Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Are cities changing local and global climates?

15.12.2003


Satellite Images of Houston Metro Area

These images show the Houston metropolitan area, where buildings, roads and other built surfaces create urban heat islands that can affect local rain patterns. The images were taken by ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer), an imaging instrument that is flying on Terra, a satellite launched in December 1999 as part of NASA’s Earth Observing System (EOS). Credit: NASA/J


Higher Rainfall Rates Downwind of Texas Cities

This image shows areas where urban heat islands influenced higher rainfall rates (in blue) downwind of major cities connected by Interstate 35, known as the I-35 corridor in Texas. The winds that carried clouds and rainfall downwind (in this case, south and east of urban areas) occurred roughly 3.0 kilometers (1.9 miles) above the surface. Rainfall was measured by the precipitation radar instrument on NASA’s Tropical Rainfall Measuring Mission (TRMM) satellite. The higher rainfall rates depicted here were derived from measurements of mean monthly rainfall during the warm seasons (May through September) from 1998 through 2000. Credit: Jim Williams, Scientific Visualization Studio, NASA/Goddard Space Flight Center


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 that 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.

Shepherd, King, Rosenfeld, and Dickinson will present their findings during a press conference on Thursday, December 11, 2003, at 3 p.m., PST in Room 2012, Moscone West, at the 2003 Fall Meeting of the American Geophysical Union in San Francisco.

They also will convene a special session, organized by Shepherd and Dr. Menglin Jin of the University of Maryland, detailing these results on Human-Induced Climate Variations Linked to Urbanization: From Observations to Modeling, sessions U51A and U51C, starting on Friday morning, December 12, at 2:00 p.m. PST at MCC 3001-3003. B-roll of video is available on this topic, by calling Wade Sisler of NASA-TV at 301/286-6256.

Krishna Ramanujan | GSFC
Further information:
http://www.gsfc.nasa.gov/topstory/2003/1211urban.html

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Future electronic components to be printed like newspapers

A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.

The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

A smart safe rechargeable zinc ion battery based on sol-gel transition electrolytes

20.07.2018 | Power and Electrical Engineering

Reversing cause and effect is no trouble for quantum computers

20.07.2018 | Information Technology

Princeton-UPenn research team finds physics treasure hidden in a wallpaper pattern

20.07.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>