Field Notes

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Other sites visited today: Rush Ranch | Gilbert Tract
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Hill Slough: 2025-02-18 10:10:00 (DOY 49)
Author: Kyle Delwiche
Others: Joe Verfaillie, Daphne Szutu, Charlie Diaz

Summary: Calibrated 7700, met with Ducks Unlimited and CDFW to discuss 2nd tower placement on Eastern parcel, rain storms in past few weeks caused short power outage

We arrived at 10:10 PST - the day was calm, mild, with only a slight breeze and some high thin clouds. We had several rain storms in the last few weeks which caused a short power outage in met and two short power outages in flux data. We're also missing LI-7700 data for a few days between the two short power outages, but it seems to be fine after the second power outage. Maybe a clock sync error that fixed itself.

We brought all the maintenance and calibration equipment out to the tower, then Kyle and Joe went back to the road to meet up with Aaron Will and James Allen from Ducks Unlimited, and Dajanae Stitts and Orlando Rocha from CDFW. Dennis also arrived for the meeting.

We discussed the logistics of adding a second flux tower to measure carbon exchange over the more vegetated areas in the Hillslough restoration project. Ease of access and reduced likelihood of vandalization were top concerns. We drove along the access levees in the Eastern parcel and looked at several potential placements for flux tower equipment. We identified 2 primary locations, and will send a proposal to CDFW for review, including equipment placement and approximate dimensions. The goal is to have this equipment in place this Spring to capture the growing season.

Aaron also talked about his interest in implementing floating peat islands. Working with Indigenous groups would be best, but they may not have the capacity so Aaron and James may try to create a few small floating islands themselves. If successful, they mentioned bringing a school group out to build more.

Meanwhile, Daphne downloaded the data and Charlie cleaned the sensors. Joe noticed that the rotating shadowband for dfPAR seemed to be spinning faster than at our other sites. He removed the DC-DC converter (used to step down from 12V) and added a motor control board. He adjusted the rotation speed so it's about 30sec per 360deg rotation.

The CO2 sensor bird spike was missing.

The SW_out data were bad, Daphne redid the wiring and tightened the screws. dfPAR and totPAR also had spikes but hopefully the slower rotation of the rotating shadowband will fix that.

Charlie and Daphne calibrated the 7700. It was actually a still day at Hill Slough for once--perfect for calibrations. The offsets were small.

Staff gauge was 4.0ft at 10:55 PST

The 7500 read: 434ppm CO2, 403 mol/m3 H2O, 13.2C, 102.4 kPa, 97 SS - 98 after cleaning
The 7700 read: 2.0 ppm, RSSI 40 – 88 after cleaning

Charlie and Daphne measured conductivity at the tower, although there wasn't a lot of surface water left. They had to lay the sensor down horizontal below the surface while trying not to disturb the sediments.
Porewater, 6.72 mS, 16.9C
Surface, 1628 uS, 14.4C

We left around 12:00 PST.

0 photos found

4 sets found

21 HS_met graphs found