DYNamics and predictability of the Atlantic Meridional Overturning and Climate (DYNAMOC)

Lead Research Organisation: National Oceanography Centre
Department Name: Science and Technology

Abstract

The 'Atlantic Meridional Overturning Circulation', or AMOC, describes a large scale circulation of the North Atlantic Ocean which carries warm surface waters northward and cooler deeper waters southwards. This circulation carries huge amounts of heat, and variations in its strength can have a substantial influence on European climate. The DYNAMOC project aims to improve understanding of how this circulation has varied in the past and how it has affected climate, and also to assess the potential for useful predictions months to years ahead.

DYNAMOC will make use of new advanced computer simulations and forecasting systems which are able to simulate the AMOC in unprecedented detail. It will also make use of the RAPID observations of the AMOC strength at 26 degrees North, available since 2004, as a benchmark for testing the models and predictions. The research will test some specific hypotheses about how the AMOC works, how it is changing now. It will investigate how a slow down or speed up in the AMOC affects summers and winters in the UK and other countries. DYNAMOC will provide an assessment of the likely behaviour of the AMOC, and its impacts on climate, over the next decade. It will also produce recommendations for improving forecasting systems in the future.

DYNAMOC is a collaboration between the National Centre for Atmospheric Science at the University of Reading, the National Oceanography Centre and the UK Met Office.

Planned Impact

The beneficiaries of DYNAMOC will include:

1. Government Departments: (e.g. DECC, Defra and DFID, cabinet office) who are customers for Met Office seasonal-to-decadal forecasts and will benefit from improved forecasts. Furthermore, because the AMOC is one of the major mechanisms via which abrupt climate change may take place over the N Atlantic it is of extreme relevance to UK policymakers. DYNAMOC will provide new insights into the likelihood of a significant slowdown in the AMOC in the near term, and the likely impacts on the climate of Europe and other regions.

2. Businesses: seasonal forecasts are of increasing interest to businesses affected by weather and climate risks. The energy industry in particular requires information about future weather to manage supply and demand. Businesses will benefit from improved forecasts and specific advice concerning potential future changes in the AMOC and the likely consequences for businesses.

3. Met Office (MO): DYNAMOC outcomes will benefit the Met Office by i) Improving understanding of the role of the AMOC in climate variability and predictability and the representation of the relevant processes in the Met Office's models; ii) Assessing MO seasonal-to-decadal predictions and identifying opportunities for improvement; iii) Assessing the impact of the RAPID array observations on predictions.

4. International Customers: will benefit from the improved quality of the Met Office contribution to the coordinated international dissemination of seasonal forecasts (www.wmolc.org)

5. NERC: DYNAMOC outcomes will affect NERC's strategy through the project's input into the international review of the RAPID array in 2018.

6. General Public: Climate variability, such as droughts and flooding are of interest to the general public, but the AMOC's role in climate variability is still uncertain. DYNAMOC will engage the public on the AMOC's role in regional variability that affects the UK.

7. Trained Staff: DYNAMOC will train scientists in climate research and to engage with the public.

Publications

10 25 50
 
Description The simulation using a high resolution ocean model (1/12°) has been extended closer to present and now simulates the years 1978 to 2015 has shown a greatly improved ability to simulate North Atlantic ocean currents at the heart of the project. In addition to this simulation we performed an ensemble of simulations with perturbed initial conditions (perturbations in 2007 and 2009). This provides us with a framework to better understand the extent to which the ocean circulation is directly forced through the atmosphere vs chaotic ocean variability. Our results suggest that up to 30% of the variability occurring in the Atlantic meridional overturning circulation is likely to be chaotic i.e. linked to processes that cannot directly be predicted from the atmospheric forcing alone (e.g. ocean mesoscale eddies). An important new finding is the link between the Atlantic meridional overturning circulation (AMOC) at 26.5N and sea surface temperatures (SSTs). Our results show that changes in the AMOC precede de development of anomalous SSTs in the subtropical and mid-latitude North Atlantic by 3-5 months. This opens to prospect of the RAPID AMOC timeseries at 26.5N to be used as an SST precursor. Another important result concerns multidecadal links between the Atlantic multidecadal oscillation (AMO) and the North Atlantic Oscillation (NAO). Positive and negative phases of the AMO are characterised by warmer and colder temperatures over much of the North Atlantic. Our research has shown that such temperature changes tend to precede changes in the NAO by about 5 years suggesting that it is the ocean that is driving the NAO on multidecadal timescales.
Exploitation Route The model described above will be the key tool to improve our understanding of the processes governing the variability of the Atlantic meridional overturning circulation. All the data of our model simulations are available on the JASMIN data server and therefore available to scientists from other research institutions. Our study linking AMOC observations to SST anomalies is to our knowledge the first concrete attempt to use the AMOC observations from 26.5N as a predictor for a climatically crucial quantity (SSTs). Even though this has not happened yet there could be some potential to use this approach to support forecasting of Atlantic hurricanes. One of the regions where we find the highest correlation between AMOC and SSTs is the mean development region for Atlantic hurricanes.
Sectors Environment,Other

 
Title Eddy-resolving simulation 
Description Performance of a new, long global ocean simulation at 1/12° (NEMO ocean model in ORCA12 configuration). The simulation covers the period from 1958 to 2014. 
Type Of Material Improvements to research infrastructure 
Provided To Others? No  
Impact This simulation will provide with a unique opportunity to improve our understanding of the mechanisms behind the variability of the North Atlantic Meridional Overturning circulation. 
 
Description Met Office - DYNAMOC 
Organisation Meteorological Office UK
Country United Kingdom 
Sector Public 
PI Contribution NOC has carried out a new simulation (global NEMO 1/12°) and output is available to project partners (via JASMIN data server)
Collaborator Contribution The Met Office provided access to output from its forecasting Systems (via JASMIN data server).
Impact Reciprocal access to data (NEMO 1/12° global ocean model simulation; output from forecasting systems)
Start Year 2015
 
Description Contributed to BBC interview (50th anniversary discovery) 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact I was asked to comment on the purpose of some instrumentation that would be deployed in order to help monitoring the Atlantic meridional overturning in real time.
Year(s) Of Engagement Activity 2015
URL https://www.facebook.com/bbcbreakfast/videos/1185374644810005/
 
Description Invited Seminar - University of Berne (Switzerland) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Other audiences
Results and Impact About 100-150 people attended my seminar at the University of Berne on 21st October 2015
Year(s) Of Engagement Activity 2015
 
Description Presentation - Southwestern Arms 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact Around 30-40 people attended my presentation in the Southwestern Arms Pub (Southampton)
Year(s) Of Engagement Activity 2015