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15 results on '"Duderstadt, K. A."'

2. Cryo-EM structure of NR5A2-nucleosome complex SHL+5.5

Author

Kobayashi, W., primary, Sappler, A., additional, Bollschweiler, D., additional, Kummecke, M., additional, Basquin, J., additional, Arslantas, E., additional, Ruangroengkulrith, S., additional, Hornberger, R., additional, Duderstadt, K., additional, and Tachibana, K., additional

Published
2024
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4. Comment on 'Atmospheric ionization by high-fluence, hard spectrum solar proton events and their probable appearance in the ice core archive' by A.L. Melott et al

Author

Duderstadt, K. A., Dibb, J. E., Jackman, C. H., Randall, C. E., Schwadron, N. A., Solomon, S. C., and Spence, H. E.

Subjects
Physics - Atmospheric and Oceanic Physics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics, Physics - Geophysics
Abstract

Melott et al. [2016] suggest that individual solar proton events (SPEs) are detectable as nitrate ion spikes in ice cores. They use the high fluence, high energy (hard spectrum) SPE of 23 February 1956 to calculate an enhancement of HNO3 from the surface to 46 km that is equivalent to a ~120 ng cm-2 nitrate ion spike observed in the GISP2H ice core. The Melott et al. [2016] approach is fundamentally flawed, since it considers only the absolute column burden of SPE-produced nitrate and not the pre-existing nitrate in the stratosphere. Modeling studies supported by extensive observations [Duderstadt et al., 2014, 2016, and this comment] show background HNO3 in the lower and middle stratosphere equivalent to 2000 to 3000 ng cm-2 nitrate. These high levels of background nitrate must also be included when estimating SPE enhancements to the deposition of nitrate ions that might eventually be preserved in an ice core. The 1956 SPE results in less than a 5% increase in the column burden of atmospheric HNO3, not large enough to explain the nitrate spike seen in the GISP2H ice core. Even extreme SPE enhancements cannot explain nitrate peaks (typically hundreds of percent increases) observed in the ice record [Duderstadt et al., 2016]. Realistic mechanisms linking nitrate ions in ice cores to SPEs have not been established. It is time to move the search for indicators of SPEs away from nitrate ions: Nitrate ions cannot be used as proxies for individual SPEs in the ice core record., Comment: 17 pages, 3 figures Corrected to address typographical error

Published
2016
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5. Is A Common Goal A False Hope in Convergence Research? : Opportunities and Challenges of International Convergence Research to Address Arctic Change

Author

Ernakovich, J. G., Eklund, N., Varner, R. K., Kirchner, N., Jeuring, J., Duderstadt, K., Granebeck, A., Golubeva, E., Messori, Gabriele, Ernakovich, J. G., Eklund, N., Varner, R. K., Kirchner, N., Jeuring, J., Duderstadt, K., Granebeck, A., Golubeva, E., and Messori, Gabriele

Abstract

The Arctic faces multiple pressures including climate change, shifting demographics, human health risks, social justice imbalances, governance issues, and expanding resource extraction. A convergence of academic disciplines—such as natural and social sciences, engineering and technology, health and medicine—and international perspectives is required to meaningfully contribute to solving the challenges of Arctic peoples and ecosystems. However, successfully carrying out convergent, international research and education remains a challenge. Here, lessons from the planning phase of a convergence research project concerned with the health of Arctic waters developed by the Arctic Science IntegrAtion Quest (ASIAQ) are discussed. We discuss our perspective on the challenges, as well as strategies for success, in convergence research as gained from the ASIAQ project which assembled an international consortium of researchers from disparate disciplines representing six universities from four countries (Sweden, Japan, Russia, and the United States) during 2018–2020.

Published
2021
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10. Photochemical production and loss rates of ozone at Sable Island, Nova Scotia during the North Atlantic Regional Experiment (NARE) 1993 summer intensive

Author

Duderstadt, K. A., primary, Carroll, M. A., additional, Sillman, S., additional, Wang, T., additional, Albercook, G. M., additional, Feng, L., additional, Parrish, D. D., additional, Holloway, J. S., additional, Fehsenfeld, F. C., additional, Blake, D. R., additional, Blake, N. J., additional, and Forbes, G., additional

Published
1998
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11. Ground‐based measurements of NOx and total reactive oxidized nitrogen (NOy) at Sable Island, Nova Scotia, during the NARE 1993 summer intensive

Author

Wang, T., primary, Carroll, M. A., additional, Albercook, G. M., additional, Owens, K. R., additional, Duderstadt, K. A., additional, Markevitch, A. N., additional, Parrish, D. D., additional, Holloway, J. S., additional, Fehsenfeld, F. C., additional, Forbes, G., additional, and Ogren, J., additional

Published
1996
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13. Comment on 'Atmospheric ionization by high-fluence, hard spectrum solar proton events and their probable appearance in the ice core archive' by A.L. Melott et al

Author

Duderstadt, K. A., Dibb, J. E., Jackman, C. H., Randall, C. E., Schwadron, N. A., Solomon, S. C., and Spence, H. E.

Subjects
Physics - Geophysics, Earth and Planetary Astrophysics (astro-ph.EP), Physics - Atmospheric and Oceanic Physics, Astrophysics - Solar and Stellar Astrophysics, bepress|Physical Sciences and Mathematics|Physics, Atmospheric and Oceanic Physics (physics.ao-ph), FOS: Physical sciences, Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Solar and Stellar Astrophysics (astro-ph.SR), Astrophysics - Earth and Planetary Astrophysics, Geophysics (physics.geo-ph)
Abstract

Melott et al. [2016] suggest that individual solar proton events (SPEs) are detectable as nitrate ion spikes in ice cores. They use the high fluence, high energy (hard spectrum) SPE of 23 February 1956 to calculate an enhancement of HNO3 from the surface to 46 km that is equivalent to a ~120 ng cm-2 nitrate ion spike observed in the GISP2H ice core. The Melott et al. [2016] approach is fundamentally flawed, since it considers only the absolute column burden of SPE-produced nitrate and not the pre-existing nitrate in the stratosphere. Modeling studies supported by extensive observations [Duderstadt et al., 2014, 2016, and this comment] show background HNO3 in the lower and middle stratosphere equivalent to 2000 to 3000 ng cm-2 nitrate. These high levels of background nitrate must also be included when estimating SPE enhancements to the deposition of nitrate ions that might eventually be preserved in an ice core. The 1956 SPE results in less than a 5% increase in the column burden of atmospheric HNO3, not large enough to explain the nitrate spike seen in the GISP2H ice core. Even extreme SPE enhancements cannot explain nitrate peaks (typically hundreds of percent increases) observed in the ice record [Duderstadt et al., 2016]. Realistic mechanisms linking nitrate ions in ice cores to SPEs have not been established. It is time to move the search for indicators of SPEs away from nitrate ions: Nitrate ions cannot be used as proxies for individual SPEs in the ice core record., Comment: 17 pages, 3 figures Corrected to address typographical error

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