Field Notes
<--2014-06-12 09:00:00 | 2014-06-17 11:00:00-->Mayberry: 2014-06-13 09:00:00 (DOY 164)
Author: Cove Sturtevant
Others: Dennis
Summary: Turned portable tower into stationary tower at low veg site. Installed conductivity and temp profile on portable 10x. Swapped portable 7700. Moved portable tower clock back one hour. Took general survey of low veg location. Visited permanent tower.
| Mayberry 2014-06-13 Portable Tower Dennis and I arrived at the low veg portable tower location at about 09:00 PDT. Dennis needed his truck because he was moving so we turned the portable tower into a stationary one temporarily. Joe downloaded the data from the tower yesterday and saw that we were still experiencing frequent dropouts in the 7700 linelock, so we kept the tower at this site. We replaced the center pole with a longer one. The height from the berm to the arm holding the sonic was 3.45m. The berm is about 60cm above the water line. Need to grab the height from the arm to mid-sonic next time. Sonic Orientation: 256°N magnetic. Swapped out LI-7700 to diagnose line lock issue in lab. Removed sn TG1-0224, installed sn TG1-0357. I had updated the settings of the new 7700 earlier in the week. They looked good upon install. I watched the time trace of the new sensor for about 20 minutes and did not see any line-lock dropouts. The portable tower 7550 clock was one hour ahead. I removed the USB stick, downloaded the data, corrected the clock, restarted the 7550, and re-inserted the clean USB stick. Swapped the 10x with new one complete with conductivity probe (sn 5688 with home-made board) and soil temperature profile (5 depths, see below). I installed both these sensors in the open water near the tower. Unfortunately, the length of the cables (~4 m) restricted the measurement location to shallow water about 20 cm in depth with a thick layer of soft sediment. We would need an additional 20-30 m of cable to get the profile into the area of open water representative of the rest of the footprint. The 0 cm depth of the temperature profile is aligned with the sediment-water interface. The conductivity probe is approximately 10 cm below the water surface. Conductivity at this location was reading ~6 mS cm-1, whereas at the permanent tower it read ~2.6 mS cm-1. Set the station clock on the 10x. Soil temperature profile depths: #1: -16 cm #2: -8 cm #3: 0 cm #4: +10 cm #5: +30 cm (currently in air) I took water samples in the near footprint. Two in water, two in perimeter veg. I also walked around in the rest of the footprint to get a sense of the water depth and vegetation. The water depth slowly increases from about 20 cm close to the tower to 40 cm where the “inlet†to the tower broadens to the large area of open water. At this point the water depth rapidly increases to a stable 80-85 cm throughout the open water. At the perimeter of vegetation patches, the water depth decreases to ~40 cm. Vegetation close to the tower is predominantly the thin cattail species. There are some stands of the thick cattail species about 100 from the tower to the NW. There isn’t much tule to be found until 200-300 m out from the tower, at which point it is the dominant species. Tower readings after switch to stationary and 7700 swap: CO2: 410 ppm H2O: 560 mmol m-3 signal strength = 91.0% p = 101.4 kPa t: 23.6 °C sos = 344.2 m s-1 CH4: 1.96 ppm RSSI: 60% Reservoir full. Permanent Tower All was well. The vegetation is clearly still filling in at this site. The part we used to walk through to get to the tule tower just few months ago is no closed in with tules. Downloaded data. Took sonic N reading: 348° N magnetic. 7500 readings: CO2: 392 ppm (399 after cleaning) H2O: 620 mmol m-3 (580 after cleaning) signal strength = 95.9% (96.1% after cleaning) p = 101.4 kPa t: 26 °C sos = 347.6 m s-1 Current 7700 readings: CH4 = 2.0 ppm (same after cleaning) RSSI = 40-46% variable (73% after cleaning) Reservoir was full. Met looked good. |
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