June-July
2007
Nuts about science
CHATS team does research in walnut orchard
Don Lenschow measures leaf area index
during CHATS. |
CHATS, the Canopy Horizontal Array Turbulence Study, wrapped
up in June. During the field campaign, NCAR researchers traveled
to Dixon, California, to measure winds and turbulence within
and above a walnut orchard that functioned as a uniformly
vegetated canopy. Their broad goal is to improve modeling
of surface-atmosphere exchange in regional and global land,
atmosphere, and chemical models.
At right, Don Lenschow (ESSL/MMM) climbs a tower to measure
leaf area index for determining the density of the canopy.
Using the plant canopy analyzer seen hanging from his belt,
Don measured incoming solar radiation in one-meter increments
up to 11 meters (about 36 feet) above the ground.
“If you measure sunlight coming in at a series of
levels, as you go down through the canopy you get less and
less sunlight, and you can invert that to estimate how dense
the canopy is,” Don explains.
Determining the density of the canopy was an important
part of CHATS. “We want to relate the turbulence structure
to how dense the canopy is and to how much the trees obstruct
the flow.”
Alex Guenther (ESSL/ACD) uses a
gas-exchange enclosure system to measure emissions
of volatile organic compounds (VOCs) from the leaves
of a walnut tree. The measurements will be used
as the basis for a canopy-scale emission model. |
On the Web
More
about CHATS
In this issue...
Christmas
in August
Nuts
about science
NCAR
welcomes new researchers
SOARS
protégés in the thick of another summer
Just
before Sunrise....
Strong
winds damage hangar roof at Jeffco
Short
Takes
Bill
Randel to lead ESSL/ACD
Just One Look
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