan, Vishnu; Niubom, Alexey; Oggier, Marc; Oppelt, Natascha; Pätzold, Falk; Perron, Christophe; Petrovsky, Tomasz; Pirazzini, Roberta; Polashenski, Chris; Rabe, Benjamin; Raphael, Ian A.; Regnery, Julia; Rex, Markus; Ricker, Robert; Riemann-Campe, Kathrin; Rinke, Annette; Rohde, Jan; Scharien, Randall K.; Schiller, Martin; Schneebeli, Martin; Semmling, Maximilian; Shimanchuk, Egor; Stroeve, Julienne; Thielke, Linda; Timofeeva, Anna; Tonboe, Rasmus Tage; Tavri, Aikterini; Tsamados, Michel; Wagner, David N.; Watkins, Daniel; Webster, Melinda; Wendisch, Manfred (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-02-07)
      Year-round observations of the physical snow and ice properties and processes that govern the ice pack evolution and its interaction with the atmosphere and the ocean were conducted during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition of the research vessel Polarstern in the Arctic Ocean from October 2019 to September 2020. This work was embedded ...

    • Radar size inference from statistics of RCS samples 

      Anfinsen, Stian Normann; Grydeland, Tom; Vierinen, Juha; Kastinen, Daniel; Ricker, Robert; Arntzen, Ingar M; Kero, J.; Høgda, Kjell Arild (Journal article; Tidsskriftartikkel; Peer reviewed, 2023)
      Radar Beam-park experiments have been very successful in characterizing the distribution of space debris objects, both in terms of orbital parameters but also in terms of limiting the estimates of their radar cross section, or RCS. A recent paper \[0\] used observed range and range rates to refine orbit estimates by matching up the observed SNR curve to that predicted by simulations. This gives good ...

    • Retrieval of Snow Depth on Arctic Sea Ice From Surface-Based, Polarimetric, Dual-Frequency Radar Altimetry 

      Willatt, Rosemary; Stroeve, Julienne; Nandan, Vishnu; Newman, Thomas; Mallett, Robbie; Hendricks, Stefan; Ricker, Robert; Mead, James; Itkin, Polona; Tonboe, Rasmus; Wagner, David N.; Spreen, Gunnar; Liston, Glen; Schneebeli, Martin; Krampe, Daniela; Tsamados, Michel; Demir, Oguz; Wilkinson, Jeremy; Jaggi, Matthias; Zhou, Lu; Huntemann, Marcus; Raphael, Ian A.; Jutila, Arttu; Oggier, Marc (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-10-18)
      Snow depth on sea ice is an Essential Climate Variable and a major source of uncertainty in satellite altimetry-derived sea ice thickness. During winter of the MOSAiC Expedition, the “KuKa” dual-frequency, fully polarized Ku- and Ka-band radar was deployed in “stare” nadir-looking mode to investigate the possibility of combining these two frequencies to retrieve snow depth. Three approaches ...

    • Sea ice and snow characteristics from year-long transects at the MOSAiC Central Observatory 

      Itkin, Polona; Hendricks, Stefan; Webster, Melinda A.; Albedyll, Luisa von; Arndt, Stefanie; Divine, Dmitry; Jaggi, Matthias; Oggier, Marc; Raphael, Ian A.; Ricker, Robert; Rohde, Jan; Schneebeli, Martin; Liston, Glen E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-16)
      Repeated transects have become the backbone of spatially distributed ice and snow thickness measurements crucial for understanding of ice mass balance. Here we detail the transects at the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) 2019–2020, which represent the first such measurements collected across an entire season. Compared with similar historical transects, ...

    • Snowfall and snow accumulation during the MOSAiC winter and spring seasons 

      Wagner, David N.; Shupe, Matthew D.; Cox, Christopher; Persson, Ola G.; Uttal, Taneil; Frey, Markus M.; Kirchgaessner, Amélie; Schneebeli, Martin; Jaggi, Matthias; MacFarlane, Amy R.; Itkin, Polona; Arndt, Stefanie; Hendricks, Stefan; Krampe, Daniela; Nicolaus, Marcel; Ricker, Robert; Regnery, Julia; Kolabutin, Nikolai; Shimanshuck, Egor; Oggier, Marc; Raphael, Ian; Stroeve, Julienne; Lehning, Michael (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-06-17)
      Data from the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition allowed us to investigate the temporal dynamics of snowfall, snow accumulation and erosion in great detail for almost the whole accumulation season (November 2019 to May 2020). We computed cumulative snow water equivalent (SWE) over the sea ice based on snow depth and density retrievals from a ...

    • Surface-based Ku-and Ka-band polarimetric radar for sea ice studies 

      Stroeve, Julienne C.; Nandan, Vishnu; Willatt, Rosemary; Tonboe, Rasmus; Hendricks, Stefan; Ricker, Robert; Mead, James; Mallett, Robbie; Huntemann, Marcus; Itkin, Polona; Schneebeli, Martin; Krampe, Daniela; Spreen, Gunnar; Wilkinson, Jeremy; Matero, Ilkka; Hoppmann, Mario; Tsamados, Michel (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-04)
      To improve our understanding of how snow properties influence sea ice thickness retrievals from presently operational and upcoming satellite radar altimeter missions, as well as to investigate the potential for combining dual frequencies to simultaneously map snow depth and sea ice thickness, a new, surface-based, fully polarimetric Ku- and Ka-band radar (KuKa radar) was built and deployed ...

    • Thermodynamic and dynamic contributions to seasonal Arctic sea ice thickness distributions from airborne observations 

      von Albeldyll, Luisa; Hendricks, Stefan; Grodofzig, Raphael; Krumpen, Thomas; Arndt, Stefanie; Belter, H. Jakob; Birnbaum, Gerit; Cheng, Bin; Hoppmann, Mario; Hutchings, Jennifer; Itkin, Polona; Lei, Ruibo; Nicolaus, Marcel; Ricker, Robert; Rohde, Jan; Suhrhoff, Mira; Timofeeva, Anna; Watkins, Daniel; Webster, Melinda; Haas, Christian (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-18)
      Sea ice thickness is a key parameter in the polar climate and ecosystem. Thermodynamic and dynamic processes alter the sea ice thickness.The Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition provided a unique opportunity to study seasonal sea ice thickness changes of the same sea ice. We analyzed 11 large-scale (*50 km) airborne electromagnetic sea thickness ...

    • Wind redistribution of snow impacts the Ka- and Ku-band radar signatures of Arctic sea ice 

      Nandan, Vishnu; Willatt, Rosemary; Mallett, Robbie; Stroeve, Julienne; Geldsetzer, Torsten; Scharien, Randall; Tonboe, Rasmus; Yackel, John; Landy, Jack Christopher; Clemens-Sewall, David; Jutila, Arttu; Wagner, David N.; Krampe, Daniela; Huntemann, Marcus; Mahmud, Mallik; Jensen, David; Newman, Thomas; Hendricks, Stefan; Spreen, Gunnar; Macfarlane, Amy; Schneebeli, Martin; Mead, James; Ricker, Robert; Gallagher, Michael; Duguay, Claude; Raphael, Ian; Polashenski, Chris; Tsamados, Michel; Matero, Ilkka; Hoppmann, Mario (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-02)
      Wind-driven redistribution of snow on sea ice alters its topography and microstructure, yet the impact of these processes on radar signatures is poorly understood. Here, we examine the effects of snow redistribution over Arctic sea ice on radar waveforms and backscatter signatures obtained from a surface-based, fully polarimetric Ka- and Ku-band radar at incidence angles between 0∘ (nadir) and 50∘. ...