Corporate Banner
Satellite Banner
Environmental Analysis
Scientific Community
Become a Member | Sign in
Home>News>This Article

North Atlantic Atmospheric Circulation Increases Mountainous Weather Systems and River Flow in Upland Britain

Published: Friday, August 09, 2013
Last Updated: Friday, August 09, 2013
Bookmark and Share
The North Atlantic Oscillation (NAO) is the most important type of climatic variability in the northern hemisphere.

It controls the strength of westerly winds between the “Azores high”’ and the “Icelandic low” that bring a succession of weather systems to Western Europe. New research has looked at the influence of the NAO on orographic precipitation, mountainous weather systems, and river flow in upland Britain.

Orographic precipitation is when moist air rises and flows over a mountain. The side with the wind will have a much wetter climate than the other side.  In the UK, the heaviest orographic precipitation has long been associated with strong southwest to westerly winds in the warm, moist sectors of frontal depression.

The study, by the Universities of Durham and Bristol, has calculated seasonal precipitation totals for 90 station records over the last 180 years.  The team used precipitation data from the British Atmospheric Data Centre Met Office Integrated Data Archive Service database and the UK Meteorological Office historic station database, together with other available long records.

The study has found that the hydroclimatology of rainfall and river flow in upland areas is closely linked to the strength of atmospheric circulation, an effect which strengthens with increasing altitude. The identified effects are large enough to cause very high river flow during periods of highly positive NAO but may also lead to severe drought when the NAO is highly negative.

Professor Tim Burt in the Department of Geography at Durham University said: “Our results cast a new light on rainfall variability in upland Britain and have implications worldwide for any mountainous region where significant orographic precipitation is generated.”

Dr Nicholas Howden, Senior Lecturer in Water in the Department of Civil Engineering at the University of Bristol, added: “What is novel here is the identification of large-scale interannual variability in seasonal precipitation and river flow totals across the British uplands controlled by the varying strength of atmospheric circulation in the North Atlantic region.”

The researchers have found that NAO variations cause large differences in seasonal precipitation totals compared to NAO-neutral conditions, an effect increased with altitude - what is known as “double orographic enhancement.”  For NAO conditions since 1825, this gives a maximum range of 150 per cent in precipitation totals at the wettest upland location compared to NAO-neutral conditions.

The team have shown in autumn, winter, and spring, there is a strong positive relationship between upland precipitation and NAO, which is not seen at low altitude except on northwest coasts.  In summer, significant negative relationships are evident in the English lowlands. These precipitation patterns directly translate to seasonal run-off.

The study concluded that on an interannual timescale, ocean-atmosphere drivers like NAO and El Niño-Southern Oscillation will have more immediate effect on extreme precipitation. How these drivers behave in the longer term in response to anthropogenic climate change is an issue of some significance and further research is needed in this area.

Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,800+ scientific posters on ePosters
  • More than 4,000+ scientific videos on LabTube
  • 35 community eNewsletters

Sign In

Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Global Carbon Dioxide Emissions to Reach 36 Billion Tonnes in 2013
Global emissions of carbon dioxide from the combustion of fossil fuels will reach 36 billion tonnes for the year 2013 – a level unprecedented in human history.
Tuesday, November 26, 2013
Top Honours for University’s Environmental Efforts
The University of Bristol’s efforts to be environmentally friendly and ethical are first class, according to a new league table.
Wednesday, June 12, 2013
The University of Bristol to Partner with FERA
Collaboration to help ensure vital research into the environment, food security and animal welfare is communicated and utilised by policy makers.
Tuesday, May 14, 2013
Scientists Awarded Grant to Determine UK's Greenhouse Gas Emissions
Researchers in the University of Bristol’s Atmospheric Chemistry Research Group have been awarded funding to provide an independent 'top-down' check on the UK's greenhouse gas emissions estimates.
Friday, March 01, 2013
University Establishes Europe's First Tall Tower Greenhouse Gas Measurements Network
The UK DECC network makes high-frequency measurements of all major greenhouse gases from tall towers.
Tuesday, November 20, 2012
Scientific News
Safer, Faster Way To Remove Pollutants From Water
Using nanoparticles filled with enzymes proves more effective than current methods.
Low Impact Fracking Fluid on Top at IChemE Global Awards
A novel fracturing fluid designed to make fracking greener.
Marine Invasive Species May Benefit From Rising CO2 Levels
Ocean acidification may well be helping invasive species of algae, jellyfish, crabs and shellfish to move to new areas of the planet with damaging consequences, according to the findings of a new report.
Game for Climate Adaptation
MIT-led project shows a new method to help communities manage climate risks.
Tufts Chemist Discovers Way to Isolate Single-crystal Ice Surfaces
Promises insights into climate, environment and age-old riddles, such as why no two snowflakes are alike.
Potential Indirect Effects of Humans on Water Quality
Newly studied class of water contaminants occur naturally, but are more prevalent in populated areas.
Rapid Method for Water, Air and Soil Pathogen Screening
Researchers at BGU and the Massachusetts Institute of Technology (MIT) have developed a highly sensitive, cost-effective technology for rapid bacterial pathogen screening of air, soil, water, and agricultural produce in as little as 24 hours.
First Results Describing Sick Sea Star Immune Response
Though millions of sea stars along the West Coast have perished in the past several years from an apparent wasting disease, scientists still don’t know why.
Microbe Sleuth
Tanja Bosak examines how life and the Earth evolved in tandem during their early history together.
The Age of Humans Controlling Microbes
Engineered bacteria could soon be used to detect environmental toxins, treat diseases, and sustainably produce chemicals and fuels.
Scroll Up
Scroll Down

Skyscraper Banner
Go to LabTube
Go to eposters
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,800+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
4,000+ scientific videos