Field Notes

Gilbert Tract: 2023-05-31 09:30:00 (DOY 151)
Author: Daphne Szutu
Others: Carlos, Jerry

Summary: Regular data collection/cleaning, pleasant day, flowering tules, adjusted ADCP mount so roll closer to 0deg

2023-05-31
Gilbert Tract

Carlos, Jerry Sun, and I arrived at 9:30 PDT. It's been a cool spring so it was a very pleasant day. It was mild and clear with a cool breeze and visible fog over the Diablo range. Jerry is an undergrad student exploring ideas for his senior thesis and today was his first time in the field.

The tules in the wetland are super tall and full of flowers. Cattails are right behind them with slender green catkins. The staff gauge read 53cm at 8:52 PST.

Carlos gave Jerry a tour of the tower instrumentation and they cleaned the sensors together. They topped off the wash reservoir. I downloaded met, cam, and USB GHG data. I changed the eddy clock +45sec to match the laptop time from 8:44 to 8:44:45 PST and restarted logging.

The 7500 read: 418ppm CO2, 589mmol/m3 H2O, 17.1C, 101.0kPa,100SS --> 101 after cleaning
The 7700 read: 2.1ppm CH4, 35RSSI –> 86 after cleaning

We got to the channel to download Flo's data around 10:10 PDT. I downloaded data, reset the clock to match the laptop clock, and restarted logging. Submerged aquatic vegetation by Flo was plentiful (and flowering), although there did seem to be about at 30cm gap in the canopy right above the sensor. Carlos put on waders and used the telescoping rake to clear some of the submerged weeds. Plenty of submerged aquatic vegetation was visible as well on the northern bank across from Flo.

I talked to Ari earlier this week via e-mail about the ADCP roll. Joe and I had previously adjusted the roll so it was slightly steeper than -5 degrees to try to compensate for the beams coming out of the water at low tide. Ari said that roll/pitches greater than 5 degrees required coordinate rotation in post processing, which is not recommended for small channels like ours. She preferred to throw out the low tide data rather than apply the needed coordinate rotation. A roll/pitch within +/- 5 degrees is considered close enough to 0 that a coordinate rotation is unnecessary. Today, we pulled up the sensor again and Carlos removed the washers that we had installed last time. We pushed the sensor back down the rail again. The new roll was -4.3 degrees and the pitch was the same, 1.6 degrees.

We left at 10:40 PDT.

2 photos found

gilberttract_2023_05_31_084405.jpg ( 2023-05-31 16:46:42 ) Full size: 1296x960
Carlos and visitor on tower