‘Global chimney’ drives distribution of key atmospheric gases
By Summit Voice
FRISCO — A team of atmospheric scientists will examine the atmosphere over the western tropical Pacific Ocean from top to bottom, trying to increase understanding of how the vertical transport of air in the region affects climate worldwide.
One of the goals of the mission is to understand how those atmospheric processes might change in coming decades as global warming drives temperatures over the Pacific higher and higher.
Warm ocean temperatures in the western tropical Pacific fuel a global climate engine that feeds heat and moisture into huge clusters of thunderstorms that loft gases and particles into the stratosphere, where they spread out over the entire planet and influence the climate, according to a press release from the National Center for Atmospheric Research.
“To figure out the future of the air above our heads, we need to go to the western Pacific,” said NCAR scientist Laura Pan. “This region has been called the holy grail for understanding global air transport, because so much surface air gets lifted by the storms and then spreads globally.”
Data for the research effort will be gathered by a Global Hawk, a robotic aerial vehicle, to study upper-atmospheric water vapor, which influences global climate. The other, CAST (Coordinated Airborne Studies in the Tropics) is funded by Britain’s Natural Environment Research Council Facility and will deploy a BAe146 research aircraft that will focus on air near the ocean surface.
Together, the sensor-laden research flights will provide a comprehensive view of the atmosphere from the ocean surface, where gases produced by marine organisms enter the air, to the stratosphere, more than 60,000 feet above.
“It’s a huge region, and that means we have to use multiple aircraft,” said University of Maryland scientists Ross Salawitch. “We will attempt to stage these three airplanes in harmony to measure the atmospheric composition over the western Pacific when both ocean biology and atmospheric storms are raging.”
As trade winds flow across the tropical Pacific, they push warm water to the west, where it piles up in and near the CONTRAST study region. The waters around Guam have the world’s highest sea surface temperatures of open oceans. They provide heat and moisture to feed clusters of thunderstorms that lift air through the troposphere (the lowest level of the atmosphere) and the tropopause (a cold, shallow region atop the troposphere) and then up into the stratosphere.
Once in the stratosphere—where the air tends to flow horizontally more than rising or sinking—the gases and particles spread out around the world and linger for years or even decades.
Some of the gases, such as ozone and water vapor, affect the amount of energy from the Sun that reaches Earth’s surface. The amount of these gases in the stratosphere is important for the planet’s climate. Other chemicals, such as bromine compounds, have indirect effects by destroying ozone or otherwise altering the chemistry of the stratosphere. And the gases produced by ocean organisms create a signature of marine biology in the stratosphere.
As atmospheric patterns evolve and sea surface temperatures warm further due to climate change, the storm clusters over the Pacific are likely to influence climate in ways that are now challenging to anticipate, NCAR’s Pan said.
“Understanding the impact of these storms will help us gain ground truth for improving the chemistry-climate models we use to project future climate,” she said.
The researchers are planning as many as 16 flights, targeting both towering storms that loft fresh air into the stratosphere as well as collapsed storms to examine the composition of the air that remains lower down, in the troposphere.
While the scientists will have considerable follow-up research to do in their labs, some of the airborne instruments will provide real-time measurements to the team. State-of-the-art models of atmospheric chemistry will help guide the research flights in the field, as well as aid in subsequent analysis of the observations.
“There will be a lot of discovery and science in the field,” Pan said.