Petersen Guðrún N.

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Petersen
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Guðrún N.
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  • Article
    The Greenland Flow Distortion Experiment
    (American Meteorological Society, 2008-09) Renfrew, Ian A. ; Petersen, Guðrún N. ; Outten, S. ; Sproson, D. ; Moore, G. W. K. ; Hay, C. ; Ohigashi, T. ; Zhang, S. ; Kristjansson, J. E. ; Fore, I. ; Olafsson, H. ; Gray, S. L. ; Irvine, E. A. ; Bovis, K. ; Brown, P. R. A. ; Swinbank, R. ; Haine, Thomas W. N. ; Lawrence, A. ; Pickart, Robert S. ; Shapiro, M. ; Woolley, A.
    Greenland has a major influence on the atmospheric circulation of the North Atlantic–western European region, dictating the location and strength of mesoscale weather systems around the coastal seas of Greenland and directly influencing synoptic-scale weather systems both locally and downstream over Europe. High winds associated with the local weather systems can induce large air–sea fluxes of heat, moisture, and momentum in a region that is critical to the overturning of the thermohaline circulation, and thus play a key role in controlling the coupled atmosphere–ocean climate system. The Greenland Flow Distortion Experiment (GFDex) is investigating the role of Greenland in defining the structure and predictability of both local and downstream weather systems through a program of aircraft-based observation and numerical modeling. The GFDex observational program is centered upon an aircraft-based field campaign in February and March 2007, at the dawn of the International Polar Year. Twelve missions were flown with the Facility for Airborne Atmospheric Measurements' BAe-146, based out of the Keflavik, Iceland. These included the first aircraft-based observations of a reverse tip jet event, the first aircraft-based observations of barrier winds off of southeast Greenland, two polar mesoscale cyclones, a dramatic case of lee cyclogenesis, and several targeted observation missions into areas where additional observations were predicted to improve forecasts. In this overview of GFDex the background, aims and objectives, and facilities and logistics are described. A summary of the campaign is provided, along with some of the highlights of the experiment.
  • Article
    Meteorological buoy observations from the central Iceland Sea
    (John Wiley & Sons, 2015-04-24) Harden, Benjamin E. ; Renfrew, Ian A. ; Petersen, Guðrún N.
    We present the first continuous in situ atmospheric observations from the central Iceland Sea collected from a meteorological buoy deployed for a 2 year period between 23 November 2007 and 21 August 2009. We use these observations to evaluate the ERA-Interim reanalysis product and demonstrate that it represented low-level meteorological fields and surface turbulent fluxes in this region very well. The buoy observations showed that moderate to strong winds were common from any direction, while wind speeds below 5 ms−1 were relatively rare. The observed low-level air temperature and surface heat fluxes were related to the wind direction with cold-air outbreaks most common from the northwest. Mean wintertime turbulent heat fluxes were modest (<60 Wm−2), but the range was substantial. High heat flux events, greater than 200 Wm−2, typically occurred every 1–2 weeks in the winter, with each event lasting on average 2.5 days with an average total turbulent heat flux of ∼200 Wm−2 out of the ocean. The most pronounced high heat flux events over the central Iceland Sea were associated with cold-air outbreaks from the north and west forced by a deep Lofoten Low over the Norwegian Sea.
  • Article
    The Iceland Greenland Seas Project
    (American Meteorological Society, 2019-09-27) Renfrew, Ian A. ; Pickart, Robert S. ; Vage, Kjetil ; Moore, G. W. K. ; Bracegirde, Thomas J. ; Elvidge, Andrew D. ; Jeansson, Emil ; Lachlan-Cope, Thomas ; McRaven, Leah T. ; Papritz, Lukas ; Reuder, Joachim ; Sodemann, Harald ; Terpstra, Annick ; Waterman, Stephanie N. ; Valdimarsson, Héðinn ; Weiss, Albert ; Almansi, Mattia ; Bahr, Frank B. ; Brakstad, Ailin ; Barrell, Christopher ; Brooke, Jennifer K. ; Brooks, Barbara J. ; Brooks, Ian M. ; Brooks, Malcolm E. ; Bruvik, Erik Magnus ; Duscha, Christiane ; Fer, Ilker ; Golid, H. M. ; Hallerstig, M. ; Hessevik, Idar ; Huang, Jie ; Houghton, Leah A. ; Jonsson, Steingrimur ; Jonassen, Marius ; Jackson, K. ; Kvalsund, K. ; Kolstad, Erik W. ; Konstali, K. ; Kristiansen, Jorn ; Ladkin, Russell ; Lin, Peigen ; Macrander, Andreas ; Mitchell, Alexandra ; Olafsson, H. ; Pacini, Astrid ; Payne, Chris ; Palmason, Bolli ; Perez-Hernandez, M. Dolores ; Peterson, Algot K. ; Petersen, Guðrún N. ; Pisareva, Maria N. ; Pope, James O. ; Seidl, Andrew D. ; Semper, Stefanie ; Sergeev, Denis ; Skjelsvik, Silje ; Søiland, Henrik ; Smith, D. ; Spall, Michael A. ; Spengler, Thomas ; Touzeau, Alexandra ; Tupper, George H. ; Weng, Y. ; Williams, Keith D. ; Yang, Xiaohau ; Zhou, Shenjie
    The Iceland Greenland Seas Project (IGP) is a coordinated atmosphere–ocean research program investigating climate processes in the source region of the densest waters of the Atlantic meridional overturning circulation. During February and March 2018, a field campaign was executed over the Iceland and southern Greenland Seas that utilized a range of observing platforms to investigate critical processes in the region, including a research vessel, a research aircraft, moorings, sea gliders, floats, and a meteorological buoy. A remarkable feature of the field campaign was the highly coordinated deployment of the observing platforms, whereby the research vessel and aircraft tracks were planned in concert to allow simultaneous sampling of the atmosphere, the ocean, and their interactions. This joint planning was supported by tailor-made convection-permitting weather forecasts and novel diagnostics from an ensemble prediction system. The scientific aims of the IGP are to characterize the atmospheric forcing and the ocean response of coupled processes; in particular, cold-air outbreaks in the vicinity of the marginal ice zone and their triggering of oceanic heat loss, and the role of freshwater in the generation of dense water masses. The campaign observed the life cycle of a long-lasting cold-air outbreak over the Iceland Sea and the development of a cold-air outbreak over the Greenland Sea. Repeated profiling revealed the immediate impact on the ocean, while a comprehensive hydrographic survey provided a rare picture of these subpolar seas in winter. A joint atmosphere–ocean approach is also being used in the analysis phase, with coupled observational analysis and coordinated numerical modeling activities underway.