Hall Julie A.

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Julie A.

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  • Preprint
    The SOLAS air-sea gas exchange experiment (SAGE) 2004
    ( 2010-03-11) Harvey, Mike J. ; Law, Cliff S. ; Smith, Murray J. ; Hall, Julie A. ; Abraham, Edward R. ; Stevens, Craig L. ; Hadfield, Mark G. ; Ho, David T. ; Ward, Brian ; Archer, Stephen D. ; Cainey, Jill M. ; Currie, Kim I. ; Devries, Dawn ; Ellwood, Michael J. ; Hill, Peter ; Jones, Graham B. ; Katz, Dave ; Kuparinen, Jorma ; Macaskill, Burns ; Main, William ; Marriner, Andrew ; McGregor, John ; McNeil, Craig L. ; Minnett, Peter J. ; Nodder, Scott D. ; Peloquin, Jill ; Pickmere, Stuart ; Pinkerton, Matthew H. ; Safi, Karl A. ; Thompson, Rona ; Walkington, Matthew ; Wright, Simon W. ; Ziolkowski, Lori A.
    The SOLAS air-sea gas exchange experiment (SAGE) was a multiple-objective study investigating gas-transfer processes and the influence of iron fertilisation on biologically driven gas exchange in high-nitrate low-silicic acid low-chlorophyll (HNLSiLC) Sub-Antarctic waters characteristic of the expansive Subpolar Zone of the southern oceans. This paper provides a general introduction and summary of the main experimental findings. The release site was selected from a pre-voyage desktop study of environmental parameters to be in the south-west Bounty Trough (46.5°S 172.5°E) to the south-east of New Zealand and the experiment conducted between mid-March and mid-April 2004. In common with other mesoscale iron addition experiments (FeAX’s), SAGE was designed as a Lagrangian study quantifying key biological and physical drivers influencing the air-sea gas exchange processes of CO2, DMS and other biogenic gases associated with an iron-induced phytoplankton bloom. A dual tracer SF6/3He release enabled quantification of both the lateral evolution of a labelled volume (patch) of ocean and the air-sea tracer exchange at the 10’s of km’s scale, in conjunction with the iron fertilisation. Estimates from the dual-tracer experiment found a quadratic dependency of the gas exchange coefficient on windspeed that is widely applicable and describes air-sea gas exchange in strong wind regimes. Within the patch, local and micrometeorological gas exchange process studies (100 m scale) and physical variables such as near-surface turbulence, temperature microstructure at the interface, wave properties, and wind speed were quantified to further assist the development of gas exchange models for high-wind environments. There was a significant increase in the photosynthetic competence (Fv/Fm) of resident phytoplankton within the first day following iron addition, but in contrast to other FeAX’s, rates of net primary production and column-integrated chlorophyll a concentrations had only doubled relative to the unfertilised surrounding waters by the end of the experiment. After 15 days and four iron additions totalling 1.1 tonne Fe2+, this was a very modest response compared to the other mesoscale iron enrichment experiments. An investigation of the factors limiting bloom development considered co- limitation by light and other nutrients, the phytoplankton seed-stock and grazing regulation. Whilst incident light levels and the initial Si:N ratio were the lowest recorded in all FeAX’s to date, there was only a small seed-stock of diatoms (less than 1% of biomass) and the main response to iron addition was by the picophytoplankton. A high rate of dilution of the fertilised patch relative to phytoplankton growth rate, the greater than expected depth of the surface mixed layer and microzooplankton grazing were all considered as factors that prevented significant biomass accumulation. In line with the limited response, the enhanced biological draw-down of pCO2 was small and masked by a general increase in pCO2 due to mixing with higher pCO2 waters. The DMS precursor DMSP was kept in check through grazing activity and in contrast to most FeAX’s dissolved dimethylsulfide (DMS) concentration declined through the experiment. SAGE is an important low-end member in the range of responses to iron addition in FeAX’s. In the context of iron fertilisation as a geoengineering tool for atmospheric CO2 removal, SAGE has clearly demonstrated that a significant proportion of the low iron ocean may not produce a phytoplankton bloom in response to iron addition.
  • Article
    A decade of incorporating social sciences in the Integrated Marine Biosphere Research Project (IMBeR): much done, much to do?
    (Frontiers Media, 2021-06-21) van Putten, Ingrid ; Kelly, Rachel ; Cavanagh, Rachel D. ; Murphy, Eugene J. ; Breckwoldt, Annette ; Brodie, Stephanie ; Cvitanovic, Christopher ; Dickey-Collas, Mark ; Maddison, Lisa ; Melbourne-Thomas, Jessica ; Arrizabalaga, Haritz ; Azetsu-Scott, Kumiko ; Beckley, Lynnath E. ; Bellerby, Richard G. J. ; Constable, Andrew ; Cowie, Greg ; Evans, Karen ; Glaser, Marion ; Hall, Julie A. ; Hobday, Alistair J. ; Johnston, Nadine M. ; Llopiz, Joel K. ; Mueter, Franz ; Muller-Karger, Frank E. ; Weng, Kevin ; Wolf-Gladrow, Dieter A. ; Xavier, José C.
    Successful management and mitigation of marine challenges depends on cooperation and knowledge sharing which often occurs across culturally diverse geographic regions. Global ocean science collaboration is therefore essential for developing global solutions. Building effective global research networks that can enable collaboration also need to ensure inter- and transdisciplinary research approaches to tackle complex marine socio-ecological challenges. To understand the contribution of interdisciplinary global research networks to solving these complex challenges, we use the Integrated Marine Biosphere Research (IMBeR) project as a case study. We investigated the diversity and characteristics of 1,827 scientists from 11 global regions who were attendees at different IMBeR global science engagement opportunities since 2009. We also determined the role of social science engagement in natural science based regional programmes (using key informants) and identified the potential for enhanced collaboration in the future. Event attendees were predominantly from western Europe, North America, and East Asia. But overall, in the global network, there was growing participation by females, students and early career researchers, and social scientists, thus assisting in moving toward interdisciplinarity in IMBeR research. The mainly natural science oriented regional programmes showed mixed success in engaging and collaborating with social scientists. This was mostly attributed to the largely natural science (i.e., biological, physical) goals and agendas of the programmes, and the lack of institutional support and push to initiate connections with social science. Recognising that social science research may not be relevant to all the aims and activities of all regional programmes, all researchers however, recognised the (potential) benefits of interdisciplinarity, which included broadening scientists’ understanding and perspectives, developing connections and interlinkages, and making science more useful. Pathways to achieve progress in regional programmes fell into four groups: specific funding, events to come together, within-programme-reflections, and social science champions. Future research programmes should have a strategic plan to be truly interdisciplinary, engaging natural and social sciences, as well as aiding early career professionals to actively engage in such programmes.