GeoLog

Atmospheric Sciences

Imaggeo on Mondays: how short-term storms can impact our landscapes

Imaggeo on Mondays: how short-term storms can impact our landscapes

In the Sierra de Aconquija, a mountain range in the southern Central Andes of Argentina, strong storms often come and go at a moment’s notice, but they can have a long-lasting impact on the Earth’s surface.

The thunderstorm cell featured in this photo formed in less than half an hour, giving all those nearby only a few minutes to take cover. Mitch D’Arcy, a geomorphologist and postdoctoral researcher at the University of Potsdam and the GFZ German Research Centre for Geosciences, had the opportunity to witness this storm (and snap this picture!) while carrying out field work in the area.

“It was a spectacular experience, pouring heavy rain onto a very localised part of the mountain range, but it was also a hazard because the storm was quickly moving towards us with a lot of lightning. Without any trees around, we were likely targets for lightning strikes!” said D’Arcy. Luckily, he and his colleagues were able to find shelter in their truck while the huge downpour passed over them.

These kinds of thunderstorms are short-lived, but have intense precipitation rates. In this case, the temperature dropped by 14 degrees Celsius, and the storm was accompanied by heavy hail and lightning. And while these natural hazards are transient, they can have a long-term impact on the region’s landscape. Severe storms are capable of triggering landslides and floods and can relocate large amounts of sediment and debris in a short period of time.

D’Arcy is part of an international research programme called StRATEGy (Surface processes, Tectonics and Georesources: The Andean foreland basin of Argentina), which looks into how past and present climate change makes a mark on the terrain of the Argentine Andes, among other topics.

This research is essential for understanding and predicting how human-caused climate change will alter weather patterns and impact surface processes (such as how quickly sediments are eroded and transported across landscapes), according to D’Arcy. Having a better understanding of these surface processes and their sensitivity to the climate could help scientists better inform the public about how to prepare for natural hazards, such as flooding, erosion and landslides.

D’Arcy notes that it’s also important to assess how climate and weather trends will impact the sedimentary record, since it is one of the only physical records that scientists can use to examine how the Earth’s surface has change through time.

“North-western Argentina is a fascinating place to study how climate change affects surface processes, because it has experienced pronounced and abrupt changes in hydroclimate through time,” said D’Arcy. Their research has found that even subtle changes in the region’s climate have produced large changes to the surface environment, impacting how rivers take shape and how sediments move.

For example, while the Sierra de Aconquija is a semi-arid environment today, more than 12,000 years ago it used to be much wetter as a result of global climate changes. In fact, back then the mountain range was covered in glaciers and many of the basins were filled with lakes.

“It’s really important that we understand how different landscapes function and how they react to changes in climate. When we look at places like the southern Central Andes in Argentina, we find that the landscape records interesting signatures of ancient climate changes in Earth’s past. However, one of the big questions we still don’t have a good answer to, is how important are these very intense but rare storms for shaping landscapes and creating the sedimentary record from the geological past,” said D’Arcy.

By Olivia Trani, EGU Communications Officer

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their photographs and videos to this repository and, since it is open access, these images can be used for free by scientists for their presentations or publications, by educators and the general public, and some images can even be used freely for commercial purposes. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. Submit your photos at http://imaggeo.egu.eu/upload/.

Conversations on a century of geoscience in Europe: Part 1

Conversations on a century of geoscience in Europe: Part 1

When you think about the last century of geoscience, what comes to mind? Perhaps Alfred Wegener’s theory of continental drift? Or Inge Lehmann’s discovery of Earth’s solid inner core?

Over the last 100 years, geoscientists have made incredible contributions to our understanding of the Earth, the solar system, and beyond. The science community has explored uncharted territory, challenged previously held conceptions, provided vital information to policymakers, worked to address societal challenges, and put forth paths for sustainability. Through the years, researchers have also worked to promote diversity, inclusion, transparency, and accessibility in the geosciences. Many Europe-based scientists have been at the forefront of these advances.

Inspired by the centennials of the American Geophysical Union (AGU) and the International Union of Geodesy and Geophysics (IUGG), which were both founded in 1919, we would like to highlight Europe’s role in shaping the geosciences and the great achievements of European geoscientists within the last century.

In this series of interviews, scientists across different disciplines and scientific fields reflect on the last 100 years of Earth, space and planetary sciences in Europe and share their perspectives on the future:


Anne-Marie Treguier: Research Director at the French National Centre for Scientific Research and the European Institute for Marine Studies in the Ocean Physics Laboratory

The responsibility of geoscientists is huge. We must frame our scientific questions in the context of a wide range of future scenarios..

Read interview →

 

John Burrows: Professor of the Physics of the Ocean and Atmosphere and a Director of the Institutes of Environmental Physics and Remote Sensing at the University of Bremen

The history of discoveries in the geosciences is a fascinating story, involving unexpected and perplexing observations..

Read interview →

 

Günter Blöschl: Head of the Institute of Hydraulic Engineering and Water Resources Management and Director of the Centre for Water Resource Systems of the Vienna University of Technology

As Heraclitus said, there is nothing permanent except change. Innovation needs to be permanent. We are in for an exciting future..

 

Read interview →

 

Antje Boetius: Director of the Alfred Wegener Institute (AWI) Helmholtz Center for Polar and Marine Research and Professor of Geomicrobiology at the University of Bremen

When one reads the original reports and letters, we can learn how relevant expeditions and fieldwork were – and still are – for the international, collaborative spirit of the geosciences worldwide. The amazing thing is, in many ways we have remained explorers of our own planet Earth even today..

 

 

Read interview →

 

Bernhard Diekmann, Head of the Research Unit Potsdam of the Alfred Wegener Institute (AWI) Helmholtz Center for Polar and Marine Research and Professor of Quaternary Geology at Potsdam University

During the last 100 years, the focus in geological research was understanding of processes in Earth’s interior and skin…The geosciences should no longer be seen as an individual field of research, but must be integrated into a holistic view of natural and social sciences..

 

Read interview →

Interviews by Olivia Trani, EGU Communications Officer

Imaggeo on Mondays: Inside the whale’s mouth

Imaggeo on Mondays: Inside the whale’s mouth

Often there are moments in our lives when we are reminded of the strength and magnitude of our environment, whether that’s trekking through a mountain range or gazing at the horizon from the ocean shore. Yet arguably there are few things that can make you feel as small as a particularly powerful summer storm.

“The atmosphere is undoubtedly one of the most dynamic components in the Earth System. Nothing can demonstrate the power of nature to an observer as well as a strong thunderstorm rolling in,” said Michiel Baatsen, a climate researcher at Utrecht University in the Netherlands who snapped this week’s featured photo. Besides being a climate researcher, Baatsen is also a weather enthusiast and storm chaser, fascinated by severe weather and thick towering cloud formations.

He and a team of friends will often hit the road, travelling across Western Europe in pursuit of extreme thunderstorms that pass the continent. “In these ventures, we try to capture some inspiring scenes and have been amazed many times by the things we end up seeing,” said Baatsen.

This photo was taken in June last year while Baatsen was traveling through the northeastern corner of the Netherlands. He and his friends were searching for a thunderstorm that had crossed the border from Germany, but the local humidity was relatively high, making visibility too poor to properly locate the approaching storm. “After several failed attempts to locate the approaching storms, we realised the conditions were so hazy that they completely obscured the leading cloud structures,” said Baatsen. But once the first clouds passed overhead, the conditions suddenly changed and the sky became clearer, revealing a dramatic view of the storm.

If you feel as if the storm feature in the photo is about to engulf you, you’re not alone. This kind of cloud structure is called a shelf cloud, but it’s also often referred to as a ‘whale’s mouth’, since the formations often give the impression of being consumed by a giant whale.

‘Whale’s mouth’ clouds take shape when cold, dense air surging out of a thunderstorm collides with warm air entering the storm. When the two currents make contact, the air goes upward and condenses into a thick sheet of clouds. This kind of formation appears at the leading edge of a thunderstorm, a harbinger to the incoming rainfall.

For Baatsen and his colleagues, the storm offered a short window between its first gusts and the subsequent rainfall, allowing them to observe this natural phenomenon. “With the whale’s mouth being overhead, there was a brief moment to appreciate this scene during which one was basically trapped in a cage surrounded by the rain rolling in on one side and the haze drawing away on the other side,” said Baatsen.

By Olivia Trani, EGU Communications Officer

Geosciences Column: How erupting African volcanoes impact the Amazon’s atmosphere

Geosciences Column: How erupting African volcanoes impact the Amazon’s atmosphere

When volcanoes erupt, they can release into the atmosphere a number of different gases initially stored in their magma, such as carbon dioxide, hydrogen sulfide, and sulfur dioxide. These kinds of gases can have a big influence on Earth’s atmosphere, even at distances hundreds to thousands of kilometres away.

A team of researchers have found evidence that sulfur emissions from volcanic eruptions in Africa can be observed as far as South America, even creating an impact on the Amazon rainforest’s atmosphere. The results of their study were published last year in the EGU journal Atmospheric Chemistry and Physics.

Amazon Tall Tower Observatory based in the Amazon rainforest of Brazil (Credit: Jsaturno via Wikimedia Commons)

In September 2014, the Amazon rainforest’s atmosphere experienced an unusually sharp spike in the concentration of sulfate aerosols. During this period, the Amazon Tall Tower Observatory (ATTO) based in Brazil reported levels of sulfate never recorded before in the Amazon Basin.

Sulfate aerosols are particles that take form naturally from sulfur dioxide compounds in the atmosphere. When sulfate aerosols spread throughout the atmosphere, the particles often get in the way of the sun’s rays, reflecting the sunlight’s energy back to space. These aerosols can also help clouds take shape. Through these processes, the particles can create a cooling effect on Earth’s climate. Sulfate aerosols can also facilitate chemical reactions that degrade Earth’s ozone layer.

Fossil fuel and biomass burning have been known cause an increase in atmospheric sulfate, but researchers involved in the study found that neither human activity increased the level of sulfate in the atmosphere significantly. Instead, they examined whether a volcanic eruption could be responsible.

Scientists have suggested for some time that sulfur emissions in the Amazon could come from African volcanoes, but until now they’ve lacked proof to properly justify this idea.

Edited Landsat 8 image of the volcanoes Nyamuragira and Nyiragongo in Congo near the city of Goma. (Credit: Stuart Rankin via flickr, NASA Earth Observatory images by Jesse Allen, using Landsat data from the U.S. Geological Survey.

However, in this study the research team involved caught volcanic pair in the act. By analysing satellite images and aerosol measurements, the researchers found evidence that in 2014, emissions from the neighboring Nyiragongo-Nyamuragira volcano complex in the Democratic Republic of the Congo, central Africa, increased the level of sulfate particles in the Amazon rainforest’s atmosphere.

Satellite observations revealed that volcanoes experienced two explosive events in September 2014, releasing sulfur emissions into the atmosphere. During that year, the volcanic complex was reportedly subject to frequent eruptive events, sending on average 14,400 tonnes of sulfur dioxide into the atmosphere a day during such occasions. This amount of gas would weigh more than London’s supertall Shard skyscraper.

Map of SO2 plumes with VCD > 2.5 × 1014 molecules cm−2 color-coded by date of observation. The 15-day forward trajectories started at 4 km (above mean sea level, a.m.s.l.) at four locations within the plume detected on 13 September 2014 (light blue) are indicated by black lines with markers at 24 h intervals. (Credit: Jorge Saturno et al.)

The images further show that these emissions were transported across the South Atlantic Ocean to South America. The sulfate particles created from the emissions were then eventually picked up by an airborne atmospheric survey campaign and the ATTO in the Amazon.

The researchers of the study suggest that these observations indicate that African volcanoes can have an effect on the Amazon Basin’s atmosphere, though more research is needed to understand the full extent of this impact.

By Olivia Trani, EGU Communications Officer

References and further reading

Volcanic gases can be harmful to health, vegetation and infrastructure. Volcano Hazards Program. USGS.

Aerosols and Incoming Sunlight (Direct Effects). NASA Earth Observatory

Saturno, J., Ditas, F., Penning de Vries, M., Holanda, B. A., Pöhlker, M. L., Carbone, S., Walter, D., Bobrowski, N., Brito, J., Chi, X., Gutmann, A., Hrabe de Angelis, I., Machado, L. A. T., Moran-Zuloaga, D., Rüdiger, J., Schneider, J., Schulz, C., Wang, Q., Wendisch, M., Artaxo, P., Wagner, T., Pöschl, U., Andreae, M. O. and Pöhlker, C.: African volcanic emissions influencing atmospheric aerosols over the Amazon rain forest, Atmospheric Chemistry and Physics, 18(14), 10391–10405, doi:10.5194/acp-18-10391-2018, 2018.