Field Notes

<--2023-08-08 15:40:00 | 2023-08-29 15:00:00-->
Other sites visited today: Bouldin Corn | Hill Slough

Bouldin Alfalfa: 2023-08-24 09:30:00 (DOY 236)
Author: Joe Verfaillie
Others: Daphne, Jiangong, Brian Leen

Summary: Beginning of NKIRA water vapor inter-comparison, swapped 7500 for mount repairs, Testing LI-7810 chamber system, cut alfalfa under tower, Installed phenocam

Bouldin Alfalfa
2023-08-24

Daphne, Jiangong and Brian Leen from NKIRA and I arrived at 9:30 PDT. It was warm sunny and hazy with a nice breeze. Our field has been mowed and a strip near our tower seems to have been raked and baled but there are still dried cuttings on most of the field.

One goal today is to add a prototype instrument from NKIRA to the tower as part of an SBIR grant. I added a vertical post to the scaffolding downwind from our eddy sensors and Brian mounted the instrument at about the same height as the 7500. We had to borrow a power line the HMP fan to get him 24V and added an analog out cable to the 7550 box to give him a data channel (7500 H2O) to time sync the two systems. After some confusion and fussing with units and analog ranges we settled on 0-3V = 200-1200mmol/m3. The NKIRA instrument will log PA, TA and H2O at 60Hz and our analog H2O at 10Hz.

The NKIRA device is interesting. A lot more spectroscopy than I can understand. Seems they can get both water vapor and air temperature from the spectrum - CO2 and CH4 are technically possible with more lasers. Super lightweight - mostly designed for UAV and high altitude measurements. I think Brian said the path length is dynamically adjustable depending on concentration. Raw measurement is ppm not density. Expensive - probably 30-40k (the only functioning one they've got is on our tower).

We are also testing our new Licor LI-7810 (CO2/CH4/H2O) analyzer and LI-8100 Smart Chamber. Jiangong ran the chamber system mostly with his phone measuring five reps of a bare patch and five more of a healthy, re-sprouting alfalfa plant. He also took a time lapse video hoping to see the alfalfa leaves track the sun.

Daphne did the regular tower work collecting the met, flux, FD and IRT data. She swapped the 7500 because some of the mounting screws are stripped and the bird spike mount came off: sn 75H-2180 came off and sn 0035 went on.
2180 read: 410ppm CO2, 850mmol/m3 H2O, 28.2C, 101.0kPa, 96SS – 100 after cleaning
0035 read: 422ppm CO2, 735mmol/m3 H2O, 31.1C, 101.0kPa, 99SS
The change in CO2 and water are due to the slightly dirty windows I think. Daphne adjusted the 7550 clock by +1 min, uploaded the new config, adjusted the pressure coefficients and restarted logging.

Last time the phenocam camera was not working. Today we installed the spare we had in the lab sn 0030f4d0b0b3. Daphne had set it all up in the lab but there were some extra characters on the user password line for both the RGB and IRT ftp scripts that were initially causing it to fail to send images to the CR1000. We fixed this and it was working.

Jiangong and I cut the alfalfa under the tower and around the Planet Labs Arable. I found a great big praying mantis under the tower. I took one of the old Arable cameras off the tower and I’m checking with Arable if we can remove the Planet Labs units.

I did spectral measurements but not much veg height to measure yet. I washed the solar panels. They were not too dirty accept for some bird poop at the top edge.

We left at about 12:15 PDT

Next Mowing: 2023-09-19

2 photos found

20230824BA_PrayingMantis.jpg ( 2023-08-24 10:42:30 ) Full size: 1440x1920
Big tan praying mantis at Alfalfa

20230824BA_BrianNikira.jpg ( 2023-08-24 00:00:00 ) Full size: 1920x1440
Brian from Nikira setting up their prototype fast water vapor and temperature sensor to compare against our Licor measurements. Daphne and Joe servicing the tower.