2005
8 November 2005. Looking
for Lawns. By Rebecca Lindsey, for NASA
Earth Observatory. Cristina
Milesi is too busy to think much about her
small Northern California lawn, and it shows.
She waters a little, when she can remember.
Never fertilizes. She definitely doesn't
bag up her grass clippings. Where would
she find the time for that? The mother of
two young children, Milesi also works almost
full time in the ecological forecasting
research group at NASA's Ames Research Center
in California.
"I have already let part of the yard
go,"
she says, which means some of it is a combination
of bare patches and weeds. Part of the reason
Milesi has little time to be concerned with
her own lawn is that she is busy thinking
about everyone else's. Since 2003, Milesi
has been calculating how much of America's
land surface is lawn-covered and what impact
all that grass has on our country's water
and carbon cycles.
October 2005. Urban
Heat Islands Developing in Coastal Tropical
Cities. EOS TRANSACTIONS, American Geophysical
Union Vol. 86, No. 42, 18; PAGES 397, 403
[accessible only to members of American
Geophysical Union (AGU)] By Jorge E. González,
Jeffrey C Luvall, Douglas Rickman, Daniel
Comarazamy, Anan J. Picón, Eric W.
Harmsen, Hamed Parsiani, Nazario Ramírez,
Ramon E. Vásquez, Robin Williams,
Robert B Waide, and Craig A. Tepley.
Beautiful and breezy cities on small tropical
islands, it turns out, may not be exempt
from the same local climate change effects
and urban heat island effects seen in large
continental cities such as Los Angeles or
Mexico City. A surprising, recent discovery
indicates that this is the case for San
Juan, Puerto Rico, a relatively affluent
coastal tropical city of about two million
inhabitants that is spreading rapidly into
the once-rural areas around it. A recent
climatological analysis of the surface temperature
of the city has revealed that the local
temperature has been increasing over the
neighboring vegetated areas at a rate of
0.06°C per year for the past 30 years.This
is a trend that may be comparable to climate
changes induced by global warming ... differences
between urbanized and limited vegetation
areas are in excess of 30°C. ... It
is estimated that by the year 2025, 60 percent
of the world's population will live in cities,
according to the United Nations Population
Fund [UNPF, 1999]. Human activity in urban
environments has impact at the local scale
by changing atmospheric composition, affecting
components of the water cycle (i.e., cloud
cover and height, and convective activity),
modifying ecosystems, and increasing energy
demands. ...The clearest local indicator
of climate changes due to urbanization is
an urban/rural convective circulation known
as urban heat islands (UHIs). This convective
circulation is larger in clear and calm
conditions and tends to disappear in cloudy
and windy weather. [Fig. 1. Daytime ATLAS
five-meter-resolution thermal image for
downtown San Juan, Puerto Rico, 11 February
2004, 1420-1430 UTZ.
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