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Long-range forecast

UW-Madison group marks 30 years tracking Antarctic weather

 

On the roof of the Space Science and Engineering Center (SSEC), festooned with antenna that grab data from orbiting satellites in space, Matthew Lazzara gestures to the various dishes, describing the unique history of each one, as if recounting royal lineage.

Two on top of the penthouse date back to the 1970s, he explains. One points to a NOAA satellite that provides imagery over the Antarctic Peninsula. Others receive information from a pair of important Earth-observing satellites launched by NASA, Terra and Aqua.

“A lot of different satellite observations are made available here, which allows us to do some of the work we do,” Lazzara explains before ducking back inside the penthouse of the 15-story building as an October rain drizzle on the University of Wisconsin-Madison (UW-Madison) campus turns heavy.

That work involves making now hourly satellite composites of the Antarctic continent and the weather systems that swirl around and over it in the Southern Hemisphere. The imagery is the hallmark product of the Antarctic Meteorological Research Center (AMRC), which occupies the ninth floor of the SSEC.

Lazzara is the principal investigator (PI) for the center as well as one of the PIs for the Antarctic Automatic Weather Station (AWS) Program, a network of about 60 weather stations that collect data year-round and account for more than half of all such observatories on the continent. The National Science Foundation’s Office of Polar Programs funds both programs.

Lazzara became a PI on the AWS program in 2007 and took over the AMRC from its founder, Charles Stearns, last year. A World War II veteran, Stearns established the AWS program in 1980 and began generating the satellite weather composites of Antarctica in 1992, launching the AMRC.

Now Lazzara, who received his doctorate from UW-Madison by studying the occurrence of fog in Antarctica, wants to improve access to the center’s vast archive of weather data while pursuing new research on wind and cloud movement using the satellite composites.

The AWS system

“That’s one of the things that’s maybe unique about our group. We release the data out rapidly, get it out to people as fast as we can get it,” he says. “Our goal is going to get to be a lot more self-sufficient — easy access — all of the things you might expect a data center would provide.”

The data are used for various purposes, from weather forecasting for flight operations around the continent to climate change research. Lazzara notes that information collected from the AWS program was used in a major paper published in the journal Nature earlier this year by Eric Steig at the University of Washington. Steig and his co-authors suggested that Antarctica overall is warming in step with the rest of the planet.

Each year, a team from UW-Madison, usually with some of their collaborators from other institutions, head to the Ice to service and repair various AWS towers and install new ones. For example, during the 2008-09 field season, the group visited about 27 AWS sites and installed two new stations.

The three-meter-tall towers — with various low-energy sensors powered by solar and batteries — collect basic meteorological data such as temperature, pressure and wind speed. In the future, Lazzara’s team will install a 30-meter-tall tower on the Ross Ice Shelf — the first “tall tower” in the network.

The AWS system turns 30 years old this year, a significant milestone because 30 years is the standard timeframe for establishing climatological trends, according to Lazzara. A few of the sites have survived for almost that long, he said.

A tower called Ferrell (named after a U.S. Navy captain, while many others carry the names of pilots or even family members of the science team) has been running for 30 years as it moves with the flow of ice on the Ross Ice Shelf, Lazzara says. Another unit at Marble Point, near McMurdo Station, may host some original gear from 1980 as well.

The hardware is built to military specification, Lazzara adds, which has proved to be fairly hardy in the extreme Antarctic environment.

“It’s a great investment that NSF has put into the weather station program. It’s solid hardware that can last a long, long time,” he says. Each AWS package costs about $15,000 to $20,000.

But even the tough AWS units can get hammered by winds. Cape Denison on the Adélie coast regularly records wind speeds of 60 to 90 kilometers per hour, and once clocked the winds at 196 kph.

“The Adélie coast is bad news,” Lazzara says. “It’s a place to throw away hardware.”

A map of AWS sites in Antarctica hangs nearby in one of the AMRC offices, showing all 120-plus stations. Lazzara says that the continent, about 1½ times the size of the United States, is in reality sparsely monitored.

“It looks like a big forest of weather stations, but it really isn’t,” he says. “This is really bare minimum of weather stations you could have compared to what we have [in the United States].”

AMRC studies

In another room at AMRC, a flat-screen monitor displays a graphic of Antarctica, pictured upside down from the image normally seen of the continent, with the Antarctic Peninsula pointing up.

The perspective is deliberate: Lazzara wants to observe the wind and weather patterns between Antarctica and New Zealand, located in the upper left-hand corner in this view, because of the numerous flights along that route.

The screen shows satellite images taken from the last 10 days, with swirls of clouds flashing across the picture as time leaps in one- or three-hour chunks. The image is composed of about 10 different geostationary (equatorial-orbiting) and polar-orbiting satellites.

“It’s like doing a jigsaw puzzle. We’ve done it for many, many years every three hours. Now we’re doing it every hour, which is very exciting,” Lazzara says.

The hourly composite has allowed his team to track clouds more accurately, which wasn’t possible with the every-three-hour compilations. That has provided the meteorologists a way to calculate wind speed — an estimate they previously used only polar orbiting or geostationary satellites to do.

The hourly composites are timely enough to be useful to weather forecasters, he says.

“It’s cheaper doing [the composites in] real-time. If you go back to build these later, it’s far more expensive,” Lazzara says. He has a different grant from the NSF for similar composites of the Arctic.

There are some gaps in the imagery, however, as satellite coverage is not always available throughout the day. A full, data-rich image is possible, he explains, but it would take a day to complete and would not be as useful. “You can’t see the day evolve, which is what a weather forecaster wants,” he explains.

Forecasters on the ground at South Pole Station learned that it’s all about location, location, location when observing the winds at the bottom of the world. AMRC installed new instruments at the farthest end of the skiway, or airfield landing strip, from the new research building.

To ensure the new and old equipment — located on the other side of the elevated station — were recording similar information, the sites ran simultaneously for a year. An analysis of the results from the instruments and visible observations on the ground found some striking disparities.

“You would get [observations of] blowing snow that doesn’t match the wind speed. It’s because the profile of the station gets in the way,” Lazzara says. “South Pole is now big enough that it matters where you observe because it’s so large and influences the weather.”

Lazzara’s own influences into the field of meteorology include his father, who worked as an environmental sciences high school teacher for 35 years. A native of Massachusetts, Lazzara ended up doing his graduate work at UW-Madison on the recommendation of a couple of undergraduate advisors who attended the university.

In 1995, he made his first trip to Antarctica — and has been back seven times since, returning to the field for the 2009-10 summer season.

“I have to admit that I like the Antarctic for the following reason, and it’s maybe one that you don’t think of: the sharing environment, the collaborations, a little less competitiveness,” Lazzara says.

NSF-funded research in this story: Matthew Lazzara, University of Wisconsin-Madison, Award Nos. 0838834 (Linda Keller, co-principal investigator), 0636873 (Gregory Tripoli and George Weidner, co-principal investigators) and 0713843 (Shelly Knuth, co-principal investigator).

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Curator: Peter Rejcek, Antarctic Support Contract | NSF Official: Winifred Reuning, Division of Polar Programs