Field Notes

Bouldin Alfalfa: 2021-08-04 10:00:00 (DOY 216)
Author: Daphne Szutu
Others: Carlos

Summary: Regular data collection/cleaning, bales still on the field, installed 3 RH/T sensors to pair with advection sonics, uploaded new datalogger programs, veg height, spectral

2021-08-04
Bouldin Alfalfa

Carlos and I arrived around 10:00 PDT. I got slightly lost driving the inside route from the corn site because I didnâ€™t turn east at the right place. I went south all the way to the levee road and ended up taking that around to the alfalfa site. We could smell smoke from the Bradford fire and there was ash on the bouncer tower solar panel.

Alfalfa was about shin high and the bales were still on the field. A tractor with a bale loader was collecting bales on the neighboring fields and drove past us while we were at the bouncer tower, but probably decided to come back later after we were no longer in the field.

Bouncer Tower
We stopped at the bouncer tower first to install two HMP45s, to download data, and to upload a new datalogger program, LatFlux_20210804.CR6. The new program stores the upper and lower RH/T measurements to the 20Hz and 30min data tables stored on the card. Both sensors are aspirated with 12V computer fans. Both sensors and both fans are powered with a screw terminal power strip wired to the datalogger plug for incoming power.

The radiation shield bolts are 3/16 steel rods that we cut threads into because we couldnâ€™t find 10-32 allthread or 3/16 aluminum rods. The plastic collars holding the sensors in the shield are the usual threaded collars, but with a few threads cut off and jammed in instead of screwed in because the current shields do not have a threaded female entry. This will be improved for the next iteration.

The upper RH/T is a HMP45: Wired as SE measurement to U9/U10 on the datalogger, sn T1250012, height = 387cm agl.

The lower RH/T is a HMP45: Wired as SE measurement to U11/U12 on the datalogger, sn U3030041, height=240cm agl.

After plugging the sensors in, the upper sensor read T=23.5C, RH=42% and the lower sensor read T=24.4C, RH=47%. Donâ€™t take these numbers as accurate yet because we need to do an intercomparison between them.

Carlos added small zip ties to the top of both the upper and lower sonics to act as bird spikes. He also took veg height and spectral measurements while waiting for me to finalize the wiring and the program. I had to remove the thermocouple to have enough ports to install both HMPs.

Main tower
We then drove to the main tower for the regular data download/cleaning. I downloaded met, camera, and USB GHG data. I downloaded the FD data and cleared its memory. I also downloaded the IRT data as TOB1 files and deleted the source files. I converted the 30min data to T0A5 format and checked that the numbers looked reasonable.

Carlos cleaned flux and rad sensors and cleaned the solar panels. I checked the undercanopy PAR sensor which was clear and I leveled the sensor because it was a bit off. Carlos topped off the wash reservoir and swapped the wash box water filter. The old filter was plugged, but I forgot to check the pump after the swap.

LI-7500 readings:
CO2 393ppm
H2O 780ppm
T 26.5C
P 101.2kPa
SS 99--> 100 after cleaning
LI7700 readings:
CH4 1.95
RSSI 58--> 84 after cleaning

At the main tower, we installed the ATMOS14 RH/T sensor as the lower RH/T sensor. This is a cheaper SDI-12 sensor and is not aspirated.

The upper RH/T is a HMP155 that is permanently installed at the main tower, but we measured the height again. It was 352cm agl.

The lower RH/T is an ATMOS14: Wired as an SDI12 sensor to C7, sn 1675101058, height = 248cm agl.

After plugging the sensors in and uploading a new datalogger program, the upper sensor read T=26C, RH=43% and the lower sensor read T=27C, RH=39%. Again, donâ€™t take these numbers literally yet because we need to intercompare the sensors.

The new datalogger program â€œBA_Met_20210804.CR1â€ stores 30min data, 5min data, and 10sec data. I added the HMP155 and ATMOS14 data output to the 10sec data table, but the estimated table fill times for the internal datalogger memory was only around 13 days, which is not long enough for our regular twice-monthly field visits. After a few texts and a phone call with Joe, I was able to pre-allocate the table size for the 30min and 5min data and to save the 10sec data to the phenocam CF card. The internal datalogger memory will now hold 31 days of the 30min and 5min data and the CF card will hold 28 days of the 10sec data.

As I was trying different version of the code, I would occasionally have to pop the CF card out to delete old files manually because the card would not save new data when the pre-existing data table didnâ€™t match the new data table (the datalogger would not overwrite it in the same way it overwrites data tables in the internal datalogger memory). As I was doing this, I noticed there were some phenocam photos getting saved to the card that were not on the :15 or :45 mark, not sure why unless sending the new programs were causing the stardot camera power relay to reset which for some reason might trigger a new photos to be taken. A bit later when I checked the card again the new photos were again on the :15 or :45 mark.

We left around 13:30 PDT. On the way out, we stopped again at the bouncer tower to check the data and I confirmed that the RH/T data were getting saved (at least to the 30min data).

Next Mowing: 2021-08-19

Veg Height (cm): Tape measure from ground to top of plant
35, 34, 28, 39, 36, 30, 37, 37, 32, 24, 39, 38, avg = 34.1, stdev = 4.72

4 photos found

20210804BA_SmokePlume.jpg ( 2021-08-04 13:07:23 ) Full size: 1920x1440
Slight smoke plume visible from the Bradford Island fire that started in the early morning of Aug 2.