Computer models reveal that man-made seawater particles that alter cloud brightness, temperature and rain patterns may prove very useful in the war against global warming.
New results from modeling clouds like those seen in shipping lanes reveal the complex interplay between aerosols, the prevailing weather and even the time of day the aerosol particles hit the air, according to the research.
"We've seen ship tracks affect the reflectivity of clouds," said Phil Rasch, chief climate scientist at the Department of Energy's Pacific Northwest National Laboratory in Richland, Washington.
"We want to know if we can do the same thing when we want to, on purpose, and how that might be helpful in countering some of the effects of global warming," he added.
"We decided to see how the reflectivity of clouds is influenced by particles in a very detailed model that treats clouds much more realistically than we are able to do in a typical climate model," he said.
Previous work analyzing clouds in shipping lanes showed that large ships spewing tiny particles into the sky change the characteristics of clouds.
More aerosol particles - tiny natural or manmade bits of dirt, water and gas, such as from pollution - increase the number of droplets in clouds and make each droplet smaller.
This reflects more sunlight from the surface, and the clouds appear brighter.
But the previous work revealed that some parts of the clouds above shipping lanes became brighter and other parts darker, suggesting that using aerosols to increase cloud reflectivity will be more complex than simply adding more.
To find out, the group performed some exploratory computer simulations to determine the net effect of increased aerosols.
Rasch's team simulated three ships chugging along in a 93-mile by 37-mile block of the Pacific Ocean a few hundred miles southwest of Los Angeles.
The team showed that introducing additional particles into the model near the surface - as proposed for geoengineering - would make the clouds significantly more reflective than they would otherwise be, in certain situations.
Rasch will discuss other cloud, weather and climate characteristics affected by aerosols, such as how long the brighter clouds last, whether they burn off when the sun comes up, and what happens when they finally rain.
The team is also using the simulations to test when the best time to spray seawater using the simulations is - in the morning, late afternoon or perhaps all night long.