September 5, 2013
Flights Over South Pacific Create The Most Ozone
Brett Smith for redOrbit.com - Your Universe Online
A short-lived greenhouse gas, ozone’s formation and destruction depends mostly on the local chemical environment. Now, a new study from MIT researchers has indicated that flights passing over a certain section of the South Pacific produce the most ozone from their emissions.The results of the study, which was published in Environmental Research Letters, could have far-reaching implications for the timing and course taken by some long-distance flights.
Using a global chemistry-transport model, the researchers determined which parts of the globe are particularly sensitive to the creation of ozone from aviation emissions. They were then able to determine which flights create the highest amounts of ozone.
The MIT team discovered that an area over the Pacific, about 620 miles to the east of the Solomon Islands, is the most responsive to aircraft emissions. In this area, about 2.2 pounds of aircraft emissions will result in the creation of 33 pounds of ozone in one year, researchers said.
The sensitivity in this region was described as being five times greater than the sensitivity over Europe and 3.7 times greater than the sensitivity over North America.
"Our findings show that the cleanest parts of the atmosphere exhibit the most dramatic response to new emissions,” said study co-author Steven Barrett, an engineering professor at MIT. “New emissions in this part of the Pacific will result in a relatively larger response from the atmosphere.”
The researchers analyzed approximately 83,000 individual flights to identify the 10 highest ozone-producing flights that departed from or arrived in either New Zealand or Australia. A flight from Sydney to Bombay was named the highest producer of ozone – almost 56,000 pounds. The massive total was not only the result of the highly sensitive region that the flight passes through, but also because of the sheer amount of emissions generated by such a long flight.
Besides associating geography with ozone creation, the researchers also found that flights in October cause 40 percent more ozone-forming emissions than flights in April. They also noted that the top three ozone-producing flights generate 157 times more of the greenhouse gas than the bottom three.
"There have been many studies of the total impact of civil aviation emissions on the atmosphere, but there is very little knowledge of how individual flights change the environment,” Barrett said.
"The places that the sensitivities are highest now are the fastest growing regions in terms of civil aviation growth, so there could potentially be ways to achieve significant reductions in the climate impact of aviation by focusing on re-routing aircraft around the particular regions of the world where ozone formation is highly sensitive to (ozone-forming) emissions.”
"Of course, longer flights are going to burn more fuel and emit more carbon dioxide, so there will be a trade-off between increasing flight distance and other climate impacts, such as the effect of ozone,” he added.
“The scientific underpinning of this trade-off needs further investigation so that we have a better understanding and can see whether such a trade-off can be justified.”