Written in the clouds
Ernie Lewis uses MAGIC to help predict climate change
Ernie Lewis struggled with a weather balloon as he stood at the head of the 272-meter cargo ship’s flat expanse. To release the meter-wide sphere properly, he had to work carefully: Ocean winds of up to 53 miles per hour could easily whip the balloon back into stacks of 40-foot shipping containers or forward onto the three smaller containers holding the research equipment.
No one ever said MAGIC was easy.
The acronym stands for Marine ARM GPCI Investigations of Clouds, a scientific experiment intended to help answer a deceptively simple and crucial question: How do clouds act over the ocean? Lewis, an atmospheric scientist at Brookhaven National Laboratory, was on board the Horizon Spirit in 2013 because scientists who devise computer models of global climate don’t have enough data and can only guess at the answer, adding uncertainty to their predictions of how much, and how fast, the earth’s climate will change over the next century and beyond. Climatologists all have their own ideas about how clouds affect climate, but nobody’s models yet agree on what happens at tricky spots, like the ocean between Los Angeles and Hawaii – a place where two different types of cloud systems intersect. You can only tell so much with satellite measurements, and at $1 million a month, research vessels are a rare luxury. So MAGIC found its way onto a commercial ship instead.
“You can say there’s a cloud, but what’s the cloud height?” asks Lewis. “How big are the cloud drops? It’s like a puzzle: Those are what you need to improve your computer models so you can make predictions and understand how the world works.”
Just looking at the clouds wasn’t enough – to really know what’s going on, Lewis had to get a sensor up there. Hence the weather balloons. The first few times he launched them, the crew of the ship looked on quizzically, but before long they were helping Lewis and the instruments’ technicians rearrange containers and wrestle balloons into place. On the first round trip, the launches were merely tests with dummy cargoes – the crew tried potatoes and squash, among other vegetables – but soon the researchers started sending up instrument packages to measure brightness, moisture and particulates.
The balloons were part of an arsenal of instruments aimed at the sky from the Horizon Spirit. Three radar systems peered upward, and a squat instrument called a Total Sky Imager captured the sky’s dome in its curved lens. There was an infrared radiometer, too, that peeked over the ship’s edge, measuring the ocean’s surface temperature from above. All of the gadgetry was provided by the U.S. Department of Energy’s Atmospheric Radiation Measurement Climate Research Facility, known as ARM.
“I’m not bragging when I say MAGIC was a wonderful idea because it wasn’t mine,” says Lewis. “I kind of inherited it.”
Lewis hadn’t worked on clouds before the Horizon Spirit – his trajectory had gone from a degree in physics to oceanography to particles in the atmosphere. But then Warren Wiscombe, the former chief scientist of ARM, stopped by his office with the idea of figuring out Pacific clouds from a cargo ship. Lewis quickly agreed to draft a proposal to use ARM’s mobile research facility called AMF2.
In order to fit the mobile facility on a ship, its contents – which normally fit comfortably in nine storage containers – had to be condensed down to three. It was an especially tricky task to fit them all together because atmosphere scientists from all over were jumping at the opportunity to add their own devices to the lucky few.
“I don’t think we could have accepted one more guest instrument on there,” says Mike Ritsche, the Technical Operations Manager of AMF2. “We barely had any room to sit down.” Ritsche shepherded AMF2 through its previous engagement in the Maldive Islands, and has since restructured the experiment for earthbound use on a mountain in Finland, where it’s determining the effects of forests on cloud formation.
An ocean-bound research journey wasn’t entirely alien to Lewis, who started his work at Brookhaven in 1993 taking cruises around the world and measuring the ocean’s chemical properties and levels of dissolved carbon dioxide. Relentlessly curious, he sees every step in his career as just another angle for puzzling out what makes up the world. And there’s a lot to learn along the way.
“To me, it’s all new,” says Lewis. “If I don’t understand it, I’ve got a bunch of brilliant guys around me to help. There’s a whole lot of new questions I don’t understand yet, and I find all of it fascinating.”
MAGIC made 20 round trips between Hawaii and Los Angeles aboard the Horizon Spirit, and Lewis was on board for three of them, including the first and the last. Over the course of 2013, MAGIC amassed the largest set of cloud data ever collected from a ship. Now scientists interested in everything from particulates to humidity to cloud modeling are waiting eagerly for the data to be processed so they can start analysis.
“Understanding something as complicated as the climate is only done by understanding a bunch of little pieces along the way,” says Lewis. “And getting good data for every little thing.”
For the scientists wrestling with one of the most urgent problems in all of science – developing more accurate climate change models – the MAGIC data could be very important, according to Anthony Del Genio, a NASA scientist who works on climate modeling and clouds.
“When we compare notes,” says Del Genio, “the area in which we disagree the most is in understanding the effect that low-altitude clouds have on climate change.”
The information that MAGIC has gathered will let modelers check their predictions against real conditions in the clouds. In terms of in-depth data gathering over the ocean, Del Genio says, “this is really unlike any field experiment that has ever been run.”
Lewis, meanwhile, plans to use the hard-won MAGIC data in his research: understanding how airborne particles like dust and soot interact with the air and humidity and affect local climate.
In addition to revealing the inner workings of clouds for the world’s climate models, Lewis made sure to answer the other important scientific questions on his journey: which veggies worked best for the weather balloons?
“Launching potatoes worked better, and squash, which we thought would work well, were disappointing.” He shrugs. “That’s science.”