Blar i forfatter "Nandan, Vishnu"

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    • Faster decline and higher variability in the sea ice thickness of the marginal Arctic seas when accounting for dynamic snow cover 

      Mallett, Robbie; Stroeve, Julienne C.; Tsamados, Michel; Landy, Jack Christopher; Willatt, Rosemary; Nandan, Vishnu; Liston, Glen (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-06-04)
      Mean sea ice thickness is a sensitive indicator of Arctic climate change and is in long-term decline despite significant interannual variability. Current thickness estimations from satellite radar altimeters employ a snow climatology for converting range measurements to sea ice thickness, but this introduces unrealistically low interannual variability and trends. When the sea ice thickness in the ...

    • 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 ...

    • 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 ...

    • Snow and Ice Thickness Retrievals Using GNSS-R: Preliminary Results of the MOSAiC Experiment 

      Munoz-Martin, Joan Francesc; Perez, Adrian; Camps, Adriano; Ribó, Serni; Cardellach, Estel; Stroeve, Julienne; Nandan, Vishnu; Itkin, Polona; Tonboe, Rasmus; Hendricks, Stefan; Huntemann, Marcus; Spreen, Gunnar; Pastena, Massimiliano (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-12-10)
      The FSSCat mission was the 2017 ESA Sentinel Small Satellite (S⌃3) Challenge winner and the Copernicus Masters competition overall winner. It was successfully launched on 3 September 2020 onboard the VEGA SSMS PoC (VV16). FSSCat aims to provide coarse and downscaled soil moisture data and over polar regions, sea ice cover, and coarse resolution ice thickness using a combined L-band microwave radiometer ...

    • Sub-kilometre scale distribution of snow depth on Arctic sea ice from Soviet drifting stations 

      Mallett, Robbie; Stroeve, Julienne C.; Tsamados, Michel; Willatt, Rosemary; Newman, Thomas; Nandan, Vishnu; Landy, Jack Christopher; Itkin, Polona; Oggier, Marc; Jaggi, Matthias; Perovich, Don (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-04)
      The sub-kilometre scale distribution of snow depth on Arctic sea ice impacts atmosphere-ice fluxes of energy and mass, and is of importance for satellite estimates of sea-ice thickness from both radar and lidar altimeters. While information about the mean of this distribution is increasingly available from modelling and remote sensing, the full distribution cannot yet be resolved. We analyse 33 539 ...

    • 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 ...

    • 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∘. ...