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

September 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 and what you might have missed

This month has been an onslaught of  Earth and space science news; the majority focusing on natural hazards. Hurricanes, earthquakes and volcanic eruptions have been dominating headlines, but here we also highlight some other natural disasters which have attracted far fewer reports. Quickly recap on an action-packed month with our overview, complete with links:

Hurricanes

Thought the Atlantic hurricane season is far from over, 2017 has already shattered records: since 1st June 13 storms have been named, of which seven have gone onto become hurricanes and two registered as a category 5 storm on the Saffir-Simpson Hurricane Wind Scale. In September, Hurricanes Irma, Katia and Jose batter Caribbean islands, Mexico and the Southern U.S.; hot on the heels of the hugely destructive Hurricane Harvey which made landfall in Texas and Louisiana at the end of August. Images captured by NASA’s Operational Land Imager (OLI) on the Landsat 8 satellite show the scale of the damage caused by Hurricane Irma; while photos reveal the dire situation unfolding in Puerto Rico after Hurricane Maria.  OCHA, the United Nations Office for the coordinate of Human Affairs, released an infographic showing the impact the 2017 hurricane season has had on Caribbean islands (correct of 22nd September).

Earthquakes

At the same time, two powerful earthquakes shook Mexico in the space of 12 days causing chaos, building collapse and hundreds of fatalities.

Rumbling volcanoes

In the meantime, all eyes on the Indonesian island of Bali have been on Mount Agung which has already forced the evacuation of almost 100,000 people as the volcano threatens to erupt for the first time in 54 years. Unprecedented seismic activity around the volcano has been increasing, though no eruptive activity has been recorded yet.

Further south, the government of Vanuatu, a South Pacific Ocean nation, declared a state of emergency and ordered the evacuation of all 11,000 residents of Ambae island, as activity of its volcano, Manaro, increased. The New Zealand Defence Force (NZDF) sent an aircraft to fly over the volcano on Tuesday and discovered plumes of smoke, ash and volcanic rocks erupting from the crater.

Map of volcanic hazards for Ambae in Vanuatu. Credit: Vanatu Meteorology & Geo-hazard Department (vmgd).

The rainy season floods

The summer months mark the onset of the rainy season in regions of Sub-Saharan Africa which experience a savanna climate. Across the Arabian Sea, including the Indian subcontinent and Southeast Asia, also sees the onset of the monsoon.

Since June, widespread flooding brought on by heavy rainfall has left 56 dead and more than 185,000 homeless in Niger, one of the world’s poorest countries. But the crisis is not restricted to Niger, throughout the summer floods (and associated land and mudslides) in Africa are thought to have claimed 25 times more lives than Hurricane Harvey did.

Meanwhile Mumbai struggled when the heaviest rainfall since 2005 was recorded on 29th August, with most of Northern India experiencing widespread flooding. So far, the UN estimates that 1,200 people have lost their lives across Nepal, India and Bangladesh as a result of the rains. The Red Cross estimates that at least 41 million people have been affected by the flooding and causing the onset of a humanitarian crisis.

Record breaking temperatures and fires

Australia’s record-breaking spring heat (Birdsville, in Queensland’s outback, broke a weather record as temperatures hit 42.5C and Sydney recorded its hottest ever September day) combined with an unusually dry winter means the country is bracing itself for a particularly destructive bushfire season. Already fires rage, uncontrolled (at the time of writing), in New South Wales.

The western United States and Canada suffered one of its worst wildfire seasons to date. Earlier this month, NASA released a satellite image which showed much of the region covered in smoke. High-altitude aerosols from those fires were swept up by prevailing winds and carried across the east of the continent. By 7th September the particles were detected over Ireland, the U.K and northern France, including Paris.

Europe’s forest fire has been hugely devastating too. Much of the Mediterranean and the region North of the Black Sea continues to be in high danger of forest fires following a dry and hot summer. Fires are active in the Iberian Peninsula, Greece, and Germany (among others). Over 2,000 hectares were recently scorched by wildfires in the central mountainous area of Tejeda in Gran Canaria.

Links we liked

  • This month saw the end of NASA’s Cassini spacecraft and ESA’s Huygens probe’s spectacular journey to Saturn. After two decades of science, the mission ended on 15th September as the spacecraft crashed into the giant planet.
  • The last day of August marks the end of the Greenland snow melt season, so September was busy for scientists evaluating how the Greenland ice sheet fared in 2017.
  • “Few disciplines in today’s world play such a significant role in how society operates and what we can do to protect our future,” writes Erik Klemetti (Assoc. Prof. at Denison University), in his post on why college students should study geology.
  • The BBC launched The Prequel to its much anticipated Blue Planet II, a natural history progamme about the Earth’s oceans. Narrated by Sir Sir David Attenborough, the series will featured music by Hans Zimmer and Radiohead. The trailer is a true feast for the eyes. Don’t miss it!

The EGU story

Is it an earthquake, a nuclear test or a hurricane? How seismometers help us understand the world we live in.

Although traditionally used to study earthquakes, like the M 8.1 earthquake in Mexico,  seismometers have now become so sophisticated they are able to detect the slightest ground movements; whether they come from deep within the bowels of the planet or are triggered by events at the surface. But how, exactly, do earthquake scientists decipher the signals picked up by seismometers across the world? And more importantly, how do they know whether they are caused by an earthquake, nuclear test or a hurricane?

To find out we asked Neil Wilkins (a PhD student at the University of Bristol) and Stephen Hicks (a seismologist at the University of Southampton) to share some insights with our readers earlier on this month.

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

August 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 Stories

On August 25th Hurricane Harvey made landfall along the southern coast of the U.S.A, bringing record breaking rainfall, widespread flooding and a natural disaster on a scale not seen in the country for a long time. In fact, it’s the first time since 2005 a major hurricane has threatened mainland U.S.A. – a record long period.

But Harvey’s story began long before it brought destruction to Texas and Louisiana.

On August 17th,the National Space Agency (NASA) satellite’s first spotted a tropical depression forming off the coast of the Lesser Antilles. From there the storm moved into the eastern Caribbean and was upgraded to Tropical Storm Harvey where it already started dropping very heavy rainfall. By August 21st, it had fragmented into disorganised thunderstorms and was spotted near Honduras, where heavy local rainfall and gusty winds were predicted.

Over the next few days the remnants of the storm travelled westwards towards Nicaragua, Honduras, Belize and the Yucatan Peninsula. Forecasters predicted that, owing to warm waters of the Gulf of Mexico and favorable vertical wind shear, there was a high chance the system could reform once it moved into the Bay of Campeche (in the southern area of the Gulf of Mexico) on August 23rd. By August 24th data acquired with NASA satellites showed Harvey had began to intensify and reorganise. Heavy rainfall was found in the system.

Harvey continued to strengthen as it traveled across the Gulf of Mexico and weather warnings were issued for the central coast of Texas. Citizens were told to expect life-threatening storm surges and freshwater flooding. On August 25th, Harvey was upgraded to a devastating Category 4 hurricane, when sustained wind speeds topped 215 kph.

Since making landfall on Friday and stalling over Texas (Louisiana is also affected) – despite being downgraded to a tropical storm as it weakened – it has broken records of it’s own. “No hurricane, typhoon, or tropical storm, in all of recorded history, has dropped as much water on a single major city as Hurricane Harvey is in the process of doing right now in Houston (Texas)”, reports Forbes. In fact, the National Weather Service had to update the colour charts on their graphics in order to effectively map it. This visualisation maps Harvey’s destructive path through Texas.

A snaptshot from the tweet by the official Twitter account for NOAA’s National Weather Service.

So far the death toll is reported to be between 15 to 23 people, with the Houston Police Chief saying 30,000 people are expected to need temporary shelter and 2,000 people in the city had to be rescued by emergency services (figures correct at time of writing).

Many factors contributed toward making Hurricane Harvey so destructive. “The steering currents that would normally lift it out of that region aren’t there,” J. Marshall Shepherd, director of the atmospheric sciences program at the University of Georgia, told the New York Times. The storm surge has blocked much of the drainage which would take rainfall away from inland areas. And while it isn’t possible to say climate change caused the hurricane, “it has contributed to making it worse”, says Michael E Mann. The director of the Earth System Science Center at Pennsylvania State University argues that rising sea levels and ocean water temperatures in the region (brought about by climate change) contributed to greater rainfall and flooding.

A man carries his cattle on his shoulder as he moves to safer ground at Topa village in Saptari. Credit: The Guardian.

While all eyes are on Houston, India, Bangladesh and Nepal are also suffering the consequences of devastating flooding brought about a strong monsoon. The United Nations estimates that 41 million people are affected by the disaster across the three countires. Over 1200 people are reported dead. Authorities are stuggling with the scale of the humanitarian crisis: “Their most urgent concern is to accessing safe water and sanitation facilities,” the UN Office for the Coordination of Humanitarian Affairs (OCHA) said earlier this week, citing national authorities. And its not only people at risk. Indian authorities reported large swathes of a famous wildlife reserve park have been destroyed. In Mumbai, the downpour caused a building to collapse killing 12 people and up to 25 more are feared trapped.Photo galleries give a sense of the scale of the disaster.

Districts affected by flooding. Credit: Guardian graphic | Source: ReliefWeb. Data as of 29 August 2017

What you might have missed

In fact, it’s highly unlikely you missed the coverage of this month’s total solar eclipse over much of Northern America. But on account of it being the second biggest story this month, we felt it couldn’t be left out of the round-up. We particularly like this photo gallery which boasts some spectacular images of the astronomical event.

This composite image, made from seven frames, shows the International Space Station, with a crew of six onboard, as it transits the Sun at roughly five miles per second during a partial solar eclipse, Monday, Aug. 21, 2017 near Banner, Wyoming. Credit: (NASA/Joel Kowsky)

Since the end of July, wildfires have been raging in southwest Greenland. While small scale fires are not unheard of on the island otherwise known for its thick ice cap and deep fjords, the fires this month are estimated to extend over 1,200 hectares. What started the fires remains unknown, as do the fuel sources and the long-term impacts of the burn.

The U.S.A’s National Oceanic and Atmospheric Administration highlighted that the fires are a source of sooty “black carbon”. As the ash falls on the pristine white ice sheet, it turns the surface black, which can make it melt faster. Greenland police recently reported that unexpected rain haf all but extinguished the massive fires; though the situation continues to be monitored, as smouldering patches run the risk of reigniting the flames.

 

 

 

Links we liked

The EGU story

Do you enjoy the EGU’s annual General Assembly but wish you could play a more active role in shaping the scientific programme? Now is your chance! Help shape the scientific programme of EGU 2018.

From today, until 8 Sep 2017, you can suggest:

  • Sessions (with conveners and description), or;
  • Modifications to the existing skeleton programme sessions
  • NEW! Suggestions for Short courses (SC) will also take place during this period
  • From now until 18 January 2018, propose Townhall and splinter meetings

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: Aerosols over Hurricane Irene

This image – rather than our usual Imaggeo photo – is a simulation representation of Hurricane Irene, as it moved up the coast of the United States. The red-yellow areas in the image represent regions with high aerosol concentration that have been swept upwards in convective clouds and the blue areas are clean regions. The aerosols enter Irene along rain bands, before being wrapped into the centre and rained out as they circulate around the eye of the storm (the eyewall).

“Aerosols over Hurricane Irene” by Nir Benmoshe, distributed by the EGU under a Creative Commons licence.

Aerosols, weather natural or anthropogenic, affect cloud microphysics. Small aerosols are capable of stimulating tropical convection, and increasing both the cloud top heights and vertical velocities in convective clouds. The stimulation convection at the outer-most regions of a hurricane causes it to weaken. This is because it lowers the pressure gradient between the hurricane and surrounding air. In addition, convection at the storm periphery produces a compensatory downdraft of air that dampens convection in the eye. Hurricanes are driven by strong updrafts of warm, moist air at their centre and dampening of this process causes the storm to weaken further.

The structure of a hurricane (Credit: The COMET Program Steven Deyo/USGS Betsy Boynto).

Hurricane Irene was forecast to be a Category 3 Hurricane it approached the coast of North Carolina, but was reclassified as a Category 1 as its force waned. Hurricanes dissipate as they move over land and lose the source of warm water that drives convection in the centre of the storm. The affect and presence of aerosols would also have contributed to the weakening Hurricane Irene.

The Saffir-Simpson hurricane scale. In addition, tropical storms are in the region of 63-118 km/h and tropical depressions have wind speeds below 62 km/h. See here for descriptions of the damage expected in each case.

Reference:

Khain, A., B. Lynn, J. Dudhia, 2010: Aerosol Effects on Intensity of Landfalling Hurricanes as Seen from Simulations with the WRF Model with Spectral Bin Microphysics. J. Atmos. Sci., 67, 365–384.

Imaggeo is the EGU’s online open access geosciences image repository. All geoscientists (and others) can submit their images to this repository and since it is open access, these photos can be used by scientists for their presentations or publications as well as by the press and public for educational purposes and otherwise. If you submit your images to Imaggeo, you retain full rights of use, since they are licensed and distributed by the EGU under a Creative Commons licence.