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12. The Offspring of Doing

Author

Roth, James, primary, Loacker, Georgine, additional, Deutsch, Bernardin, additional, Gardner, Suzann, additional, and Nevers, Barbara, additional

Published
2023
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14. Measurement of low-energy cosmic-ray electron and positron spectra at 1 AU with the AESOP-Lite spectrometer

Author

Mechbal, Sarah, Mangeard, Pierre-Simon, Clem, John M., Evenson, Paul A., Johnson, Robert P., Lucas, Brian, and Roth, James

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics, Physics - Instrumentation and Detectors, Physics - Space Physics
Abstract

We report on a new measurement of the cosmic ray (CR) electron and positron spectra in the energy range of 20 MeV -- 1 GeV. The data were taken during the first flight of the balloon-borne spectrometer AESOP-Lite (Anti Electron Sub Orbital Payload), which was flown from Esrange, Sweden, to Ellesmere Island, Canada, in May 2018. The instrument accumulated over 130 hours of exposure at an average altitude of 3 g.cm$^{-2}$ of residual atmosphere. The experiment uses a gas Cherenkov detector and a magnetic spectrometer, consisting of a permanent dipole magnet and silicon strip detectors (SSDs), to identify particle type and measure the rigidity. Electrons and positrons were detected against a background of protons and atmospheric secondary particles. The primary cosmic ray spectra of electrons and positrons, as well as the re-entrant albedo fluxes, were extracted between 20 MeV -- 1 GeV during a positive solar magnetic polarity epoch. The positron fraction below 100 MeV appears flat, suggesting diffusion dominated solar modulation at low rigidity. The all-electron spectrum is presented and compared with models from a heliospheric numerical transport code., Comment: 21 pages, 13 figures

Published
2020
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30. Documenting lemming population change in the Arctic : Can we detect trends?

Author

Ehrich, Dorothée, Schmidt, Niels M., Gauthier, Gilles, Alisauskas, Ray, Angerbjörn, Anders, Clark, Karin, Ecke, Frauke, Eide, Nina E., Framstad, Erik, Frandsen, Jay, Franke, Alastair, Gilg, Olivier, Giroux, Marie-Andrée, Henttonen, Heikki, Hörnfeldt, Birger, Ims, Rolf A., Kataev, Gennadiy D., Kharitonov, Sergey P., Killengreen, Siw T., Krebs, Charles J., Lanctot, Richard B., Lecomte, Nicolas, Menyushina, Irina E., Morris, Douglas W., Morrisson, Guy, Oksanen, Lauri, Oksanen, Tarja, Olofsson, Johan, Pokrovsky, Ivan G., Popov, Igor Yu., Reid, Donald, Roth, James D., Saalfeld, Sarah T., Samelius, Gustaf, Sittler, Benoit, Sleptsov, Sergey M., Smith, Paul A., Sokolov, Aleksandr A., Sokolova, Natalya A., Soloviev, Mikhail Y., and Solovyeva, Diana V.

Published
2020

31. Seasonal estuary use of beluga whales

Author

Ehn, Jens (Environment and Geography), Ferguson, Steven (Fisheries and Oceans Canada), Watt, Cortney, Roth, James, Belanger, Amanda, Ehn, Jens (Environment and Geography), Ferguson, Steven (Fisheries and Oceans Canada), Watt, Cortney, Roth, James, and Belanger, Amanda

Abstract

Beluga whales are year-round residents of the Arctic and top predators in the ecosystem. Many beluga whale populations are migratory and spend winters in polynyas and breaks in the ice to avoid entrapment. Once the ice in begins to break up and melt, beluga whale populations migrate to the same Arctic estuaries year after year. Possible uses of estuaries include feeding, aiding in skin sloughing, protection of calves from predators, and other warm water benefits. However, much is still unknown about the use of these habitats both spatially and ecologically. I investigated estuary use by Cumberland Sound beluga whales, through their distribution. Their summering area covers northern fiords of Cumberland Sound, including Clearwater Fiord where there is a large estuary. While the whales are known the frequent the fiords, the specific distribution and core areas were unknown. Using very high resolution satellite imagery, I established critical habitat within the summering region. I also provided an updated estuary abundance estimate for this small beluga whale population. Second, I explored estuary use of Hudson Bay beluga whales by investigating the primary feeding season. Migratory species often have one season where they eat the majority of their food for the year and build fat reserves, which provides energy and supports thermoregulation. This fat can be used to investigate feeding ecology of whales. Despite being the largest beluga population, fundamental ecological knowledge of Hudson Bay beluga whales, such as the primary feeding season is unknown. I used lipid content and adipocyte size throughout the blubber of Hudson Bay beluga whales to identify when they were consuming the majority of their food. I determined that there was no consistent primary feeding season, and therefore both summering and wintering areas were used for feeding. By exploring the beluga whales’ use of seasonal habitat through distribution and foraging ecology, my thesis illuminates fundame

Published
2024

39. Correction to: Documenting lemming population change in the Arctic: Can we detect trends?

Author

Ehrich, Dorothée, Schmidt, Niels M., Gauthier, Gilles, Alisauskas, Ray, Angerbjörn, Anders, Clark, Karin, Ecke, Frauke, Eide, Nina E., Framstad, Erik, Frandsen, Jay, Franke, Alastair, Gilg, Olivier, Giroux, Marie-Andrée, Henttonen, Heikki, Hörnfeldt, Birger, Ims, Rolf A., Kataev, Gennadiy D., Kharitonov, Sergey P., Killengreen, Siw T., Krebs, Charles J., Lanctot, Richard B., Lecomte, Nicolas, Menyushina, Irina E., Morris, Douglas W., Morrisson, Guy, Oksanen, Lauri, Oksanen, Tarja, Olofsson, Johan, Pokrovsky, Ivan G., Popov, Igor Yu., Reid, Donald, Roth, James D., Saalfeld, Sarah T., Samelius, Gustaf, Sittler, Benoit, Sleptsov, Sergey M., Smith, Paul A., Sokolov, Aleksandr A., Sokolova, Natalya A., Soloviev, Mikhail Y., and Solovyeva, Diana V.

Published
2020
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