Satellite Images Show Beijing Quadrupled in Size From 2000 to 2009
Posted on July 4, 2015
Data from NASA's QuikScat satellite shows how Beijing quickly quadrupled in size from 2000 to 2009. The gray and black colors indicate buildings. The tallest and largest buildings are represented by the light gray color in the core of the city. NASA researchers found that the changes resulted in increased temperatures and reduced wind speeds in the city.
A larger animated version of images showing the growing city can be found here. The study was led by Mark Jacobson of Stanford University, Palo Alto, California, and Son Nghiem of NASA's Jet Propulsion Laboratory, Pasadena, California. The researchers used the data to determine how urban growth has changed Beijing's wind patterns and pollution. A computer model of climate and air quality developed by Jacobson was used in the study.
The researched found that the expansion of buildings and roads created a ring of impacts around the older part of Beijing. Some of the impacts include warmer temperatures, drier soil, air stagnation and increased near-surface oxidant pollution. Winter temperatures increased by about 5 to 7 degrees Fahrenheit (3 to 4 degrees Celsius). Wind speeds were reduced by about 2 to 7 mph (1 to 3 meters per second). The reduced wind speeds made the air in the city more stagnant and increased ground-level ozone pollution.
Jacobson says in a statement, "Buildings slow down winds just by blocking the air, and also by creating friction. You have higher temperatures because covering the soil reduces evaporation, which is a cooling process."
A complete report on the impact of the mega-urbanization of Beijing was published here in the Journal of Geophysical Research Atmospheres.