RAPID-WATCH Home A a directed programme for NERC


This page contains news about research, meetings and other activities in the RAPID-WATCH programme (2008-2014). The web site for the RAPID Programme (2001-2007) is still available, with information about RAPID research activities from the projects funded under the that programme.

October 2012

Atlantic Ocean blamed for run of dismal UK summers

Plot of temperature difference from normal North Atlantic temperature

The Atlantic Multi-decadal Oscillation. Click for larger figure with detailed explanation.

This year's dismal UK summer could be part of a run of poor summers caused by a major warming of the North Atlantic Ocean that occurred back in the 1990s.

According to new research at the University of Reading published in Nature Geoscience, the North Atlantic warming in the 1990s coincided with a shift to wetter summers in the UK and northern Europe and hotter, drier summers around the Mediterranean. The patterns identified match those experienced this summer (2012), when the UK had the wettest summer in 100 years, while the Mediterranean suffered with temperatures as high as 40 degrees centigrade or more.

The temperature of the North Atlantic swings slowly between warmer and cooler conditions, and the present warm phase has a similar pattern to warm conditions that persisted throughout the 1930s, 40s and 50s. During the 1960s, 70s and 80s cooler conditions occurred over the North Atlantic. Computer simulations suggest that these changes in ocean temperature affect the atmosphere above. Warmth in the North Atlantic causes a trough of low pressure over western Europe in summer and steers rain-bearing weather systems slap-bang into the UK.

Time series of MOC data

Changes in summer rainfall in the 1990s.
Click for larger figure with detailed explanation.

The previous North Atlantic warm phase also saw a run of wet summers over the UK with notable events including the August 1952 Lynmouth floods and severe flooding during August 1948 which closed the east coast mainline railway for three months.

The North Atlantic ocean has alternated slowly between warmer and cooler conditions over the last 100 years. We saw a rapid switch to a warmer North Atlantic in the 1990s and we think this is increasing the chances of wet summers over the UK and hot, dry summers around the Mediterranean – a situation that is likely to persist for as long as the North Atlantic remains in a warm phase.

The North Atlantic warming and cooling cycles are known as the Atlantic Multi-Decadal Oscillation (AMO) and they affect temperature, rainfall and wind patterns over Europe, Africa and North and South America. Previous research has suggested the warm and cold swings are related to changes in ocean circulation. Other research at Reading has suggested that it may be possible to predict the warming and cooling cycles some years ahead.

During the 1990s the North Atlantic shifted to a warm state similar to that experienced during the 1930s, 40s and 50s, and this warm state has persisted to the present day. The swings in the temperature of the North Atlantic are additional to a long term (century timescale) warming trend that is mainly due to increasing concentrations of greenhouse gases in the atmosphere. It is likely that the swings in the temperature of the North Atlantic have also been affected by human activities – both greenhouse gas emissions and other forms of pollution. Understanding how important these factors have been is a subject of active research.

Read the full paper by Sutton and Dong, 2012

Analysis of the MOC slow-down in winter 2009-10

Time series of MOC data

MOC anomaly time series 2004 - 2011.   Click on the image for a larger figure.

MOC data from 26°N are now available for 7 full years from 2004. For the first five years there seemed to be little variation from year to year once the seasonal cycle was taken into account. But the winter 2009-10 saw a severe drop in the strength of the MOC. This event coincided with a very cold winter in Europe, and has created much scientific interest. Now a paper from the 26N team reveals what took place.

The decline was not only due to anomalous winds in the winter of 2009-10, but also the result of the geostrophic (mid-ocean) flow increasing. Southward flow in the top 1100m intensified, and the deep southward return transport from high latitudes weakened. This rebalancing of the transport from the deep overturning to the upper gyre has implications for the heat transported by the Atlantic.

Read the full paper by McCarthy et.al., 2012

International praise for the RAPID observing system

diagram of the MOC observations

International experts reviewing the RAPID observing system are impressed by the new and exciting results produced from the RAPID-array across the Atlantic at 26° North. The review group see the measurements as an important element of an on-going system to observe the Meridional Overturning Circulation (MOC) and commend NERC for its international leadership in this area.

The group also recommend that the WAVE measurements further north continue until the end of the project, but see the system as insufficiently mature for a transition to long-term monitoring at the end of RAPID.

International Science Meeting on the Atlantic Meridional Overturning Circulation (AMOC)

The venue

12-15 July 2011 in Bristol, UK.

Observations and models have suggested links between variability in the Atlantic Meridional Overturning Circulation (AMOC) and global climate patterns. Reduction in the strength of the overturning may have played a key role in rapid climate change in the past and could have the potential to so in the future. The meeting will explore our scientific understanding of Atlantic variability on a range of time scales, with a main focus of the role of the meridional overturning circulation. A joint initiative between the UK Natural Environment Research Council's Rapid Climate Change programme (RAPID) and the US AMOC Program, it has four main themes:

  1. What do we know about present and past changes in the AMOC on seasonal to millennial time scales?
  2. How does the AMOC influence ocean, atmosphere and terrestrial climate and ecosystems?
  3. How will the AMOC change over the next few decades and over the 21st century?
  4. Outlook and Challenges.

For more information and to register for e-mail updates, see the meeting website at www.rapid.ac.uk/ic2011/.

New Method for Estimating Variability in the Atlantic Overturning Circulation

Satellite image of Sea Surface Temperature Diagram of the Atlantic Meridional Overturning Circulation (AMOC)
Left: Sea surface temperature in January 2009. Right: Diagram of the Atlantic overturning. Click on images for larger figures.

At present there is no monitoring system to measure the strength of the Atlantic Meridional Overturning Circulation at latitudes from about 40 °N to 65 °N. 'However, recent research shows that the strength of the overturning can be determined from the gain in the density of surface waters as a result of heat loss and evaporation to the atmosphere. The research, which builds on results from an earlier Rapid funded proposal, has been carried out by J.Grist, S. Josey and R.Marsh at the National Oceanography Centre,Southampton under the NERC Oceans 2025 programme Theme 1. This is the basis for a new method used to estimate the strength of the AMOC at these latitudes.

Stronger evaporation and cooling means leads to greater formation of North Atlantic Deep Water (NADW), which sinks and flows back south at depth. Greater deep water formation increases this flow, and strengthens the overturning at higher latitudes. For more information see news article on the NOCS web site.

Presentations from the RAPID Annual Meeting 2009 now on-line

30 July 2009

The RAPID Annual Meeting was held in Edinburgh 6-9 July. It included presentations from both RAPID and RAPID-WATCH projects. Participants in the associated Palaeo-Climate Workshop are producing a joint paper to present results from RAPID (2001-2007) and plans for future collaborations. Presentations from the workshop are available from the Agenda and Abstract list to be found on the Annual Meeting web page.

time series plot

First public data from 26°N

1 June 2009

The first 3.5 years of data from the RAPID array at 26°N is now available from the project website. To download follow links to DATA on the top menu bar. The data show that the MOC is highly variable, with large seasonal fluctuations that vary from year to year.

New RAPID-WATCH projects

April 2009

Five projects have been selected for funding in the last RAPID-WATCH AO. They will work closely with the Hadley Centre and international partners to determine and interpret recent changes in the Atlantic MOC, assess the risk of rapid climate change, and investigate the potential for predictions of the MOC and its impacts on climate.

Rapid cruise D334

Latest cruise to recover moorings at 26°N

November 2008

The photo on the right shows RAPID scientists recovering moorings on the RAPID cruise to the array at 26° North, in November, 2008.