Research Highlights

Several years ago, while studying the environmental impacts of large-scale solar farms in the Nevada desert, Desert Research Institute (DRI) scientists Yuan Luo, Ph.D. and Markus Berli, Ph.D. became interested in one particular question: how does the presence of thousands of solar panels impact desert hydrology?

In the study, Luo, Berli, and colleagues Teamrat Ghezzehei, Ph.D. of the University of California, Merced, and Zhongbo Yu, Ph.D. of the University of Hohai, China, make important improvements to our understanding of how water moves through and gets stored in dry soils by refining an existing computer model.

The model, called HYDRUS-1D, simulates how water redistributes in a sandy desert soil based on precipitation and evaporation data. A first version of the model was developed by a previous DRI graduate student named Jelle Dijkema, but was not working well under conditions where soil moisture levels near the soil surface were very low.

To refine and expand the usefulness of Dijkema’s model, Luo analyzed data from DRI’s SEPHAS Lysimeter facility, located in Boulder City, Nev. Here, large, underground, soil-filled steel tanks have been installed over truck scales to allow researchers to study natural water gains and losses in a soil column under controlled conditions.

Read the full story from Desert Research Institute here.

The impact of sea surface temperature variations in the tropical Pacific on global climate has long been recognized. For example, the episodic warming of the tropical Pacific during El Niño events causes melt of sea ice in far-reaching parts of the Southern Ocean via its effect on the global atmospheric circulation. A new study, by an international team including University of Hawaiʻi at Mānoa Assistant Professor Malte Stuecker from the Department of Oceanography and International Pacific Research Center, published in Science Advances demonstrates that the opposite pathway exists as well.

Using a hierarchy of climate model simulations, the authors demonstrate the physical pathways through which polar climate variations can affect the trade winds in the tropics.

“Climate signals can propagate from the polar regions to the tropics either via the atmosphere or the ocean,” explained Stuecker. “Our climate model simulations were designed to investigate the relative role of these pathways and whether their importance differs for perturbations originating from the North pole or the South pole.”

Read the full story from University of Hawai’i here.

A new study of airflow patterns inside a car's passenger cabin offers some suggestions for potentially reducing the risk of COVID-19 transmission while sharing rides with others. The study, by a team of Brown University researchers, used computer models to simulate the airflow inside a compact car with various combinations of windows open or closed. The simulations showed that opening windows — the more windows the better — created airflow patterns that dramatically reduced the concentration of airborne particles exchanged between a driver and a single passenger. Blasting the car’s ventilation system didn’t circulate air nearly as well as a few open windows, the researchers found.

“Driving around with the windows up and the air conditioning or heat on is definitely the worst scenario, according to our computer simulations,” said Asimanshu Das, a graduate student in Brown’s School of Engineering and co-lead author of the research. “The best scenario we found was having all four windows open, but even having one or two open was far better than having them all closed.”

Das co-led the research with Varghese Mathai, a former postdoctoral researcher at Brown who is now an assistant professor of physics at the University of Massachusetts, Amherst. The study is published in the journal Science Advances.

Read the full story from Brown University here.

Twice as much freshwater is stored offshore of Hawai'i Island than was previously thought, according to a University of Hawai'i study with important implications for volcanic islands around the world. An extensive reservoir of freshwater within the submarine southern flank of the Hualālai aquifer has been mapped by UH researchers with the Hawai'i EPSCoR 'Ike Wai project. The groundbreaking findings, published in Science Advances, reveal a novel way in which substantial volumes of freshwater are transported from onshore to offshore submarine aquifers along the coast of Hawai'i Island.

This mechanism may provide alternative renewable resources of freshwater to volcanic islands worldwide. "Their evidence for separate freshwater lenses, stacked one above the other, near the Kona coast of Hawai'i, profoundly improves the prospects for sustainable development on volcanic islands," said UH Mānoa School of Ocean and Earth Science and Technology (SOEST) Dean Brian Taylor.

Through the use of marine controlled-source electromagnetic imaging, the study revealed the onshore-to-offshore movement of freshwater through a multilayer formation of basalts embedded between layers of ash and soil, diverging from previous groundwater models of this area. Conducted as a part of the National Science Foundation-supported 'Ike Wai project, research affiliate faculty Eric Attias led the marine geophysics campaign.

Read the full story from the University of Hawai’i here.

Two recently published studies from Kansas State University researchers led by Jürgen A. Richt, the Regents distinguished professor at Kansas State University in the College of Veterinary Medicine, and collaborators have led to two important findings related to the COVID-19 pandemic: Domestic cats can be asymptomatic carriers of SARS-CoV-2, but pigs are unlikely to be significant carriers of the virus. SARS-CoV-2 is the coronavirus responsible for COVID-19.

"Other research has shown that COVID-19-infected human patients are transmitting SARS-CoV-2 to cats; this includes domestic cats and even large cats, such as lions and tigers," said Richt. "Our findings are important because of the close association between humans and companion animals."

For the study involving pigs, the researchers found that SARS-CoV-2-infected pigs are not susceptible to SARS-CoV-2 infection and do not appear to transmit the virus to contact animals.

"This research is important for risk assessment, implementing mitigation strategies, addressing animal welfare issues, and to develop preclinical animal models for evaluating drug and vaccine candidates for COVID-19," Richt said.

Richt is the senior author on the two recent collaborative publications in the journal Emerging Microbes & Infections: "SARS-CoV-2 infection, disease and transmission in domestic cats" and "Susceptibility of swine cells and domestic pigs to SARS-CoV-2."

Read the full article here

A new study led by the University of Hawai‘i at Mānoa’s Hawai‘i Institute of Marine Biology (HIMB) revealed that diversity in Hawaiian corals is likely driven by co-evolution between the coral host, the algal symbiont, and the microbial community.

As coral reef ecosystems have rapidly collapsed around the globe over the past few decades, there is widespread concern that corals might not be able to adapt to changing climate conditions, and much of the biodiversity in these ecosystems could be lost before it is studied and understood. Coral reefs are among the most highly biodiverse ecosystems on earth, yet it is not clear what drives speciation and diversification in the ocean, where there are few physical barriers that could separate populations.

The team of researchers used massive amounts of metagenomic sequencing data to try to understand what may be some of the major drivers of adaptation and variation in corals.

“Corals have incredible variation with such a wide range of shapes, sizes, and colors that it’s really hard for even the best trained experts to be able to sort out different species,” said Zac Forsman, lead author of the study and HIMB assistant researcher. “On top of that, some corals lose their algal symbionts, turning stark white or ‘bleached’ and die during marine heatwaves, while a similar looking coral right next to it seems fine. We wanted to try to better understand what might be driving some of this incredible variation that you see on a typical coral reef.”

Read the full story from University of Hawai’i here.

New University of Montana research suggests recurring continent-spanning drought patterns set the tempo for forest recovery from wildfire.

A study published Nov. 9 in the Proceedings of the National Academy of Sciences shows that forest recovery from fire follows a drought seesaw, called a climate dipole, that alternates between the Northwest and the Southwest every few years.

The researchers examined the relationship between this drought seesaw and post-fire regeneration of ponderosa pine across the Interior West of the U.S. They found that severe droughts under climate change are making it increasingly difficult for tree seedlings to regenerate after fire.

"Managers and scientists are increasingly concerned that western forests won't be able to recover from wildfire under hotter and drier conditions," said Caitlin Littlefield, the study's lead author. "Forest recovery hinges on the success of tree seedlings, which are particularly vulnerable to drought. We wanted to explore how patterns in drought variability across the western U.S. affect post-fire tree regeneration to better understand where and when we can predict robust recovery—or lack thereof."

The authors used annual ponderosa pine regeneration data from a previous UM study led by Kimberley Davis, as well as U.S. Forest Service inventory data. They examined the relationship between ponderosa pine regeneration and the dynamics of the dipole.

Read the full story from Phys.org here.

Researchers from around the world, including the University of Montana, have long observed the movements and behavior of animals in the Arctic, but have had difficulty discovering and accessing data. To solve the problem, an international team led by Sarah Davidson, data curator at the Max Planck Institute of Animal Behavior in Radolfzell, Germany, and Gil Bohrer, professor at Ohio State University, established the global data archive for studies of animal migration in the Arctic and sub-Arctic. It currently contains over 200 projects and movement data of more than 8,000 marine and terrestrial animals from 1991 to the present.

The archive, hosted on the Max Planck Institute’s Movebank platform and funded by NASA, helps scientists share their knowledge and collaborate on questions on how animals are responding to a changing Arctic – particularly important because the Arctic region extends around the world. Researchers from more 100 universities, government agencies and conservation groups across 17 countries are involved in the archive.

UM contributors include Professor Mark Hebblewhite, graduate student Stephen Lewis and former postdoctoral researcher Eliezer Gurarie. Their research is part of Hebblewhite’s funded NASA Arctic Boreal Vulnerability Experiment project that studies the effects of rapid climate change on wildlife in the Arctic, with a focus on caribou.

“UM has a long history, pioneered by researcher Steve Running, of understanding consequences of climate change to ecosystems, and this work builds on this important legacy in a region of the world undergoing some of the fastest rates of climate change, fires and impacts on people and nature,” said Hebblewhite, who studies ungulate habitat ecology.

Three recent studies from the archive reveal large-scale patterns in the behaviors of golden eagles, bears, caribou, moose and wolves in the region and illustrate how the archive can be used to recognize larger ecosystem changes. The results were published Nov. 6 in an article in Science, one of world’s premier scientific journals.

Read the full story from University of Montana here.

Fair-weather fliers may be braving stormy weather when love is on the line and on the clock, says new research from the University of Nebraska–Lincoln. Of the billions of birds that migrate annually, punching tickets for the tropics in the fall and northerly latitudes in the spring, the majority take to the skies only after the horizon has consumed the last slice of sun. And with good reason. At night, the flocking migrants often contend with less turbulence and fewer predators. But their nocturnal flight schedules can’t put them beyond the reach of another potential peril: thunderstorms.

Nebraska’s Matthew Van Den Broeke can spot the signatures of those migrating flocks on meteorological radar “pretty much every night” in the spring and fall, he said. A few years ago, the associate professor of Earth and atmospheric sciences realized that a recent advance in radar technology was offering an opportunity to meld his lifelong love of weather with his interest in ecology.

With help from graduate student Timothy Gunkel, Van Den Broeke set out to study how nocturnally migrating birds in eastern Nebraska, southern Indiana and eastern Iowa responded to isolated thunderstorms between 2013 and 2019.

More than 70% of the time in Nebraska and Indiana, meteorological radar revealed that the density of migrating birds was substantially lower in a thunderstorm’s wake — the stretch that the storm had just passed through. Van Den Broeke said the finding suggests that migrating birds in those areas may be going to the ground, or at least under the meteorological radar, to avoid danger when storms are overhead.

When the researchers compared the effect by season, though, they discovered a potentially telling difference: The reduction in density was measurably greater in the fall than the spring.

Read the full story from University of Nebraska-Lincoln here.

University of Arkansas researchers have established a link between climate patterns in the Amazon and large parts of North and South America using their newly developed tree-ring chronology from the Amazon River basin.

The discovery helps researchers better understand large-scale climate extremes and the impact of the El Niño phenomenon.

Tree growth is a well-established climate proxy. By comparing growth rings in Cedrela odorata trees found in the Rio Paru watershed of the eastern Amazon River with hundreds of similar chronologies in North and South America, scientists have shown an inverse relationship in tree growth, and therefore precipitation patterns, between the areas. Drought in the Amazon is correlated with wetness in the southwestern United States, Mexico and Patagonia, and vice versa.

The process is driven by the El Niño phenomenon, which influences surface-level winds along the equator, researchers said. El Niño is the name given to a large-scale irregularly occurring climate pattern associated with unusually warm water in the Pacific Ocean.

“The new Cedrela chronologies from the Amazon, when compared with the hundreds of tree-ring chronologies in temperate North and South America, document this Pan American resonance of climate and ecosystem extremes in the centuries before widespread deforestation or human-caused climate change,” said Dave Stahle, Distinguished Professor of geosciences and first author of a study documenting the findings in the journal Environmental Research Letters.

Read the full story from University of Arkansas here.