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Good hope for earth sciences

By the SAEON team of presenters
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SAEON’s Jethan d’Hotman tells the audience more about surface drifters that intersect ASCA

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ASCA coordinator Tammy Morris elaborates on the results from two dedicated Argo float experiments

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Delegates participate in a drumming session during the opening ceremony

The Joint IAPSO-IAMAS-IAGA Assembly, “Good Hope for Earth Sciences”, took place in Cape Town from 27 August to 1 September 2017.

The Joint Assembly saw the coming together of three physical earth science disciplines of the International Union of Geodesy and Geophysics (IUGG); the International Association for the Physical Sciences of the Oceans (IAPSO), the International Association of Geomagnetism and Aeronomy (IAGA) and the International Association of Meteorology and Atmospheric Sciences (IAMAS).

This provided an excellent opportunity to not only present scientific papers in the disciplines themselves, but allowed for 11 joint sessions, which encouraged interdisciplinary collaboration.

The Joint Assembly was endorsed by the University of Cape Town (UCT) and the South African Department of Science and Technology (DST). The National Research Foundation (NRF) and SAEON were among the conference sponsors.

Associate professor Isabelle Ansorge, head of the Department for Oceanography at UCT and vice-president of IAPSO, undertook the monumental task of organising the Joint Assembly with the help of her scientific and local organising committees. Together they ensured a memorable event that included audience participation; drumming during the opening ceremony; scientific presentations of excellent quality during a myriad of parallel sessions; opportunities for side workshops, meetings and interactions; and a fun-filled social programme for delegates.

Upwelling systems and ocean economy

One of the first sessions of the conference, “Upwelling systems and ocean economy”, showcased current research focused on all aspects of upwelling systems - from physics and biology to the economic importance of these systems.

The first presentation in this session was an invited talk by SAEON’s postdoctoral research fellow, Dr Jennifer Veitch. Her talk highlighted the highly dynamic and variable nature of the Benguela Current Upwelling system and emphasised the fact that this system cannot be characterised through a mean state.

Professor Ken Findlay, Research Chair in Oceans Economy at the Cape Peninsula University of Technology, aptly closed the session with an invited talk on expanding the oceans economy in South Africa. It is widely recognised that South Africa’s economy can greatly benefit from various provisioning, cultural and regulatory ecosystem services derived from the ocean environment. Prof. Findlay stressed that effective governance frameworks are essential to ensure sustainable resource use and to maintain ecosystem function.

Western boundary currents

Western boundary currents are warm, deep, narrow and fast flowing currents that form on the west side of ocean basins due to western intensification. They carry warm water from the tropics towards the poles, influencing both regional weather and climate across the globe.

With the meeting hosted in the Southern Hemisphere, there was an emphasis on comparing and contrasting the Brazil, East Australia and Agulhas Current systems (with the Agulhas dominating). During this session three SAEON students - Katherine Hutchinson (UCT), Neil Malan (UCT) and Jethan d'Hotman (Nelson Mandela University) - presented their recent work on the Agulhas Current.

Katherine presented on the seasonality of the Agulhas Current with respect to near and far wind fields, Neil presented his PhD work that investigated the impact of large Agulhas Current meanders on shelf waters, and Jethan presented a lagrangian study of the surface velocity structure of the Agulhas Current and its effect on leaking surface drifters into the South Atlantic Ocean.

Prof. Lisa Beal of the Rosenstiel School of Marine and Atmospheric Science (RSMAS) of the University of Miami and co-principal investigator on the Agulhas System Climate Array (ASCA), demonstrated the widening and not strengthening of the Agulhas Current since the early 1990s, while her student Kayleen McMonigal showed some results from her PhD of the meridional heat transport across the ASCA array. Dr Pierrick Penven wrapped up the session with a review of the unique challenges presented by modelling the highly dynamic Agulhas Current system, lessons learnt, and future developments.

While the seasonal cycle does not give any information about long-term changes or extreme events that have the potential to cause significant harm, it is crucial to gain an understanding of the cycle as it is the state from which we measure change and is particularly dominant in the Atlantic sector.

Seasonal cycle over the African continent and adjoining oceans

The IAMAS session, “The seasonal cycle over the African continent and adjoining oceans, today and in the past”, focused on inadequacies in observational networks as well as climate models with respect to the capturing of the seasonal cycle over the African continent and the adjoining oceans. Caroline Dunning, a PhD student from the University of Reading, showcased a methodology that she had developed for objectively determining the onset and cessation of multiple wet seasons across Africa.

Using her methodology and comparing results from observational, reanalysis, and AMIP (Atmospheric Model Intercomparison Project) and CMIP (Coupled Model Intercomparison Project) historical simulations, she found that the coupled simulations failed to capture the biannual regime over the south-west African coastline. This suggests that climate-coupled models need to be used with caution when investigating the seasonal cycle.

Dr Ross Blamey from UCT investigated the movement of the South Atlantic High (SAH) pressure system, a key component of the seasonal cycle of the Benguela upwelling system, in response to the El Niňo Southern Oscillation. He concluded that during a La Niňa (El Niňo) event the SAH moves further south (north), which primarily influences the upwelling wind in the southern Benguela system by enhancing (reducing) it.

International Indian Ocean Expedition

Juliet Hermes, manager of SAEON’s Egagasini Node and Tammy Morris, ASCA coordinator, co-convened the IIOE2 joint IAPSO/IAMAS session. Launched in February 2015, the International Indian Ocean Expedition [IIOE-2] aims to expand our knowledge of the Indian Ocean, roaming from atmospheric to oceanographic research, and coastal areas to the deep sea.

IAPSO-IAMAS-IAGA represented a good platform to present, for the first time, an overview of all research being done in conformity to this expedition. With the most up-to-date scientific content ranging from the Western Boundary Current (Agulhas Current) to the Eastern Boundary Current (Leeuwin Current), including the Northern Indian Ocean (Arabian Sea and Bay of Bengal), subtropical and upwelling regions, delegates gained a good grasp of the different topics being studied by scientists from different worldwide universities/institutions.

Delegates affiliated to SAEON were very involved in this session to showcase their latest research and chair part of the session, highlighting the contribution of the South African science community to this international programme. Some highlights from the session included a glimpse at the results from the first IIOE-2 expedition, which travelled from Goa to Mauritius; and a capacity-building initiative towards the Indian Ocean Early Career Scientist Network. From a take-home message perspective, this joint IIOE-2 session was an excellent opportunity to boost Indian Ocean research and to provide all means to establish interesting networks between institutions.

GIFT workshop

As part of the Joint Assembly, the European Geosciences Union (EGU) hosted a Geosciences Information for Teachers (GIFT) workshop, with the theme of “Atmosphere, Oceans and Earth’s Magnetism”. Educators, observers and district officials were invited from 65 schools and groups from as far afield as Nigeria, including schools in the Egagasini Node’s education network and Thomas Mtontsi, education officer at the Node, as an observer to the workshop.

Dr Ansorge presented the SEAmester Program initiative, which hosts graduate students on the SA Agulhas II for ten days each year as a floating university experience, enabling the students to gain hands-on skills in the ocean environment. Tammy Morris presented the ASCA and South Atlantic MOC Basin-wide Array (SAMBA) programmes based on an article published in Quest Magazine titled ‘Bounded by Oceans’.

SAEON presentations 

  • Morris T., Gonzalez B.A., Hermes J. Lagragian evolution of Madagascar cyclonic eddies from two dedicated Argo float experiments..
  • Collins C., Hermes J., Reason C., Roman R. Mesoscale activity in the Comoros Basin.
  • Dilmahamod F., Malan N., Gonzalez B.A., dr Ruijter W., Hermes J. Role of sub-surface intensified eddies in the southern Indian Ocean.
  • D’Hotman J., de Vos M., Malan N., Morris T., Stander J., Hermes J. A lagrangian study of the surface velocity structure of the Agulhas Current at 34° S.
  • Malan N., Reason C., Hermes J., Backeberg B. The impact of large Agulhas Current meanders on Shelf Waters.
  • Blamey R., Veitch J., Debiolles F., Hermes J., Reason C. Recent changes in the South Atlantic anticyclone and impacts on regional wind patterns.
  • Hutchinson K., Beal L., Hermes J., Penven P., Ansorge I. Seasonality of the Agulhas Current with respect to near- and far-field winds.
  • Veitch J., Penven P., Hermes J., Lamont T., Shillington F. Equilibrium Dynamics of the Benguela System.
  • Collins C., Lamont T., Backeberg B., Veitch J., Hermes J. Towards a coastal modelling system for South Africa: A St Helena Bay case study.

 

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