EGU Blogs

Guest Post

Guest Post: Dr. Sam Illingworth – To Boldy Go

May 2, 2013

Satellites are now so ubiquitous in our lives that there is something of a precedent to take them for granted. A normal daily routine for may people across the world may include watching television (satellite) as you check your twitter account (satellite) and have a look at the weather (satellite), all before you’ve even eaten your breakfast (not a satellite); whilst for those of us in the remote sensing community, whose work consists of analysing data from a large plethora of Earth-observing satellites, it can often seem that our lives are intertwined with those majestic flying machines as they dance their cosmic waltz far above the confines of planet Earth. It is almost staggering to believe that just over 50 years ago there was not a single manmade satellite in space, especially when you take into the consideration the fact that since its conception in 1957 the United States Satellite Surveillance Network (SNN) has chartered some 8,000+ anthropogenic obiters.

Sputnik 1 (souce: www.interestingfacts.org)

After the Second World War, the two global powerhouses of that era, the USA and the USSR, found themselves locked in a conflict of attrition that will come to be known as the Cold War. A war whose victors are judged not by the more conventional markers of land gain or battle tallies, but rather through the accumulation of weaponry and the rapid advancement of technology, of which the race to get into space plays a key and pivotal role. Most people, if asked who they considered to be the winners of the Space Race, would tell you that it was of course the USA, taking one small step for man and one giant leap for capitalism when Neil Alden Armstrong walked across the lunar landscape on July 21st 1969. Ask another group of people from a certain vintage or scientific persuasion, and they would probably tell you that the true winners of the Space Race were the Soviets, seeing as they were the first to actually get something up there with the launch of Sputnik 1 on October 4th 1957.  But for me there can only be one winner, and it is neither Apollo 11 nor Sputnik 1, but instead the much less lauded US satellite: Explorer 1.

The Sputnik satellite may have been the first into space, and the Apollo missions may have bee the first to demonstrate the capability of manned spaceflight, but as an Earth observational scientist it was the Explorer 1 satellite that I find to be the most intriguing, being as it was the first to carry a scientific payload; a set of instrumentation which would be used to make the first great scientific discovery from space.

The achievements of the Russian polymaths in ensuring that the Soviets were the first into space should of course never be overlooked, nor would it be strictly fair to say that the scientific significance of Sputnik 1 disappeared as soon as it had successfully reached the edge of the atmosphere – by measuring the drag on the satellite, scientists were able gain useful information about the density of the upper atmosphere – but I like to think of Sputnik 1 as that valiant guest at a wedding, who wishing to get the party started with suitable aplomb, makes a line straight for the empty dance floor only to find that once there they lack any of the necessary moves to do anything of particular note. Explorer 1 on the other hand can be thought of as the louder, more eccentric cousin of Sputnik 1, strutting up to the dance floor without a tie (incredibly there was no tape recorder installed on Explorer 1, meaning that data could only be analysed in near real time as it was transmitted back down the scientists on the ground) before starting to cut shapes that would make even a computerised lathe turn green with envy.

From left to right: William H. Pickering, director of the Jet Propulsion Laboratory, which designed and built Explorer 1. James A. Van Allen, University of Iowa physicist who directed the design and creation of Explorer’s instruments.
Wernher von Braun, head of the U.S. Army Ballistic Missile Agency team that designed and built the Jupiter-C rocket (Source: Smithsonian National Air and Space Museum).

Explorer 1 was launched on the 31st January 1958, becoming the first of the USA’s forays into the vast unknowns of the surrounding cosmos. The design and build of the scientific payload was Lead by Dr. James Van Allen of the University of Iowa, its purpose being to measure cosmic rays as they made their way from the Supernovae explosions of distant stars within our galaxy and towards the Earth. The instrumentation was effectively a Geiger-Müller counter, set up to count the number of high energy cosmic rays as they passed through the relatively fragile shell of the satellite’s metallic exterior, and it was expected that the instrument would return values of approximately 30 rays per second. However, the scientists noted that at certain points in its orbit the instrumentation was returning values of 0 rays per second. Upon closer inspection of the data (along with the measurements taken by Explorer 3, launched on 26th March 1958, and complete with requisite tape recorder) it turned out that these zero values all seemed to be concentrated around South America, and that they only seemed to be present when the satellite was flying at an altitude of greater than 2000 km; at altitudes less than this the instrument recorded the expected 30 counts per second. The team at Iowa soon deduced that these zero counts weren’t zero counts at all, rather they were errors in the data brought about by the instrumentation being bombarded by a powerful stream of highly energised particles that were beyond its measuring capabilities. Van Allen (and others at the University of Iowa) proposed that the reason for this localised concentration was a doughnut-shaped belt of highly energized particles, trapped in formation as a result of the Earth’s magnetic field. These belts have since been named after their discoverer (and not as I had assumed, much to the amusement of one of my undergraduate lecturers, after US rock-hero Eddie van Halen), becoming the first scientific discovery to be made from space.

The Van Allen belts (source: Wikipedia

It was this monumental achievement that formed a significant contribution towards the potential of satellites to inform on the many wonders of our home planet, and it is for this reason that I put forward the Explorer 1 (and by association the USA – sorry soviet fans) team as the true winners of the Space Race, a worthy recipient of a truly intergalactic (well ok, monogalactic) battle.

 

Sam is a postdoctoral research assistant at the University of Manchester, where he spends most of his time working on the development of an algorithm for the retrieval of trace and greenhouse gas measurements from aircraft measured spectra, an algorithm that he affectionately refers to as MARS (the Manchester Airborne Retrieval Scheme). In his spare time Sam enjoys convincing scientists that they can learn to communicate their research more effectively by embracing theatrical technique in all its many guises.

Thanks for reading!

 

Guest Post: Solar Storms and the Earth’s Protective Shield – Laura Roberts Artal

March 15, 2013


I am a PhD student at the University of Liverpool Geomagnetism Laboratory.  My current research project is the palaeomagentic study of 3.5-3.2 billion year old rocks from South Africa. The aim of my research is to improve our understanding of the long term evolution of the Earth and the surface conditions under which the first forms of life originated through using palaeomagnetic records. The rocks of the Barberton Greenstone Belt are excellently preserved and have only been subjected to low grade metamorphism (greenschist facies), making them good candidates for paleomagnetic studies.  I also undertook my undergraduate studies at Liverpool University, where I studied monogenetic volcanism on Tenerife. Between my undergraduate and PhD I had a brief stint in the world of industry as an environmental consultant. I’m a keen science communicator and am involved in a number of outreach projects.

 

An article last month in the U.K’s Guardian Newspaper reported on the findings of the Royal Academy of Engineers who warned the U.K government of the need to set up an expert panel which could generate plans on how the country should prepare and cope in the event of a large solar storm or corona mass ejection (CME). What was not reported in the article and is often unknown, is that we already have a shield that goes some way to protect us from the harmful effects of out giant neighbour; but I’m getting ahead of myself. Let start with a few basics.

In essence, a solar flare is a large release of energy at the Sun’s surface, which can be followed by a CME. Solar flares tend to be short lived events and eject a cloud of charged particles, including protons, electrons and atoms. CMEs often follow flares and tend to emit considerable gusts of solar wind and magnetic fields. When the winds and charged particles reach the proximity of planet Earth, they interact with the Earth’s magnetic field causing a magnetic storm with the charged particles being preferentially deflected towards the Earth’s magnetic poles. Magnetic storms can cause disruption to electronic grids and communication systems, including satellites, aircraft, GPS navigation systems and mobile phone networks, amongst others. The Royal Academy of Engineer’s report was making reference to these potential harmful effects and arguing that the U.K. should prepare itself against them. In truth, they don’t exaggerate, the damage that solar flares can cause is not negligible: In September 1859, a large solar flare caused telegraph wires in both the United States and Europe to spontaneously short circuit, causing numerous fires; Northern Lights were seen as far south as Rome, Havana and Hawaii, with similar effects at the South Pole. More recently, in March 1989, a large solar flare caused a blackout in the whole of the Quebec province of Canada, whilst the Canadian television network and newspapers were disrupted by damage caused by a solar flare to communication satellites orbiting the Earth in 1994.  I won’t go into the details of how and what we ought to be doing to protect ourselves against these (this is not my field!). Instead, I’ll tell you about the Earth’s Magnetic field and its role in protecting us against the harmful storm winds and particulate clouds.

My research focuses on some of the oldest rocks in the world. I study the Barberton Greenstone Belt (BGB), which is located in North Eastern South Africa and is one of a few Archean aged terrains located across the globe.

The BGB is characterised by volcanic sequences which are interspersed with layers of sediments. It has been subjected to a number of tectonic events which have led to folding and low-grade metamorphism in the area. The world famous type-section of Komatiite lavas, as discovered by the Viljoen brothers in 1969, is exposed in the BGB. My research is concentrated on three Complexes of the Onvenwacht Suite, with rocks showing ages between 3.5 and 3.2 billion years (geological map modified from de Wit et al. 2011). But, how can these rocks tell us anything about solar storms, CMEs and the Earth’s magnetic field?

We now that the Earth’s magnetic field acts a shield against the harmful particles ejected by solar flares, deflecting them pole wards. In addition, it protects us against atmospheric erosion and water loss caused by solar wind. The lack of a magnetic field on Mars (generate by a geodynamo in the core), leaves the planet barren with no atmosphere or water. The early Earth was able to retain its atmosphere and water and so became habitable (with early forms of life being reported in the BGB). However, we know little about the Earth’s magnetic field during this time. Studying the paleomagnetic signature of the rocks of the BGB might enlighten us about the processes that were taking place in the core, mantle and crust during the Archean.  My research focuses on the directions of the magnetic field recorded in the BGB during its formation. Recent studies (Tarduno et al, 2010) have attempted to understand the strength of the field during the Archean and what bearing that might have on the ability of the planet to protect itself against solar winds. In their study, Tarduno and collegues, report paleointensities (obtained from single silicate crystal bearing magnetic inclusions) that are ~50-70% lower than the intensity of the present day field.  How much then, could the Earth’s magnetic field reasonably be expected to shield the planet from the Sun? Tarduno et al. argue that solar particles would have greater access to the Earth’s atmosphere during this period, due to an increased polar cap area. During the Archean, the stand-off distance between the Sun and the Earth could also be estimated to be smaller. These two facts combined would promote loss of volatiles and water, suggesting that the early Earth had a larger water inventory than presently. Overall, the young Earth was able to produce a magnetic field strong enough to protect the planet from large scale atmospheric erosion and water loss, it is likely that there were important changes to these in the first billion years of the Earth’s history.

I find it reassuring that there is this invisible shield that is protecting us humans, (perhaps not our technology), and has been doing for most of the Earth’s history. The Magnetic field has contributed to the conditions being right for evolution to happen. I think we should give it a lot more credit!

Please see below for a selection of links that might be of interest for those who might want a bit more reading on the subject!

http://www.geomagnetism.org/

http://www.peeringintobarberton.com/project.html

http://news.bbc.co.uk/1/hi/sci/tech/8659019.stm

http://www.nasa.gov/topics/earth/features/sun_darkness.html

http://science.nasa.gov/science-news/science-at-nasa/2003/23oct_superstorm/

Laura Roberts Artal

Guest Post – Things go up, things go down – Dr. Martin Wolstencroft

November 29, 2012

This post is the first of hopefully many guest posts by graduate students and geologists I work with. This post is by Dr. Martin Wolstencroft, a post doctoral fellow with Dr. Glenn Milne here at UOttawa. Martin is a geophysicist by trade and hails from a small town in central England. He did his undergraduate degree and PhD. at Cardiff University in Wales. His PhD. research focussed on the solid Earth, its evolution and responses to surface processes. He plans on returning to his homeland in 2013 and his future research plans involve incorporating several currently separate geophysical modelling methods to improve the understanding of very long term sea level change.

Matt

 

Over the summer, North Carolina legislators ended up looking very stupid. They passed a law stating that sea level rise in their little corner of the world will only be linear, as extrapolated from historic 20th Century trends. You can read the actual wording here (PDF, Section 2, Part E). This is all the more crazy because there is published evidence that North Carolina is actually in a sea level rise hotspot. This example probably has more to do with the politics of costal development than actual science (one hopes), but it does highlight some very obvious flaws in the understanding of sea level change in general.

Spring storm on the West Wales coast. (Photo: Martin Wolstencroft)

The ocean is dynamic, any surfer can tell you that. Tides come in, go out, currents stream, the wind can drive immense waves. Beneath these already complex day-to-day motions of the ocean is another world of complexity. In 2007 the IPCC summary suggested an average sea level rise of 3.5 mm/yr over the next century is likely. The figure is widely quoted in the popular press and most non-expert readers will have been left with the impression that the sea level change where they live would be 3.5 mm/yr. This is badly wrong. The misunderstanding comes from the fact that the 3.5 mm/yr is a global average value. Average is a useful statistical construct, not necessarily representing physical reality. Consider a room with 4 people in it: Emma is 1.74 m tall, Dave 1.80 m, Sam 1.67m and Sarah 1.79. The (mean) average height of people in the room is 1.75 m, but given this information no one would walk into the room and expect everyone to be 1.75 m tall. Indeed, in this toy example, no one is of ‘average’ height. This is so fundamental that it sounds like I am insulting your intelligence, but this is exactly what many supposedly intelligent people have done with sea level data. In practice, some places will get around 3.5 mm/yr rise but other places will get significantly more or less. This figure is also purely a rise in the ocean surface; no vertical motions of the land surface are included.

The sea level change that matters to us humans in a: “where do I build my house?” sense is known as relative sea level. This is what defines how a shoreline migrates over time. It is a function of ocean surface height and land surface height.  If global sea level was static but you live in a region that is subsiding, you would experience (relative) sea level rise. If sea level was rising at 5 mm/yr but your region was uplifting at 6 mm/yr, you would experience 1mm/yr sea level fall. What sea level change you experience depends very much on where you are on Earth.

Some factors that affect local sea level are: sediment deposition, ongoing uplift of formerly glaciated regions and long term ocean surface dynamics. The Mississippi delta is a region of sediment deposition and is therefore subsiding, increasing the local rate of sea level rise above global averages. In Greenland, if the ice cap is reduced, the reduced mass of ice on the land causes local uplift. Ice caps are also large enough to have a significant gravitational effect, pulling ocean water towards them. Remove the ice cap and you remove this effect, resulting in further sea level falls. As a final example, long lived ocean currents tend to ‘pile’ water up where they meet the coast, shifts in these currents in response to a changing climate can change the location of these piles. Also consider that these processes don’t even include the issue of acceleration in the rate of sea level change. This is a very real possibility, given the apparent accelerating melting of the Greenland ice cap.

Clearly there are many aspects, which control experienced sea level change. Even using accurate global averages to make local policy is doomed to failure. It is said that all politics are local; the same is true for sea level change. Concerning North Carolina, many commentators have pointed out that a lesson from King Canute would be in order. I am inclined to agree.

Martin