Field Notes

Sherman Island: 2013-09-05 08:20:00 (DOY 248)
Author: Cove Sturtevant
Others: Joe, Laurie

Summary: Regular field work. Dug new water well with perforated PVC tube at southern location. Some interesting water table properties noted, west Moisture Point broken.

Sherman
2013-09-05

We arrived about 08:20 PDT. It was sunny, with a mild breeze, and warm (19.5 C). There was a moderate amount of water under the bridge on the way in. The pepperweed is dry and senescent, about 45 cm in height and becoming sparser with continued cow trampling. There is also a very patchy and very short green grass understory.

Joe and I attended to the tower, dug a new water well next to the southern one (more below), and took well depth measurements while Laurie did moisture point, spectral, and soil CO2 flux. We also removed another big wasp next on the door to the computer box.

The west Moisture Point has a broken pin. The bottom most pin is completely broken off and the probe no longer reads correctly.

LGR readings: 1.86 ppm, 08:23, 25.9 C, 134.1 Torr (adjusted to 146 Torr), 12.56 us, 10 Hz

7500 readings:
CO2: 16.08 mmol m-3 (16.55 after cleaning)
H2O: 625 mmol m-3 (610 after cleaning)
diag: 248
p: 101.6 kPa
t: 21.8 C
sos: 345.0 m s-1

MET looked good.
Soil CO2 looked good.
Cleaned radiation instruments.

We dug a new water well next to the well at the southern end (near the computer box). The northern well (by soil CO2 sensors) has a perforated PVC tube and shows weekly measurements of well depth much more variable than the southern well which has a PVC tube without holes. To resolve whether the lack of tube holes is the reason behind the more stable southern well, we added a new well with perforated PVC tube and water pressure sensor next to the existing southern well. The water pressure sensor (s/n 20010026) is installed 124 cm below the top of the PVC pipe, and the top of the PVC pipe extends 13 cm above the ground surface.

An interesting thing happened while digging the new hole with the auger. When the hole depth reached about the full length of the auger, the auger just fell in with a splash without further resistance (I didnt really know this was possible!). At this point I measured the water table at 86 cm below ground, different from the 49 cm depth measured at the existing southern well but very similar to the 84 cm water table depth measured at the north well. After we installed the perforated PVC pipe and water pressure sensor in the new hole, and updated the MET program, the water table at the new hole was measured at 82 cm below ground. The water pressure reading was 0.43 at this time. Next week it should be interesting to see the readings after the water depth in the new hole has stabilized.

The new CR10X met program adds the water pressure sensor to the C7 port and outputs psi at the end of the averages and before the STDVs in final storage. I also fixed a bug where atm pressure was reporting mv - it now reports in kPa.

0 photos found

7 sets found

No data found for SI_mp.
11 SI_met graphs found