Field Notes

Trip note On Mar 17, 2003 (d076)
Who: Liukang Xu & Jianwu Tang

Weather; Heavy rain on previous day. Soil profile saturated. Patchy cloud, windy, temperature lower 60s, About 60% of oak trees leaves out. I thought leaves out earlier than last year, but Mr. Tonzi told me leaves out usually around this time of the year.

Problem: I found there was lot of liquid water inside the box for the CR23X at the top of the tower. The yellow material to plug the big hole (about 4 cm in diameter) at the top of the box is not waterproof. There was already some water condensed inside the display window of the datalogger. I guess the water damaged the first 23X. Yesterday I left the box open for awhile to dry it out and tried to seal the hole with a piece of plastic and black tape. Ted: I guess we need replace that box.

Vaira site: 10:45 arrived. Fence OK. The gillsonic program was frozen about 2.5 hr before I got there. Met and soil sensors seems working good. Download data, PV reading 13.0, 4.7 and 2.6 (under cloud) and solar panels gave me 24.1 A under sunny conditions. Battery fully charged. Took 3 LAI samples, grass height measurement (n=30, m=9.8cm and std=3.76cm). Tried to swap the licor 7500 0418 with the newly calibrated one (0042), but 0042 wouldn’t talk to the computer, so I had to put 0418 back to the flux system, we need replace next trip.

Soil moisture reading see blow: Soil is saturated after the big storm.

Tower system; fence Ok, flux system running good. Download the flux data. Gillsonic output after reboot was OK. Replaced the licor 7500 sn 0035 came off and sn 0041 went on. PV reading 14.1, 15.8 and 2.2 at 1:30 pm (under sunny conditions). After tasks, reboot PC gave me good output for w, u, v, Tsonic, q, and CO2. The laptop clock was 14 min faster than my watch and my cell phone, I reset the pc clock.

Floor system: Fence OK, flux system running, PV reading 14.7, 7.8 and 1.7 with fully charged battery. Swaped licor 7500 sn 0073 came off and sn 0065 went on. PC also 14 min faster, I reset. Reboot PC , output from gillsonic good.

Tonzi: Took 3 LAI samples, grass height measurements (n=40, m=7.1cm std=3.56cm).

Dendrometer reading.

Jianwu did soil respiration and stem respiration. He found that the soil respiration under the oak canopy (around 4-5 mmol/m2s) was much higher than in the open space (1-2 mmol/m2s).