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Atmospheric Sciences

Imaggeo on Mondays: Nor’Wester in the Southern Alps of New Zealand

Imaggeo on Mondays: Nor’Wester in the Southern Alps of New Zealand

Stephan Winkler’s 2017 Imaggeo Photo Contest finalist photo showcases an unusual weather phenomenon…

The image shows a typical weather situation in the Southern Alps of New Zealand with a moist, westerly airflow pushing over the Main Divide [which separates the water catchments of the more heavily populated eastern side of the island from those on the west coast] to create a typical foehn wind [dry and warm winds which form on the downside of a mountain range] pattern (locally called Nor’Wester) in the region. Immediately west of this Main Divide, annual precipitation of up to 15,000 mm has been estimated.

The upper part of Tasman Glacier, as other glaciers around and immediately east of the Main Divide, receive impressive amounts of snow due to an overspill effect and can still be regarded as maritime.

In the image, however, the situation is displayed when right at the Main Divide the clouds disappear due to increasing temperatures when flowing over the Divide. The foehn wind developing with such weather pattern can be very strong. However, the image nicely shows how the glaciation of the central Southern Alps is influence by the availability of moisture and the dynamic character of the regional climate.

Description by Stephan Winkler (Senior Lecturer in Quaternary Geology and Palaeoclimatology at the University of Canterbury), as published previously on imaggeo.egu.eu

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/.

 

GeoSciences Column: Is smoke on your mind? Using social media to assess smoke exposure from wildfires

GeoSciences Column: Is smoke on your mind? Using social media to assess smoke exposure from wildfires

Wildfires have been raging across the globe this summer. Six U.S. States, including California and Nevada, are currently battling fierce flames spurred on by high temperatures and dry conditions. Up to 10,000 people have been evacuated in Canada, where wildfires have swept through British Columbia. Closer to home, 700 tourists were rescued by boat from fires in Sicily, while last month, over 60 people lost their lives in one of the worst forest fires in Portugal’s history.

The impacts of this natural hazard are far reaching: destruction of pristine landscapes, costly infrastructure damage and threat to human life, to name but a few. Perhaps less talked about, but no less serious, are the negative effects exposure to wildfire smoke can have on human health.

Using social media posts which mention smoke, haze and air quality on Facebook, a team of researchers have assessed human exposure to smoke from wildfires during the summer of 2015 in the western US. The findings, published recently in the EGU’s open access journal Atmospheric Chemistry and Physics, are particularly useful in areas where direct ground measurements of particulate matter (solid and liquid particles suspended in air, like ash, for example) aren’t available.

Particulate matter, or PM as it is also known, contributes significantly to air quality – or lack thereof, to be more precise.  In the U.S, the Environment Protection Agency has set quality standards which limit the concentrations of pollutants in air; forcing industry to reduce harmful emissions.

However, controlling the concentrations of PM in air is much harder because it is often produced by natural means, such as wildfires and prescribed burns (as well as agricultural burns). A 2011 inventory found that up to 20% of PM emissions in the U.S. could be attributed to wildfires alone.

Research assumes that all PM (natural and man-made) affects human health equally. The question of how detrimental smoke from wildfires is to human health is, therefore, a difficult one to answer.

To shed some light on the problem, researchers first need to establish who has been exposed to smoke from natural fires. Usually, they rely on site (ground) measurements and satellite data, but these aren’t always reliable. For instance, site monitors are few and far between in the western US; while satellite data doesn’t provide surface-level concentrations on its own.

To overcome these challenges, the authors of the Atmospheric Chemistry and Physics paper, used Facebook data to determine population-level exposure.

Fires during the summer of 2015 in Canada, as well as Idaho, Washington and Oregon, caused poor air quality conditions in the U.S Midwest. The generated smoke plume was obvious in satellite images. The team used this period as a case study to test their idea.

Facebook was mined for posts which contained the words ‘smoke’,’smoky’, ‘smokey’, ‘haze’, ‘hazey’ or ‘air quality’. The results were then plotted onto a map. To ensure the study was balanced, multiple posts by a single person and those which referenced cigarette smoke or smoke not related to natural causes were filtered out. In addition, towns with small populations were weighted so that those with higher populations didn’t skew the results.

The social media results were then compared to smoke measurements acquired by more traditional means: ground station and satellite data.

Example datasets from 29 June 2015. (a) Population – weighted, (b) average surface concentrations of particulate matter, (c) gridded HMS smoke product – satellite data, (d) gridded, unfiltered MODIS Aqua and MODIS Terra satellite data (white signifies no vaild observation), and (e) computer simulated average surface particulate matter. Image and caption (modified) from B.Ford et al., 2017.

The smoke plume ‘mapped out’ by the Facebook results correlates well with the plume observed by the satellites. The ‘Facebook plume’ doesn’t extend as far south (into Arkansas and Missouri) as the plume seen in the satellite image, but neither does the plume mapped out by the ground-level data.

Satellites will detect smoke plumes even when they have lifted off the surface and into the atmosphere. The absence of poor air quality measurements in the ground and Facebook data, likely indicates that the smoke plume had lifted by the time it reached Arkansas and Missouri.

The finding highlights, not only that the Facebook data can give meaningful information about the extend and location of smoke plume caused by wildfires, but that is has potential to more accurately reveal the air quality at the Earth’s surface than satellite data.

The relationship between the Facebook data and the amount of exposure to particular matter is complex and more difficult to establish. More research into how the two are linked will mean the researchers can quantify the health response associated with wildfire smoke. The findings will be useful for policy and decision-makers when it comes to limiting exposure in the future and have the added bonus of providing a cheap way to improve the predictions, without having to invest in expanding the ground monitor network.

By Laura Roberts, EGU Communications Officer

References

Ford, B., Burke, M., Lassman, W., Pfister, G., and Pierce, J. R.: Status update: is smoke on your mind? Using social media to assess smoke exposure, Atmos. Chem. Phys., 17, 7541-7554, https://doi.org/10.5194/acp-17-7541-2017, 2017.

June GeoRoundUp: the best of the Earth sciences from around the web

June GeoRoundUp: the best of the Earth sciences from around the web

Drawing inspiration from popular stories on our social media channels, as well as unique and quirky research news, this monthly column aims to bring you the best of the Earth and planetary sciences from around the web.

Major Story

With June being the month when the world’s oceans are celebrated with World Ocean Day (8th June) and the month when the UN’s Ocean Conference took place, it seemed apt to dedicate our major story to this precious, diverse and remote landscape.

In fact, so remote and inaccessible are vast swathes of our oceans, that 95% of them are unseen (or unvisited) by human eyes. Despite their inaccessibility, humans are hugely reliant on the oceans.  According to The World Bank, the livelihoods of approximately 10 to 12% of the global population depends on healthy oceans and more than 90%of those employed by capture fisheries are working in small-scale operations in developing countries. Not only that, but the oceans trap vast amounts of heat from the atmosphere, limiting global temperature rise.

Yet we take this valuable and beautiful resource for granted.

As greenhouse gas emissions rise, the oceans must absorb more and more heat. The ocean is warmer today than it has been since recordkeeping began in 1880. Over the past two decades this has resulted in a significant change in the composition of the upper layer of water in our oceans. Research published this month confirms that ocean temperatures are rising at an alarming rate, with dire consequences.

Corals are highly sensitive to changes in ocean temperatures. The 2015 to 2016 El Niño was particularly powerful. As its effects faded, ocean temperatures in the Pacific, Atlantic and Indian oceans remained high, meaning 70 percent of corals were exposed to conditions that can cause bleaching. Almost all of the 29 coral reefs on the U.N. World Heritage list have now been damaged by bleaching.

This month, the National Oceanic and Atmospheric Administration (NOAA) declared that bleaching was subsiding for the first time in three years. Some of the affected corals are expected to take 10 to 15 years to recover, in stress-free conditions. But as global and ocean temperatures continue to rise, corals are being pushed closer to their limits.

Warmer ocean temperatures are also causing fish to travel to cooler waters, affecting the livelihoods of fishermen who depend on their daily catch to keep families afloat and changing marine ecosystems forever. And early this month, millions of sea-pickles – a mysterious warm water loving sea creature- washed up along the western coast of the U.S, from Oregon to Alaska. Though scientists aren’t quite sure what caused the bloom, speculation is focused on warming water temperatures.

It is not only warming waters which are threatening the world’s oceans. Our thirst for convenience means a million plastic bottles are bought around the world every minute. Campaigners believe that the environmental crisis brought about by the demand for disposable plastic products will soon rival climate change.

In 2015 researchers estimated that 5-13 million tonnes of plastics flow into the world’s oceans annually, much coming from developing Asian nations where waste management practices are poor and the culture for recycling is limited. To tackle the problem, China, Thailand, Indonesia and the Philippines vouched to try and keep more plastics out of ocean waters. And, with a plastic bottle taking up to 450 years to break down completely, what happens to it if you drop it in the ocean? Some of it, will likely find it’s way to the Arctic. Indeed, recent research suggests that there are roughly 300 billion pieces of floating plastic in the polar ocean alone.

A bottle dropped in the water off the coast of China is likely be carried eastward by the north Pacific gyre and end up a few hundred miles off the coast of the US. Photograph: Graphic. Credit: If you drop plastic in the ocean, where does it end up? The Guardian. Original Source: Plastic Adrift by oceanographer Erik van Sebille. Click to run.

And it’s not only the ocean waters that are feeling the heat. As the demand for resources increases, the need to find them does too. The sea floor is a treasure trove of mineral and geological resources, but deep-sea mining is not without environmental concerns. Despite the ethical unease, nations are rushing to buy up swathes of the ocean floor to ensure their right to mine them in the future. But to realise these deep-water mining dreams, advanced technological solutions are needed, such as the remote-controlled robots Nautilus Minerals will use to exploit the Bismarck Sea, off the coast of Papua New Guinea.

What you might have missed

Lightning reportedly ignited a deadly wildfire in Portugal, seen here by ESA’s Proba-V satellite on 18 June.

“On June 17, 2017, lightning reportedly ignited a deadly wildfire that spread across the mountainous areas of Pedrógão Grande—a municipality in central Portugal located about 160 kilometers (100 miles) northeast of Lisbon”, reported NASA – National Aeronautics and Space Administration. The death toll stands at 62 people (as reported by BBC News). The fires were seen from space by satellites of both NASA and ESA – European Space Agency satellites.

Large wildfires are also becoming increasing common and severe in boreal forests around the world. Natural-color images captured by NASA satellites on June 23rd, shows wildfires raging near Lake Baikal and the Angara River in Siberia. At the same time, a new study has found a link between lightning storms and boreal wildfires, with lightning strikes thought to be behind massive fire years in Alaska and northern Canada. This infographic further explores the link between wildfires triggered both by lightning and human activities.

Meanwhile, in the world’s southernmost continent the crack on the Larsen C ice-shelf continues its inexorable journey across the ice. The rift is set to create on of the largest iceberg ever recorded. Now plunged in the darkness of the Antarctic winter, obtaining images of the crack’s progress is becoming a little tricker. NASA used the Thermal Infrared Sensor (TIRS) on Landsat 8 to capture a false-color image of the crack. The new data, which shows an acceleration of the speed at which the crack is advancing, has lead scientists to believe that calving of the iceberg to the Weddell Sea is imminent.

Links we liked

The EGU story

This month saw the launch of two new division blogs over on the EGU Blogs: The Solar-Terrestrial Sciences and the Geodynamics Division Blogs. The EGU scientific divisions blogs share division-specific news, events, and activities, as well as updates on the latest research in their field.

And don’t forget! To stay abreast of all the EGU’s events and activities, from highlighting papers published in our open access journals to providing news relating to EGU’s scientific divisions and meetings, including the General Assembly, subscribe to receive our monthly newsletter.

Imaggeo on Mondays: Airplane views of the Alps

Imaggeo on Mondays: Airplane views of the Alps

The forward scattering of sunlight, which is caused by a large number of aerosol particles (moist haze) in Alpine valleys, gives the mountain massifs a rather plastic appearance.

The hazy area in the foreground lies above the Koenigsee lake; behind it the Watzmann, Hochkalter, Loferer Steinberge and Wilder Kaiser massifs loom up behind one other to the right of the centre line. Behind them is the wide Inn valley, which extends right across the picture. In the far distance in the middle of the picture, the Wetterstein massif projects upwards with the Zugspitze mountain as its highest peak.

The left side shows Steinernes Meer, Leoganger Steinberge and a sequence of at least 10 mountain chains that extend as far as Kellerjoch, which is in front of the whitish area of haze above Innsbruck. The noon sounding from Munich showed that relative humidity exceeded 75% up to 1,400 m above sea level, with distinctly lower values above (less than 20 %).

The view is from an aircraft window approximately 10 km to the east of the Salzach valley.

Description by Hans Volkert, as published previously on imaggeo.egu.eu

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