Atmospheric Sciences


Thomas Webb is a tropical meteorologist who uses a mixture of computer models, GPS data, satellite information and other experimental techniques. His current research is focussed on volcanic plumes at Piton de la Fournaise, Réunion and he has previously studied convection at Soufrière Hills volcano, Montserrat. His interests are broad and include meteorological model parameterisation, volcanic processes and interferometric synthetic aperture radar. Thomas supports open-source numerical models for atmospheric research and tweets at @ThomasLWebb

Science Communication – Brexit, Climate Change and the Bluedot Festival

Science Communication – Brexit, Climate Change and the Bluedot Festival

Earlier this summer journalists, broadcasters, writers and scientists gathered in Manchester, UK for the Third European Conference of Science Journalists (ECSJ) arranged by two prestigious organisations. Firstly, the Association of British Science Writers (ABSW) who provides support to those who write about science and technology in the UK through debates, events and awards. Secondly the European Union of Science Journalists’ Associations (EUSJA) who are responsible for representing 2,500 science journalists from 23 national associations in 20 European countries. EUSJA promotes scientific and technical communication between the international scientific community and journalists. This is mainly by organising events, workshops and by working with the European Commission in the interest of Science and Society.

The pre-conference networking event began a towering twenty-three floors above the ground at the highest Champagne bar in Manchester. Here the delegates were introduced to the notion of Manchester as a hub for science with a fly-by video of the ‘science quarter’. This stems from the library at the heart of the city and fans outwards to the south like a segment in an orange. This segment engulfs an impressive two universities, several hospitals and a science park.

Looking towards the south west of the city from "Cloud 23", the bar on the 23rd floor of the Beetham Tower, Manchester, UK. Image credit: David Dixon

Looking towards the south west of the city from “Cloud 23”, the bar on the 23rd floor of the Beetham Tower, Manchester, UK. Image credit: David Dixon

The following morning the conference began at the Manchester Conference Complex in the city-centre focussing on contemporary issues in science journalism and skills for professional development. The panellists and chairs were a mixture of academics and journalists, a range of nationalities and, with experience of the field of science communication. They were allowed to discuss a topic amongst themselves before the conversation was opened to all-comers.

The opening plenary began a discussion on how independent Europe’s science news is and how it can become hijacked by vested interests. For example, if a person writes a scientific story for a newspaper, are they biased by being paid by an external company to write that story? There was a consensus for openness in the funding process behind news stories so that the merits of the story lie in how impartial the writer is perceived to be as well as the content itself.

Although the second session of the day was focussed on the reporting of EU funded science (an 80 billion Euro question) it also gave delegates a chance to mention the elephant in the room – the Brexit. This is the will of a spectrum of people representing the whole political horseshoe for the UK to leave the EU. There was a feeling from the panel that the EU funding structure has allowed science to work on projects that are not just commercially viable in the short-term. The large benefit of cross-country collaboration in Europe was stressed repeatedly. This related to the general acknowledgement that in research the country of origin of specific researchers becomes irrelevant. These thoughts played into the much discussed post-Brexit question(s) – Will it be harder in time for the UK to access EU science funding given its determination to curb net migration and what exemptions (from the UK and EU) can be made for experts in their field? It was also discussed how the UK’s pot of EU science funding may be allowed to be divided up amongst other EU countries in the future. The discussion ended with a series of brief historical anecdotes of governments who favoured local policies/competition which have had a tendency to derail international collaboration. The main point being that research continued but the job was made harder.

The next two sessions focussed on starting a new publication and pitching your idea to an existing publication (sales idea). Using the case-studies of a range of recent start-up publications it was decided that what matters most for creating a publication is: focus, editorial quality, being online, design, collaboration and content.

The closing plenary was concerned with how to work for media that are sceptical about climate change – a place where a science communicator may be forced to go along with the editorial line against their own conviction. A conviction shared by the majority of scientists world-wide who say climate change is happening but argue over the rate that it is occurring. A good recommendation was not to preach but to state facts. The dangers of saying something sceptical as a way into the topic were debated. It was thought that this may backfire if the sceptical comment is later quoted as an expert opinion. At the end of the session the delegates pondered that if the building blocks of climate change were first conceived in 1896 how it is amazing to think that this topic is still controversial 120 years later!

For the final event of the day, the delegates made their way to the Bluedot festival at Jodrell Bank – a festival of music, science, arts, technology, culture, food and film in the shadow of the Lovell Telescope which was illuminated by Brian Eno using large scale projections to create a visual installation. Here the ABSW Science Writers’ Awards was hosted and this blog was short-listed for an award. It provided another great opportunity to network at this thought-provoking conference.



How does weather affect volcanoes?

How does weather affect volcanoes?

I was taking a plane trip home recently. To kill the time I got talking with the person sitting next to me and naturally one of their first questions was to ask me what I did for a living. To avoid a complicated discussion about the nuances of my research I summarised – ‘I am a volcanic meteorologist’. They were interested and wanted to know all about how volcanoes affect the weather, my opinion on ‘that Icelandic eruption’ and told me some slightly left-field opinions on climate change. It was an interesting chat and it got me thinking, volcanoes seem to have several well known impacts on weather but can weather have an impact on volcanoes?

At first it appears quite strange that something seemingly so solid can be altered by atmospheric processes. But in the case of mudflows this is exactly what can happen – rain mixing with soil causing soft wet mud to slide down a hill. In the case of volcanoes, a lahar can form, a mudflow consisting of volcanic debris with the consistency of wet concrete which cascades down the slopes of a volcano.

Water has also been known to trigger rockfalls by getting into the cracks between rocks and weakening them. This same erosion process can erode scree from the summit of a volcano.

Lava domes (a roughly circular shaped mound created from the slow extrusion of lava from a volcano) are known to grow in the absence of rainfall. When it rains water seeps into the cracks between rocks in the lava dome. The lava dome is very hot so rain instantly vapourises. Hence a large rain rate is needed to get further inside cracks in the rocks. Once deep inside, the rainwater vapourises into high pressure steam as it encounters temperatures in excess of 300 C. This destabilises the lava dome and sometimes leads to a collapse.

A collapsing lava dome creates a pyroclastic flow, a high-density mix of volcanic rocks and gas travelling down the slopes of a volcano at high speed and destroying almost everything it its path. A 2001 lava dome collapse is thought to have been triggered by rainfall.

Excessive rainfall can and does impact volcanoes. Having said this hurricanes and other large storms, having a rainfall rate needed to cause water to seep into the lava dome of a volcano are mostly found in the tropics.

Do you know of any other cases of weather affecting volcanoes? The author would be interested to know – please post your suggestions in the comments.

Atmospheric Modelling with Meso-NH

Atmospheric Modelling with Meso-NH

Twice a year in Toulouse Meteo-France runs a tutorial on Meso-NH – the non-hydrostatic mesoscale atmospheric model of the French research community. Last week I was fortunate enough to attend their autumn 2015 tutorial. But, what is this model and was the tutorial useful?

Atmospheric models solve the governing equations for atmospheric motions. This allows us, for example, to forecast future atmospheric conditions, to study past climates or even to visualise tiny features over a range of a few tens on metres. Over the last 90 years atmospheric models have developed from a thought concept to low resolution global simulations to high resolution models being able to simulate all kinds of small scale meteorological phenomena. The last of these achievements has been made within the last 15 years using a set of equations and assumptions known as non-hydrostatic modelling.

A non-hydrostatic model is quite simply one in which the atmosphere is not assumed to be in hydrostatic equilibrium. This means that high resolution features can be simulated such as small-scale convection. Processes that are very small or too complex are simulated via parametrisations whereby each small process is represented by relating them to variables at a resolution that the model can resolve. In this way very complex models can be built up simulating many small features of the atmosphere. A mesoscale model has sufficiently high resolution that it can simulate mesoscale weather features.

There are many different non-hydrostatic mesoscale models with different parametrisations for different applications and they are run by different organisations across the world. Recent increases in computing capacity have meant that the complexity of these models is greater than ever before. There are many popular non-hydrostatic mesoscale models including but not limited to the Weather Research and Forecasting Model (WRF), Unified Model (UM), and Meso-NH. This is definitely not the place to start a debate on the drawbacks of different models! However a feature of many but not all of these models is that they are open source, the programming code used to run them is available for modification or enhancement by anyone, this is great for the development of new parametrisations.

The Meso-NH tutorial was split over three days, the first spent on theory about the model. The second was concerned with theory and practise with an idealised atmosphere over fictitious terrain. The third concentrated just on theory and practise with an actual case study of a real meteorological event. Approaching the tutorial in French as a non-native speaker was initially daunting but there are English subtitles and all the documentation is provided in English – this is no excuse not to become fully immersed in this model. Meso-NH is by no means a basic model and the learning curve is steep but coming from a background in a different non-hydrostatic mesoscale model (WRF) it was very intuitive. Impressive features of the model included the breadth of options for the details of different parametrisations and the post-processing display and interpretation options for the model simulations.

What is the biggest air pollution event in the modern era?

What is the biggest air pollution event in the modern era?

It’s hard to think of the scale of the biggest air pollution event in the modern era. Immediately my mind conjures up memories of black and white photographs of the Great London Smog of 1952. Then I start thinking bigger, how about the 1.2 billion vehicles world-wide on the road churning out nitrogen dioxide every single day? Well these are a drop in the ocean compared with bigger industrial polluters. A recent study by the World Health Organisation pegged the financial damage to Europe by anthropogenic air pollution in 2010 at a whopping €2 Trillion. However all of these anthropogenic pollution events pale in comparison compared with mother Earth. A single volcano, Mt. Etna in Sicily has been known to emit the same amount of sulphur in a year as all of French industry.

So, perhaps we just need to find the biggest volcanic eruption in the modern era? This is the 1815 Tambora eruption, the biggest in the last 10,000 years. Actually, no – how explosive a volcanic eruption is and the amount of potentially harmful sulphur dioxide it emits are not always related and even then the dangers these pose to humans depend on weather conditions. In the modern era there is one natural contender: pumping out 15 times more sulphur as the whole European region in 2010, the 1783 volcanic eruption of Laki.

The eruption carried gases into the atmosphere to the start of the tropopause. This is not abnormal, the 2010 eruptions of Eyjafjallajökull followed the same path. What was different from other eruptions was the amount of gas. The Laki eruption carried an estimated 8 million tons of poisonous hydrofluoric acid and 120 million tons of sulphur dioxide into the atmosphere. Here the gases entered the jet stream; a narrow band of intense winds found at about 16 km altitude and this had far-reaching effects.

A high pressure area over Iceland at the time of the eruption caused the poison ridden winds to move south-east and subside over Europe. This resulted in many thousands of deaths because sulphur dioxide gas reacts with moisture in lungs to form sulphurous acid.

High pressure blocking over Iceland (1783)

High pressure blocking over Iceland (top-left) during Laki eruption caused eruption clouds to move over Europe. Image adapted from: Thordarsson and Self (2003).

The ‘Laki haze’ did not dissipate due to hot weather until the autumn and acted like a heat blanket creating convection from increased surface heating resulting in thunderstorms. This directly led to severe flood damage in central Europe. Crop and livestock damage followed. A famine began in Iceland where most of the livestock died from skeletal fluorosis; a condition caused by ingesting fluoride which leads to decreased bone strength, increased risk of fractures and impaired mobility.

This one event weakened the African monsoon circulation leading to less precipitation over the Sahel and resulting in an Egyptian famine due to a shortage of water in the Nile. The Chalisa famine in India occurred also the same year and resulted in 11 million deaths on the subcontinent. However the second of these famines can also be linked to changing El-Niño conditions over the preceding years. The volcanic eruption gases on the atmosphere were as far reaching as North America where there was reported to be ice in the Gulf of Mexico.

A cycle of unusual seasons continued for several years after and caused huge global economic hardship which has been thought to be one of the drivers behind the French Revolution. The large amounts of Sulphur dioxide that remained in the atmosphere may have caused global average temperatures to fall by 1°C for the next couple of years. About 6 million people died as a result of the eruption, either directly or indirectly – this was about 1% of the world’s population at the time.

The Laki 1783 eruption is troubling. In the popular imagination big explosive volcanic events are the most devastating and cone shaped volcanos like Krakatoa are more embedded in our consciousness. However a lesser-known less explosive volcano, if well placed in terms of weather patterns, could potentially be more devastating. If an event like the Laki eruption were to happen again we could expect cold weather and maybe a year without summer. Modern volcanic monitoring practises could help us prepare for such an event but its global nature would still be very disrupting to our lives.


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