Feb 1, 2023 | Announcements, News releases
Wildfires Are Increasingly Burning California’s Snowy Landscapes and Colliding with Winter Droughts to Shrink California’s Snowpack
February 1, 2023
RENO, Nevada
Wildfires
Winter Drought
Snowpack
Above: Burned trees on a snowy mountain. The trees in the photo were burned by the Caldor Fire.
A new study shows that midwinter dry spells lead to dramatic losses of winter snowpack in burned areas
The early pandemic years overlapped with some of California’s worst wildfires on record, creating haunting, orange-tinted skies and wide swathes of burned landscape. Some of the impacts of these fires are well known, including drastic declines in air quality, and now a new study shows how these wildfires combined with midwinter drought conditions to accelerate snowmelt.
In a study published Jan. 20 in Geophysical Research Letters, a DRI-led research team examined what happens to mountain snowpacks when sunny, midwinter dry spells occur in forests impacted by severe wildfire. The researchers found a substantial increase in wildfires burning in California’s snowy landscapes throughout 2020 and 2021, when large blazes like the Dixie, Caldor, and Creek fires concentrated in snow zones. Using a 2013 midwinter dry spell as comparison, they found that similar weather in the winter of 2021-2022 led to 50% less snow cover. The compounding impacts of wildfire on snow melt include an increase in sun exposure due to loss of forest canopy, and a reduction in the snow’s ability to reflect sunlight.
“It’s already established that wildfires are increasing spring snow melt, but we wanted to know what happens when you add a long winter dry spell on top of that,” said Arielle Koshkin, M.S., a Ph.D. student now at the Colorado School of Mines who co-led the study as part of her master’s research at DRI and the University of Nevada, Reno. “The Caldor fire burned in our backyard, it was so close to where we live and work. So, the following winter, we wanted to investigate what it looked like.”
Satellite data showed that compared to the 2001-2019 average, 2020 and 2021 saw a nearly ten-fold increase in wildfires burning in California’s seasonal snow zones. “What that implies is that there’s this increasing overlap between the fire and snow and there’s all these cascading and compounding impacts on the system and especially the hydrology,” said Ben Hatchett, Ph.D., a climatologist at DRI who co-led the study with Koshkin. “This huge increase of fire activity in California snowy regions is exactly what we expect to see more of going forward.”
A strong winter drought followed during the winter of 2021-2022, when Tahoe City experienced a 46-day long midwinter dry spell (the second-longest since reliable records began in 1917; the long-term median is 22 days without precipitation). A comparable midwinter drought following a wet start to the winter occurred in 2013, giving the researchers the ability to compare and contrast the impacts under more typical conditions with those that occurred in a severely burnt landscape.
“In 2013 and 2022, we had very similar weather patterns, but we didn’t see notable melt in 2013. And in 2022, we also did not see melt in unburned areas,” Hatchett said. “So that gives two lines of evidence suggesting that it’s the fire and not the meteorology that’s driving this.”
Forests where severe wildfires have burnt the tree canopy have more exposed snowpacks, which enhances the melting caused by sunny days and warm nights (another recent DRI study examined the snowmelt impacts of spring heatwaves). Snowmelt is further exacerbated by the loss of the snowpack’s albedo, or the natural power of white snow to reflect, rather than absorb, the sun’s radiation. Particularly in the winters immediately following a wildfire, snow is dusted with the black carbon of burnt vegetation, which can accelerate snowmelt rates by up to 57%.
The enhanced snowmelt was so pronounced within the perimeter of the Caldor fire that the researchers found a total of 50 fewer days with snow cover in the winter of 2021-2022 – the lowest number of snow cover days on record.
Following a wildfire, “there are two timescales of interest: right after the fire, the loss in albedo really dominates,” said Hatchett. “But impacts from the loss of canopy last for decades, maybe longer if the forest does not recover.”
The enhanced snowmelt midwinter creates challenges for forecasting water availability from the natural snowpack reservoir. During the winter months, water managers need to leave room in reservoirs to prevent flooding; this means that earlier snowmelt may not be captured for later use in the dry season. Studies like this provide water managers with the tools to make more accurate predictions of the timing and magnitude of snowmelt.
“The fires have made major landscape disturbance that we’re not taking into account in our forecasting abilities,” Koshkin said. “I think this study is showing that wildfire impacts are huge, and we need to implement this into our ability to understand how water runs off the landscape. It’s part of our world and it’s increasing and it’s going to affect more snowy places. So, it’s important to make sure that we understand the outcomes in our models and management plans.”
Koshkin plans to expand on this research for her Ph.D. studies by examining regional variation of fire impacts on snow. She notes that how wildfire impacts snowmelt in the Sierra Nevada may look different in Colorado or Idaho, due to different weather and snowpack conditions.
The researchers emphasize that the wildfire impacts seen in this study are the result of high-severity wildfires, and not lower-severity burns like prescribed fires. “This study really highlights the importance of bringing fire back onto our landscape in the sense that we need fire – good fire is the answer to our wildfire problem,” Hatchett says. “Bringing a more natural regime of fire, through prescribed and cultural fire, back onto our landscape will help reduce the likelihood of future severe fire.”
“We can recognize that this could be our new normal,” Koshkin said, “but we also have the ability to adapt and manage and mitigate as much as possible.”
Study authors Arielle Koshkin and Ben Hatchett measure albedo in the Sierra Nevada foothills.
More information:
The full study, Midwinter dry spells amplify post-fire snowpack decline, is available from Geophysical Research Letters: https://doi.org/10.1029/2022GL101235
Study authors include: Benjamin Hatchett (DRI), Arielle Koshkin (DRI/UNR), Kristen Guirguis (Scripps Institution of Oceanography), Karl Rittger (CU Boulder), Anne Nolin (UNR), Anne Heggli (DRI), Alan Rhoades (Lawrence Berkeley National Lab), Amy East (USGS), Erica Siirila-Woodburn (Lawrence Berkeley National Lab), W. Tyler Brandt (Scripps Institution of Oceanography), Alexander Gershunov (Scripps Institution of Oceanography), and Kayden Haleakala (Scripps Institution of Oceanography/UCLA).
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About DRI
The Desert Research Institute (DRI) is a recognized world leader in basic and applied environmental research. Committed to scientific excellence and integrity, DRI faculty, students who work alongside them, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge on topics ranging from humans’ impact on the environment to the environment’s impact on humans. DRI’s impactful science and inspiring solutions support Nevada’s diverse economy, provide science-based educational opportunities, and inform policymakers, business leaders, and community members. With campuses in Las Vegas and Reno, DRI serves as the non-profit research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.
Jan 18, 2023 | Announcements, News releases
A Changing Flood Recipe for Las Vegas
January 18, 2022
LAS VEGAS, Nevada
Urbanization
Climate Change
Flooding
Above: Las Vegas after thunder storm with flood water in November 2019. Photo Credit: 4kodiak, iStock.
A new study shows that urbanization and climate change are changing the strength and seasonality of flooding in the Las Vegas region
Las Vegas, with its rapid urbanization and desert landscape, is highly vulnerable to flooding. For this reason, flood managers have built an extensive system of drainage ditches and detention basins to protect the public. Now, a new study shows how intentional engineering and urban development are interacting with climate change to alter the timing and intensity of flood risk.
In a study published Jan. 6 in The Journal of Hydrometeorology, researchers from DRI, the Clark County Regional Flood Control District, the University of Wisconsin- Madison, and Guangdong University of Technology examine Las Vegas’ changing flood regime. Their results show that flood intensity has increased since the mid-20th century, with an abrupt shift occurring in the mid-1990s. Climate change has also shifted flood seasonality, with the storms and their resultant floods now occurring more frequently in winter, in contrast with the historically stronger summer monsoon season.
“When I looked at the data for annual flood peaks, I could see that something is changing,” said Guo Yu, Ph.D., lead author on the new study and hydrologist at DRI. “I wanted to understand the reason for this change as well as the physical mechanisms driving it, because that will help water managers and the public understand whether such a change will continue in the future, given climate and land use changes here.”
Las Vegas is one of the fastest growing metropolitan regions in the country. In 1950, fewer than 35 thousand people resided in the region; by 2020, that number grew to 2.6 million. Like many cities in the arid Southwest, development centers on the valley floor and spreads up into the natural topography of the surrounding mountains. As concrete and pavement replace more porous desert soils, the risk of flooding in human communities rises – catastrophic floods have caused fatalities as recently as 2022. To mitigate this risk, the Clark County Regional Flood Control District constructed a complex series of storm drains and culverts to capture and direct the flow of water away from populated areas and toward Lake Mead.
Over the same period, climate change has led to shifts in seasonal rainfall patterns. The Southwest has two distinct flood seasons: winter floods produced by atmospheric rivers and summer floods linked to the North American monsoon. Since 1950, daily rainfall amounts have increased in winter and decreased in the summer months.
“Historically, people in Las Vegas haven’t paid as much attention to winter floods as to summer floods,” Yu said. “But our research shows that there will be more frequent winter floods happening because of climate change. This is because the warmer sea surface temperatures on the Pacific coast will cause more atmospheric rivers, like what we’re seeing this January in California. And when these are positioned to bypass the Sierra Nevada mountains, they will very likely hit Las Vegas and cause severe winter rainfall and floods.”
The new research demonstrates an overall picture of shifting intensity and seasonality of floods in Las Vegas. The study authors are continuing to refine their understanding of flood risk in the region with an upcoming study, currently under review, that examines changing rainfall patterns in more detail.
“A lot of research focuses on a single driver – either land use or climate – but in Las Vegas, our study shows that both are changing and interacting with each other,” said Yu.
More information:
The full study, The Nonstationary Flood Hydrology of an Urbanizing Arid Watershed, is available from The Journal of Hydrometeorology: https://doi.org/10.1175/JHM-D-22-0117.1
Study authors include: DRI researchers Guo Yu, Julianne Miller, Benjamin J. Hatchett, and Markus Berli; as well as Daniel B. Wright (University of Wisconsin, Madison); Craig McDougall (Clark County Regional Flood Control District); and Zhihua Zhu (Guangdong University of Technology, Guangzhou, China).
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About DRI
The Desert Research Institute (DRI) is a recognized world leader in basic and applied environmental research. Committed to scientific excellence and integrity, DRI faculty, students who work alongside them, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge on topics ranging from humans’ impact on the environment to the environment’s impact on humans. DRI’s impactful science and inspiring solutions support Nevada’s diverse economy, provide science-based educational opportunities, and inform policymakers, business leaders, and community members. With campuses in Las Vegas and Reno, DRI serves as the non-profit research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.
Nov 29, 2022 | Announcements, News releases
Successful Citizen Science Weather Tracking Effort Goes National, Receives Three Additional Years of Funding From NASA
November 29, 2022
RENO, Nevada
Mountain Rain or Snow
Citizen Science
Weather Tracking
Mountain Rain or Snow Project Invites Community Observers Around the Country to Improve Winter Weather Predictions
Satellite technologies often struggle to differentiate snow from rain near the freezing point in mountainous regions, with impacts on flood predictions, avalanche forecasting, snowpack water storage, and road safety. To help improve these technologies, researchers from Lynker, DRI, and the University of Nevada, Reno are partnering with community observers to track winter storm activity across the country through a project called Mountain Rain or Snow. The project has been so successful at collecting data that demonstrates regional variation in the rain-snow threshold that NASA’s Citizen Science for Earth Systems Program is funding an additional three years.
The project began in 2019 as Tahoe Rain or Snow and expanded last year to include mountain regions across the country. Last winter, more than 1,100 people in the Sierra Nevada, Pacific Northwest, Rocky Mountains, and Northeast submitted real-time reports of rain, snow, or mixed precipitation. Community observers submitted 15,000 observations – a six-fold increase over the previous winter.
“Scientists have noticed that satellite predictions are not as effective as ground-based observations,” says Keith Jennings, Ph.D., water resources scientist at Lynker and the project lead. “Direct observations, made by people, are the most accurate way to discover how precipitation phase varies in time and space. We are filling an important gap with this project.”
Community members sign up to receive alerts when storms with predicted temperatures near freezing are in the forecast, and submit observations of the type of precipitation they are seeing via a web-based mobile phone app. These reports show that the Sierra Nevada region transitions from rain to snow around 36 degrees Fahrenheit, rather than around the freezing temperature of 32 degrees. In the Rockies, the snow-rain threshold is closer to 40 degrees, while it’s around 33 degrees in the Northeast. Expanding the project to include more regions will help scientists understand how the rain-to-snow temperature threshold varies according to local atmospheric conditions, improve scientists’ ability to make locally-relevant predictions, and improve the technology behind rain-snow estimates.
“With the help of community observers, we are amassing a very large database of ground-based observations. These will ultimately help to improve the predictive technologies that satellites use,” says Meghan Collins, M.S., associate research scientist at DRI. “The data the community observers have helped us collect is a big step towards being able to make those improvements. We understand the state of the problem much better now and will use the next three years to advance the solution.”
Mountain Rain or Snow welcomes new community observers as it expands to additional regions this season, including the Eastern Great Lakes; the Wasatch Range around Salt Lake City; and Western Montana around Missoula. To sign up, observers find the keyword that corresponds to their region at www.rainorsnow.org. Then, text the keyword to 855-909-0798 for guidance on how to participate.
Mountain Rain or Snow is a collaboration between Lynker, DRI, and the University of Nevada-Reno. In addition to the large network of community observers, the project team includes: Keith Jennings of Lynker; Monica Arienzo, Meghan Collins, and Benjamin Hatchett of DRI; Anne Nolin of the University of Nevada, Reno; and several student researchers. The group has expertise in hydroclimatology, hydrology, and geospatial analysis.
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About Lynker
Lynker delivers innovative solutions to support global environment security and economic prosperity as a trusted partner to governments, communities, industry, and nonprofits. We are a premier science, engineering, and technology company supporting some of the nation’s most important missions from atmosphere to ocean. We are scientists, engineers, conservationists, divers, observers, developers, technologists, educators, outreach specialists, artists, economists, policy specialists, and managers.
About DRI
The Desert Research Institute (DRI) is a recognized world leader in basic and applied environmental research. Committed to scientific excellence and integrity, DRI faculty, students who work alongside them, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge on topics ranging from humans’ impact on the environment to the environment’s impact on humans. DRI’s impactful science and inspiring solutions support Nevada’s diverse economy, provide science-based educational opportunities, and inform policymakers, business leaders, and community members. With campuses in Las Vegas and Reno, DRI serves as the non-profit research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.
About the University of Nevada, Reno
The University of Nevada, Reno, is a public research university that is committed to the promise of a future powered by knowledge. Nevada’s land-grant university founded in 1874, the University serves 21,000 students. The University is a comprehensive, doctoral university, classified as an R1 institution with very high research activity by the Carnegie Classification of Institutions of Higher Education. Additionally, it has attained the prestigious “Carnegie Engaged” classification, reflecting its student and institutional impact on civic engagement and service, fostered by extensive community and statewide collaborations. More than $800 million in advanced labs, residence halls and facilities has been invested on campus since 2009. It is home to the University of Nevada, Reno School of Medicine and Wolf Pack Athletics, maintains a statewide outreach mission and presence through programs such as the University of Nevada, Reno Extension, Nevada Bureau of Mines and Geology, Small Business Development Center, Nevada Seismological Laboratory, and is part of the Nevada System of Higher Education. Through a commitment to world-improving research, student success and outreach benefiting the communities and businesses of Nevada, the University has impact across the state and around the world. For more information, visit www.unr.edu.
May 3, 2022 | Announcements, News releases
Forecasting
Flood Risk
Winter Storms
Above: During January 2017, a rain-on-snow event caused flooding along the South Fork of the Yuba River in California. Climate change is expected to make such events larger and more frequent.
Study Develops Framework for Forecasting Contribution of Snowpack to Flood Risk During Winter Storms
New research advances effort to create a decision-support tool for reservoir operators and flood managers
Lead author Anne Heggli of DRI digs through deep snow to reach a monitoring site during a 2019 field project at the UC Berkeley Central Sierra Snow Laboratory in the Tahoe National Forest.
Reno, Nev. (May 3, 2022) –In the Sierra Nevada, midwinter “rain-on-snow” events occur when rain falls onto existing snowpack and have resulted in some of the region’s biggest and most damaging floods. Rain-on-snow events are projected to increase in size and frequency in the coming years, but little guidance exists for water resource managers on how to mitigate flood risk during times of rapidly changing snowpack. Their minute-by-minute decisions during winter storms can have long-lasting impacts to people, property, and water supplies.
A new study by a team from DRI, University of California, Berkeley, the National Weather Service, and University of Nevada, Reno, provides the first framework for a snowpack decision support tool that could help water managers prepare for potential flooding during rain-on-snow events, using hourly data from existing snow monitoring stations.
“During rain-on-snow events, the people managing our water resources always have decisions to make, and it’s really challenging when you’re dealing with people’s lives and property and livelihood,” said DRI Graduate Assistant and lead author Anne Heggli, M.S. “With this work, we’re leveraging existing monitoring networks to maximize the investment that has already been made, and give the data new meaning as we work to solve existing problems that will potentially become larger as we confront climate change.”
Lead author Anne Heggli of DRI installing a snow depth sensor at the UC Berkeley Central Sierra Snow Laboratory in the Tahoe National Forest for the 2021-2022 winter.
To develop a testable framework for a decision support tool, Heggli and her colleagues used hourly soil moisture data from UC Berkeley’s Central Sierra Snow Laboratory from 2006-2019 to identify periods of terrestrial water input. Next, they developed quality control procedures to improve model accuracy. From their results, they learned lessons about midwinter runoff that can be used to develop the framework for a more broadly applicable snowpack runoff decision support tool.
“We know the condition (cold content) of the snowpack leading into a rain-on-snow event can either help mitigate or exacerbate flooding concerns,” said study coauthor Tim Bardsley of the National Weather Service in Reno. “The challenge is that the simplified physics and lumped nature of our current operational river forecast models struggle to provide helpful guidance here. This research and framework aims to help fill that information gap.”
“This study and the runoff decision framework that has been built from its data are great examples of the research-to-operations focus that has been so important at the Central Sierra Snow Lab for the past 75 years,” said study coauthor Andrew Schwartz, Ph.D., manager of the snow lab. “This work can help inform decisions by water managers as the climate and our water resources change, and that’s the goal – to have better tools available for our water.”
The idea for this project was sparked during the winter of 2017, when Heggli and her brother were testing snow water content sensors in California. Several large rain-on-snow events occurred, including a series of January and February storms that culminated in the Oroville Dam Spillway Crisis.
“I noticed in our sensors that there were these interesting signatures – and I heard a prominent water manager say that they had no idea how the snowpack was going to respond to these rain-on-snow events,” Heggli explained. “After hearing the need of the water manager and seeing the pattern in the data, I wondered if we could use some of that hourly snowpack data to shave off some level of uncertainty about how the snowpack would react to rain.”
Heggli is currently enrolled in a Ph.D. program at UNR, and has been working under the direction of DRI faculty advisor Benjamin Hatchett, Ph.D., to advance her long-term goal of creating a decision support tool for reservoir operators and flood managers.
The results of this study can next be used to develop basin-specific decision support systems that will provide real-time guidance for water resource managers. The study results will also be used in a new project with the Nevada Department of Transportation.
“Anne’s work, inspired by observation, demonstrates how much we still can learn from creatively analyzing existing data to produce actionable information supporting resource management during high-impact weather events as well as the value of continued investment to maintain and expand our environmental networks,” said Hatchett, DRI Assistant Research Professor of Atmospheric Science.
More information:
The full text of the study, Toward snowpack runoff decision support, is available from iScience: https://www.cell.com/iscience/fulltext/S2589-0042(22)00510-7.
This project was funded by University Corporation for Atmospheric Research’s COMET Outreach program, Desert Research Institute’s Internal Project Assignment program, and the Nevada Space Grant Consortium Graduate Research Opportunity Fellowship. Study authors included Anne Heggli (DRI), Benjamin Hatchett (DRI), Andrew Schwartz (University of California, Berkeley), Tim Bardsley (National Weather Service, Reno), and Emily Hand (University of Nevada, Reno).
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About DRI
The Desert Research Institute (DRI) is a recognized world leader in basic and applied environmental research. Committed to scientific excellence and integrity, DRI faculty, students who work alongside them, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge on topics ranging from humans’ impact on the environment to the environment’s impact on humans. DRI’s impactful science and inspiring solutions support Nevada’s diverse economy, provide science-based educational opportunities, and inform policymakers, business leaders, and community members. With campuses in Las Vegas and Reno, DRI serves as the non-profit research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.
Apr 4, 2022 | Announcements, News releases
Reno, Nev. (April 4, 2022) – DRI scientist Benjamin Hatchett, Ph.D., has been honored with the 2022 Rising Researcher Award from the Nevada System of Higher Education (NSHE) Board of Regents, in recognition of his early-career accomplishments and potential for future advancement in Earth and environmental sciences.
Hatchett is an Assistant Research Professor in DRI’s Division of Atmospheric Sciences and specializes in hydrometeorology and hydroclimatology of dryland and alpine regions spanning the past, present, and future.
“I am honored to receive this award from the NSHE Board of Regents,” Hatchett said. “I look forward to continuing to shift my efforts towards scientific activities with tangible, actionable outcomes and appreciate this recognition of my accomplishments.”
During the past decade, Hatchett has worked on Great Basin paleoclimate and paleohydrologic reconstructions spanning the past 21,000 years; atmospheric modeling of downslope winds (such as Santa Anas) primarily in California but also globally; the observation, analysis, and prediction of western U.S. natural hazards including floods, heat waves, wildfire, drought, air pollution, landslides, and avalanches; strategies to improve communication of weather forecasts in the U.S.; impacts of environmental extremes on human mobility; and projections of 21st-century climate from urban to continental scales with a specific focus on mountain environments along the Pacific Cordillera.
Dr. Hatchett has published 38 articles in a wide variety of peer-reviewed journals and 24 additional peer-reviewed book chapters, non-reviewed articles, and technical reports. He has worked with numerous research teams, partners, and stakeholders to complete projects funded by agencies such as the National Oceanic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration, and the National Science Foundation. He is most proud of his projects that support decision-making and promote climate resilience.
“Dr. Hatchett has excelled not only in publishing his research in peer-reviewed journals, but also in making science accessible to decision-makers and the public via media interviews, public presentations, and STEM outreach,” said DRI Vice President for Research Vic Etyemezian, Ph.D.
In addition to his research, Hatchett is an active mentor and educator to students of Earth and environmental sciences. He co-teaches a course in air pollution at UNR and is an adjunct faculty member at the Lake Tahoe Community College. He has advised several undergraduate students, served on committees for graduate students in both the Atmospheric Sciences and Hydrologic Sciences programs, and is currently advising one Ph.D. student.
Hatchett holds a B.S. in geography with a minor in hydrogeology, an M.S. in atmospheric sciences, and a Ph.D. in geography, all from the University of Nevada, Reno. He joined DRI as a postdoctoral fellow in 2016 under the mentorship of Professors Michael Kaplan and Craig Smith and became an Assistant Research Professor in 2018.
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About DRI
The Desert Research Institute (DRI) is a recognized world leader in basic and applied environmental research. Committed to scientific excellence and integrity, DRI faculty, students who work alongside them, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge on topics ranging from humans’ impact on the environment to the environment’s impact on humans. DRI’s impactful science and inspiring solutions support Nevada’s diverse economy, provide science-based educational opportunities, and inform policymakers, business leaders, and community members. With campuses in Las Vegas and Reno, DRI serves as the non-profit research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.
Feb 25, 2021 | Blog, Featured projects
New DRI projects for 2021 include microplastics, microfossils, snowmelt risk, and solute transport
FEB 26, 2021
RENO & LAS VEGAS, NEV.
Introducing the winners of DRI’s 2021 Institute Project Assignment (IPA) competition.
Each year, the Desert Research Institute awards funding to several new faculty and staff projects each year through its Institute Project Assignment (IPA) competition. Winners of the IPA competition receive a research grant from DRI to pursue a topic that interests them and develop ideas that can ultimately be turned into externally funded research projects. This year, winners of the IPA competition are DRI scientists Erick Bandala, Monica Arienzo, Sandra Bruegger, Benjamin Hatchett, and Lazaro Perez. Details about each project are below.
Erick Bandala and Monica Arienzo: Assessing environmental aging of microplastics
Microplastics, defined as plastic fragments smaller than 5mm, were first discovered in the natural environment in the early 2000s. Two decades later, much is still unknown about these pollutants – including how microplastic particles degrade or break down as they age. A new project led by Erick Bandala, Ph.D., and Monica Arienzo, Ph.D., will assess the environmental aging of microplastic particles through accelerated aging tests, using UV-A radiation to imitate the effects of unfiltered sunlight over different time spans on microplastics of different types, shapes, and sizes. Their results will provide new insight into the fate of microplastics after their release into the environment.
A close-up image of microplastic fibers. Credit: DRI.
Benjamin Hatchett and Anne Heggli: Towards improved decision support for snow-covered watersheds: A snowmelt risk advisory
Rain-on-snow events (in which a warm winter storm rains onto existing snowpack under windy and humid conditions) are linked to many of the largest floods in Nevada and other parts of the United States. These types of events are projected to increase in frequency and magnitude as the climate warms. This change creates new challenges for water managers, who are tasked with deciding when water should be stored in reservoirs for economic and ecological benefits, and when water should be released downstream for flood control and public safety. To help water managers make decisions using the best available data, Division of Atmospheric Sciences graduate student Anne Heggli, advised by Benjamin Hatchett, Ph.D., will design and develop a tool called a Snowmelt Risk Advisory (SRA). This framework will combine risk matrices with weather datasets to create a tool that will help inform reservoir operations in snow-dominated watersheds.
A rain-on-snow event at Kirkwood Ski Area. Credit: Ben Hatchett/DRI.
Sandra Brugger: Microfossils in Greenland Ice – Establishing a new method at DRI
Greenland’s ice sheets hold important records of pollen grains and other microfossils that can provide researchers with insight into long-term environmental change in the Arctic, however, these resources have not yet been studied extensively. Recently, Sandra Brugger, Ph.D., developed a new method for extracting microfossils from Greenland ice cores and created the first reliable record of microfossils from well-dated Greenland ice, with a second record currently under development. With IPA funding, Bruegger will hold a workshop to train additional scientists in her methodology, and develop a microfossil record from east-central Greenland ice spanning the past 8000 years. She will also give a talk to the local community at the Alta Skilled Nursing and Rehabilitation Center in Reno, sharing her research with an audience that has been isolated for months during the pandemic.
DRI scientist Sandra Brugger inspects samples under a microscope. Credit: Manu Friederich.
Lazaro Perez: Tortuosity Characterization via Machine Learning to Quantify Solute Transport in Berea Sandstone
Understanding and predicting the fate of solutes (dissolved substances) as they pass through various types of rocks and soils in a groundwater system is crucial for several environmental and industrial applications, but modeling this process is complex. Building on work completed as part of an IPA-funded project in 2020, Lazaro J. Perez, Ph.D., will use training data for the development of a machine-learning algorithm to predict solute transport through material containing pores of different sizes, such as sandstone. Dr. Perez’s work, focused on solute transport simulations on pore-scale images of two types of sandstones, will help scientists better understand processes as diverse as contaminant transport in groundwater flow and protein diffusion in living cells.
DRI scientist Lazaro Perez.
Aug 25, 2020 | Blog, EEL, Featured projects
DRI scientists investigate effectiveness of heat warnings along US-Mexico border
Anthropology
Meteorology
Climatology
Population Heath
Above: Aerial view of California’s Imperial Valley, where daytime temperatures during summer months can reach as high as 120 degrees. Credit: Thomas Barrat/Shutterstock.com
Featured research by DRI’s Kristin VanderMolen, Ben Hatchett, Erick Bandala, and Tamara Wall
In July and August, daytime temperatures along parts of the US-Mexico border can reach as high as 120 degrees – more than 20 degrees above normal human body temperature. For agricultural workers and others who live and work in the region, exposure to these extreme high temperatures can result in serious health impacts including heat cramps, heat exhaustion, heat stroke, and heat-related death.
Although the National Weather Service and public health organizations issue heat warnings to communicate risk during extreme heat events, heat-related illness and death are still common among vulnerable populations. Now, a group of DRI scientists led by Kristin VanderMolen, Ph.D., Assistant Research Professor with DRI’s Division of Atmospheric Sciences, is trying to figure out why.
“With the continued increase in episodes of extreme heat and heat waves, there has been an increase in warning messaging programs, yet there continue to be high numbers of heat-related illness and death in communities along the US-Mexico border,” VanderMolen said. “So, there’s this question – if agencies are doing all of this messaging, and people are still getting sick and even dying, then what’s going on?”
An agricultural field in California’s Imperial Valley, where DRI researchers are exploring questions about heat messaging and vulnerability in populations of agricultural workers and others who are vulnerable to heat-related illness and death.
Credit: Winthrop Brookhouse/Shutterstock.com
Assessing heat messaging: An interdisciplinary approach
In 2018, VanderMolen and colleagues Ben Hatchett, Ph.D., Erick Bandala, Ph.D., and Tamara Wall, Ph.D. received funding from NOAA’s International Research and Applications Project (IRAP) to explore questions about heat messaging and vulnerability in two pairs of US-Mexico border cities, San Diego-Tijuana and Calexico-Mexicali. Collectively these areas form the boundaries of the Cali-Baja Bi-national Megaregion. This unique transboundary location integrates the economies of the United States and Mexico, exporting approximately $24.3 billion worth of goods and services each year.
With expertise in the areas of anthropology, meteorology, climatology, and population health, this interdisciplinary team of researchers is now working on this problem from several angles. They are using climate data to characterize and assess past heat extremes as well as using long-range weather forecasts and climate projections to help improve the ability to put out advance messaging about future heat waves. They are working to identify and map populations that are particularly vulnerable to extreme heat and are collaborating with local agencies to understand why people may or may not take protective action during heat waves.
From initial conversations with local civic organizations and public health agencies, the team has learned that the reasons people may not be following heat warnings are complex. Recommended actions such as “stay indoors and seek air-conditioned buildings,” or “take longer and more frequent breaks,” may not be realistic for agricultural workers or others who don’t have access to air-conditioned spaces. There can even be negative consequences for those who choose to seek medical help.
“A big piece of the story that we’ve heard from some of the independent groups that work with agricultural workers in the region is that if someone gets sick and doesn’t show up for work, they can lose their job,” Hatchett explained. “If they go to the hospital and somebody sees them or hears about it, they can lose their job. There are some really big issues related to people not feeling okay with trying to get the help they need.”
“There is evidence to suggest that cases of heat-related illness and death are underreported, probably severely underreported,” VanderMolen added. “The demographics of the individuals for documented cases don’t reflect the population demographics overall. We know that there are a lot of inequalities in that area that may get in the way of people reporting illness.”
A map of summer maximum near-surface temperatures over the 30-year period from 1981–2010 shows that Imperial Valley (at the border between Mexico and the southeastern corner of California) is the hottest place in in North America, with an average maximum temperature from June to August of 40° Celsius (104° Fahrenheit). Data is from the North American Regional Reanalysis.
COVID-19 complications and next steps
Originally, VanderMolen was planning to travel to the US-Mexico border this summer to do one-on-one interviews with members of vulnerable populations, but the COVID-19 pandemic has resulted in unforeseen complications.
Imperial County has been hit very hard by COVID-19, compounding the effects of extreme heat for the vulnerable populations that VanderMolen and her team hope to work with. The pandemic has also made it unfeasible to travel to the region to do face-to-face interviews, and has created challenges in coordinating with local agencies that are now overwhelmed in their efforts to address COVID-19.
“It’s a really interesting place and time to do this work because there are questions about what it means to be on stay-at-home orders and limited travel orders when it’s 114 degrees outside and you don’t have reliable air conditioning or its cost is prohibitive,” VanderMolen said. “At the same time, because they’re so overwhelmed right now with caseload, most folks in the area can’t really afford to address issues beyond COVID-19.”
As the research team works to navigate a path forward that is safe for both the interviewers and interviewees, they remain committed to developing information that will help vulnerable populations along the border.
“I hope that the information we provide is something decision-makers can use to make the right decision or create legislation that can help protect workers in the field, or at least call attention to the kind of inequalities and risk that the people there are being exposed to,” Bandala said. “Or, if we can produce information to change the mindset of the people to start thinking of themselves as a population at risk, and put more attention on the heat warnings, that will suffice for me to feel satisfied with the results of our research.”
The US-Mexico border is just one of many places around the globe where heat-related illness is a problem, added Hatchett – and many of those places happen to be where a lot of our food is grown or where important industries are located.
“I think this is a somewhat ubiquitous problem around the planet. We have these really important places that are susceptible to environmental extremes and these people that we rely on to have these regions be productive in terms of agriculture or industry. Unfortunately, those people are often the most susceptible and underserved populations to these compound environmental hazards,” Hatchett said. “It’s so easy to forget them, but one of the goals of this project is really to bring to light the importance of aiming much-needed resources at trying to help those populations and those places.”
Apr 28, 2020 | Blog, Featured researchers
Benjamin Hatchett, Ph.D., is an assistant research professor in the Division of Atmospheric Sciences at the Desert Research Institute in Reno. Ben has been a member of the DRI community since 2005 when he began as an undergraduate lab assistant. He holds a Bachelor’s degree in geography, Master’s in atmospheric sciences, and Ph.D. in geography, all from the University of Nevada, Reno. Ben specializes in dryland and alpine hydroclimatology and hydrometeorology. In addition to his research and teaching, he enjoys watching the sunrise with a cup of coffee before going backcountry skiing, climbing, or mountain biking in the Sierra Nevada.
DRI: You’ve been in Reno for some time now. Could you tell us about what brought you to Reno originally and your educational background?
BH: I came to the University of Nevada as an undergraduate. I was always planning on going to Montana State, but I grew up snowboarding on Donner Summit, and friends and I would ride Boreal for the night sessions. I remember riding there one night, in the evening when the sun was setting and everything was purple and pink in alpenglow, and I thought, I just can’t leave. This is where I’m from, and this is what I do, and I want to keep doing this. And I can go to school right down the street from here. Perfect! So, that’s what brought me to UNR.
During my time as an undergrad, I took the full sequence of avalanche safety courses because I’d gotten really into being in the backcountry. Those courses started convincing me that I needed to learn more about meteorology, then I spent a summer in Chamonix, which reinforced that idea. Skiing in the Alps, in an environment so different than the Sierra Nevada with huge glaciers and extreme hazards, and seeing how fast the weather changed there, made me realize that I really needed to learn more about weather and its relationship to snow science.
DRI: Now you do quite a bit of work related to avalanches. What does that research involve, and what are the big questions?
BH: My goal is to better apply what we know about meteorology to understand the timescales and prediction skill for avalanches and how we can use that to minimize risk. Subtle changes in weather, like wind direction or snow crystal shape, can quickly create massive changes in the safety of a slope and the state of a given snowpack. As soon as you want to apply what you know about snow to understand its relation to the mountain environment, you need meteorology so you can say, for example, this is the sort of storm that can create large and widespread avalanche activity, thus we’ll need extra patrollers at the resorts.
For me, it all comes from the question: where’s the best safe place to ski and why? So much of my work is seeing something interesting while I’m in the mountains and thinking “I wonder why that happened?” For example, why did that slope slide when another didn’t? How does that tie into the meteorological history of the snow season?
A skier poses on the massive pile of snow and debris left behind by the Valentine’s Day 2019 avalanche on Mt. Shasta. Credit: Ben Hatchett.
DRI: Can you tell us about one of those times you saw something interesting out in the field and investigated it?
BH: Probably the best recent example I have is the avalanche that took place on Valentine’s Day 2019 on Mt. Shasta. In late June of last year, we skied up what was left after the avalanche, a fifty-foot-tall pile of debris. Skiing up it and seeing the remnants many months later was really striking and made me want to look further into it.
The big question that folks in my field were speculating about was when it happened, because that can tell us a lot about why it happened. I thought of checking the seismic network to see if it would have registered there, and sure enough, it did! This allowed us to pinpoint the time of the slide to the second it occurred. From there, we could evaluate all the other information we typically look at, like wind speed and direction, precipitation phase, and temperature, and begin to make more-informed hypotheses about what caused the avalanche.
DRI: Have you seen that snowpacks, and the potential for avalanches, are changing under warming climate conditions?
BH: Climates have always changed, but what we’re seeing now across mountain landscapes is something different. We have background warming, which is causing more precipitation to fall as rain instead of snow in middle and lower elevation mountains. This warming is also causing fewer freezing nights in the spring, which goofs up our historically awesome spring skiing. We’re seeing more extreme loading events, with lots of snow falling all at once, but also more prolonged (and warmer) dry spells. High elevation rain-on-snow events are becoming more frequent, which creates an unstable surface for additional snowfall once they freeze. All of this favors weaker snowpacks, which suggests more, and larger, avalanches may be possible.
I’m working on an article right now related to this and the future of skiing. As lower elevation snowpacks disappear, more skiers and snowboarders are pushed into the higher elevations, where conditions are often sketchier and more objectively hazardous. With more people recreating in a relatively small area, there’s a greater likelihood that people will be exposed to avalanches.
This graphic shows that snowpack accumulation is taking longer and longer–it’s now happening about 15 days later in the season than it did in 1985. Credit: Ben Hatchett.
DRI: What’s happening with our snowpack in the Sierra Nevada this year?
BH: This winter is a classic “what the heck?!” winter. It started off very dry, with well-below normal precipitation into November. Then we had a warm, wet storm around Thanksgiving to get us back to “normal” mid-winter conditions up high. Throughout December, the storms we got were cold enough to accumulate a healthy, above-average snowpack. January was very dry, but we had a few nice cold storms. This was followed by one of the driest Februaries on record. Basically, we enjoyed spring skiing conditions in February and early March that are more typical of April. Mid-March brought us an ideal snow-producing storm that did wonders for the ski conditions and made a nice dent in the snowpack deficit. So far, April has brought us another decent storm. These spring storms help to create interesting avalanche situations as the sun becomes increasingly intense and temperatures warm. While we’re still looking likely to end up with a below-average year, compared to the other recent drought years this season has far and away had the best ski conditions.
This winter, along with the other variable winters we’ve seen in the last decade, makes me wonder whether this is the jumping off point into a new kind of mountain recreation landscape, where we can go from excellent conditions to something that’s not so great in no time. I think the Sierra Nevada, and other maritime mountain ranges, are going to continue to become more susceptible to changes in weather and climate variability.
DRI: What drives you to continue doing this work?
BH: Just being in the mountains and trying to pick the optimal weather conditions for ski runs or mountain bike rides has been a huge motivation for my research. I’m most mentally productive when I’m climbing up mountains. You’re able to just let go of everything when you’re spending several hours going up a hill, whether that’s on skis, on a trail, on rock, wherever! It gives you a lot of time to think, observe, and consider.
I’m always trying to see new things and then better understand what I’ve seen. As a backcountry enthusiast, you get to see all kinds of interesting environments with different kinds of weather, geology, as well as human relationships to those places. Wanting to protect alpine environments and get other people psyched on them inspires my research quite a bit.
Lake Tahoe. Credit: Ben Hatchett.
Jan 22, 2019 | News releases, Research findings
Reno, Nev. (January 22, 2019): For meteorologists, effectively communicating weather forecasts and their related dangers is essential in maintaining the health, safety, and resilience of communities. A new study published by a team of researchers from the University of Nevada, Reno (UNR), the Desert Research Institute (DRI), and the National Weather Service (NWS) Reno suggests that effective communication isn’t only about sharing information on upcoming weather events—it’s about building trust and common ground between forecasters and the public.
A common focus of science communication research is the difficulty of communicating technical information about weather forecasts to the public, including the likelihood that the forecasted events will actually come to pass. However, personal risks and uncertainty about potential impacts also affect how people respond to and act upon information about subjects like weather forecasts.
In a study published in the Bulletin of the American Meteorological Society, researchers sought to investigate the effect of personal uncertainties on people’s responses to weather forecasts by analyzing posts by the NWS Reno on Facebook. Researchers analyzed a total of 470 Facebook posts by the NWS Reno and 6,467 user comments on the posts about high impact weather events from January to May 2017. This range overlapped with the Reno area’s record wet period during from October 2016 to April 2017, a time when the region’s residents were impacted by several high impact weather events.
The team’s analysis showed that the public’s uncertainty about weather forecasts isn’t usually technical—more often, it’s personal.
“The NWS Reno’s Facebook community engages far less with the technical uncertainties of forecasts than with the personal risks implied in those forecasts,” said Kathryn Lambrecht, Ph.D., lead author on the study and Assistant Director of the Composition and Communication in the Disciplines program at UNR. “People in this community frequently use the NWS posts to share their own experiences with weather, express concern, and reach out to family and friends, not to calculate the technical likelihood of a forecast.”
What’s more, this study’s results showed that posts that used “commonplaces”—or expressions of common values or norms among a community—generated the strongest responses, many of which acknowledged a connection or understanding between the NWS Reno and its followers on Facebook.
Most of the population in the Reno area is located in valleys where it only snows occasionally. Feet of snow can fall in the higher elevations of the Sierra Nevada with the Reno area receiving little to no snow accumulation, so the public often asks “Is it really going to snow down here [in the valley]?” The commonplace “down here” was added to what became a widely shared and commented forecast graphic on the NWS Reno Facebook page.
Because high-impact weather events can severely impact life and property, it is imperative that the public trusts the information coming from the National Weather Service or emergency managers. Commonplaces, this study revealed, can be an effective way for forecasters to build trust with the community and encourage behavioral changes—like changing driving routes or stocking up on sandbags—that ultimately promote public safety.
From here, the team is considering applying for more funding in order to scale up their research and see if their results are consistent in other regions beyond the Reno area.
Researchers on this study included a meteorologist, an atmospheric scientist, a STEM education expert, and a pair of rhetoricians, scholars who study how communication forms communities—an unusual combination of disciplines.
“Past research has shown that science communication benefits from bringing together multiple types of expertise,” Hatchett said. “Our group came together organically, and the result was a highly transdisciplinary project. Personally, I think it is one of the most unique and collaborative projects I have been a part of, which made it even more fun.”
This project was supported by the Nevada NASA Space Grant Consortium and the Desert Research Institute.
The full study, titled “Improving Visual Communication of Weather Forecasts with Rhetoric” is available online from the Bulletin of the American Meteorological Society: https://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-18-0186.1
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The Desert Research Institute (DRI) is a recognized world leader in basic and applied interdisciplinary research. Committed to scientific excellence and integrity, DRI faculty, students, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge, supported Nevada’s diversifying economy, provided science-based educational opportunities, and informed policy makers, business leaders, and community members. With campuses in Reno and Las Vegas, DRI is one of eight institutions in the Nevada System of Higher Education.
Nevada’s land-grant university founded in 1874, the University of Nevada, Renoranks in the top tier of best national universities by U.S. News and World Report and is steadily growing in enrollment, excellence and reputation. The University serves nearly 22,000 students. Part of the Nevada System of Higher Education, the University is home to the University of Nevada, Reno School of Medicine, University of Nevada Cooperative Extension and Wolf Pack Athletics. Through a commitment to world-improving research, student success and outreach benefiting the communities and businesses of Nevada, the University has impact across the state and around the world. For more information, visit www.unr.edu.
Jan 3, 2019 | News releases, Research findings
Reno, Nev. (January 3, 2018): To protect communities in arid landscapes from devastating wildfires, preparation is key. New research from the Desert Research Institute (DRI) in Reno may aid in the prevention of large fires by helping meteorologists and fire managers in the Southwestern U.S. to forecast periods of likely wildfire activity.
Each summer, from June through September, a weather pattern called the North American monsoon brings thunderstorms to the Southwestern U.S., with lightning that often sparks wildfires.
The new study, which published in the International Journal of Climatology, examined twenty common weather patterns that occur during the North American monsoon season, and identified relationships between certain weather patterns and times of increased fire activity.
One of the most problematic weather patterns, the team learned, was when dry and windy conditions gave way to lightning storms in May and June – a time when fuels tended to be at their driest and monsoon rains had not yet soaked the region with added moisture. When lightning storms were followed by another hot, dry, windy period, increased fire activity was even more likely.
“A lot of fire meteorologists know from experience that this is how things happen, but our study actually quantified it and showed how the patterns unfold,” said lead author Nick Nauslar, Ph.D., who completed this research while working as a graduate student at DRI under Tim Brown, Ph.D. “No one had ever really looked at large fire occurrence in the Southwest and how it related to atmospheric patterns.”
To identify problematic weather patterns, Nauslar and his team looked at monsoon season weather data collected from April through September over the 18-year period from 1995-2013. They then classified wildfire activity over the same period into days or events that were considered “busy” by fire managers in their study area, and used an analysis technique called Self-Organizing Maps to detect relationships between the two datasets.
In addition to identifying relationships between specific weather patterns and fire activity, their analysis also looked for patterns in wildfire occurrence and fire size throughout the season. Analysis of more than 84,000 wildfires showed that although July was the month that the most wildfires occurred, wildfires that occurred during the month of June (prior to the arrival of much monsoonal moisture) were more likely to develop into large fires. In July and August, when the heaviest monsoonal precipitation typically occurs, the percentage of fires that developed into large fires decreased.
“Our goal with this study was to provide fire weather meteorologists in the region with information to help inform fire forecasts, and I think we were able to identify some important patterns,” said Brown, Director of the Western Regional Climate Center at DRI.
Nauslar, who is now employed as a mesoscale assistant and fire weather forecaster for the National Oceanic and Atmospheric Administration (NOAA) Storm Prediction Center in Norman, Oklahoma, hopes that the findings of this study will help fire managers in the Southwest to proactively identify periods when wildfires are more likely to occur, and to allocate firefighting resources accordingly.
“I think a lot of what we learned confirms forecaster experience about the types of atmospheric patterns that are problematic with regard to wildfire occurrence in the Southwest,” Nauslar said. “I hope that people in operations can really use this information, and help refine it and build upon it.
Other DRI scientists who contributed to this research included Benjamin Hatchett, Ph.D., Michael Kaplan, Ph.D., and John Mejia, Ph.D. The full study, titled “Impact of the North American monsoon on wildfire activity in the southwest United States,” is available online from the International Journal of Climatology: https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/joc.5899
The Desert Research Institute (DRI) is a recognized world leader in basic and applied interdisciplinary research. Committed to scientific excellence and integrity, DRI faculty, students, and staff have developed scientific knowledge and innovative technologies in research projects around the globe. Since 1959, DRI’s research has advanced scientific knowledge, supported Nevada’s diversifying economy, provided science-based educational opportunities, and informed policy makers, business leaders, and community members. With campuses in Reno and Las Vegas, DRI serves as the non-profit research arm of the Nevada System of Higher Education. Learn more at www.dri.edu, and connect with us on social media on Facebook, Instagram and Twitter.
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Jan 7, 2018 | News releases, Research findings
Above: From the east side of Washoe Lake, the view of Slide Mountain and Mount Rose on January 7, 2018, showed the effects of the ongoing snow drought. Warm wet and dry periods in November and a dry period in December created snow drought conditions throughout the region. Credit Benjamin Hatchett, DRI.
Reno, NV (Wednesday, January 17, 2018): The Lake Tahoe Basin and northern Sierra Nevada are currently experiencing a condition known as snow drought, according to new research and data from scientists at the Desert Research Institute (DRI). Snow droughts, or periods of below-normal snowpack, occur when abnormally warm storms or abnormally dry climate conditions prevent mountain snowpack from accumulating.
“As of early January, the snowpack in the Lake Tahoe Basin was only 28 percent of normal,” said Benjamin Hatchett, Ph.D., a postdoctoral researcher with DRI’s Division of Atmospheric Sciences. “We experienced warm wet and dry periods in November and a dry period in December that has created snow drought conditions throughout the region, followed by warm, rainy weather so far in January that has caused snowpack levels to decline further, especially at low elevation sites.”
Snow droughts have become increasingly common in the Sierra Nevada and Cascade mountains in recent years, as warming temperatures push snow lines higher up mountainsides and cause more precipitation to fall as rain.
Hatchett, an avid backcountry skier, began to notice the trend several years ago and recently published research outlining an approximately 1,200-foot rise in the winter snow levels over the last ten years across the northern Sierra Nevada.
Looking deeper into the rising snow levels and a general continued lack of snow in their local region, Hatchett and fellow DRI climate researcher Daniel McEvoy, Ph.D., an assistant research professor of climatology and regional climatologist at DRI’s Western Regional Climate Center (WRCC), sought to expand upon the little that is currently known about snow droughts and their impacts to local watersheds and economies.
In a new study recently published in the journal Earth Interactions, Hatchett and McEvoy explored the root causes of snow droughts in the northern Sierra Nevada, and investigate how snow droughts evolve throughout a winter season. To do this, they used hourly, daily and monthly data to analyze the progression of eight historic snow droughts that occurred in the northern Sierra Nevada between 1951 and 2017.
“We were interested in looking at the different pathways that can lead to a snow drought, and the different implications that each pathway has for mountain systems,” McEvoy explained.
The snow drought of 2017/2018 as observed at Fallen Leaf Lake, Calif. and the Central Sierra Snow Lab in Soda Springs, Calif. Map created by ClimateEngine.org – Powered by Google Earth Engine. Credit Benjamin Hatchett, DRI.
Previous research has used April 1st (the date that snowpack levels, measured as snow water equivalent or SWE, in the Sierra Nevada typically reach a maximum) as the primary date for calculating snow drought, and classified each snow drought as one of two types, warm or dry. “Warm snow drought” years were characterized by above-average levels of precipitation and below-average snow accumulation (SWE); “Dry snow drought” years were characterized by below-average levels of precipitation and below-average snow accumulation (SWE).
Hatchett and McEvoy’s work expanded upon these concepts by examining the progression of snow droughts throughout the entire winter season.
Their results illustrate that each snow drought originates and develops along a different timeline, with some beginning early in the season and some not appearing until later. Snow droughts often occurred as a result of frequent rain-on-snow events, low precipitation years, and persistent dry periods with warmer than normal temperatures. The severity of each snow drought changed throughout the season, and effects were different at different elevations.
“We learned that if you just look at snow levels on April 1st, you miss out on a lot of important information,” McEvoy said. “For example, if you are in a snow drought all winter long and come out of it right at the end due to a few big storms, there are probably implications to that.”
Sometimes, McEvoy explained, snow droughts were found to occur in years with above-average precipitation. For example, in 1997, a powerful atmospheric river storm event led to record-breaking flooding throughout the region – but much of the moisture arrived as rain rather than snow, with detrimental effects on the snowpack.
Climate change is likely to make snow drought an even more common phenomenon in the future, said Hatchett, as temperatures in the northern Sierra Nevada are expected to continue warming.
“There has always been an occasional snow drought year in the mountains, but that was typically the ‘dry’ type of snow drought caused by lack of precipitation,” Hatchett said. “As the climate grows warmer and more precipitation falls as rain instead of snow, we are seeing that we can have an average or above-average precipitation year and still have a well below-average snowpack.”
The implications of snow drought have not yet been studied extensively, but may include impacts to water resources, snowmelt runoff, flooding, soil moisture, tree mortality, ecological system health, fuel moisture levels that drive fire danger, human recreation, and much more. In regions such as the Lake Tahoe Basin, where mountain snowpack sustains wildlife, ecosystems, local economies, and provides crucial water resources to downstream communities throughout the year, the impacts of snow droughts could be enormous.
The last four winters, Hatchett and McEvoy noted, have all exhibited some degree of snow drought in the northern Sierra Nevada. Even the recent huge winter of 2016/17, which ended with far above-average snowpack levels (205% of the long-term median on April 1, 2017 in the Lake Tahoe Basin), began with a period of early-season snow drought during a dry November. This winter has been no exception, with snow drought taking hold over low elevation areas in November, and moving to higher elevation sites in December.
Only time will tell how the 2017/2018 winter season will end, but in the meantime, snow drought is affecting the region in ways that have not yet been fully quantified.
Hatchet and McEvoy hope that their research will prompt further investigations into the potentially devastating impacts of snow drought, and will help to inform regional climate adaptation planning efforts.
“We spend a lot of time going out and skiing, climbing, and hiking in the mountains, which is what inspired us to study these things,” Hatchett said. “We’re seeing and experiencing snow drought first-hand, and we have to quantify it and understand it because these are changing patterns on the landscape that will have massive implications for the mountain environments that we experience each day and the mountain communities that we live in.”
The full version of the study—“Exploring the Origins of snow drought in the northern Sierra Nevada, California”—is available online at –http://journals.ametsoc.org/doi/10.1175/EI-D-17-0027.1
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The Desert Research Institute (DRI) is a recognized world leader in investigating the effects of natural and human-induced environmental change and advancing technologies aimed at assessing a changing planet. For more than 50 years DRI research faculty, students, and staff have applied scientific understanding to support the effective management of natural resources while meeting Nevada’s needs for economic diversification and science-based educational opportunities. With campuses in Reno and Las Vegas, DRI serves as the non-profit environmental research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.
Jul 14, 2017 | News releases, Research findings
RENO, Nev. (July 14, 2017) – Recently published research led by atmospheric scientists at the Desert Research Institute (DRI) demonstrates a connection between the occurrence of atmospheric river (AR) events and avalanche fatalities in the West.
Published in the May issue of the Journal of Hydrometeorology, the pilot study assessed avalanche reports, weather station data, and a catalog of AR data from a previous study to determine that AR conditions were present for 105 unique avalanches between 1998 and 2014, resulting in 123 fatalities (31 percent of all western avalanche fatalities during this time frame).
Atmospheric Rivers, as described by the National Oceanic and Atmospheric Administration (NOAA), are “relatively long, narrow regions in the atmosphere – like rivers in the sky – that transport most of the water vapor outside of the tropics.”
When ARs make landfall on the West Coast of the US they release water vapor as rain or snow, supplying 30 to 50 percent of annual precipitation in the West and contributing to cool season (November to April) extreme weather events and flooding.
Researchers conclude that the intense precipitation associated with AR events is paralleled by an increase in avalanche fatalities. Coastal regions experience the highest percentage of avalanche fatalities during AR conditions; however, the ratio of avalanche deaths during AR conditions to the total number of AR days is actually higher further inland, in states like Colorado and Utah.
“Although ARs are less frequent in inland locations, they have relatively more important roles in intermountain and continental regions where snowpacks are characteristically weaker and less capable of supporting heavy rain or snowfall,” explained Benjamin Hatchett, a postdoctoral fellow of meteorology at DRI and lead author on the study.
“This means that avalanche forecasters, ski resort employees, backcountry skiers, and emergency managers who have an increased awareness of forecasted AR conditions can potentially reduce exposure to resultant avalanche hazards, particularly if snowpack conditions already indicate weakness,” he added.
The study also reports that shallow snowpacks weakened by persistent cold and dry weather can produce deadly and widespread avalanche cycles when combined with AR conditions. Climate projections indicate that this combination is likely to become more frequent in the mid- to late- 21st century, which could create significant avalanche risk to winter backcountry enthusiasts in the West.
“With increasing numbers of recreational backcountry users and changing mountain snowpack conditions, we might expect the future to be characterized by enhanced exposure to avalanche hazard throughout the western United States,” Hatchett said. “Our results provide motivation to further increase public awareness about avalanche threats during AR events.”
Including integrated vapor transport (IVT) forecasting tools in analyses of avalanche danger, researchers suggest, could potentially allow experts to increase the accuracy of avalanche forecasts when AR conditions are present. These tools can identify structure and movement of ARs when they make landfall, and also model how ARs move inland through gaps in mountainous terrain and cause heavy precipitation further inland.
“Our study provides motivation for additional examinations of avalanche data and meteorological conditions,” Hatchett said. “Our team recommends that following all, but especially fatal, avalanches, as much detailed information should be recorded as possible so that the field can continue to learn about the relationship between atmospheric river events and avalanches.”
The full version of the study – “Avalanche Fatalities during Atmospheric River Events in the Western United States” – is available online at the link below. http://journals.ametsoc.org/doi/full/10.1175/JHM-D-16-0219.1
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The Desert Research Institute (DRI) is a recognized world leader in investigating the effects of natural and human-induced environmental change and advancing technologies aimed at assessing a changing planet. For more than 50 years DRI research faculty, students, and staff have applied scientific understanding to support the effective management of natural resources while meeting Nevada’s needs for economic diversification and science-based educational opportunities. With campuses in Reno and Las Vegas, DRI serves as the non-profit environmental research arm of the Nevada System of Higher Education. For more information, please visit www.dri.edu.
