Featured Research

from universities, journals, and other organizations

Are Cities Changing Local And Global Climates?

Date:
December 12, 2003
Source:
NASA/Goddard Space Flight Center
Summary:
New evidence from satellites, models, and ground observations reveal urban areas, with all their asphalt, buildings, and aerosols, are impacting local and possibly global climate processes. This is according to some of the world's top scientists convening in a special session at the Fall Meeting of the American Geophysical Union in San Francisco.

New evidence from satellites, models, and ground observations reveal urban areas, with all their asphalt, buildings, and aerosols, are impacting local and possibly global climate processes. This is according to some of the world's top scientists convening in a special session at the Fall Meeting of the American Geophysical Union in San Francisco.

To study urban impact on local rainfall, Dr. J. Marshall Shepherd of NASA's Goddard Space Flight Center, Greenbelt, Md., and Steve Burian of the University of Utah, Salt Lake City, used the world's first space-based rain radar, aboard the Tropical Rainfall Measuring Mission (TRMM) satellite, and dense rain gauge networks on land to determine there are higher rainfall rates during the summer months downwind of large cities like Houston and Atlanta. Burian and Shepherd offer new evidence rainfall patterns and daily precipitation trends have changed in regions downwind of Houston from a period of pre-urban growth, 1940 to 1958, to a post-urban growth period, 1984 to 1999.

Cities tend to be one to 10 degrees Fahrenheit (0.56 to 5.6 degrees Celsius) warmer than surrounding suburbs and rural areas. Warming from urban heat islands, the varied heights of urban structures that alter winds, and interactions with sea breezes are believed to be the primary causes for the findings in a coastal city like Houston.

In related work, Dr. Daniel Rosenfeld, an atmospheric scientist at Hebrew University, Jerusalem, reveals the increased amount of aerosols, tiny air particles, added by human activity to those naturally occurring also alter local rainfall rates around cities. Rosenfeld suggests the particles provide many surfaces upon which water can collect, preventing droplets from condensing into larger drops and slowing conversion of cloud water into precipitation. In summer, rain and thunder increases downwind of big cities, as rising air from urban heat islands combines with 'delayed' rainfall resulting from the presence of aerosols, creating bigger clouds and heavier rain.

To help scientists like Shepherd and Rosenfeld improve understanding of links between city landscapes and climate processes like rainfall, NASA's suite of Earth observing satellites provides information about the land cover/land use properties that initiate the urban effects. The satellites also track the aerosols, clouds, water vapor, and temperature that describe atmospheric conditions in urban environments. Their measurements allow scientists to make end-to-end studies of urban impacts on the climate system practically anywhere on Earth.

"The space-borne instruments on Terra, Aqua, TRMM, and Landsat provide a wealth of new observations of aerosol particles near and downwind of cities, the cloud optical properties, and surface reflectance characteristics that can help us understand the effects that urban environments have on our atmosphere and precipitation patterns," said Dr. Michael King, NASA Earth Observing System Senior Project Scientist. "Aura, to be launched in 2004, will add even more data," he said.

With growing evidence of the effects of urbanization on climate, climate modelers, like Georgia Institute of Technology's Dr. Robert Dickinson, hope to account for the cumulative effects of urban areas on regional and global climate models. For example, since asphalt has such a large effect on local heat transfer, water run-off, and how winds behave, characterizing asphalt cover is probably the biggest urban effect to be factored into global models.

NASA's Earth Science Enterprise is dedicated to understanding the Earth as an integrated system and applying Earth System Science to improve prediction of climate, weather and natural hazards using the unique vantage point of space.

For more information and images on the Internet, visit:

http://www.gsfc.nasa.gov/topstory/2003/1211urban.html


Story Source:

The above story is based on materials provided by NASA/Goddard Space Flight Center. Note: Materials may be edited for content and length.


Cite This Page:

NASA/Goddard Space Flight Center. "Are Cities Changing Local And Global Climates?." ScienceDaily. ScienceDaily, 12 December 2003. <www.sciencedaily.com/releases/2003/12/031212080526.htm>.
NASA/Goddard Space Flight Center. (2003, December 12). Are Cities Changing Local And Global Climates?. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2003/12/031212080526.htm
NASA/Goddard Space Flight Center. "Are Cities Changing Local And Global Climates?." ScienceDaily. www.sciencedaily.com/releases/2003/12/031212080526.htm (accessed September 16, 2014).

Share This



More Earth & Climate News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Scientists Examine Colossal Squid

Raw: Scientists Examine Colossal Squid

AP (Sep. 16, 2014) Squid experts in New Zealand thawed and examined an unusual catch on Tuesday: a colossal squid. It was captured in Antarctica's remote Ross Sea in December last year and has been frozen for eight months. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Man Floats for 31 Hours in Gulf Waters

Man Floats for 31 Hours in Gulf Waters

AP (Sep. 16, 2014) A Texas man is lucky to be alive after he and three others floated for more than a day in the Gulf of Mexico when their boat sank during a fishing trip. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Researchers Explore Shipwrecks Off Calif. Coast

Researchers Explore Shipwrecks Off Calif. Coast

AP (Sep. 16, 2014) Federal researchers are exploring more than a dozen underwater sites where they believe ships sank in the treacherous waters west of San Francisco in the decades following the Gold Rush. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Conservationists Face Uphill PR Battle With New Shark Rules

Conservationists Face Uphill PR Battle With New Shark Rules

Newsy (Sep. 14, 2014) New conservation measures for shark fishing face an uphill PR battle in the fight to slow shark extinction. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins