December 29th, 2014 by Adam Voiland
Shortly after we posted our December puzzler, Dan Mahr had responded with the correct answer. “This is definitely a scene of the McMurdo Dry Valleys in Antarctica. Specifically, I think this is Wright Valley, and the body of water at center is Don Juan Pond, one of the most saline lakes in the world. The high salinity prevents the water from freezing despite the temperature being well below the freezing point of normal, non-saline water,” wrote Mahr. About an hour later, Lee Saper chimed in with a link to the Dickson et al study that helped inspire the post. Meanwhile, Edwin Clatworthy was the first of many to weigh in with the correct location on Facebook.
If you read our Image of the Day caption, you know that Don Juan’s water is the saltiest in the world. But where exactly does the water come from in such an arid environment? While scientists suspected deep groundwater bubbling up was the source for decades, the Dickson et al study comes to a different conclusion. By setting up a monitoring station that took thousands of photographs, the scientists showed that salts in the soil suck available moisture from the air through a process called deliquescence.
These water-rich salts then trickle down slopes toward the pond, often mixing with small amounts of melt water from snow and ice. Fresh melt water flows in from the west, while a briny trickle arrives from the east. For a more visual explanation of how this works, check out the two videos from Jay Dickson below. By stringing together all the photographs, you can literally see how Don Juan pond gets its water. The captions accompanying the videos are straight from Dickson’s Antarctic time-lapse research page.
Time-lapse data show water tracks hydrating at the exact moment that a front of moist air passes through Upper Wright Valley. This is confirmation that salts (specifically CaCl2) absorb water out of the atmosphere, generating brines that match the composition of Don Juan Pond, the saltiest body of water in the world.
Two months of 5-minute interval imaging allowed for detailed mapping of inputs into Don Juan Pond. Freshwater is input from the west (right), while previously undocumented seeps of brine provide input from the east (left). These pulses are controlled by diurnal spikes in surface temperature, consistent with a near-surface source. Input from deep groundwater sources was not observed.
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December 22nd, 2014 by Adam Voiland
Update: The answer has been posted here.
Every month on Earth Matters, we offer a puzzling satellite image. The December 2014 puzzler is above. Your challenge is to use the comments section to tell us what part of the world we are looking at, when the image was acquired, what the image shows, and why the scene is interesting.
How to answer. Your answer can be a few words or several paragraphs. (Try to keep it shorter than 200 words). You might simply tell us what part of the world an image shows. Or you can dig deeper and explain what satellite and instrument produced the image, what spectral bands were used to create it, or what is compelling about some obscure speck in the far corner of an image. If you think something is interesting or noteworthy, tell us about it.
The prize. We can’t offer prize money, but, we can promise you credit and glory (well, maybe just credit). Roughly one week after a puzzler image appears on this blog, we will post an annotated and captioned version as our Image of the Day. In the credits, we’ll acknowledge the person who was first to correctly ID the image. We’ll also recognize people who offer the most interesting tidbits of information about the geological, meteorological, or human processes that have played a role in molding the landscape. Please include your preferred name or alias with your comment. If you work for or attend an institution that you want us to recognize, please mention that as well.
Recent winners. If you’ve won the puzzler in the last few months or work in geospatial imaging, please sit on your hands for at least a day to give others a chance to play.
Releasing Comments. Savvy readers have solved some of our puzzlers after only a few minutes or hours. To give more people a chance to play, we may wait between 24-48 hours before posting the answers we receive in the comment thread.
December 18th, 2014 by Kathryn Hansen
The 2014 fall meeting of the American Geological Union (AGU) is more than halfway over. Throughout the week we’ve been enjoying a series of cartoons drawn live at the meeting by Miles Traer, a multimedia producer at Stanford’s School of Earth Sciences, inspired by various sessions. Below is a cartoon from December 16 titled: “Atlas of Global Urban Change, a compendium of Earth’s rapid urbanization.” See the full collection here.
Also on December 16 at AGU, scientists presented images demonstrating an aspect of urbanization that appeared less like a cartoon and a bit more festive. The images showed that city lights shine brighter during the holidays in the U.S. when compared with the rest of the year. In central urban areas, brightness was shown to increase by 20 to 30 percent, while suburbs and outskirts of major cities saw light intensity increase by 30 to 50 percent. Read more about the holiday lights images here and here.
December 17th, 2014 by Adam Voiland
December 16th, 2014 by Kathryn Hansen
A record 25,000 researchers and exhibitors descended on San Francisco this week for the 2014 meeting of the American Geophysical Union (AGU). That number of attendees translates to a tremendous amount of Earth science being discussed via presentations and posters, and we can’t possibly cover it all in this blog. Fortunately, this buzz word graphic posted by @AGU_Eos helped us sort what attendees are talking about, at least on twitter at #AGU14.
Drought was certainly a hot topic, particularly California’s multi-year episode. NASA scientists announced at a press briefing that it would take about 11 trillion gallons of water (42 cubic kilometers)—or 1.5 times the maximum volume of the largest U.S. reservoir—to recover from the current drought. The calculation, based on data from the Gravity Recovery and Climate Experiment (GRACE) satellites, is the first of its kind. Read the full story here.
The buzz word “ice” probably stems from the abundance of research on Greenland that was presented on December 15. Scientists using ground-based and airborne radar instruments found that liquid water can now persist throughout the year on the perimeter of the ice sheet; it might help kick off melting in the spring and summer. Read more about those studies here. Look, too, at this new study that used satellite data to get a better picture of how the ice sheet is losing mass.
And finally, take a minute to browse some of the cool photos presented by Anders Bjørk of the Natural History Museum of Denmark, which included the portrait of Arctic explorers (below) and this image pair demonstrating glacial retreat in Greenland.
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December 10th, 2014 by hhanson
Editor’s Note: The following is an excerpt from the NASA Earth Science in the News column, published in the November/December issue of The Earth Observer newsletter. You can download the current issue here.
America’s Tiny Four Corners Region is an Outsized Methane Hotspot; TIME.com. One small spot in the U.S. Southwest is surprisingly the producer of the largest concentration of methane (CH4) gas seen across the nation. Levels of CH4 over the Four Corners region are more than triple the standard groundbased estimate of the greenhouse gas, as reported in a point study of satellite data by scientists at NASA/Jet Propulsion Laboratory (JPL) and the University of Michigan. CH4 is a heat-trapping gas whose increasing quantities in the atmosphere have fueled concerns about global climate change. The methane “hotspot,” seen on the map as a small splotch—see map above—measures approximately 6475 km2 (2500 mi2) at the junction of Arizona, New Mexico, Colorado, and Utah. For scale, the state of Arizona is about 292,668 km2 (113,000 mi2). But the area generated an annual 0.59 million metric tons of methane between 2003 and 2009—about as much CH4 as the entire coal, oil, and gas industries of the U.K. give off each year.
The Four Corners area (red) is the major U.S. hot spot for methane emissions in this map showing how much emissions varied from average background concentrations from 2003-2009 (dark colors are lower than average; lighter colors are higher). Image Credit: NASA/JPL-Caltech/University of Michigan
Scientists Say Ozone Layer is Recovering; Associated Press. Earth’s protective ozone layer is beginning to recover from its previously reduced levels, largely because of the phase-out since the 1980s of certain chemicals used in refrigerants and aerosol cans, a U.N. scientific panel reported. Scientists said the development demonstrates that when the world’s peoples come together, we can counteract a brewing ecological crisis. For the first time in 35 years, scientists were able to confirm a statistically significant and sustained increase in stratospheric ozone, which shields the planet from solar radiation that causes skin cancer, crop damage, and other problems. From 2000 to 2013, ozone levels climbed 4% in the key mid-northern latitudes at about 48 km (30 mi) above Earth’s surface, said scientist Paul Newman [NASA’s Goddard Space Flight Center (GSFC)].
Deep Ocean Hasn’t Warmed Measurably in a Decade, Says NASA; The Weather Channel. Deep below the ocean surface, there’s a place global warming hasn’t yet reached. According to a study published on October 5, 2014, in Nature Climate Change, scientists at NASA/Jet Propulsion Laboratory (JPL) have found that over the last decade the deepest part of the world’s ocean has not warmed measurably. The scientists analyzed ocean temperatures from between 2005 and 2013 and found that below a depth of approximately 2 km (~1.2 mi)—roughly halfway to the bottom at this location—the global ocean has not warmed nearly as quickly as the top half. The scientists collected the temperature data using both satellite measurements and data from the Argo array, a network of some 3500 floating probes scattered throughout the world that measure ocean temperatures and salinity. “The sea level is still rising,” said study coauthor Josh Willis [JPL] in a news release. “We’re just trying to understand the nitty-gritty details.”
Antarctic Sea Ice Level Breaks Record, NASA Says; CBSNews.com. Sea ice surrounding Antarctica is at an all-time high, even as global temperature averages continue to climb. NASA reports that ice formation in the continent’s southern oceans peaked this year, breaking ice-measuring satellite records dating back to the late 1970s. For the first time since 1979, on September 19, 2014, Antarctic sea ice extent exceeded ~20 million km2 (~7.7 million mi2) whereas the average maximum extent between 1981 and 2010 was ~19 million km2 (~7.3 million mi2). Despite this trend, sea ice as a whole is decreasing on a global scale. Researchers say that, just like global warming, trends have different outcomes in different parts of the world; not every location with sea ice will experience ice loss or gain. “When we think about global warming we would expect intuitively that ice should also be declining in the Antarctic region as in the Arctic,” explained senior research scientist Josefino Comiso [GSFC]. “But station and satellite data currently show that the trends in surface temperatures are most positive in the Arctic, while in the Antarctic region the trends are a mixture of positive and negative trends,” he said, adding that cooling and declining sea surface temperatures could also contribute to a “more rapid advance at the ice edge.”
1934’s Dust Bowl Drought Was the Worst in a Thousand Years for U.S.; NBCNews.com. The drought of 1934 wasn’t just bad, it was the worst. That’s the finding of a reconstruction of North American drought history over the past 1000 years, done by scientists from NASA and Columbia University’s Lamont-Doherty Earth Observatory. Their study, published in the October 17 issue of Geophysical Research Letters, concludes the drought of 1934, during the Dust Bowl years in the North American Plains, was 30% more severe than the next worst, which occurred in 1580, NASA scientists said. The scientists used tree ring records from 1000 to 2005 along with modern observations. They found that the 1934 drought extended across over 71% of western North America, compared with almost 60% during the 2012 drought. “It was the worst by a large margin,” said lead author of the study Ben Cook [NASA’s Goddard Institute for Space Studies—Climate Scientist]. The scientists found two main reasons: a winter high-pressure system over the West Coast that blocked precipitation and spring dust storms that suppressed rainfall.
GRACE Spacecraft Changed the Way Groundwater was Measured; CBS’ 60 Minutes. Leslie Stahl hosted a segment on California’s groundwater issues. The segment described the difficulty in sampling groundwater levels until NASA’s Gravity Recovery and Climate Experiment (GRACE) spacecraft was launched. Mike Watkins [JPL—GRACE Project Scientist] described how GRACE “can tell whether an area has gained water weight or lost it.” Jay Famiglietti [University of California, Irvine] said that he thought the method was “complete nonsense” until he started examining the data, which changed his position. The broadcast noted that Famiglietti was so worried by what he saw in the data that he is working “to alert governments and academics to the problem.”