DSC Seminar #7 | Global ocean modelling in the Deep South Challenge

Giant wave in the Southern Ocean

The oceans are the largest ecosystem on our planet, with complex physical and bio-geochemical interaction between the atmosphere, sea ice and ice shelves. Oceans are the main storage for human-produced heat and carbon. At the same, oceans have the ability to redistribute heat and carbon both across large distances and over time, which makes them the key component in the climate system. 

Our understanding of the oceans has improved substantially in recent decades, thanks largely to satellite and Argo observations (a global network of ocean floats). Models are still (and will always be) necessary to fill data gaps, to put observations into a larger spatial and temporal context, and to forecast future changes. 

The ocean model in our New Zealand Earth System Model (NZESM) is based on the NEMO and MEDUSA models, and can be used to model past, present and future conditions. 

This presentation will include a brief introduction into the NEMO model and to the model configuration (eORCA1) which is used in NZESM. It will also focus on recent NEMO applications and scientific research using nesting (grid refinement) techniques within NEMO. Within the Deep South Challenge, a new model has been developed which uses nests to obtain a 1/15° resolution over the Ross and Amundsen Seas. In this way we can investigate how model resolution influences the spreading of Antarctic Bottom Water from these regions.

Finally, we will be presenting results on the recent NZ marine heat wave, demonstrating that subsurface heat transport plays an important role in the years-to-decades occurrence of marine heat waves in the Tasman Sea. 

About the presenter

Erik Behrens (NIWA) studied physical oceanography in Kiel, GEOMAR, Germany and obtained his Diploma in 2008 by investigating the Indonesian Throughflow. He continued as a PhD at the GEOMAR, researching the effects of increased melting of the Greenland ice sheet on the Atlantic Ocean. He then began work at NIWA, where his research focus has shifted towards the Southern Ocean and investigating coupled earth system models.

Physical hubs:

Please note, all NIWA visitors must sign in on arrival.

  • NIWA Wellington: Conference Room*
  • NIWA Auckland: Seminar Room
  • NIWA Lauder: Computer Room
  • NIWA Hamilton: C-Block Meeting Room
  • NIWA Christchurch: Tekapo Seminar Room
  • Victoria University of Wellington: LABY Lecture Theatre 118
  • University of Canterbury: Room 411, Law Building
  • University of Otago: Room 229, Science III building

*Our speaker will be presenting from this hub.

We encourage you to set up your own hub and bring friends and colleagues together to participate in the seminar. Please let us know if you do set up your own hub.

Email: [email protected]


Erik Behrens

Erik is an ocean modeller with expertise in developing high resolution nested earth system models. As part of the Deep South Challenge he developed a nested model for the New Zealand Exclusive Economic Zone (NZEEZ) to improve the representation of the oceanic circulation around NZ and, therefore, climate projections.