The first major review in three decades of physical oceanography in New Zealand shelf-seas (waters under 200 m depth) has just been published in The Royal Society Te Apārangi New Zealand Journal of Marine and Freshwater Research.
This NIWA-authored review follows Physical Oceanographer Steve Chiswell's 2015 review of deep-water oceanography which is the most cited paper for the Journal since 2011.
Physical oceanography of New Zealand/Aotearoa shelf seas – a review was lead authored by NIWA and University of Auckland Joint Graduate School Marine Physicist Craig Stevens.
He says, says the significant report spans early ocean science that used messages in a bottle and hand-calculations, through to autonomous robots, satellites and simulations of the entire global ocean at hourly timesteps.
It summarises the present state of knowledge of the physical processes that control ocean transport and mixing in this domain. The focus is on documenting recent regional advances in understanding the balance between oﬀ-shelf drivers, land sourced freshwater, winds, tides, stratiﬁcation and the underlying topography. The review goes on to describe important growing themes such as connectivity, climate and stratiﬁcation.
“While many of the points made for blue-water oceanography in the 2015 Chiswell paper hold true for shelf-seas, there are differences,” Craig says.
“Thanks to the Leigh and Portobello marine laboratory timeseries, we have better baseline in-shore data for quantifying climate-driven changes over the past century as there are a number of multi-decade-long temperature datasets available.
“Also, because there is greater economic activity in shelf areas, there is stronger demand for predictive tools and associated understanding for efficiency and impact assessment.”
Craig says there is still so much to learn and understand – and a real sense of urgency.
“Future perspectives will involve a changing climate, advancing technology and evolving human demands on the marine space.
“Now we have entered the Anthropocene (the period during which human activity has been the dominant influence on climate and the environment), climate drivers are increasing the level of interest in changing shelf-seas and their utilisation.”
The review concludes with a prediction that the need for improved understanding of the shelf-seas will continue to increase, and likely hand-in-hand with technological development.
The review will be the cornerstone for an upcoming special issue on the physics of New Zealand's shelf-seas that will appear in 2020 and is being edited by NIWA’s Craig Stevens, Joe O'Callaghan and Steve Chiswell, and Moninya Roughan from Metservice.