Field Notes

Twitchell Rice: 2013-07-16 11:00:00 (DOY 197)
Author: Cove Sturtevant
Others: Sara, Yanel

Summary: Need to re-clip cattails in front of tower next week. Leveled sonic. Took instrument orientation measurements. Check soil/water temperature data for anomalously high readings.

Twitchell Rice
2013-07-16

We arrived about 11:00 PDT. It was sunny, cool(20 C), and windy . I attended to the tower while Sara did clip plots and Yanel did spectral.

The rice continues to grow, I measured it to be ~50 cm above the water. The swath of high cattails in front of the tower had almost completely regrown since I clipped it two weeks ago. We didnt have the large clippers this time so I will bring next time and cut them down again. I checked the zenith rotation angle of the flux data and there was a significant rotation (4), likely a result of the cattails but the tower was also slightly off-level, tilted toward the east. I leveled it by putting a stake under the east tripod leg.

I checked the sonic model a WM 1590. Therefore, no post-processing crosswind correction necessary (it is done internally). I will remove it from the processing.

Took some instrument orientation measurements:
Height to middle of sonic: 3.25 m from water
Sonic orientation (+x direction): 345 N (magnetic)
Laterally from mid-sonic to mid-7500: 20 cm @ 305 N (magnetic)
Laterally from mid-sonic to mid-7700: 35 cm @ 0 N (magnetic)

We checked to see if one of the water temperature sensors was out of water, as Sara had noted that the readings seemed high in the data, but there was no visible sensor out of water and the readings matched the other water temp measurements. Sara is going to revisit the data again and we will return to the issue next week. I noted that the temperature reading for SoilT1_04 looked high (reading 27 C while others were reading 20-21 C). Sara could you check the data for this sensor as well?

7500 readings:
CO2 = 371 ppm (380 after cleaning)
H2O = 670 mmol m-3 (620 after cleaning)
signal strength = 79.6% (80.0% after cleaning)
t = 20.42 C
p = 101.85 kPa
sos = 345.0 m s-1

7700 readings:
CH4 = 1.85 ppm (same after cleaning)
RSSI = 50 (bumped to 74 after cleaning)
Reservoir was full.

1 photos found

TW_autocam_20130716_1015.jpg ( 2013-07-16 10:15:02 ) Full size: 1920x1440
Fieldwork