The North Atlantic Ocean and Climate Observing System

Stuart A. CunninghamScottish Association for Marine Science

Stuart.Cunningham@sams.ac.uk

Barbara Berx1, Eleanor Frajka-Williams2 and Mark Inall3

1Marine Laboratory Science, Aberdeen,2National Oceanography Centre, University of Southampton, 3SAMS.

MASTS ASM, Herriot Watt, August 2013

Tickling the Dragon’s TailThe Role of the Atlantic in Global Climate

The strategic focus for MASTS Deep Sea Research

1. Sustained observations of the varying and evolving ocean circulation.2. Analysis and interpretations of observations for comparison with

climate models.3. Focused field experiments to understand ocean processes not resolved

in coupled climate models so these processes may be better represented in models.

This will rely on:• New Technologies (platforms, sensors, power).• Enhancement of sustained observation programmes (in time, space

and parameters).• Multi-disciplinary teams of brilliant scientists focused on strategic

research issues.

Definition of ocean circulation: Physical, chemical and biological properties (currents, temperature, salinity, sea-surface level, oxygen, nitrate, carbon dioxide, phytoplankton etc.)

Sustained Observations of the Varying and Evolving Ocean

Strategic focus of MASTS deep-seas research must be to observe the patterns of climate change in the ocean, to interpret the observations to understand the process of climate change and to improve our ability to accurately predict the course of climate change globally and regionally.

1. Long time series establish the amplitude and variability on sub-annual, seasonal and inter-annual timescales against which climate change on decadal timescales can be assessed.

2. Monitoring establishes the spatial pattern of decadal changes which are essential for assessing the mechanisms of change.

3. Comparing spatial pattern of change of model predictions with and without anthropogenic forcing establishes whether the decadal changes are the result of natural variability or anthropogenically driven change.

Ocean State Estimation

Estimating the Circulation and Climate of the Ocean (ECCO)

Aim: to produce increasingly accurate syntheses of all available global-scale ocean and sea-ice data at resolutions that start to resolve ocean eddies and other narrow current systems, which transport heat, carbon, and other properties within the ocean.

• MIT OGCM• 0.3-1° resolution• 1993-now

1. Monthly, 10-day, daily or 12-hourly ocean model state, adjusted forcing fields and mixing coefficients.

Atlantic-Nordic/Arctic Ocean Inflows & Outflows

• Atlantic Inflows to the Nordic Seas (e.g. FSC, Marlab)

• Atlantic Outflows (FBC, Iceland Ridge, Denmark Strait, Davis Strait)

Lab Sea Exit ArrayLine W @ 35°NRAPID @ 26.5°NMOVE @ 16°NSAMOC @ 35°S

From 1996

Since 2004

Deep Western Boundary Current Flux Arrays

Sustained Observations of the Atlantic Meridional Overturning Circulation at 26.5°N

2004-2021

The RAPID array at 26.5°N

Cunningham, S. A. et al. (2007). "Temporal variability of the Atlantic Meridional Overturning Circulation at 26.5°N." Science 317(17 Aug 2007): 935-938.

Sustained Observations of the Varying and Evolving Ocean

Surface to ~1100m

1100m to 5000m

Sub-Tropical Atlantic Ocean Heat Content

Cunningham, S. A., et al., (2013). "Atlantic Meridional Overturning Circulation slowdown causes widespread cooling in the Atlantic." Geophys. Res. Letters submitted.

Slowing of the AMOC

1.6 to 2.7 Sv slowdown

Smeed, McCarthy and Cunningham 2013: Slowing of the AMOC, Ocean Sci. Discussion, submitted.

Slowing of the AMOC

1.6 to 2.7 Sv slowdown

Slowing of the AMOC

1.6 to 2.7 Sv slowdown

Ocean Observatories Initiative2014 to 2039

http://oceanobservatories.org

Irminger Sea Node

1. Air-sea fluxes of heat, moisture and momentum.

2. Physical, biological and chemical properties throughout the water column.

3. Geophysical observations made on the sea-floor.

1. Horizontally fixed platforms (moorings).2. Moored profilers to sample the full water column.3. Mobile platforms (gliders) for spatial and temporal

sampling capabilities.

Observing the Sub-Polar North Atlantic Programme2013-2018

The OSNAP line, comprising: (A) German 53°N western boundaryarray and Canadian shelf-break array; (B) US West Greenland boundary array;(C) US/UK East Greenland boundary array; (D) Netherlands western Mid-Atlantic Ridge array; (E) US eastern Mid-Atlantic Ridge array; (F) UK glidersurvey (yellow) over the Rockall-Hatton Plateau and Rockall Trough; (G) UKRockall Trough and Scottish Slope Current array. Red dots: US float launchsites. Blue star: US OOI Irminger Sea global node. Black concentric circles:US sound sources.

Fluxes Across Sloping Topography of the North East Atlantic

The use of multiple AUVs in FASTNEt: a study of Ocean Shelf ExchangeMark Inall

Standard Glider Pairs

+ Turbulence Glider

+ AutoSub Long Range (planned)

Internal tide generation at the shelf break

And decay and mixing on shelf

Exchange drainage in the bottom boundary

Summary

Deep Seas needs to have a motivating strategic focus

1. Sustained Observations2. Analysis and interpretation (for understanding and to compare

to climate models)3. Focused field experiments/process studies

Opportunities:• New Technologies (platforms and sensors)• Enhancement of existing arrays (RAPID, OSNAP, OOI, Argo)• Multi-disciplinary teams of brilliant scientists

The research leading to these results has received funding from the European Union 7th Framework Programme (FP7 2007-2013), under grant agreement n.308299NACLIM www.naclim.eu