Field Notes

Trip note On June 13 2003 (d164)
Who: Liukang Xu & Ted

Weather: Sunny, Temperature around mid 80s. Except some spots under trees at Tonzi site, grass was all dead.

Purpose: instrument maintenance, download data, aboveground grass biomass sample at Vaira site. Next time need sample grass at Tonzi site. Ted calibrated Licor 800 of the CO2 profile system.

Tonzi ranch: arrived 11:25:

Tower system: fence OK, flux system was running pretty good. Download data and restart the laptop, output from gillsonic as follows;

Notes that output of CO2 channel was only 1.284. Normally, it shouldn’t be lower than 1.4 V. Checked the licor 7500 at the top of the tower, found bird poop on the 7500 lens. Cleaned with wet tissue, output changed to 1.4 V. So if somebody sees the output of CO2 channel is below 1.4 V, something probably is wrong. Only under extremely hot day in the summer, it might be around 1.4 V.

I and Ted also tried to determine the causes of abnormally high number of spikes for q and CO2 channels from licor at the tower around noontime. We first thought it might be caused by sunlight, but we rule it out as a cause after we did a simple experiment. Ted didn’t see any differences of those spikes when I covered the licor with my hat and when I uncovered the sensor.

Floor system:

Fence and flux system were running good. Uploaded md9_5tz.exe and md9_7tz.exe at laptop. Those two files were used to rename the CR10X5.dat and CR10X7.dat at the beginning of day. PV reading 13.9, 12.9, and 1.8.

Dendrometer reading:

Soil moisture reading:

Jianwu’s soil CO2 probe reading at open space: 480 ppm, -120ppm (seems not working), and 0.30%; under the tree, 1390ppm, 0.58% and 0.85%.

Vaira site: 4:40 arrived fence oK. Gillsonic program was running. Download. Soil moisture probe reading (see above). PV reading 13.5, 7.0 and 2.9.

Took 6 grass above ground biomass samples (3 outside fence, and 3 inside the fence).

Each sample size is 0.5×0.5 m.