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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

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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