Caltech and JPL Experts Discuss Climate Change

In today's installment of our Earth Week 2014 features, Caltech experts share their knowledge about climate change.

 

Caltech professor Jess Adkins, a geochemist and paleoclimatologist, offers insight into global warming in the video "Is There Hope for Planet Earth?" produced by Green Wish, a nonprofit organization that funds green initiatives at the local level. In the video, Adkins talks about the history of climate change, where we are today, and what we can do to mitigate its impact in the future.

 

On April 22—Earth Day—the Caltech Center for Teaching, Learning, & Outreach sponsored an "Ask A Scientist" panel on the Caltech campus to answer questions about climate change and earth sciences. Panel members included David Crisp, JPL senior research scientist and principal investigator of the NASA Earth System Science Pathfinder Orbiting Carbon Observatory mission; Joshua Fisher, JPL research scientist, Water and Carbon Cycles Group; science communicator and education specialist Laura Tenenbaum; and Caltech alumnus Julius Su (BS '98 and '99, PhD '07), cofounder of Su-Kam Intelligent Education Systems (SKIES). Su used the SKIES iPad app, an online learning and information crowdsourcing tool, to relay online and audience questions to the panelists. The video is a recording of the live event.

 

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Monday, May 5, 2014
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Experiences from two years of MOOCs at Caltech: A WEST Public Seminar

Spring Break in the Galápagos

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Spring Break in the Galápagos
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Credit: Kevin Yu

As the culminating event of the new Evolution course at Caltech, a dozen Techers, their TA, and two professors—Rob Phillips and Victoria Orphan—spent a week of spring break living as field researchers on the Galápagos Islands.

Credit: Kevin Yu

Ecuadorian naturalist Ernesto Vaca led the group in their studies of the natural world on the Galápagos. Here, at Playa Las Bachas on Santa Cruz Island, he is describing the molting of the Sally Lightfoot crab. The students kept scientific journals during the trip, writing down questions and observations along the way.

Credit: Laura Santoso

Marine iguanas are endemic to the Galápagos and are the only modern lizards that swim. They offer an excellent example of the way isolation on islands can lead to unique speciation.

Credit: Jeff Marlow

The group's home base for the trip was the research vessel Daphne, shown here anchored in James Bay.

Credit: Jeff Marlow

The group walks over solidified volcanic ash on Santiago Island.

Credit: Victoria Orphan

Flightlessness is one of the key evolutionary adaptations seen on islands. Here, a flightless cormorant is seen diving to gather food.

Credit: Kevin Yu

The landscape of Cerro Dragón (Dragon Hill) on Santa Cruz Island. This was one of many sites where the students were able to see the impact of invasive species such as goats.

Credit: Laura Santoso

The group's mascot—a Darwin bobblehead doll—posing in front of the third largest oceanic caldera in the world at the Sierra Negra volcano.

Credit: Pushpa Neppala

The Sierra Negra volcano on Santa Cruz Island.

Credit: Jeff Marlow

A young sea lion serves as an unexpected roadblock upon the group's arrival at North Seymour Island.

Credit: Ketaki Panse

A blue-footed booby perched atop a volcanic rock on North Seymour Island.

Credit: Laura Santoso

A land iguana with the island Daphne Minor in the background. One of the central questions about the iguanas on the Galápagos is how they arrived on the islands in the first place.

Credit: Aleena Patel

Part of the group explores a mangrove lagoon in Elizabeth Bay on Isla Isabela. According to Orphan, the mangroves are a nursery for many animals, and she encouraged the students to examine the mangrove roots closely. "Really looking closely, you start to see little transparent shrimp running up and down. There's a lot of richness that you can see even by just sitting and observing," she says.

Credit: Ketaki Panse

A beautiful sunset seen from the top of Bartholomew Island.

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As the final element of Evolution, Caltech's new Bi/Ge 105 course, a dozen students spent their spring break snorkeling with penguins and sharks, hiking a volcano, and otherwise taking in the natural laboratory for evolution that is the Galápagos Islands. The second-term course was created and is taught by Rob Phillips, the Fred and Nancy Morris Professor of Biophysics and Biology, and Victoria Orphan, professor of geobiology, and is designed to give students both a broad picture of evolution and a chance to make their own up-close-and-personal observations.

 

A New Tool for Unscrambling the Rock Record

Caltech-developed technique shows sulfur reducers were at work on the early Earth

A lot can happen to a rock over the course of two and a half billion years. It can get buried and heated; fluids remove some of its minerals and precipitate others; its chemistry changes. So if you want to use that rock to learn about the conditions on the early Earth, you have to do some geologic sleuthing: You have to figure out which parts of the rock are original and which came later. That is a tricky task, but now a team of Caltech researchers has developed and applied a unique technique that removes much of the guesswork.

"We want to know what Earth looked like when these ancient rocks were deposited. That's a giant challenge because a number of processes have scrambled and erased the original history," says Woodward Fischer, an assistant professor of geobiology at Caltech. "This is a first big effort to try to wrestle with that."

Fischer is the lead author on a paper that describes the new technique and findings in the current issue of the Proceedings of the National Academy of Sciences.

Using the new method, Fischer and his colleagues have examined ancient rocks dating to an age before the rise of oxygen. Today, water feeds the biosphere, providing the electrons needed to support life. But before the evolution of photosynthesis and the accumulation of oxygen in the atmosphere, elements such as iron and sulfur were the source of electrons. Researchers interested in the early Earth would like to determine how and when life figured out how to use these elements. The Caltech team has identified clear evidence that 2.5 billion years ago, sulfate-reducing microbes were already at work.

The researchers studied drill core samples collected in South Africa from sedimentary rocks that are slightly older than 2.5 billion years old. They focused on small features within the rocks, called nodules, made of the mineral pyrite. Also known as fool's gold, pyrite can be made in a number of ways, including as a product of respiratory metabolism: sulfate-reducing microbes reduce sulfate, which is present in seawater, yielding hydrogen sulfide, and when that hydrogen sulfide mingles with iron, pyrite is produced.

Today, sulfate-reducing microbes are often found in anoxic environments such as marine sediments where the oxygen has been consumed by aerobes but where there is still plenty of organic matter. It is logical, then, to suspect that these microbes would have been important players on the early Earth, when oxygen was scarce. Comparative genomics studies of sulfate reducers that are living today also suggest that these microbes should have been present 2.5 billion years ago. But this has been difficult to confirm in the rock record.

From current studies, scientists know that sulfate reducers metabolize the various stable isotopes of sulfur in a predictable way: producing light sulfur isotopes first before moving on to produce heavier ones as they run out of substrate. This provides a chemical thumbprint that researchers can look for as they examine pyrite nodules. The nodules crystalize early within the sediments, with the material at their core forming before the material at their edges. Therefore, to check whether sulfur-reducing organisms were active when a particular pyrite-containing rock formed, a geobiologist should be able to measure the ratios of a nodule's sulfur isotopes at different points—both near the core and closer to the edges—to see how those ratios changed as the nodule grew. But the nodules are only about a millimeter in diameter, so researchers have not been able to collect the fine-grained measurements they need in order to identify the isotopic thumbprint. Instead, they often grind up an entire rock sample, measure its isotopic composition, and then compare it to another rock.

Muddying the interpretation even more, these ancient rocks have all been deeply complicated by the wrinkles of time. All of the events and circumstances that have affected them since their deposition have left their chemical marks, by carving away old materials and precipitating new ones. A geologist can use some of the textures—the marks left in the fabric of the rock—to unravel some of a rock's history, but only if those textures clearly crosscut or overlap one another. Some of the visual cues can also be misleading. So it can be difficult just to identify which parts of a rock are original and can therefore provide insight about the early Earth.

Fischer's new technique changes all that. It allows researchers to untangle a rock's history and to then zoom in and measure the isotopic ratios at a number of points within a single pyrite nodule.

He begins as any geologist would—by looking at a sample with light and electron microscopy to identify the different textures within the rock. Doing that, he might identify a number of pyrite nodules that "look good"—that appear to date to the rock's original deposition.

He then uses a technique called scanning SQUID (superconducting quantum interference device) microscopy, which uses a quantum detector to produce a magnetic map of the sample at a very small scale. Pyrite itself is not magnetic, but when it is later altered, it forms a mineral called pyrrhotite, which is magnetic. Using scanning SQUID microscopy, Fischer has been able to rule out a number of nodules that had appeared to be original but that were in fact magnetic, meaning that they included pyrrhotite. In his South African samples, those deceptive features dated to a volcanic event 500 million years after the rocks were deposited, which sent chemistry-altering fluids through all the layers of sediment and rock that were present at the time.

"If you weren't using this technique, you'd miss the later alteration," Fischer says. "Those textures looked good. They would have passed naive tests."

The final step in the process is to measure the isotopic composition of the nodules using an analytical method called secondary ion mass spectrometry (SIMS). This specialized technique is used to measure the chemistry of thin films and solids with very fine spatial resolution. Materials scientists use it to analyze silicon wafers, for example, and planetary scientists have used it to study bits of rock from the moon. Fischer's group is one of the few in the world that uses it to study ancient rocks.

In SIMS, a sample under very strong vacuum is bombarded with a beam of cesium ions, which displaces ions from the surface of the sample. A mass spectrometer can measure those so-called secondary ions, providing a count of the sample's sulfur isotopes. Since the beam can be focused very precisely, the method allows researchers to sample many points within a single nodule, measuring a 13 x 5 grid within a millimeter, for example. The product is essentially a map of the sample's isotopic composition.

"It's one thing to say, 'Wow, rocks are really complicated. There's just going to be information lost.' It's another thing to be able to go back in and say, 'I know how to piece together the history of this rock and learn something about the early Earth that I didn't know previously.'"

Using the new technique, Fischer and his colleagues were able to identify which parts of their drill core samples were truly ancient and to then measure the sulfur isotopic composition of those nodules as they grew. And indeed they found the isotopic signature expected as a result of the activity of sulfur-reducing microbes.

"This work supports the hypothesis that microbial sulfate reduction was an important metabolism in organic-rich environments on the early Earth," Fischer says. "What's more, we now know how we can ask better questions about ancient rocks. That, for me, is incredibly exciting."

The paper is titled "SQUID-SIMS is a useful approach to uncover primary signals in the Archean sulfur cycle." Along with Fischer, additional Caltech coauthors are John Eiler, the Robert P. Sharp Professor of Geology and professor of geochemistry; Joseph Kirschvink, the Nico and Marilyn Van Wingen Professor of Geobiology; Jena Johnson, a graduate student in geobiology; and Yunbin Guan, director of the Center for Microanalysis. David Fike of Washington University in St. Louis and Timothy Raub of the University of St. Andrews are also coauthors. Scanning SQUID microscopy is a technique that was developed by researchers at Caltech and Vanderbilt University. The work was supported by the Agouron Institute and by a NASA Exobiology Award.

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Kimm Fesenmaier
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Friday, April 11, 2014
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Spring Ombudsperson Training

Gravity Measurements Confirm Subsurface Ocean on Enceladus

In 2005, NASA's Cassini spacecraft sent pictures back to Earth depicting an icy Saturnian moon spewing water vapor and ice from fractures, known as "tiger stripes," in its frozen surface. It was big news that tiny Enceladus—a mere 500 kilometers in diameter—was such an active place. Since then, scientists have hypothesized that a large reservoir of water lies beneath that icy surface, possibly fueling the plumes. Now, using gravity measurements collected by Cassini, scientists have confirmed that Enceladus does in fact harbor a large subsurface ocean near its south pole, beneath those tiger stripes.

"For the first time, we have used a geophysical method to determine the internal structure of Enceladus, and the data suggest that indeed there is a large, possibly regional ocean about 50 kilometers below the surface of the south pole," says David Stevenson, the Marvin L. Goldberger Professor of Planetary Science at Caltech and an expert in studies of the interior of planetary bodies. "This then provides one possible story to explain why water is gushing out of these fractures we see at the south pole."

Stevenson is one of the authors on a paper that describes the finding in the current issue of the journal Science. Luciano Iess of Sapienza University of Rome is the paper's lead author.

During three flybys of Enceladus, between April 2010 and May 2012, the scientists collected extremely precise measurements of Cassini's trajectory by tracking the spacecraft's microwave carrier signal with NASA's Deep Space Network. The gravitational tug of a planetary body, such as Enceladus, alters a spacecraft's flight path ever so slightly. By measuring the effect of such deflections on the frequency of Cassini's signal as the orbiter traveled past Enceladus, the scientists were able to learn about the moon's gravitational field. This, in turn, revealed details about the distribution of mass within the moon.

"This is really the only way to learn about internal structure from remote sensing," Stevenson says. In fact, more precise measurements would require the placement of seismometers on Enceladus's surface—something that is certainly not going to happen anytime soon.

The key feature in the gravity data was a so-called negative mass anomaly at Enceladus's south pole. Put simply, such an anomaly exists when there is less mass in a particular location than would be expected in the case of a uniform spherical body. Since there is a known depression in the surface of Enceladus's south pole, the scientists expected to find a negative mass anomaly. However, the anomaly was quite a bit smaller than would be predicted by the depression alone.

"So, you say, 'Aha! This is compensated at depth,'" Stevenson says.

Such compensation for mass is commonly found on planetary bodies, including on Earth. In some cases, the absence of material at the surface is compensated at depth by the presence of denser material. In other cases, the presence of extra material at the surface is compensated by the existence of less dense material at depth. In fact, when the first gravity measurements were made in India, people were struck by the fact that Mount Everest did not seem to produce much of an effect. Today we know that, like most mountains on Earth, Mount Everest is compensated by a low-density root that extends many tens of kilometers below the surface. In other words, the material protruding above the surface is compensated by a reduction of density at depth.

In the case of Enceladus, the opposite is true. The absence of material at the surface is compensated at depth by the presence of material that is denser than ice. "The only sensible candidate for that material is water," Stevenson says. "So if I have this depression at the south pole, and I have beneath the surface 50 kilometers down a layer of water or an ocean, that layer of water at depth is a positive mass anomaly. Together the two anomalies account for our measurements."

Although no one can say for certain whether the subsurface ocean supplies the water that has been seen spraying out of the tiger stripes on Enceladus's surface, the scientists say that it is possible. The suspicion is that the fractures—in some way that is not yet fully understood—connect down to a part of the moon that is being tidally heated by the globe's repeated flexing as it traces its eccentric orbit. "Presumably the tidal heating is also replenishing the ocean," Stevenson says, "so it is possible that some of that water is making its way up through the tiger stripes."

The paper is titled "The Gravity Field and Interior Structure of Enceladus." Additional coauthors are Marzia Parisi, Douglas Hemingway, Robert A. Jacobson, Jonathan I. Lunine, Francis Nimmo, John W. Armstrong, Sami W. Asmar, Maria Ducci, and Paolo Tortora. The work was supported by the Italian Space Agency and by NASA through the Cassini project. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency, and the Italian Space Agency. The Jet Propulsion Laboratory manages the mission for NASA's Science Mission Directorate.

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Kimm Fesenmaier
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Wednesday, April 16, 2014
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Teaching & Learning in the American System: Student-Teacher Interactions

When Rocks Roll: How Sediment Transport Shapes Planetary Surfaces

Watson Lecture Preview

On Wednesday, March 19, Professor of Geology Michael Lamb will describe how flowing water and grains of sand create Earth's dramatic landscapes. Mars and Saturn's moon Titan show signs of similar processes. Lamb's work on the mechanics of landscape evolution may change how we think about debris flows in the San Gabriel Mountains, the effects of wildfires on erosion, and water on Mars.

The talk begins at 8:00 p.m. in Caltech's Beckman Auditorium. Admission is free.

 

Q: What do you do?

A: I'm a geologist. I study the basic mechanics of how sediment moves—how rivers erode rock and form canyons, how sediment builds deltas like the Mississippi's, how landslides work, and so on.

In the U.S., my field dates back to John Wesley Powell, who led a survey party by boat down the Grand Canyon a few years after the Civil War. For decades, geomorphology consisted of classifying landforms—identifying different types of mountain ranges, or hills, or canyons. Now, we're quantifying the processes that operate at Earth's surface to shape those landforms.

One challenge, which is true of much of the Earth sciences, is to link these process studies with the evolution of Earth's surface over geologic time. So in addition to field work, my research group has a lab where we make indoor rivers and landslides, and 'speed up time' to observe their dynamics. For example, the Mississippi River jumps to a new course from time to time, and each jump builds a new lobe of the delta. These jumps happen about once every 1,000 years, but by scaling things properly we can speed up the clock and build deltas much faster in the laboratory. We also study rare, catastrophic events, such as megafloods, which would be difficult or dangerous to measure in nature.

It's an exciting time to be a geomorphologist because we have the opportunity to apply lessons learned on Earth to Mars and Titan—two other planetary bodies with river networks. Titan's surface appears to be active, with rainfall feeding into lakes and rivers with enough force to move gravel and even cobbles, which are roughly tennis- to basketball-sized. Titan is so cold that the "rain" is liquid methane and the "rocks" are water ice, but otherwise the system seems very similar to the water cycle on Earth. On Mars, the river canyons are now dry, probably long dry. In many ways, Mars represents the ultimate inversion problem. With little to go on except for images and topographic data, what can we deduce about the water flows and climate on Mars that led to the formation of these ancient features?

 

Q: How did you get into this line of work?

A: I started college at the University of Minnesota in civil engineering. I always was fond of mechanics, and thought that I would likely become an engineer. But I also was fond of the outdoors—natural landscapes and national parks—so I had a desire to connect both interests. I took elective classes in geology and found them to be much more interesting than my engineering classes, so I switched majors. I also had an opportunity as an undergrad to work in the St. Anthony Falls Hydraulics Laboratory at the University of Minnesota, which introduced me to the indoor-analogue river experiments I now do.

Flume experiments have been used in civil engineering for many decades—for example, if you dam a river, what will the effects be? In fact, what we're doing today is similar in some ways to techniques that were pioneered here at Caltech by Professors Vito Vanoni [BS '26, MS '32, PhD '40], Norm Brooks [PhD '54], and others—first in the Sediment Lab, which was built in 1936, and later in the W. M. Keck Laboratory of Hydraulics and Water Resources. But now we're addressing how the natural world works over geologic time, rather than how the engineered world works over human time.

 

Q: In light of our recent mudslides, do you have any take-home lessons for the general public?

A: I have been working on the connection between the wildfires, floods, and debris flows that tend to plague not only Los Angeles but other areas in the southwestern United States, and I will focus my lecture on this topic. For now I'll just say that what you hear in the news about hillsides giving way and causing landslides after wildfires is probably not accurate in many landscapes. Our work shows that there might be a different way to think about the fire-flood problem, especially in very steep and rapidly eroding landscapes like the San Gabriel Mountains.

 

Named for the late Caltech professor Earnest C. Watson, who founded the series in 1922, the Watson Lectures present Caltech and JPL researchers describing their work to the public. Many past Watson Lectures are available online at Caltech's iTunes U site.

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Douglas Smith
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Watson Lecture: "When Rocks Roll: How Sediment Transport Shapes Planetary Surfaces"
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Airborne Over Iceland: Charting Glacier Dynamics

Mark Simons, professor of geophysics at Caltech, along with graduate student Brent Minchew, recently logged over 40 hours of flight time mapping the surface of Iceland's glaciers. Flying over two comparatively small ice caps, Hofsjökull and Langjökull, they traveled with NASA pilots and engineers in a retrofitted Gulfstream III business jet, crisscrossing the glaciers numerous times. Using a radar instrument designed at the Jet Propulsion Laboratory (JPL) and mounted on the underbelly of the plane, they imaged the surface of the glaciers, obtaining precise data on the velocity at which these rivers of ice flow downstream.

Following a set of test flights in Iceland in 2009, Simons and Minchew went to Iceland in June 2012 to systematically image the two ice caps at the beginning of the summer melt season. They have just returned from a February 2014 expedition aimed at setting a baseline for glacier velocity—during the winter freeze, meltwater should not play as significant a role in glacier dynamics. They sat down recently to discuss the science and the adventure of monitoring Iceland's glaciers.

Why go to Iceland to study glaciers?

Mark Simons: Iceland is an ideal natural laboratory. The glaciers there are small enough that you can do detailed measurements of them, and afterward you can process the data and analyze each ice cap in its entirety without needing overwhelming computer resources. This manageable scale lets us explore a wide range of models. Glaciers in Greenland or Antarctica are far too big for that. Logistics are also a lot easier in Iceland. We can drive up to the glaciers in just a few hours from downtown Reykjavik.

Most importantly, the Icelanders have a long history of studying these ice caps. In particular, they have nearly complete maps of the ice-bedrock interface. We can complement this information with continuous maps of the daily movement or strain of the glacier surface as well as maps of the topography of the glacier surface. These data are then combined to constrain models of glacier dynamics.

How can you map bedrock that is under hundreds of feet of ice?

Brent Minchew: Our collaborators at the University of Iceland have been doing this work for decades. Helgi Björnsson and Finnur Pálsson mapped the subglacial bedrock by dragging long radar antennas behind snowmobiles driven over the glaciers. They use long-wavelength radar that penetrates through the ice to the underlying bedrock. By looking at the reflection of the radar signals, they can estimate where the interface is between ice and bedrock. They are expert at studying the cryosphere—the earth's frozen regions, including ice caps, glaciers, and sea ice—as you might expect given their location so far north of the equator.

Is this similar to the radar you use in your airplane flights over Iceland's glaciers?

Simons: It's a similar principle. Radar is an active imaging system, so unlike optical observations, where you're just looking at the reflected light from the sun, we're actually illuminating the surface like a flashlight, but using radar instead.

Was this radar technology developed specifically for imaging glaciers?

Minchew: No. The technique we use, InSAR [Interferometric Synthetic Aperture Radar], has been available since the mid-1990s. It has revolutionized a number of disciplines in the earth sciences, including glaciology. The system we are using in Iceland is truly state-of-the-art. It enables complete control over where and when we collect data, and it returns images with millions of independent pixels. It's a very rich data source.

Simons: Actually, the exact same airplane we use in Iceland to study glaciers is also used to measure motion above restless volcanoes due to changes in magma pressure or along major seismically active faults such as the San Andreas fault. Repeated radar imaging can show us the parts of the fault that are stuck—those are the places that will generate earthquakes every so often—and the other parts that are steadily creeping year after year. Basically, we're bringing our experience from earthquake physics, both in terms of observation and modeling, to see if it can help us address important problems in glaciology.

Are there other methods besides radar for studying glacier dynamics?

Minchew: We can drill to the bed and take direct measurements, but a lot of effort is involved in this. Compared to Greenland, where the ice is close to a mile thick, or Antarctica, where it is even thicker, Iceland's glaciers are relatively thin. But they're still on average 300 meters thick. That's a long way to drill down for one data point.

Simons: Traditionally people measured velocities of glaciers by putting stakes in the glacier, and then returning to see how far downstream those stakes had moved by the end of the melting season. This approach can give an average velocity over the season. We still utilize this principle by installing GPS units at various spots on the glacier. These GPS units also help us calibrate our radar-based measurements and confirm that our velocity estimates are accurate.

What advantages does radar have over these other methods?

Simons: One of the wonderful things about radar imaging, unlike optical imaging, is that we can "see" the glacier whether it's day or night, whether it's cloudy or clear.

Minchew: Right. Another major advantage of radar technology is that we don't just see the average velocity for the season; we can detect short-term dynamics and variability over the entire glacier if the imaging is done sufficiently often.

How exactly does radar work to image the ice cap?

Simons: Radar images are usually taken at oblique angles to the surface of the earth, not straight down in a perpendicular line. Given two radar images taken from nearly identical positions but at different times, we can combine them in such a way as to measure changes in ground position that occurred in the intervening period along the oblique direction of the transmitted energy. We quantify these displacements in terms of fractions of a radar wavelength. This process is called repeat pass interferometry. We design the plane's flight path to make several interferometric measurements from different viewing angles, in order that the surface of the glacier is imaged at least three times and often as many as six times. We then combine these different perspectives to create accurate 3-D maps of the surface velocity of the glaciers, detecting its underlying east, north, and up components.

How can you be so precise in your measurements from that high up in the air?

Simons: The altitude itself isn't a problem. The trick is making certain the plane is at the same absolute position over consecutive flights. We owe this precision to engineers at NASA/JPL; it has nothing to do with us down here at Caltech. They have developed the technology to fly this plane at 40,000 feet, at 450 miles per hour, and then to come back an hour later, a day later, or a year later, and fly that exact same path in coordinates relative to the ground. Essentially they are flying in a "virtual tube" in the air that's less than 10 meters in diameter. That's how accurate it is.

Minchew: Of course even within this virtual tube, the plane moves around; that's what aircraft do. But aircraft motion has a characteristic appearance in the data, and it's possible for us to remove this effect. It never ceases to amaze me that we can get centimeter-scale, even millimeter-scale accuracy from an airplane. But we can do it, and it works beautifully.

What was the motivation for JPL and NASA to develop this radar technology in the first place?

Simons: Part of what NASA has been doing with airborne radar technology is prototyping what they want to do with radar from satellites, and to understand the characteristics of this kind of measurement for different scientific targets. The instrument is called UAVSAR, for Uninhabited Aerial Vehicle Synthetic Aperture Radar. Right now it's clearly not uninhabited because the radar is on a plane with pilots and engineers on board. But the idea is that eventually we could do these radar measurements from a drone that would stay aloft making observations for a day or a day and a half at a stretch. We can also use satellites to make the same type of measurements.

Minchew: In ways, satellites are an easier platform for radar measurements. In space, there aren't a whole lot of dramatic perturbations to their motions; they fly a very steady path. But one advantage of an airborne platform is that we can collect data more frequently. We can sample the glacier surface every 24 hours if we wish. Satellites typically sample on the order of once a week to every several weeks.

What do you hope to learn from observing glacier dynamics in Iceland?

Simons: We want to use measurements of the ice cap to explore what is happening at the bottom of the glacier. We already know from the previous campaign in 2012 that over half of the movement measured in the early summer is associated with sliding at the bed rather than deformation of the ice. In the early part of the melt season, water gets down to the bottom of the glacier and doesn't have anywhere to go, so it increases the pressure at the bottom. It ends up reducing the friction so the glacier can flow faster over the bedrock. At some point there's so much water flow that it starts to make tunnels in the ice, and then the glacier drains more efficiently. But then the tunnels will collapse on themselves, and the whole glacier settles back down, compacting on itself. The glacier actually slides faster in the early part of the melt season than later in the melt season.

Minchew: The thing that propels glaciers is simply gravity. Ice is a viscous fluid, like honey. Very cold honey. Once it warms up and begins to melt slightly, the dynamics change tremendously. That's something we can observe in Iceland—unlike in Antarctica—where temperatures regularly go above the freezing point in summer. In Iceland, we think almost all the meltwater at the bed comes from surface melting. Geothermal heating from the earth and frictional heating from the sliding itself can also contribute to melting in Iceland's glaciers. These are the main sources of melting in Antarctica. But geothermal and frictional heating don't have anything to do with climate change nor should they vary with the seasons in the way that meltwater does.

Is climate change the major reason why you're studying glaciers?

Minchew: No, I just like cold and inhospitable places. Seriously, I was drawn to the field work aspect of geophysics, the opportunity to go to places in the world that are for the most part the way nature intends them to be. I'm also drawn to glaciers because they are fascinating and surprisingly complex physical systems. A number of fundamental problems in glaciology remain unsolved, so there is tremendous potential for discovery in this field. But helping to understand the potential effects of climate change is an obvious application of our work. People are much more interested in glaciers now as a result of climate change. One of the glaciologists at the University of Iceland likes to say, "We've turned a very cold subject into a hot one."

Simons: Iceland is actually a very good place to learn about how glaciers will react to climate change. We can watch these glaciers on a seasonal basis and see how they respond to temperature variation rather than trying to compare the behavior of those glaciers in Antarctica that have yet to experience surface melting to what we think their behavior might be 50 years from now. But for me, glaciology has always been interesting in itself. My job is to study the mechanics of the earth and how it deforms. And the cryosphere is just as much a part of that as the crust.

 

Simons's initial exploratory campaign on Iceland's glaciers was partially supported by the Terrestrial Hazard Observation and Reporting (THOR) Center at Caltech, funded by an endowed gift from Foster and Coco Stanback. Current efforts are supported by NASA.

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Cynthia Eller
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Caltech Appoints Diana Jergovic to Newly Created Position of Vice President for Strategy Implementation

Caltech has named Diana Jergovic as its vice president for strategy implementation. In the newly created position, Jergovic will collaborate closely with the president and provost, and with the division chairs, faculty, and senior leadership on campus and at the Jet Propulsion Laboratory, to execute and integrate Caltech's strategic initiatives and projects and ensure that they complement and support the overall education and research missions of the campus and JPL. This appointment returns the number of vice presidents at the Institute to six.

"Supporting the faculty is Caltech's highest priority," says Edward Stolper, provost and interim president, "and as we pursue complex interdisciplinary and institutional initiatives, we do so with the expectation that they will evolve over a long time horizon. The VP for strategy implementation will help the Institute ensure long-term success for our most important new activities."

In her present role as associate provost for academic and budgetary initiatives at the University of Chicago, Jergovic serves as a liaison between the Office of the Provost and the other academic and administrative offices on campus, and advances campus-wide strategic initiatives. She engages in efforts spanning every university function, including development, major construction, and budgeting, as well as with faculty governance and stewardship matters. Jergovic also serves as chief of staff to University of Chicago provost Thomas F. Rosenbaum, Caltech's president-elect.

"In order to continue Caltech's leadership role and to define new areas of eminence, we will inevitably have to forge new partnerships and collaborations—some internal, some external, some both," Rosenbaum says. "The VP for strategy implementation is intended to provide support for the faculty and faculty leaders in realizing their goals for the most ambitious projects and collaborations, implementing ideas and helping create the structures that make them possible. I was looking for a person who had experience in delivering large-scale projects, understood deeply the culture of a top-tier research university, and could think creatively about a national treasure like JPL."

"My career has evolved in an environment where faculty governance is paramount," Jergovic says. "Over the years, I have cultivated a collaborative approach working alongside a very dedicated faculty leadership. My hope is to bring this experience to Caltech and to integrate it into the existing leadership team in a manner that simultaneously leverages my strengths and allows us together to ensure that the Institute continues to flourish, to retain its position as the world's leading research university, and to retain its recognition as such."

Prior to her position as associate provost, Jergovic was the University of Chicago's assistant vice president for research and education, responsible for the financial management and oversight of all administrative aspects of the Office of the Vice President for Research and Argonne National Laboratory. She engaged in research-related programmatic planning with a special emphasis on the interface between the university and Argonne National Laboratory. This ranged from the development of the university's Science and Technology Outreach and Mentoring Program (STOMP), a weekly outreach program administered by university faculty, staff, and students in low-income neighborhood schools on the South Side of Chicago, to extensive responsibilities with the university's successful bid to retain management of Argonne National Laboratory.

From 1994 to 2001, Jergovic was a research scientist with the university-affiliated National Opinion Research Center (NORC) and, in 2001, served as project director for NORC's Florida Ballot Project, an initiative that examined, classified, and created an archive of the markings on Florida's 175,000 uncertified ballots from its contested 2000 presidential election.

Jergovic earned a BS in psychology and an MA and PhD in developmental psychology, all from Loyola University Chicago, and an MBA from the Booth School of Business at the University of Chicago.

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