“When the plane was about 30 minutes from touchdown, we could start to smell the air,” said David Giles. “It was shocking.”
Giles — a young scientist at NASA’s Goddard Space Flight Center — was en route to Kanpur, a large Indian industrial city on the banks of the Ganges river. Dust and soot tend to hover over the region, which is sandwiched between the sharp edge of the Tibetan Plateau to the north and the highlands of the Deccan Plateau to the south.
There’s so much soot in the air that satellites can routinely see a cloud of haze blanketing the region.
The bowl-like Indo-Gangetic Plain is second only to some parts of China for having the heaviest load of air pollution in the world. In the spring, when dust blows in from the deserts to the West, aerosols from factories, buses and trucks, and fires are especially heavy. So much so, in fact, that NASA researchers suggested recently that dust and soot may be driving the retreat of Himalayan glaciers by altering the monsoon.
Giles was in Kanpur to man one of NASA’s AERONET stations in the region as part of the ongoing TIGERZ campaign. He spent 17 days in Kanpur hauling the instrument around and getting harassed by local police officers, the occasional herd of roaming sheep and dust storms. In between all that, he spent the bulk of his time collecting measurements to determine whether dust and soot can glom onto one another to create new types of hybrid aerosols.
They do, he found, a seemingly mundane point but one that’s of considerable interest to the scientists trying to sort out how these two types of aerosols affect the climate. He presented his results in detail this week to colleagues at the American Geophysical Union fall meeting in San Francisco.
I nabbed him after his talk in the afternoon, to have a beer and talk through his travels. I asked him what was the most memorable part of the trip to India. “Well, it was unbelievably hot,” he said with a laugh. “Temperatures routinely hit 105 degrees.”
And how was the air? “You’d get used to it after a while,” said Giles, “but, at first, in the taxi, we were holding our sleeves over our mouths just to avoid breathing the stuff.”
Giles and colleagues using sun photometers to measure aerosols from a rooftop in Kanpur. (Credit: Giles)