Archive for May, 2018

Making a Map of Water and Ice

May 23rd, 2018 by NASA Earth Science News Team

This is a cross-post of a story by Ellen Gray. It provides deeper insight into our May 23 Image of the Day.

Ominous beginning: Garbage data from a new satellite

Six months after GRACE launched in March 2002, we got our first look at the data fields. They had these big vertical, pole-to-pole stripes that obscured everything. We’re like, holy cow this is garbage. All this work and it’s going to be useless.

But it didn’t take the science team long to realize that they could use some pretty common data filters to remove the noise, and after that they were able to clean up the fields and we could see quite a bit more of the signal. We definitely breathed a sigh of relief. Steadily over the course of the mission, the science team became better and better at processing the data, removing errors, and some of the features came into focus. Then it became clear that we could do useful things with it.

And then trends emerged

It only took a couple of years. By 2004, 2005, the science team working on mass changes in the Arctic and Antarctic could see the ice sheet depletion of Greenland and Antarctica. We’d never been able before to get the total mass change of ice being lost. It was always the elevation changes – there’s this much ice, we guess – but this was like wow, this is the real number.

Not long after that we started to see, maybe, that there were some trends on the land, although it’s a little harder on the land because with terrestrial water storage — the groundwater, soil moisture, snow, and everything. There’s inter-annual variability, so if you go from a drought one year to wet a couple years later, it will look like you’re gaining all this water, but really, it’s just natural variability.

By around 2006, there was a pretty clear trend over Northern India. At the GRACE science team meeting, it turned out another group had noticed that as well. We were friendly with them, so we decided to work on it separately. Our research ended up being published in 2009, a couple years after the trends had started to become apparent. By the time we looked at India, we knew that there were other trends around the world. Slowly not just our team but all sorts of teams, all different scientists around the world, were looking at different apparent trends and diagnosing them and trying to decide if they were real and what was causing them.

A world of big blobs of red and blue

I think the map, the global trends map, is the key. By 2010 we were getting the broad-brush outline, and I wanted to tell a story about what is happening in that map. For me the easiest way was to just look at the data around the continents and talk about the major blobs of red or blue that you see and explain each one of them and not worry about what country it’s in or placing it in a climate region or whatever. We can just draw an outline around these big blobs. Water is being gained or lost. The possible explanations are not that difficult to understand. It’s just trying to figure out which one is right.

Not everywhere you see as red or blue on the map is a real trend. It could be natural variability in part of the cycle where freshwater is increasing or decreasing. But some of the blobs were real trends. If it’s lined up in a place where we know that there’s a lot of agriculture, that they’re using a lot of water for irrigation, there’s a good chance it’s a decreasing trend that’s caused by human-induced groundwater depletion.

And then, there’s the question: are any of the changes related to climate change? There have been predictions of precipitation changes, that they’re going to get more precipitation in the high latitudes and more precipitation as rain as opposed to snow. Sometimes people say that the wet get wetter and the dry get dryer. That’s not always the case, but we’ve been looking for that sort of thing. These are large-scale features that are observed by a relatively new satellite system and we’re lucky enough to be some of the first to try and explain them.

What kept me up at night

The past couple years when I’d been working the most intensely on the map, the best parts of my time in the office were when I was working on it. Because I’m a lab chief, I spend about half my time on managerial and administrative things. But I love being able to do the science, and in particular this, looking at the GRACE data, trying to diagnose what’s happening, has been very enjoyable and fulfilling. We’ve been scrutinizing this map going on eight, nine years now, and I really do have a strong connection to it.

What kept me up at night was finding the right explanations and the evidence to support our hypotheses – or evidence to say that this hypothesis is wrong and we need to consider something else. In some cases, you have a strong feeling you know what’s happening but there’s no published paper or data that supports it. Or maybe there is anecdotal evidence or a map that corroborates what you think but is not enough to quantify it. So being able to come up with defendable explanations is what kept me up at night. I knew the reviewers, rightly, couldn’t let us just go and be completely speculative. We have to back up everything we say.

A tangled mix of answers

The world is a complicated place. I think it helped, in the end, that we categorized these changes as natural variability or as a direct human impact or a climate change related impact. But then there can be a mix of those – any of those three can be combined, and when they’re combined, that’s when it’s more difficult to disentangle them and say this one is dominant or whatever. It’s often not obvious. Because these are moving parts and particularly with the natural variability, you know it’s going to take another 15 years, probably the length of the GRACE Follow-On mission, before we become completely confident about some of these. So it’ll be interesting to return to this in 15 years and see which ones we got right and which ones we got wrong.

You can read about Matt’s research here:

Tracking the Kilauea Eruption

May 14th, 2018 by Adam Voiland

An active fissure in Leilani Estates subdivision. This photo shows fissure 7 on May 5, 2018. Image Credit: U.S. Geological Survey

You have probably seen dramatic images and videos of several new fissure eruptions cracking open the land surface in Hawaii, emitting plumes of gas, and spitting up fountains of lava in the middle of a residential neighborhood.

If you are tracking Kilauea’s eruptions, the U.S. Geological Survey Hawaiian Volcano Observatory (HVO) and Hawaii County Civil Defense are the best sources for the latest information. HVO releases status reports, photos, videos, maps, and near-real time data that are invaluable to understanding what is happening. Hawaii County issues frequent alerts with details about evacuations, road closures, and the status of utilities.

If you want to dig into the science of this eruption, HVO and the Smithsonian Global Volcanism Program both have informative summaries that synthesize what scientists know of Kilauea’s geologic history. There are also knowledgeable volcanologists tracking the eruption closely and offering science-based commentary. Janine Krippner of Concord University (@janinekrippner) is a trained volcanologist who tweets regularly about developments. Ken Rubin @kenhrubin), based at the University of Hawaii, does the same. Erik Klemetti, a volcanologist at Denison University, is reporting on the eruption on his Rocky Planet blog.

To extend the scientific conversation, Earth Matters reached out to a handful of researchers from NASA and elsewhere who are monitoring the volcano. Among those who responded were Simon Carn (Michigan Technological University), Ashley Davies (NASA Jet Propulsion Laboratory),  Jean-Paul Vernier (NASA Langley Research Center), Verity Flower (Universities Space Research Association/NASA Goddard Space Flight Center) and Krippner.

NASA astronaut Drew Feustel tweeted this photograph of a volcanic plume at the summit of Kilauea on May 13, 2018. Image Credit: NASA

Can you briefly describe the steps that happen in an eruption like we’re seeing with Kīlauea?
“First, USGS HVO tiltmeters recorded inflation of the volcano. This was caused by magma moving up from depth, causing the volcano to bulge outwards.  The lava lake level in the summit caldera (Halema’uma’u) rose, an indication of the influx of magma into the volcanic plumbing system. Local seismic activity increased due to rock breaking as magma forces its way upwards, and as the broader volcanic edifice adjusted and reacted to the changing stress field.  As magma rose, more volcanic gas (including sulfur dioxide) was released. As magma moved into the near surface East Rift Zone, the summit started to deflate, and the lava lake level dropped. There were structural adjustments along the rift, from the summit, to Pu’u O’o, and along the rift, causing earthquakes. Then lava erupted, the whole system began to depressurize, and deflation continued.”
– Ashley Davies

Starting on the afternoon of Monday, April 30, 2018, magma beneath Pu‘u ‘Ō‘ō drained and triggered the collapse of the crater floor. Within hours, earthquakes began migrating east of Pu‘u ‘Ō‘ō, signaling an intrusion of magma along the middle and lower East Rift Zone. Map credit: U.S. Geological Survey. More maps here.

How would you describe the significance or scope of this eruption?
“This eruption is part of the normal life cycle of Kilauea volcano and is comparable to past activity. In fact, 90 percent of the surface of Kilauea is less than 1,000 years old  very young on a geologic time scale. The significance of this eruption is that it is directly occurring in the Leilani community. These people need help and support. Even though we all live with natural hazards, no matter where we are, we don’t often imagine it happening to us.” Janine Krippner

What can we expect to happen next? Is the fissure eruption likely to persist for a long time?
“It could be a major risk to the Leilani Estates area if the eruption continues. So far, the lava flows have not traveled very far from the eruptive fissure. If this changes or the fissure extends in length, then more property will be destroyed and major roads could be cut.”
Simon Carn

This map overlays a georegistered mosaic of thermal images collected during a U.S. Geological Survey helicopter overflight of the fissures in Leilani Estates on May 9, 2018. The base is a copyrighted satellite image (used with permission) provided by Digital Globe. Temperature in the thermal image is displayed as gray-scale values, with the brightest pixels indicating the hottest areas (white shows active breakouts). Image: Courtesy of USGS, Copyright Digital Globe, NextView License.

“This eruption could persist for quite a while, but it is impossible to tell how long. This is a dynamic situation, and new fissures could start and stop with little to no warning. The risk of lava inundation is real and significant, depending on where lava is extruded at the surface and how much.” Janine Krippner

Can you address the health hazards associated with sulfur dioxide?
“The problem with sulfur dioxide is that if you breathe it in, it can combine with water in the lungs to create an acid. With sulfur dioxide issuing from the fissures in an inhabited area, it makes for unhealthy concentrations locally. HVO has more on this here.” Ashley Davies

This false-color ASTER image was acquired on May 6, 2018. It shows the sulfur dioxide plume in yellow and yellow-green coming from new activity in Leilani Estates. A smaller, but thicker, sulfur dioxide plume can be seen coming from Kilauea’s main vent. Image Credit: NASA/ASTER

“Sulfur dioxide is a common occurrence in Hawaii, as vog (volcanic smog), which is a mixture of sulfur and aerosols. Sulfur dioxide and/or vog can cause irritation to eyes and airways, causing coughing, wheezing, headaches, and sore throats. People with preexisting conditions, such as asthma, are more at risk. Sulfur dioxide levels have been measured at dangerous and deadly levels near the fissures.”  Janine Krippner

Volcanic gases rise from a fissure on Nohea Street, Leilani Estates. An HVO geologist measured a temperature of 103 degrees C (218 degree F). The asphalt road was describes as “mushy” from the heat. Image Credit: U.S. Geological Survey.

Which satellites sensors are making observations of Kilauea’s plume?
There are several. The Multi-angle Imaging SpectroRadiometer (MISR) can measure the height of plumes from stereo imagery, and makes observations of the size and shape of the particles, which is useful for determining the degree to which the plume is rich in liquid sulfate and water particles versus solid, angular ash particles. The Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) are collecting daily snapshots of the amount of particulate matter in the plume as well as making observations of the sulfur dioxide plumes based on their thermal bands. The Operational Land Imager (OLI) and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) provide more detailed images, though overpasses are less frequent. Finally, synthetic aperture radar on Sentinel 1 is tracking how much the land deforms as the eruption progresses.
— Verity Flower

To what degree are satellites sensors like OMPS and OMI useful for monitoring sulfur dioxide emissions?
Satellites provide unique information on the total sulfur dioxide mass and spatial distribution in a plume ‘snapshot’, but provide minimal information on sulfur dioxide at ground level. Other techniques provide more localized measurements but can detect surface concentrations. Simon Carn

The Ozone Mapping Profiler Suite (OMPS) detected increasing concentrations of sulfur dioxide over Hawaii in May 2018. Image Credit: NASA Earth Observatory. Learn more about this map.

Are there other reasons to monitor volcanic plumes aside from health hazards?
The particles in volcanic ash have sharp, angular edges that can abrade aircraft windows hindering the pilots ability to navigate. Where these ash particles enter aircraft engines the high temperatures cause ash to melt, coating the rotors, air intakes and casings that can lead to engine failure. Plumes can also have effects—sometimes even positive effects—on the wider environment. Ash falls can destroy crops and damage infrastructure during an eruption, but they can also add nutrients to the ocean that fuel phytoplankton blooms and nutrients to the soil that make farmland more fertile on longer timescales. — Verity Flower

Can you tell me anything about the wind patterns around Hawaii?
So far, northwesterly trade winds, which are common in this area, have kept the plume over the ocean. The winds do occasionally shift for short periods, which could bring more volcanic pollution over populated areas. — Verity Flower

What has NASA been doing in response to the eruption?
“The NASA Disasters Program is working with several teams to assess the eruption and make information available to first responders and others. We are working with several instrument teams to monitor the sulfur dioxide plume. We are also looking at thermal imagery from VIIRS to detect the position of the new fissures. The VIIRS thermal anomaly is usually used for fire detection, but it appears to be a useful tool for detecting the fissure events in Leilani Estates. We are also using ASTER thermal anomaly data in near-real time to detect the fissures. You can find imagery and data from several sources showing different aspects of the eruption here.” Jean-Paul Vernier

A screenshot from a repository of maps and images related to the eruption compiled by the NASA Earth Science Disasters Program. Image Credit: NASA


Ground to Space: Yaguas National Park

May 8th, 2018 by Kathryn Hansen

In January 2018, Peru’s protected area grew by more than 2 million acres with the creation of Yaguas National Park. The forest is largely intact, unbroken by roads and human activity. Only the Yaguas River cuts through the continuous canopy, visible in this image acquired by Landsat 8 in August 2017.

Scientists from the Field Museum got an even closer look at the forest when they flew over it before it was designated a national park. “When you see it from the air, it appears to stretch to the horizon,” said Corine Vriesendorp, a conservation ecologist at the Field, in a story about the new park. The following photographs by Álvaro del Campo offer this aerial perspective.

The first photo shows an area of intact forest inside Yaguas National Park. Expanses like this one are important for the diversity of the region’s plants and animals.

The park preserves more than forest; it protects an entire watershed. A segment of the Yaguas River is visible in the the second photograph. According to an inventory conducted by the Field Museum in 2010, the diversity of fish in this river could be the highest in Peru. Over the span of three weeks, experts counted 337 species of fish.

In the satellite image at the top of this page, notice the yellow areas on either side of the river that appear to be bare. These are actually peatlands: grounds rich with a soil-like mixture of partly decayed plant material that can build up in the abandoned river meanders. The photograph above provides an aerial view of peatlands.

“Ten years ago, we were just beginning to realize that there were important peat deposits in the Peruvian Amazon,” Vriesendorp said in a March 2018 Image of the Day. “Although there has been no comprehensive mapping of the Putumayo’s peatlands to date, it is likely that the below-ground carbon stock is immense.”

Spring Has Sprung in the Arctic Ocean

May 2nd, 2018 by Kathryn Hansen

With springtime comes sunlight and warmth that advance the melting and breakup of Arctic sea ice. Varied patterns and textures appear across the icescape, and many are visible in this image, which was our Image of the Day on April 30. This satellite image includes the area photographed a day earlier by Operation IceBridge—the same photograph that sparked discussion on our blog and on news and social media about what might have caused the holes in the ice.

The holes were not a research focus of the mission; scientists were flying that day to measure the thickness of sea ice. Rather, as some scientists explain below, the holes were simply a sign of spring, and just one of the many interesting and photogenic sights seen from the aircraft in 10 years of research flights over the Arctic.

Nathan Kurtz, IceBridge project scientist
“The main purpose of these IceBridge flights is to measure the thickness of the sea ice. Ice thickness is an important factor which allows us to assess the health of the pack and its ability to survive the summer melt. It is also an important regulator in the exchange of energy and moisture between the ocean and the atmosphere.”

“While on the flights, I’ll stare out the windows for hours looking at the surface. The movement of the ice leads to huge variability over small scales, with many interesting scenes and patterns visible and a variety of color shades. But there’s only so much that can be discerned with human eyes. That is why we have the sensitive instrument suite on the plane: to map the intricacies of the ice cover which may otherwise be invisible to us and to quantify parameters for scientific interpretation.”

Chris Shuman, UMBC glaciologist based at NASA’s Goddard Space Flight Center
“Well back into March, satellites show a whole series of relatively clear images over Mackenzie Bay, indicating lots of sunshine coming in. The ‘holes’ in the sea ice are just a sign of spring, augmented by some particular process—‘submarine groundwater discharge,’ large mammals, algae growth, brine pockets draining, or something else entirely. Attributing any particular area of open water to a particular process is speculation. There is always a lot going on in the spring sea ice pack of the Beaufort Sea.”

John Sonntag, IceBridge mission scientist
“As scientists, we have the privilege of witnessing the beauty and mystery of the cryosphere firsthand, even as we work to collect that data. The Beaufort “ice circles” were among those. We have heard a number of plausible explanations for those fascinating features. In a more personal sense, I have been genuinely gratified to see the high level of interest from the public in the ice circles. The public’s clear enthusiasm for the puzzles of nature matches my own. It’s why I like my job!”