Heidi Toth

July 29, 2019

Triton orbits Neptune, the eighth planet from the Sun, some 2.7 billion miles from Earth—at the cold outer fringe of the Solar System’s major planet zone. Surface temperatures hover near absolute zero, so low that common compounds we know as gases on Earth freeze into ices. Triton’s atmosphere, which is 70,000 times less dense than Earth’s, is composed of nitrogen, methane and carbon monoxide.

These extreme conditions have led to an extraordinary discovery on Triton. An international team of scientists used the 8-meter Gemini South Telescope in Chile to pinpoint a very specific type of infrared light signature produced when carbon monoxide and nitrogen molecules join together and vibrate in unison. Individually, carbon monoxide and nitrogen ices each absorb their own distinct wavelengths of infrared light, but the tandem vibration of an ice mixture absorbs at an additional, distinct wavelength identified in this study.

The discovery, recently published in the Astronomical Journal, offers insights into how this volatile mixture can transport material across the moon’s surface via geysers, trigger seasonal atmospheric changes and provide a context for conditions on other distant, icy worlds.

“While the icy spectral fingerprint we uncovered was entirely reasonable, especially as this combination of ices can be created in the lab, pinpointing this specific wavelength of infrared light on another world is unprecedented,” said NAU professor Stephen Tegler, who led the study, collaborating with Will Grundy and Jennifer Hanley of Lowell Observatory. Other co-authors from NAU are Terry Stufflebeam, Shyanne Dustrud, Gerrick Lindberg, Anna Engle, Thomas Dillingham, Daniel Matthew and David Trilling.

In the Earth’s atmosphere, carbon monoxide and nitrogen molecules exist as gases, not ices. In fact, molecular nitrogen is the dominant gas in the air we breathe, and carbon monoxide is a rare contaminant that can be lethal. On distant Triton, however, carbon monoxide and nitrogen freeze solid as ices. They can form their own independent ices or can condense together in the icy mix detected in the Gemini data. This icy mix could be involved in Triton’s iconic geysers first seen in Voyager 2 spacecraft images as dark, windblown streaks on the surface of the distant, icy moon.

Looking ahead, the researchers expect these findings will shed light on the composition of ices on other distant worlds beyond Neptune. Astronomers have suspected that the mixing of carbon monoxide and nitrogen ice exists not only on Triton, but also on Pluto, where the New Horizons spacecraft found the two ices coexisting. This Gemini finding is the first direct spectroscopic evidence of these ices mixing and absorbing this type of light on either world.

Tegler studies ices relevant to the surfaces of Kuiper Belt Objects in the Astrophysical Ice Laboratory using transmission and Raman spectroscopy. The laboratory is a collaboration between Lowell Observatory and NAU’s Department of Physics and Astronomy, which facilitates studies of cryogenic outer solar system materials, such as the methane and nitrogen ices that dominate the surfaces of Pluto, Triton, Eris and Makemake, and the ethane-methane-nitrogen liquids that flow across the surface of Titan.

The laboratory consists of two experimental stations, one for vapor deposition of thin ice films, and one for more massive samples of cryogenic liquids and ices up to 2 cm thick. Instruments used to analyze cryogenic materials include Fourier-transform infrared spectroscopy, mass spectroscopy and X-ray photoelectron spectroscopy.

Photo: Voyager 2 image of Triton showing the moon’s south polar region. Credit: NASA/JPL

July 24, 2019

A team of climate scientists at Northern Arizona University, along with their international collaborators, has completed new reconstructions of Earth’s temperature over the past 2,000 years, placing the exceptional 20^th-century warming into a longer-term context, as chronicled in a study published today in Nature Geoscience.

This international collaboration, part of the PAGES 2k Consortium, used a new, highly curated set of paleoclimate data and compared seven different statistical methods for reconstructing past global average temperature. Put simply, they found these different ways of measuring climate change in the last two millennia all came back with similar results, especially when focusing on decade-to-decade changes. This allowed the researchers to explore important questions about how much of the past temperature changes can be ascribed to different natural causes, including the randomness of the climate system, which is difficult to quantify without a long-term perspective.

Results showed the most rapid, multi-decade-long global warming of the past 2,000 years occurred during the second half of the 20th century, highlighting the extraordinary pace of current climate change, due mostly to human emissions of heat-trapping gases. The study also quantified changes in global temperature due to volcanic eruptions and natural variability before the industrial revolution. These are important benchmarks for evaluating whether climate models accurately simulate changing global climate.

“Reconstructions of the past help us place recent climate changes into an appropriate context,” said Michael Erb, co-author and a postdoctoral scholar at NAU’s School of Earth and Sustainability. “This study allowed us to estimate climate variability over the past 2,000 years, showing just how large recent man-made warming is compared to natural and volcano-forced climate variations over the recent past. It also showed that climate models are doing a good job capturing these sort of changes, which is helpful for model validation.”

The PAGES 2k Consortium includes Regents’ Professor Darrell Kaufman and assistant professor Nicholas McKay, also from NAU’s School of Earth and Sustainability, and a host of collaborators from around the nation and world, such as Costa Rica, China, Switzerland, Germany and Australia. To generate the new temperature reconstructions, they first needed to gather together the PAGES 2k database, which consists of biological and geological sources that provide information on historical temperatures and climate. These data sources include tree rings, corals, glacier ice and sediments, providing information from all of the world’s continents and oceans. The collaboration is coordinated through the Past Global Changes (PAGES) project, which makes this valuable data available to other scientists for use in diverse paleoclimate research as well.

McKay and Kaufman led the development of this database and are delighted to see that effort paying off.

“Pulling together such a diverse dataset is extremely challenging, but it’s exciting to see that work help us better understand the climate system,” McKay said. “This is only the tip of the iceberg of what scientists can learn from these data.”

“This study used the recently developed PAGES 2k database to improve on previous temperature reconstructions at the global scale,” Kaufman said. “This is a major accomplishment that was completed in time for the results to be considered in the upcoming climate assessment report from the Intergovernmental Panel on Climate Change.

A companion study, which used the same database to map how temperature over the past 2,000 years varied from place to place around the Earth, was published concurrently in Nature.

July 24, 2019

In the last 20 years, rapid advances in DNA sequencing and bioinformatics technologies have significantly improved scientists’ understanding of the microbial world. Examples include increased knowledge about the vast diversity of microorganisms; how microbiota and microbiomes impact disease and medical treatment; how microorganisms impact the health of our planet; and the potential for applications of microbiome biotechnology in the medical, forensic, environmental and agricultural fields.

In 2009, Northern Arizona University associate professor Greg Caporaso of the Center for Applied Microbiome Science, part of the Pathogen and Microbiome Institute—who was at that time working as a postdoctoral scholar in Rob Knight’s laboratory, then at the University of Colorado at Boulder—led the development of the first open-source QIIME (Quantitative Insights Into Microbial Ecology) bioinformatics software platform under Knight’s guidance. An announcement of the software launch was published in Nature Methods in 2010. The software enables scientists to perform microbiome analysis from increasingly large amounts of DNA sequencing data, and was designed to take users from raw sequencing data through publication-quality graphics and statistics.

Since its initial release, QIIME (pronounced “chime”) has supported many microbiome studies and gained a broad user and developer community. In fact, QIIME has been cited in more than 15,000 academic papers, making it one of the most often-cited scholarly works by an NAU author.

Beginning in 2016, Caporaso and his team reengineered the platform to facilitate reproducible and modular analysis of microbiome data. The project to redesign and disseminate QIIME 2 was funded by a National Science Foundation grant awarded to Caporaso and Knight and is described in a paper published July 24 in Nature Biotechnology.

“As we interacted with QIIME users in our online support forum, in our workshops and through direct collaborations, we realized there was potential for better serving the growing community of microbiome researchers in academia, government and industry,” Caporaso said. “QIIME 2 retains the features that made QIIME a powerful and widely used analysis pipeline, while providing new features that will drive the next generation of microbiome research, including interactive spatial and temporal analysis and visualization tools; support for metabolomics and shotgun metagenomics analysis; and automated data provenance tracking to ensure reproducible, transparent microbiome data science.

“A core goal of QIIME 2 is to cultivate a diverse and inclusive community of scientists, software engineers, statisticians, educators, students and other microbiome stakeholders who are openly sharing methods, data and knowledge to advance microbiome research.”

A global community effort

Caporaso said QIIME 2 is a community effort that his team is leading. Collaborators on the project represent 77 research institutions from nine countries: Canada, China, Denmark, Germany, Italy, South Korea, the Netherlands, Australia and the United Kingdom.

NAU research software engineers Evan Bolyen, Matthew Dillon and Jai Ram Rideout performed the primary development of QIIME 2, along with postdoctoral scholar Nicholas Bokulich. Additional NAU collaborators include faculty researchers Paul Keim, Emily Cope and Tal Pearson; research staff Jorden Kreps and Charles HD Williamson; and students John Chase, Kestrel Gorlick, Chris Keefe, Ahmad Turan Naimey and Arron Shiffer.

“Advances in microbiome research promise to improve many aspects of our health and our world, and QIIME 2 will help drive those advances by enabling accessible, community-driven microbiome data science,” Caporaso said.

Caporaso and others on the team have already led 25 workshops for QIIME 2 users all over the world, including two workshops at the National Institutes for Health—each one attracting 75 participants—as well as a workshop for 40 students in Copenhagen, Denmark, conducted in June.

To learn more about QIIME 2, visit https://qiime2.org.

Image derived from DOI 10.1038/s41587-019-0209-9 published in Nature Biotechnology. See paper for list of authors.

July 22, 2019

In a world of smart watches, smart homes and smart appliances that monitor their environments to keep users safe and informed, can whole cities be smarter? Short answer: Probably, using cutting-edge information technologies to keep citizens and property safer. The long answer: NAU researchers Eck Doerry and Ben Ruddell aim to find out through their FloodAware project, which allows them to explore what it would mean for a city to be “smart” about floodwater management. 

“We realized that cutting-edge hydrological modeling, image processing and real-time sensing techniques could be brought together to help citizens, city administrators and first responders better react to flooding and, ideally, be warned of imminent flooding before the water arrives” said Doerry, a professor in the School of Informatics, Computing, and Cyber Systems (SICCS). “The system will integrate numerous data streams to calculate real-time maps of current and upcoming flooding and can then send a notification to citizens in endangered areas. This is really what being a smart city means to us: the city keeps an eye on threats and warns citizens in appropriate ways.”

The key to making all of this happen is finding clever, low-cost, low-impact ways to gather accurate water level readings in real-time from as many places around the city as possible.  Most cities, including Flagstaff, already have some flow monitoring equipment placed in various washes and drainages around the city. The challenge in getting more of this equipment is the sensors are so expensive that neither the city nor FloodAware can afford many of them. 

The solution explored by the FloodAware project is to develop smart image processing techniques to determine water level from a simple snapshot image. If this could be done, researchers could piggyback on the hundreds of cameras already in place in the city to control traffic lights, monitor intersections and deploy as public webcams.

Citizens will soon be strongly encouraged to participate in making their city smarter as well. 

“When a simple snapshot image becomes a valuable data point, every citizen with a cell phone will be able to contribute to improving flood map accuracy, as well as get real-time information on flood dangers right on their cell phone,” Doerry said. “Citizen-contributed readings collected in this way can make a huge difference. We’ll never have enough cameras to cover all places that flooding happens. People tend to take pictures of flooding anyway to show their friends, and this could provide a high-volume data stream right when and where we need it, right where flooding is the worst.” 

As the project moves into its second year this fall, residents will be able to download a prototype of the FloodAware mobile app to their smartphones. Whenever they see flooding happening, they can snap a picture with the app, which will use smart image processing to determine the water depth and integrate this reading into the evolving flood maps on the central server. 

This approach to data collection using citizens and their cell phones as a powerful data stream is called “crowd-sourcing” and has already proven its value in numerous other contexts. For instance, the popular traffic navigation app Waze uses crowdsourcing to generate timely and accurate information on urban traffic flows to help users avoid slow-downs or jams.

“The city is excited to partner with NAU in developing technologies that will help with public safety and designing flood resilient communities,” said Edward Schenk, stormwater section project manager for the city of Flagstaff. “The timing of this study works well with moving forward with the Rio de Flag Flood Control Project and the rapid expansion of our own real-time rain and stream gauge flood alert system. The camera system can work well in neighborhoods historically known to flood, while traditional stream gauges can continue to provide flood monitoring in the washes and streams, combining these two sources of data will help scientists and engineers determine how to improve storm water drains, pipes and detention basins.”

In the initial year of the project, the focus has been on developing the fundamental technologies and algorithms needed to make FloodAware a reality. In addition to the city’s traffic control cameras around town, the team has developed specialized solar-powered camera systems that will allow them to explore what kinds and resolution of images are best suited to drive the smart image processing algorithms that determine water level from a snapshot. A total of 10 of these cameras are being installed in flood-prone locations in Flagstaff and Phoenix.

These cameras, which don’t move or take video and are narrowly focused at the curb level, will take and upload snapshots at frequencies ranging from once every 24 hours to a maximum of once per minute during heavy rain events. The snapshots are sent to the central FloodAware server, which applies artificial intelligence and other algorithms to determine the water level at that point. Combining all such values from all cameras will allow the system to generate a real-time flood map. From there, feeding all current water levels into the real-time modeling system will allow predictions of imminent flooding. The flood maps generated in this way would then be made available, both through a website and the FloodAware mobile app, to city officials, first responders and citizens.

Put all of this together, Doerry said, and you get the big picture: Creating a simple “shrink-wrapped” flood monitoring solution complete with camera recommendations, algorithms and tools needed so any city manager anywhere in the country can easily connect their community into a nationwide FloodAware smart city network. In the even bigger picture, having thousands of FloodAware smart cities online across the nation will provide enormous new streams of high value urban water flow data to feed the national water model being developed at NOAA’s new National Water Center with the ambitious goal of understanding water movement across the entire surface of our nation.

The FloodAware project is funded through a Smart & Connected Communities (S&CC) grant from the National Science Foundation (#1831475). The purpose of the S&CC program is to use innovative technology to make U.S. cities smarter and make life in urban areas more efficient, safe and fast. It also requires grantees to discuss how to make their project sustainable in the long-term for their and city and others throughout the country.

“The city of the future will be smart and connected, and that includes connecting people with much more rapid and more accurate information about flooding in their community,” Ruddell said.

People interested in learning more about FloodAware can contact Doerry and Ruddell at Benjamin.ruddell@nau.edu and Eck.Doerry@nau.edu. In the meantime, keep an eye out for the flood cameras, flood gauge signs posted at key washes and flooding areas around Flagstaff and Phoenix.