Wednesday, 20 May 2015

Abandoned mines provide low carbon heating... by Gareth Farr

New 3D Geological model of the South Wales coalfield (Andy Hulbert)
Gareth Farr from BGS in Wales has been discovering how abandoned mines in South Wales could once again be used to supply energy. Mine waters in flooded workings can be passed through a heat exchanger, producing hot water to heat homes and offices. The technology has been proven at a test site in South Wales and offers a secure, low carbon alternative to traditional fossil fuels....
At the BGS we've been working with Cardiff University and WDS Green Energy Ltd on the ‘Seren’ project supported by the European Regional Development Fund (ERDF).

Seren has been aimed at helping businesses find new opportunities by developing innovative engineering technologies to exploit geo-energy. One of these opportunities that has been investigated by the BGS and Cardiff University is the potential for exploiting geothermal energy from mine-waters in the South Wales Coalfield.
Measuring mine water temperature and chemistry at the inflow to a treatment lagoon with Dr Siva Sadasivam (Cardiff University)

We undertook a program of temperature monitoring temperature and chemistry of mine waters, which has accompanied creation of a new 3D geological model of the coalfield and developing a new coal properties database populated by capturing many thousands of historical coal analysis records. The commercial partners have installed a working GSHP system into abandoned mine workings.

Ground source heating relies on the recovery of low grade heat energy from the earth or from groundwater, with the energy being harvested using a ground source heat pump (GSHP). There is little use for mine waters as they are often below drinking water standards, however the large volumes of water could offer a potential source of low grade heat. In the South Wales area it is estimated that as much as 2000 – 3000 litres per second is still being pumped or drained from old mine workings.

WDS Green Energy Ltd have installed a working GSHP system into abandoned mine workings as part of this project. The system is working well, heating a large property and several outbuildings. This photograph shows some of the above ground workings.
To assess this potential we installed temperature monitors where water flows out of the abandoned mines. The temperature was recorded every 30 minutes and by the end of the project we had collected over 300,000 individual temperature readings. We found that many of the mine waters had temperatures above that of ‘normal’ groundwater (~11°C) and offered an exciting potential for use with GSHPs.

Combining what we had learnt about the temperatures of mine waters with information collected by the Coal Authority on the volumes of water leaving the mines we were able to estimate that there was potential to generate enough energy to heat 20,000 homes. This estimate is based on sites where data has been collected so the real potential is likely to be much greater.

Temperatures of mine water discharges measured every 30 minutes over a one year period
To prove this concept our commercial partners WDS Green Energy Ltd installed a real GSHP system into flooded mine working and have been successfully providing heating energy for a large house and outbuildings in South Wales.

Seren has shown that there is considerable potential to use mine waters as a source of heating, providing energy security, reduction in carbon emissions and reducing reliance on traditional fossil fuels.
by Gareth

Wednesday, 6 May 2015

Managing Malawi's spatial data ... by Carl Watson

CSCUK fellows collecting field samples in
Devon, Salome Mkandawire (left) and
Grace Manzeke (right)
Salome Mkandawire, a GIS expert from the Malawi government Surveys Department, has just spent a busy month training with Carl Watson, a Systems Developer & Analyst at the BGS. Their aim was to share good data practice and information management experience as well as research international standards for spatial metadata. Here Carl explains why BGS is a leader in these fields and asks Salome how this CSCUK Professional Fellowship is helping the National Spatial Data Centre in Malawi...

Salome is one of two Fellowships visiting BGS via funding from the Commonwealth Scholarship Council (CSCUK) gained through the combined BGS-University of Nottingham Centre for Environmental Geochemistry. Grace Manzeke from the University of Zimbabwe is the other Fellowship and will follow-up soon with another blog on her experience. 

Salome was motivated to come to BGS and learn about our practices because of recent developments in the Malawian geospatial community,
"In Malawi we are setting up the National Spatial Data Centre (NSDC) which will be the data bank for spatial data. The NSDC is important for facilitating seamless data development, information sharing, and collaborative decision making across multiple sectors of the economy.

The National Spatial Data Centre should have well trained staff in different areas of Geographical Information systems and Web GIS, Information management, Metadata creation and also human resource management."

My first objective when organising the training programme was to make sure Salome experienced the wide range of activities carried out by the BGS and partners. I arranged a series of meetings with experts who could describe their roles in the data management workflow, from field data capture through to public dissemination of spatial knowledge built on well structured, fully managed data.
Over the four weeks we spent time talking to data verification and information management officers, observed how the physical and digital records were managed and even fitted in a couple of field trips to Devon and Derbyshire to experience how important it is to collect and describe data correctly.
High level data model for metadata, taken from
Database design principles and best practice was covered by walking through BGS examples and corporate documentation and supplemented by the book ‘Database Systems: A Practical Approach to Design, Implementation and Management’ by Connolly and Begg.

With the help of BGS experts and online resources (see external links listed at the end of the article) we explored why data centres need to take metadata seriously. By walking through documented standards on spatial metadata and logical data models such as that available at we identified what the most important attributes were for Malawian spatial datasets. This work will feed directly into the section of metadata in the NSDC standards document and may even lead to the development of new functionality in the Malawi Spatial Data Portal (MASDAP).
“The Commonwealth Fellowship has enabled the transfer of skills and knowledge relevant to my home country [Malawi] because I have learned the importance of information management, the creation of metadata and systems by seeing how important this is to the British Geological Survey.
I will be able to teach other members of staff in Malawi the importance of managing the various datasets from different organizations which we have at NSDC and the Department of Surveys, this will help to avoid the duplication of efforts and easily find data.
Currently, we are digitizing our analogue data therefore, the training came at the right time as I will help in data management and creation of metadata of all the scanned sheets and digitized maps. The metadata creation for all the physical and non-physical data will be done using knowledge gained.”
This month has illustrated that the BGS has a lot of staff who are very experienced and knowledgeable about all manner of data management issues, we have spent so many years working with and adapting international standards that we almost take it for granted. The CSCUK Professional Fellowship has been a great way to share our knowledge and develop closer relationships with spatial data experts in an interesting part of the world. I hope that the Malawi NSDC is a great success and I’m sure we will work with Salome and her colleagues again in the future.
External links / suggested further reading:
GoGeo, containing training course on metadata.
Previously blogs about BGS work in Malawi.

Tuesday, 5 May 2015

Ancient links between climate and vegetation... by Jonathan Dean

Skyline of Minneapolis
Dr Jonathan Dean is part of a new multi-million pound project that hopes to shed new light on the possible links between environmental change and the emergence of our species...

I'm a Post Doctoral Research Assistant based in the Stable Isotope Facility at BGS Keyworth.  In April, myself and 14 other scientists from the UK, Germany and Ethiopia flew out to Minneapolis. We were there to begin our study of half a kilometre of sediment cores that were taken from an ancient lake on the Ethiopian-Kenyan border last year. Our multi-million pound project, funded by NERC, ICDP and German and American funding bodies, aims to help us to understand how climate and vegetation has changed over the past 500,000 years, and is part of a wider project that involved the drilling of 5 lakes across the region. The UK team is led by Prof. Henry Lamb from Aberystwyth University.

Our home for a week, 6 stories underground, at the University of Minnesota in Minneapolis
So far, such long-term reconstructions of environmental change from east Africa have been lacking, which means we do not yet understand how the environment changed through the time when our species, and our ancestor species, evolved in the region. Scientists have speculated that environmental changes could have played a role in the timing of our evolution and subsequent dispersal from east Africa, but only when our studies are complete will we be able to test this thoroughly for the first time.

The cores were then split in half lengthways, so we could see the patterns of sediments inside, and so we could take samples for analysis back in our home labs.
The sediment cores are being stored at the world-leading LacCore facility at the University of Minneapolis, where we were able to split open, photograph and scan with instruments to investigate changes in the elements present. We also took samples at intervals along the core; I will analyse mine at Keyworth for oxygen and carbon isotopes, to reconstruct changes in the amount of rainfall over time. Other people took samples to date the cores and to investigate changes in vegetation through time.

Scanning the cores.
So, watch this space over the next few years as we publish our results and shed new light on the possible links between environmental change and the emergence of our species…

Follow me on Twitter @jrdean_uk

Monday, 4 May 2015

Sea Shells on the Sea Bed... by Henrieka Detlef

Henrieka Detlef
Henrieka Detlef is using shells which are over a million years old to reconstruct the different climatic components of the Bering Sea. She's a 1st year PhD student at Cardiff University and a BUFI CASE student at the British Geological Survey studying Paleoclimatology and Marine Geology. Find out from Henrieka why she's so interested in investigating climate systems of the past and how marine sediment cores will unlock the answers...

My PhD project focuses on reconstructing continental ice volume and deep sea hydrography changes, such as oxygen concentrations and temperatures, in the Bering Sea. I am working on the Integrated Ocean Drilling Program (IODP) core U1343 from the eastern Bering Sea, which is a unique area with extremely high primary productivity in the surface ocean and an oxygen minimum zone along the continental slope. The Bering Sea today is the gateway between the Pacific and Atlantic Ocean via outflow of Pacific waters through the Bering Strait. During cold stages of at least the past 2 million years continental ice volume increased significantly, causing sea level to fall by up to 130 m. During such events the Bering Strait was exposed and the Pacific Atlantic throughflow was cut-off. Together with other hydrographical and atmospherical changes this caused major shifts of sea ice extent, primary productivity, and ocean circulation in the Bering Sea during glacial intervals.

My research mainly focuses on the Mid-Pleistocene Climate Transition, 1.25 to 0.7 million years ago. During this time the frequency of cold stages changed from 41,000 years to 100,000 years and continental ice volume grew larger during glacial intervals. I plan to unravel the timing of continental ice volume change in the northern hemisphere in combination with deep sea temperature and sea ice shifts to investigate leads and lags of climatic signals and to investigate the influence of sea ice in high northern latitudes on ice sheet build up. Further I plan to look at oxygenation changes of mid-depth waters along the eastern Bering slope and their causes in combination with changes in the ocean’s carbon cycle.

Location map of sediment cores retrieved during IODP cruise 323 in the Bering Sea (red dots). U1343 is located in the eastern Bering slope. (

I plan to mainly use the shell chemistry of benthic foraminifera (little calcareous microfossils living on/in the seafloor) and assemblage changes of dinoflagellate cysts (organic walled cysts of marine protists living in the surface ocean) to reconstruct all the different climatic components.

To begin with I have to make sure that the foraminifera recovered from sediment core U1343 actually record the primary climatic signal and are not influenced by post-depositional carbonate precipitation on the shell or diagenetic recrystallization of the calcium carbonate. Therefore I plan to use a combination of imaging and chemical mapping techniques such as Scanning Electron Microscopy, Laser Inductively Coupled Plasma Mass Spectrometer (LA-ICP-MS) and solution ICP-MS.
This is where I am at the moment…

I hope you now know a little bit more about me and what I am doing during my PhD project. I will keep you updated on any exciting results 


Hennie is being supervised by Dr Sindia Sosdian, Dr Carrie Leah, Prof Ian Hall (University of Cardiff) and Dr Sev Kender, Prof Melanie Leng (BGS). 

Wednesday, 22 April 2015

Groundhog explores deep beneath our feet... by Gerry Wildman

To cope with 21st century issues like rapidly expanding cities and demands for natural resources we need clever 21st century solutions. 'Groundhog' is a new digital tool from the BGS which delivers 3D geological models to communities, planners and policy makers. It allows users to understand the issues and solutions that literally lay at their feet. Gerry Wildman, Data and Science Services Manager, explains more...

Geology is a phenomenon that changes at depth. Layers of rock are built up on top of each other over vast quantities of time.  These layers are then subjected to stresses and strains, which fold, fault and deform the ground. Through geological time, older rock layers may be ground down by erosion before younger layers are deposited on top. When considering the geology, it’s important to look not only at the type of the geology you find at the surface, but also how and when this changes at depth. Knowing how these layers change is important in understanding how we can use the ground. For example it can help us to understand where groundwater can flow, where the natural resources are, and what to consider when designing buildings and structures above and below the ground. 

Over the last decade many Geological Surveys across the world, including BGS, have begun to communicate their geological understanding of the ‘subsurface’ through 3D geological models. BGS now has a number of different 3D  geological models ranging from a national resolution ‘fence diagram’ model of the onshore bedrock geology: the GB3D  bedrock model to shallow, local-scale models,  typically for use in ground investigations, groundwater studies and tunnelling projects.

London Geological Model
Recently, BGS has begun releasing data from a selection of their local-scale models in their Groundhog system. Developed by BGS, Groundhog is a tool that is used to deliver geological models over the web. It allows the user to explore the 3D models by creating ‘virtual boreholes’ or ‘virtual sections’.  Groundhog delivers the results straight to the user as pdf reports. Currently 3D models for London, Manchester and part of Suffolk are available in this system, with more planned.

The ethos behind Groundhog is to provide a service that conveys complicated geology in a simple way. As it runs in a web browser, it removes the need for expensive and specialised software, enabling anyone to use the models. But behind the simplicity is some very clever stuff. In creating the underlying models BGS uses a range of methods to capture our geological understanding varying from direct interpretations by geologists to semi-automated modelling involving advanced maths. The methods used depend on the geological situation and how much data is available. Each model takes account of existing BGS experience and data that may include our vast collections of borehole logs, seismic lines and regional geophysical data.

Screenshot from Groundhog, visit here
To enable Groundhog to produce virtual boreholes and sections, the models are represented behind the scenes as a stack of 2D elevation grids, each grid representing the stratigraphic base of one geological layer, and a further grid to represent the ground surface (the digital terrain model, DTM).  The grids are then converted to a binary format for use in Groundhog making them much quicker for the drawing tool to access the required data points within them.  A simple database provides an index to the available models and their grid file and fault file layers. By querying a stack of grids for a given X,Y position on a map, Groundhog can create a vertical log through the 3D model.  A series of vertical logs along a specified line can be used to create a cross-section. By considering a collection of vertical logs sampled on a 2D grid with respect to a fixed or DTM-relative elevation value, a horizontal slice can also be produced.

For more information, or to order your own virtual borehole or section, please see our website. Every Wednesday throughout April and May 2015 Groundhog reports are half price, follow #3Dgroundhog on Twitter for more links and info.


Sunday, 12 April 2015

Mud, monsters and murders: can geology really help to solve crime? Kirstin Lemon

The recent NI Science Festival was the first of its kind in Northern Ireland and attracted thousands of people to an amazing diversity of science events across the country. This eclectic mix included traditional lectures and demonstrations, and a range of not so traditional such as theatre, comedy, music and film.

One of the less conventional events that took place was called 'How do volcanoes solve crimes?' and was jointly organised by Dr Alastair Ruffell and Dr Jenny McKinley from the Queen's University of Belfast, and Dr Kirstin Lemon from the British Geological Survey. Hosted by the Ulster Museum, this unusual event looked at forensic geology and how it could be used to solve a fictional crime based in the museum itself. A crime scene was created, with the famous 'Minnis Monster', a fossil Ichthyosaur, being stolen and children were asked to see if they could find where the monster was hidden using the mud found on the shoe of the key suspect.

Sediment on wheel arches of cars are often used to place a car
at the scene of a crime. Such evidence was used in the
Soham murder case
What exactly is forensic geology? To put it simply, it is using earth-related material such as minerals, pollen/spores and organic matter as part of a forensic investigation. The concept was probably first used by Sir Arthur Conan Doyle in his Sherlock Holmes books when Sherlock was able to identify where an individual had been using the clay found on their shoe. But forensic geology is not just in fiction as it has been used to solve many crimes including a high profile case that involved locating a body of a murder victim in March 2005 based on soil material believed to be from the body deposition site.

How does forensic geology work? Generally, earth-related materials are collected from a suspect's clothing, footwear, vehicles or dwellings and are used as a comparative material from the crime scene.  Given the sheer amount of potential variables it can be a rather difficult line of evidence to pursue. However, if a number of different analytical techniques are used then the chances of success are much higher. Dr Barry Rawlins, the Soils and Landscape Team Leader with the British Geological Survey has worked on forensic geology and has outlined the key techniques used:

1. XRD or X-Ray Diffraction is used to detect any crystalline or partially crystalline substances in the sample. The advantage of this technique is that it can be used on event the smallest of samples. It is very useful for identifying clay minerals and can help to determine the provenance of rocks and soils.

2. SEM or Scanning Electron Microscopy is used to produce images at a much higher spatial resolution than using a conventional microscope. It also allows for chemical analyses on isolated areas of the specimen and is particularly useful for soil samples.

3. Molecular Organic Matter Signatures can be looked at to identify specific plant communities from the soil sample and thus helping to identify where it came from.

4. Palynology is the study of organic microfossils and their modern counterparts and can be used to identify bedrock or the bedrock that soil samples originate from.

The mineralogy of geological samples was used to identify 
the provenance of aggregate used to bury bodies in a trench 
in Devon. The thin section above is seen under polarised light
A number of these techniques rely on soil samples, all of which formed in the last 10,000 years. Their characteristics are closely related to the parent material from which they formed including underlying bedrock and any Quaternary material such as glacial deposits. Once a soil is identified, its provenance can be determined by combining this with detailed geological knowledge of an area. This ultimately can prove or disprove the location of a crime scene or the presence of a suspect at one.

Forensic geology is being used increasingly to solve crimes, especially those of an environmental nature. Whilst the NI Science Festival event was purely for fun it played a vital role in raising the awareness of this specialist branch of geology, and the role that organisations such as the British Geological Survey play in this.

Given that 2015 is the International Year of Soil and the Year of Mud, then perhaps now is the time to raise the profile of this exciting science.

For more information on forensic geology at the British Geological Survey contact Dr Lauren Selby at or Dr Barry Rawlins at


Rawlins BG, Kemp SJ, Hodgkinson EH, Riding JB, Vane CH, Poulton C & Freeborough K 2006. Potential and Pitfalls in Establishing the Provenance of Earth-Related Samples in Forensic Investigation. Journal of Forensic Science, 51, 4: 832-845.

Thursday, 9 April 2015

Isotopes and the bones and teeth of King Richard III ... by Catherine Pennington

Professor Jane Evans (right) and Dr Angela Lamb (left) in their lab in NIGF
Professor Jane Evans (right) and Dr Angela Lamb (left) in their lab in NIGF
Professor Jane Evans and Dr Angela Lamb work in the NERC Isotope Geosciences Facilities (NIGF) at the BGS in Keyworth.  NIGF is one of the largest isotope laboratories in Europe for studying naturally occurring isotopes. 

Jane and Angela front the Science-Based Archaeology programme where they use isotopes to uncover information about the past. 

Some of Jane and Angela’s work is not quite what you might expect.  They have been involved with assisting the police with forensics, identifying fraudulent ceramics, mapping the migratory patterns of fallow deer, understanding how humans have transported chickens around the world and reconstructing past agricultural practices.  More lately, they have been involved with the much reported lifestyle of King Richard III (see below).

But what exactly are isotopes?  How do we use them to date rocks? What can isotopes in teeth and bones tell us?  Jane explains in this video:

King Richard III's teeth

King Richard III died at the Battle of Bosworth in 1485 and teams from the University of Leicester and the Richard III Society uncovered this warrior king’s remains under a council car park in 2012.  The skeleton was then tested to confirm his identity and to try to reveal how he died.  Jane and Angela were asked to find out more about his lifestyle and movements.  They were given a pre-molar tooth and small pieces of femur and rib bone as these all form at different stages of life, giving a range of information across the king’s lifetime as Angela explains:
By looking at the oxygen and strontium isotopes in his bones and teeth we were able to look at where he lived through his life. The teeth, which form in childhood, confirmed that Richard had moved from Fotheringay castle in eastern England by the time he was seven and that he had moved back to eastern England as an adolescent or young adult.  We then looked at the dietary isotopes, carbon and nitrogen, to look at how his diet changed throughout his life
One of the most important findings from their isotope analysis was that there were marked changes in his diet when Richard became king in 1483; he began eating a diet only the highest aristocracy could afford.  This included freshwater fish and birds, such as swans, crane, heron and egret.  In addition, the bone chemistry suggested he was drinking more wine during his short reign as King and reinforces the idea that food and drink were strongly linked to social status in Medieval England. 

You can read more about the work Angela and Jane did by reading their paper:

Professor Jane Evans is the Head of Science-Based Archaeology at the NERC Isotope Geosciences Facilities.

Dr Angela Lamb is a Research Scientist within the NERC Isotope Geosciences Facilities.

Both work within the Centre for Environmental Geochemistry, a joint venture between BGS and the University of Nottingham.


Wednesday, 1 April 2015

Why learn good Science Communication?... by Jonathan Dean

Our scientists never stop striving to improve their understanding of the world around them. Equally they never stop learning new ways to better communicate their work and discoveries to the wider world. One such scientist is Jonathan Dean, a Postdoctoral Research Assistant at BGS, who's just back from a 2 day public engagement course run by NERC. Here Jonathan reflects on the importance of good science communication and the skills learnt on the NERC Engaging the Public with your Research training course...

Public engagement – letting non-scientists know what science we’re doing with their taxes – is important. Many people are interested in finding out, for example, when humans evolved from apes, what caused an extreme flooding event and if there is life on Mars, but they are going to be left in the dark unless they trawl through academic journals on their evening commute (unlikely) or unless we make an effort to reach them. We can get our message out to the public in a variety of ways, for example via the media, in blogs on our websites and at talks in schools. Lots of our work could benefit society – we might have discovered mineral deposits that could stimulate economic growth, found a way of reducing the pollution emitted from cars or established how changes in solar activity influence the Earth’s climate. But if policy-makers don’t know what we’ve found, then policy can’t be changed and our findings might go to waste.

NERC - the parent body of BGS
We began our training course with instruction from a BBC News science reporter on how to write a good press release. We found that they are written the opposite way round to how we’d write up our results for a peer-reviewed journal – the snappy summary of the findings, which would be in the conclusion of a paper, should come first, followed by more detail about why it is important and how we carried out the research. Unless their imagination is captured within the first few seconds, journalists will stop reading and move onto the next press release, and our research will never find it onto the Today programme or into The Times (other media outlets do exist).

We then learnt about how to design public engagement activities, such as talks in school or in pubs, before moving onto radio interviews. While listening to the sound of your own voice played-back in front of everyone is never enjoyable, our practice interviews were really useful. We realised the importance of avoiding jargon (for example using the word ‘results’ rather than ‘data’) and in coming across enthusiastic – making yourself smile during the interview helps this! Finally, we had the chance to produce our own media, by making a podcast. I played the role of a radio presenter interviewing two people about fracking.

The course takes place in the NERC office in Swindon 9 times a year and can be attended by anyone who works for NERC or holds a NERC grant, including NERC PhD students and PDRAs. I would thoroughly recommend it as a really useful and enjoyable course that gives you new ideas for engaging with the public and more confidence when dealing with the media.

Find me on Twitter @jrdean_uk

Tuesday, 31 March 2015

Welcome to Iceland fieldwork from above... by Jez Everest

Jez Everest established our Virkisjökull Glacier Observatory in 2009, and new equipment has been installed each year to monitor climate, ice dynamics, landscape change, hydrology and groundwater. Today, with the snow keeping them close to camp, Jez has put together a little intro video with the new hexacopter footage...

The BGS Glacier Project machine grinds into gear once more, boldly going where none have gone before. Well almost. This time the team consists of a mixture of BGS and GSNI staff, plus staff and MSc and MRes students from Dundee and Lancaster Universities, here for 10 days with a huge range of research activities to complete.

Atypically the trip started with delays caused by a late shipment of equipment from the UK. Who would have thought it was so hard to transport LiPo batteries between countries? However the blue roof of Austurbaer at Svinafell hove into view on Wednesday evening, bathed in sunshine. Thursday was spent steam drilling holes in the glacier to discover meltwater pathways along faults and thrusts, sampling various water sources for sulphur isotopes, and testing the hexacopter which will carry our thermal imaging kit to be used on the trip… more on this hopefully later in the week. There was still a bit of time for Paul and Ali to go for a run before dinner, and for me to do some video using the quadcopter.

Unfortunately today has seen bucket loads of snow, hiding crevasses on the glacier, and blanketing the ground, obscuring features and their thermal properties from the two drone helicopters. The only work possible has been to download all the groundwater borehole data, test various bits of kit, and piece together a short intro video for your enjoyment. The Dundee students have also had to do a series of presentations for their MSc coursework, via the internet to their classmates and staff back at home. So still plenty to do, despite the Christmassy weather outside.

Hopefully we will be able to get back on the ice, and get all our birds in the air tomorrow, really getting the research programme underway.
I’ll keep you posted

The St. Patrick’s Day Geomagnetic Storm... by Sarah Reay

On the 17th March 2015 the Earth experienced a strong geomagnetic storm. This ‘St. Patrick’s Day storm’ was the largest storm in over 10 years, and the largest of the current solar cycle! Sarah Reay, from the BGS Geomagnetism team, expands on the science behind the solar storm...

So what happened?

The storm began at 04:46 UT on the 17th March 2015 when a shock in the solar wind (a stream of charged particles emanating from the Sun) hit the Earth’s magnetic field signalling the arrival of a coronal mass ejection (CME). A CME is a massive burst of charged gas and magnetic field ejected from the Sun’s corona which is carried away from the Sun by the solar wind. The sunspot region responsible for the CME was centrally placed on the solar disc and so the Earth was directly in the line of fire! This CME travelled quickly towards Earth arriving earlier than space weather forecasters had predicted, taking us a little by surprise.

BGS magnetometers, which measure the variations in the strength and direction of the Earth’s magnetic field, recorded the impact of the CME. We observed a rapid variation in the magnetic field signalling the start of the geomagnetic storm. At Eskdalemuir observatory in the Scottish Borders the rapid variation was approximately a fifth of a degree in compass variation (i.e. declination). 

A magnetogram showing the variation in the compass variation (in degrees west of true north) for the three UK magnetic observatories the 17th – 18th March 2015. You can see the shock arrival and storm commencement followed by larger variations later in the day
Shortly after the shock impact those on the night-side of the Earth were treated to a spectacular auroral display. There were various sightings reported across North America, and more unusually, some great sightings of the aurora australis in New Zealand (New Zealand is of similar geomagnetic latitude to the south of UK). If it had been dark, we should certainly have seen the northern lights across the UK. However our night-time was many hours away. The question everyone was asking was how long would the storm last and how strong would it be?

Why the storm was so strong?

One of the main factors that influence how big a magnetic storm will be is the direction and strength of the interplanetary magnetic field (IMF). That is, the magnetic field carried in the solar wind. If this turns southwards it allows much more energy into the Earth’s magnetic field. If it turns northwards it can effectively ‘shut down’ a magnetic storm. This key aspect is, unfortunately, not one space weather forecasters can predict well in advance so it is difficult to know what nature a storm may have in the coming hours.

Solar wind conditions measure by the ACE satellite. The top trace (red) shows IMF turning southward for extended period of time. Orange, yellow and green traces show the change in density, speed and temperature and the CME arrived.
Remarkably in this case the IMF went strongly southwards for well over 12 hours allowing a lot of energy to flow into the Earth’s magnetic field. This produced a major magnetic storm. The Space Weather Prediction Centre (run by NOAA in the USA) has five defined levels of geomagnetic storm activity from G1 to G5 with G5 being the most severe. This storm, at its peak, reached G4 level for several hours. G4 levels were seen globally between 12:00 – 18:00 UT and again between 21:00 – 00:00 UT on the 17th March 2015. Space weather forecasters in BGS and Met Office continually monitored the situation throughout the day and consulted with each other as the storm progressed. 

A snapshot of BGS's activity monitor when global geomagnetic activity was at the G3 storm level on the 17th March 2015.

A northern light show

When a geomagnetic storm is in progress the auroral ovals, usually located near the Arctic and Antarctic circles, broaden and move out towards the equator. That is why during a magnetic storm the aurora can be seen more easily in the UK.

As the geomagnetic storm rumbled on throughout the St Patrick’s Day more people around the world were treated to a spectacular auroral display - that is, if they were lucky enough to find a gap in the clouds. Unfortunately for the UK many places were covered in thick cloud or fog so missed out on this event. However many more were lucky and sightings were reported across Scotland, Northern Ireland, Wales and the parts of England even as far south as Hampshire and Sussex. In Europe, aurora was seen as far south as Germany and The Netherlands.

Model of aurora oval over the northern hemisphere at 21:40UT on the 17th March 2015. The line of auroral visibility in UK is located around the Midlands. Image SWPC NOAA.

The day after the solar wind conditions remained heightened and geomagnetic activity, whilst no longer at the peak of activity, continued at a moderate storm level throughout the 18th March. Once again parts of the UK reported aurora sightings but these were mainly confined to Scotland.

So how big was this storm?

One way of measuring how large a magnetic storm is by a type geomagnetic index – the Ap index. This is measure of global geomagnetic disturbance. When Ap is greater than 100 (out of maximum of 400) this is classed as a ‘severe storm’ (severe in this case refers to the magnitude of the storm rather than a comment on the possible impact). The St Patrick’s Day storm had an estimated daily Ap of 108. This is the largest magnetic storm of the current solar cycle (which began in 2008). We need to go back 10 years to September 2005 for the last storm with an Ap >100. The last magnetic storm which was bigger than the St Patrick’s Day storm was in November 2004, almost 11 years ago!

Chart showing all the major magnetic storm with a daily Ap greater than 100 since 1980. Notice the large 10-year gap before the St. Patrick’s day storm.
Do you want to keep track of current geomagnetic activity and watch out for the next chance to see the aurora in the UK?

You can keep up with the current geomagnetic activity levels here.
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Sarah Reay
BGS Geomagnetism Team