The researchers used the technique to study the rapid urban growth in Beijing, China, finding that its physical area had grown 4 folds between 2000 and 2009.

A team led by Mark Jacobson of Stanford University, Palo Alto, California, and Son Nghiem of NASA’s Jet Propulsion Laboratory, Pasadena, California, used data from QuikScat to measure the extent of infrastructure changes, such as new buildings and roads, in China’s capital. They then measured how urban growth has changed Beijing's wind patterns and pollution, using a computer model of climate and air quality developed by Jacobson.

The new infrastructure alone like the buildings and roads themselves, not including additional pollution created by the new city dwellers and their vehicles, created a ring of impacts around the older parts of Beijing. The impacts included increasing winter temperatures and reducing wind speed, making the city air more stagnant.

"Buildings slow down winds just by blocking the air, and also by creating friction," Jacobson explained. "You have higher temperatures because covering the soil reduces evaporation, which is a cooling process." Roads and roofs heat up more during the day than soil or vegetation would because they are drier. Nghiem used advanced data-processing techniques on measurements from NASA's QuikScat scatterometer, a satellite radar managed by JPL that operated from 1999 to 2009. Like all radars, QuikScat sent pulses of microwaves toward Earth and recorded the waves that bounced back, called backscatter. Nghiem's technique takes advantage of the fact that human-built structures produce stronger backscatter than soil or vegetation. The more, larger or taller the buildings are, the stronger the backscatter.

Nghiem emphasized that the study set only the lower bounds for the impacts of urbanization on local weather and pollution. "If you were to develop a city that didn't allow any pollution sources, not even a single gas-powered car, you would still have these bad effects.

You can find the link to the full study here.