September 11, 2013
Life and lasers in Antarctica: Faces behind the balaclavas
Four months of darkness, minus-30-degree temperatures, 40-mile-per-hour winds—just another day at the lab for the Chu Research Group. The lab just happens to be at McMurdo Station in Antarctica, where CIRES Fellow Xinzhao Chu and her team spend many months every year studying the polar atmosphere. Using remote-sensing technology called lidar (light detection and ranging), they use laser light to analyze the middle and upper atmosphere. Their research is shedding light on the planet’s weather patterns, climate processes, and even the fertilization of life on Earth with essential minerals, such as iron.
To collect year-round lidar observations, one scientist from the Chu group must stay through the winter at McMurdo, operating and maintaining the equipment; three students have wintered-over thus far. The United States Antarctic Program (USAP) requires these scientists to pass rigorous physical and psychological tests before they can winter-over (see sidebar: Are you fit enough?).
“The scientists sacrifice their personal lives and do extremely hard work to collect invaluable data to enable our studies,” Chu said.
That hard work has not gone unnoticed. In July, Chu received a Provost’s Faculty Achievement Award from the University of Colorado Boulder for her highly influential research on the upper atmosphere. Additionally, for three years in a row, students from Chu’s group have won first-place prizes in the poster competition at the prestigious Coupling, Energetics and Dynamics of Atmospheric Regions (CEDAR) Workshop sponsored by the National Science Foundation. Chihoko Yamashita won in 2011, Cao Chen in 2012, and Zhibin Yu in 2013. “As far as we know, this is the first time that the same group of students has won first place three years in a row,” Chu said.
Meet the faces behind the balaclava with these highlights from the Chu Research Group.
Antarctica is the coldest, driest, windiest, and loneliest continent on Earth, with limited medical-care capability. So American scientists who want to work there first have to be deemed physically qualified—or be “PQed”—by the United States Antarctic Program. This involves passing rigorous medical, dental, and—for those wintering-over—psychological tests. The latter, with questions such as, “Do you ever hate yourself?”, can sometimes carry a cultural bias or language barrier for nonnative English speakers. The Chu group’s first winter-over candidate, from Taiwan, didn’t pass for this reason. Next to try was Zhibin Yu. “I took the PQ challenge, and I just tried to be myself when answering the questions,” Yu said. “There were more than 700 questions.” Yu passed and became the first team member to winter-over. “I’m happy I had a chance to serve our group,” he said.
CIRES Fellow and associate professor in the CU-Boulder Department of Aerospace Engineering Science
Xinzhao Chu explores advanced spectroscopy principles, develops new lidar technologies, and studies the fundamental physical and chemical processes that govern the structure and dynamics of the whole atmosphere. In essence, this means using innovative lidar systems to better understand Earth’s atmosphere and space. From 1999 to 2005, Chu made lidar observations at the North Pole and the South Pole, the latter at Britain's Rothera Research Station. She first was stationed at McMurdo in 2010, and January 2013 marked Chu's seventh trip to Antarctica.
“Seeing the Antarctic wildlife, including seals, birds, and penguins, is a high point of the field work,” Chu said. On one occasion, four emperor penguins lined up alongside the plane to see her off on her trip home. “Every time you see a penguin, it lifts your spirits,” she said.
CIRES research scientist
Wentao Huang was instrumental in the successful development of several lidars and the deployment of a specialized instrument—the iron Boltzmann temperature lidar—to McMurdo Station. This enabled the surprising discovery of neutral iron atoms more than 100 miles high in the atmosphere.
Huang is currently characterizing the atmospheric iron and sodium layers, which can be influenced by climate as well as geomagnetic storms that impact satellites, power grids, and radio communication.
Iron-rich particles play a crucial role in Earth’s environment; they settle on land and water and can fertilize life by providing nutrients for plants and small animals. “Through this research, we will better understand the evolving atmosphere and its responses to anthropogenic and extraterrestrial impacts and, thus, better understand our future,” Huang said.
"I like the hospitality of the scientists and staff working in Antarctica and the diversity of the research concentrated in a relatively small region,” Huang said. “I also enjoy the 24-hour sunshine during summer visits, as well as the amazing landscape and unique weather."
CIRES Postdoctoral Visiting Fellow
Although Xian Lu has not worked in Antarctica, she uses the data from there to investivate atmospheric waves, specifically gravity waves, thermal tides, and planetary waves. Like waves in the ocean, these ripples of air parcels play a key role in mixing air, transferring energy, and driving atmospheric circulation, thus affecting weather and climate.
Lu is using lidar, radar, and satellite data, as well as model simulations, to assess the origins, mechanisms, and impacts of these waves on polar atmospheric processes, space weather, and the behavior of the global atmosphere.
“Polar waves are believed to have distinct features from their counterparts at mid- and low-latitudes,” Lu said. “Until now, they have not been thoroughly studied in the polar region, yet they are fundamental to understanding atmospheric behavior.”
Ph.D. Candidate in the Department of Aerospace Engineering Sciences
In 2011, Zhibin Yu became the first winter-over student for the McMurdo lidar campaign (and the first winter-over scientist in the last 20 years at McMurdo Station). He is modeling the iron layers found in the thermosphere (the layer of atmosphere that starts about 50 miles above Earth’s surface and extends 500 miles up).
“The most exciting things from the 2011 winter operation were some new scientific phenomena discovered by Dr. Chu from the data,” Yu said. “Because of the new sciences we discovered, it led to a new scientific direction—investigating neutral metal layers in the thermosphere.”
In 2013, Zhibin Yu was the CEDAR first-place winner for his poster, “Lidar observations and numerical modeling studies of thermospheric Fe/Fe+ layers.” Yu is currently developing a new model to study the mechanism by which neutral metal layers form in the thermosphere.
“It is a unique experience—four months polar day, four months polar night, and four months day and night,” Yu said. “I enjoyed my winter, and I’m excited about the science we’ve discovered. We got four publications out of the first year of data, and there will be more.”
Ph.D. student in the Department of Aerospace Engineering Sciences
John Smith’s research focuses on the advancement of a special type of lidar technology—resonance-fluorescence lidar—to investigate the dynamic boundary between the atmosphere and space. “Many pressing science questions exist about how this region behaves and how it affects, and is affected by, the rest of the atmosphere,” Smith said.
Smith is currently working on realizing a mobile, single-beam “whole-atmosphere” lidar, which would be the first lidar capable of making routine measurements of wind and temperature contiguously through the whole atmospheric column.
“Participating in an Antarctic science mission was always a dream of mine, so when the opportunity presented itself back in November 2010, I seized it,” Smith said. “Working closely with passionate scientists and energetic support staff from such a diverse array of backgrounds was truly invigorating and a privilege. There were very few trails left unexplored by the time I left. My only regret was leaving before the arrival of the emperor penguins, which came waddling in across the airfield in droves shortly after I returned to Christchurch.”
Ph.D. student in the Department of Aerospace Engineering Sciences
As the third winter-over scientist at McMurdo, Fong made a new record of observing the iron layers up to about 105 miles in the thermosphere. Weichun Fong arrived in Antarctica in August 2012 and will be there through October 2013, braving through the austral winter (from March to September). At McMurdo, Fong studies the atmospheric thermal structure, including thermal tides, gravity waves, and annual temperature climatology. He currently is analyzing winter thermal tides based on the lidar data collected in 2011 and 2012.
“Temperature is an important parameter and also a key factor in understanding and monitoring climate change,” Fong said. “This is especially true in polar regions since it has been proven that they are more sensitive to global climate change than the equatorial areas.” Fong is also using the lidar data to validate current atmospheric models and provide ground-truth observations for satellite measurements of temperature.
"I am glad that I flew to McMurdo Station during late August last year, since during that time, the dark sky still dominates most of the day,” Fong said. “I saw the first aurora in my life and was amazed by the sky scattered with tons of stars during the lidar run."
Ph.D. student in the Department of Aerospace Engineering Sciences
While analyzing McMurdo Station lidar data, Cao Chen reported for the first time a special type of gravity wave event—called an inertia gravity wave (IGW) event—in the Antarctic mesosphere/lower thermosphere. His research has begun to show an unexpectedly high occurrence of such events above McMurdo, suggesting a significant gap in the understanding of the polar atmospheric dynamics. “Underestimated wave drag from such IGWs in polar regions may be responsible for the long-standing ‘cold pole’ problem—that is, a cold bias of Antarctic winter stratosphere temperature in many general circulation and chemistry climate models,” Chen said. Through his research, Chen hopes to help solve this problem by better defining the wave parameters used in models.
Additionally, “establishing a temperature record in a polar atmosphere from the stratosphere to the lower thermosphere, we can monitor climate change in the middle atmosphere,” he said. “Our observations provide ground-truth to the satellites and validate global circulation models, which are used to project the future state of our climate system.” In 2012, Chen was the CEDAR first-place winner for his poster “Inertia-gravity waves in Antarctica: A case study with simultaneous lidar and radar measurements at McMurdo (77.8° S, 166.7° E).”
"McMurdo is a great place to work because people here are very friendly, and they work hard to guarantee that science happens,” Chen said. “Also, the facility is very convenient, and we can do a lot of sports we like. I especially like playing indoor soccer with a bunch of people twice a week."
Ph.D. recipient in the CU-Boulder Department of Aerospace Engineering Sciences
Using the Chu group's Antarctic data and Whole Atmosphere Community Climate Model (WACCM) simulations, Bo Tan completed his Ph.D. on lidar, satellite, and modeling studies of global teleconnection patterns and the “cold problem“ in general circulation models. The latter refers to the tendency for models to show a global mean cold bias.
Winter-over lidar engineer
Brendan Roberts earned his master of science degree in May 2012 from the University of Colorado Boulder. As a winter-over lidar engineer, he operated the iron Boltzmann lidar at McMurdo through the Antarctic winter in 2012 and collected numerous valuable data. Roberts completed the campaign’s first 48-hour solo data-collection run. “I am proud that many papers and conference posters created by the Chu group came from the data I collected,” Roberts said. “There was a general gap in atmospheric data at that latitude range, and the lidar system is helping to fill that in, improving atmospheric data coverage and models.”
"The best parts were camping on the ice shelf at McMurdo Sound, seeing the bright stars every time I opened the door at Arrival Heights where the lidar system was operated, and seeing the aurora for the first time,” Roberts said. “The lows were when the fresh food ran out about a month after the station switched over to winter operations and the flight crews returned to the United States, leaving us on our own for the season.” Sharing a small, dorm-size room with two roommates also took adjustment, he said. As for the cold, Roberts was surprised at how quickly the body acclimates. “Around the end of July, I was walking outside from building to building in minus-40-degree weather in only a sweatshirt and felt fine,” Roberts said. “Around the same time, the temperature rose to about minus 5 degrees, and I lay on the roof of the building to watch the stars and night sky. I was wearing only a hoodie and jeans, but it still seemed really warm!"