ORCHESTRA

ORCHESTRA WP2 meeting report

On the 4th of March the ORCHESTRA WP2 meeting was held at BAS. WP2 focuses on the processes that exchange heat between the ocean mixed layer and interior. Despite travel restrictions on many participants there was an active group of online listeners and speakers from ORCHESTRA and beyond, and a very productive meeting was held, hosted by WP2 lead Dave Munday aided by Andrew Meijers and Alex Brearley. The meeting focused on updates from the various observations, modelling and model analysis groups, as well as planning on how best to synthesize results together into cross disciplinary papers. Additionally ideas for the one year ORCHESTRA extension were scoped out.

Highlights included the showcasing of the regional z and sigma-z models developed at BAS and NOC, demonstrating that the control runs of the z-level model are completed and several perturbation runs are either completed or being run. Encouraging new results from the sigma-z model indicate that a version with fully realised ice shelves and cavities is now working, and producing dense water more ‘realistically’ than the equivalent z level model.

The coming ARCHER downtime will represent a challenge, but also an opportunity to consolidate work to date and get results published.

A slew of adjoint modelling papers looking at Southern Ocean heat uptake sensitivies have been published or in review from Dan Jones and Emma Boland. These models also are providing the basis for perturbation experiments in both ECCO and high resolution model setups to explore heat uptake dynamics.

Pat Hyder of the Met Office showed recent work demonstrating that care needs to be applied when interpreting the results of forced ocean experiments, notably in cases looking at surface heat transports under buoyancy forcing perturbation experiments.

Yavor Kostov gave a guest talk from TICTOC, demonstrating how historical SO SST trends are influenced by both the SAM and GHG forcing variability, but that variability in these processes still struggles to explain the modelled SST warming vs observed cooling.

Andrew Meijers showcased initial CMIP6 water mass heat uptake results, showing that while they largely agree with CMIP5, there is reduced sensitivities of AABW in the newer models.

Alex Brearley, Ryan Scott and Louise Biddle (Gothenburg) updated the group on the initial results from glider and EM-APEX based process studies. These are showing promising results, particularly mixed layer microstructure features and clear resolution of frontal/regional MLD deepening events at high temporal and spatial resolution. Discussion revolved around how to disentangle temporal/spatial features and how to compare these results with more traditional climatology scale analysis of MLD evolution.

Rachael Sanders, despite fighting off a bad illness gave a (remote!) presentation on her mixed layer budget work, showing that surface forcing, lateral advection and mixed layer entrainment dominates the mixed layer heat and freshwater budgets in the SAMW formation regions. Her ongoing work will be to investigate in ECCO how regional wind and buoyancy forcing impact water mass formation rates.

Webinar – SO-CHIC: Southern Ocean Carbon and Heat Impact on Climate

The EPB will host the first in a series of webinars for the project Southern Ocean Carbon and Heat Impact on Climate (SO-CHIC) on 15:00 CEST, Tuesday 7th April 2020. This first webinar, given by project coordinator Jean-Baptiste Sallée from Sorbonne Université, will introduce SO-CHIC and its objectives.

The Southern Ocean regulates the global climate by controlling heat and carbon exchanges between the atmosphere and the ocean. Rates of climate change on decadal time scales ultimately depend on oceanic processes taking place in the Southern Ocean, yet too little is known about the underlying processes. Limitations come both from the lack of observations in this extreme environment and its inherent sensitivity to intermittent small-scale processes that are not captured in current Earth system models.

To contribute to reducing uncertainties in climate change predictions, the overall objective of SO-CHIC is to understand and quantify variability of heat and carbon budgets in the Southern Ocean through an investigation of the key processes controlling exchanges between the atmosphere, ocean and sea ice using a combination of observational and modelling approaches.

The SO-CHIC project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement N°821001. For more information on SO-CHIC, please visit http://www.sochic-h2020.eu/.

To register for this webinar, please visit https://zoom.us/webinar/register/WN_Zmuk7prXQciogyJlTMgMeg

Physical Oceanographer vacancy

Description

The British Antarctic Survey is inviting applications for an observational physical oceanographer with a track record of interpreting and analysing observational polar oceanographic datasets. The successful candidate will use observational datasets and numerical model output to construct and test a dynamical framework explaining the circulation of the Weddell Gyre and its export of dense water to the global ocean.

Purpose

This is a 36 month position for a suitably qualified postdoctoral researcher and will contribute to two projects funded by the European Commission H2020 programme and Natural Environment Research Council (NERC): SO-CHIC (Southern Ocean Carbon and Heat Impact on Climate) and ORCHESTRA (Ocean regulation of climate by Heat and Carbon sequestration and Transports).

How to apply: Please visit: https://www.bas.ac.uk/jobs/vacancy/physical-oceanographer-2


The Southern Ocean in a changing climate: open-ocean physical and biogeochemical processes

The Southern Ocean in a changing climate: open-ocean physical and biogeochemical processes (OS1.12/BG4.13/CL4.28)

There will be a Southern Ocean session at the EGU General Assembly 2020 in Vienna (3–8 May 2020).

The Southern Ocean around the latitudes of the Antarctic Circumpolar Current is a key region for the vertical and lateral exchanges of heat, carbon and nutrients, with significant impacts on the climate system as a whole. The role of the Southern Ocean as a sink of anthropogenic carbon and heat, and as a source of natural carbon in present and future climate conditions remains uncertain. To reduce this uncertainty, understanding the physical and biogeochemical processes underlying the Southern Ocean internal variability and its response to external forcing is critical. Recent advances in observational capabilities, theoretical frameworks, and numerical models (e.g. CMIP6 simulations) are providing a deeper insight into the three-dimensional patterns of Southern Ocean change. This session will discuss the current state of knowledge and novel findings concerning the role of the Southern Ocean in past, present, and future climates. In particular, it will address physical, biological, and biogeochemical processes, including interior ocean mixing and transport pathways, the cycling of carbon and nutrients, as well as ocean-ice-atmosphere interactions, and their wider implications for lower latitudes and the global climate.

Highlight: Solicited speaker Michael Meredith will report on the outcomes of the Polar Regions chapter of the recent “IPCC Special Report on the Ocean and Cryosphere in a Changing Climate” during this session.

Abstarct submission: https://meetingorganizer.copernicus.org/EGU2020/session/36195 (deadline is 15 January 2020, 13:00 CET).

ECS travel support: https://egu2020.eu/about_and_support/roland_schlich_travel_support.html (deadline is 1 December 2019).




Blog: Homeward Bound – Last Leg of the ORCHESTRA Cruise

Carol Arrowsmith is a chief technician in the stable isotope facility at the BGS. She recently took part in an expedition to the Southern Ocean as part of  ORCHESTRA (Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports), a NERC funded programme with partners at the British Antarctic Survey (lead), the National Oceanography CentrePlymouth Marine Laboratory, and many more including BGS. Here she updates us as she nears the end of her expedition on the RRS James Clark Ross… 16 May 2019.

Carol at Signy

We were at sea for around 8 weeks on the RRS James Clark Ross, undertaking the ANDREXII transect. We set off from the Punta Arenas, Chile, calling in at the Falklands before crossing the Drake Passage to the tip of the Antarctic Peninsula at 60oS, and then out along over 3000 miles to the Indian Ocean at 30oE. 

Along this route we collected samples at 96 separate locations (stations), resulting in >1800 water samples for oxygen and carbon isotope analysis with help from my buddy, Margot Debyser from Edinburgh University and Ash Smith, the BAS Laboratory Manager. The samples will arrive back in the UK for analysis at the BGS in the summer for isotope analysis and will tell us about how much carbon the ocean has absorbed and how much fresh water has been added from melting of the ice caps. We also collected around 350 for radiocarbon C14 analysis which will be sent to the Woods Hole Institute, USA where we’ll be able to shed light on the age of the water. These samples form part of the 5 year ORCHESTRA research programme to try to understand the structure of the Southern Ocean and, more importantly, what changes are taking place within the ocean due to human impact.

After we finished the last sampling in the Indian Ocean our ship steamed back to the South Orkney Islands and Signy. There were plenty of seals (fur, leopard and crabeater) dotted about the ice, most of them were used to seeing ships and didn’t bother to move when they saw us coming! In particular, we got to see the British Antarctic Survey base, which is now evacuated for winter, and moved some cargo around the holds in readiness for the journey home. We then sailed down to the ice sheet forming around the Antarctic Peninsula, where we held the end of cruise dinner: a BBQ on the ship’s deck while it was snowing! 

King penguins.

The ship docked at Mare Harbour on the Falkland Islands, where we spent the day demobilizing, taking inventories of samples, packing up the equipment, and generally clearing up. We also had a flying visit to Volunteer Point to see King and Gentoo Penguins. The RRS James Clark Ross then left the Falklands for the first of 2 trips to Rothera Station to pick up scientists, crew, contractors and equipment to take them home.
Overall, it’s been a successful research cruise but I am glad to be back on land! I would like to thank PSO Andrew Meijers at BAS for his leadership and management. Also many thanks to the dedicated crew on board, engineers, deck crew and stewards who all played their part.

Group picture.