Just because we were tired of seeing red-lined Qsoil values in cockpit, I've added the offsets found from my gravimetric samples to metcraxii2.xml. The values now look much better, though I'd still like another gravimetric sample in different moisture conditions to make a better calibration.
Gordon: You might want to propagate this change to Boulder...
I've thought about how to have a discussion with Delta-T devices about the SPN1 morning "dip". Steve and I thought that reorienting the sensor would better inform such a discussion, so we did that 2 days ago. (It was oriented with the analog cable side facing north, now it is the dessicant plug facing north.) Since that time, the dips have not gone as low as zero, but the dip still is clearly present. However, both of the past mornings have had a tiny amount of haze, likely associated with the recent controlled burn to the south of the site. (This haze is clear in the ceilometer and lidar returns.) Looking at past data, obscured skies increase diffuse radiation (as expected) and can be of a magnitude to mask the "dip".
Thus, I believe we have to wait for another perfectly clear morning in order make a definitive comparison between the "dip" for different SPN1 orientations. Ideally, we would acquire data with the digital cable connector oriented north as well, but there likely won't be time during the rest of the experiment.
10:45: While showing flr to SteveC, I (SO) noticed that the sensor cable seemed to be blocking line-of-sight between the Bluetooth receivers and NNE, so I flipped the cable around to the front of the mote box. Apparently, this crashed NNE data transmission. SRS notified us about 40 min later (as we were about 1/4 way up the trail). Went back to flr, flipped the cable to the backside of the mote box and rotated the lower mote box by about 10 degrees to lessen line-of-sight blockage to NNE from the tower uprights. SRS reported that this brought NNE back and didn't adversely affect reception from the other Bluetooth motes. data_stats delta-t's still show worse reception from NNE than the others, but no worse than before. Odd that this mote is so finicky.
10:41-10:55 - SO "cleaned" the krypton at floor. He used a wipe, since he didn't have a swab and managed to make it worse (kh2oV drop from 1.8 to 1.5V).
10:20 - P.sw.flr is running again. Steve O. and Steve C. replaced the battery. Old voltage was down to 4.4V. New read upwards of 15V.
10/23/13
Summary:
- No IOP last night
- Low-level haze this morning, smelled like smoke from the fire to the south
- High cloud built up during the day (of 10/23)
Actions past 24 hours:
- generator replaced
To dos:
- Keep checking flr SPN1
- Check out P.sw.flr
- decide on orientation of SPN1 at floor
Sensor status:
T/RH: ok.
P: ok except for P.sw.flr
csat u,v: ok
csat ldiag: ok
csat w, tc: ok
kh2o: ok
motes: ok
Wetness: ok
radiation: ok
Tsoil: ok
Gsoil: ok
Qsoil: ok. Offsets based on yesterday's gravimetric samples make the data look reasonable (for the entire experiment).
Cvsoil: ok.
2D sonic: ok
Gordon pointed out to us that P.sw started dying at 12:40 today, and stopped reporting at 14:25. We're guessing that this is power related, but won't be able to do anything until tomorrow. Note that we get no response to:
rs SW-p::hci1
If we did, we could have tried "r" to restart. (This works with the other Vaisala barometers.)
13:00 - 13:30 - The generator was replaced with a new unit. The UPS kept the data system up during
the change over.
I just had this exchange with Decagon Devices -- the manufacturer of our soil moisture probes. In short, iron content will affect the probe response, so our gravimetric sampling is needed.
Hi Steve,
Whoa! Unusual minerology can have some strange affects on our probes. The probes emit an electromagnetic field that primarily detects water in soils, but iron is definitely going to affect the electrical properties of the soil. I think that you should be able to account for this with a custom calibration (http://www.decagon.com/education/calibrating-ech2o-soil-moisture-sensors-13393-04-an/). We have seen some strange things like this in volcanic soils. It isn't easy to tell what the exact effect it will have on a given soil, so it is definitely best to calibrate. I have cc'd Doug, one of our R&D scientists, who may have more to add on this topic.
Regards,
Chris Chambers
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We now have several EC-5 probes in and around the Arizona Meteor Crater. We are seeing large shifts from the default calibration (offsets of -2 to +10 %vol). I don't believe that this soil is very saline, however it does have a large iron content. (A magnet picks up dirt!) Does it make sense to you that iron in the soil would affect the EC-5 calibration? If so, would you expect an offset, gain, or other calibration shift? |
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10/22/13
Summary:
- IOP5 is ending. Not ideal, since north winds were present much of the night.
Actions past 24 hours:
- near SPN1 fixed(?) by removing battery box diode
- flr SPN1 perhaps better after reorientation (shouldn't have been the case)
- rim/near guy wire tensions measured -- range 280--510
- gravimetric soil samples taken everywhere, offsets of -10 to +2% found. Data look good with this offset correction.
- NNE antenna connections checked and found to be okay. Perhaps a bit of blocking by solar panel.
- Almost all radiometers cleaned
To dos:
- Keep checking flr SPN1
- Generator servicing today
Sensor status:
T/RH: ok.
P: ok
csat u,v: ok
csat ldiag: ok
csat w, tc: ok
kh2o: ok. Again, one small glitch on flr yesterday.
motes: ok.
Wetness: ok.
radiation: ok. dfs.flr pattern a little different this morning.
Tsoil: ok
Gsoil: ok
Qsoil: ok. Offsets based on yesterday's gravimetric samples make the data look reasonable (for the entire experiment).
Cvsoil: ok.
2D sonic: ok
A quick in-and-out this afternoon.
Arrived at flr about 15:00
- rotated SPN1 120 degrees (slot in "band" is now east-west) to see if this changes the morning diffuse drop
- took soil sample
- checked NNE antenna. connections tight, antenna a bit blocked by solar panel, but I wouldn't expect this to be a big effect
- cleaned Rsw.in
Started up the trail at 15:50.
Steve S&O:
Far at 11:08.
Near at 11:47.
Flr at 15:35 (just Rsw.in, with some bird doo on the north side of the dome)
TWH, Nov 5: The date(s) on this are ambiguous. I think that these cleanings occurred on October 21, based on the date of the 5th IOP.
Samples taken today by Steve O&S:
To be expedient (and since not much structure in sandy soil), just took one sample 0-6cm.
At far, had to dig out core from the side and support from underneath to remove.
Despite almost 2 hours before weighing, saw no evidence of moisture condensed in container.
Site | Time | Weigh Time | Tare | "Wet" | Dry | Dry Density | Moisture (%mass) | Moisture (%vol) | EC5 reading (%vol) |
|---|---|---|---|---|---|---|---|---|---|
far | 11:20 | 13:10 | 3.1 | 176.7 | 172.2 | 1.23 | 2.7 | 3.3 | -1.2 |
near | 12:00 | 13:15 | 2.4 | 161.1 | 156.9 | 1.12 | 2.7 | 3.0 | 5.4 |
flr | 15:15 | 16:45 | 2.4 | 167.0 | 159.2 | 1.14 | 5.0 | 5.7 | -3.9 |
Treating the differences as a simple offset in the EC5 calibration, the Qsoil values for the entire project become somewhat believable.
We should contact Decagon to see if odd behavior in metallic soils would be expected...
P.S.(Mar 2014): During teardown, sensor depths were noted as 5, 3, 2 cm for near, far, flr, respectively, not just our usual 5cm at all sites. Since I only sampled 0–6 cm here, we can't look for any depth variation. However, we could expect that far and flr would read drier than near, as did occur. I don't know if 2 and 3cm are shallow enough to have suffered from lack-of-depth effects.
10/21/13
Summary:
- Only issue is both SPN1s.
- IOP5 will start tonight.
Actions past 24 hours:
- Reseated connector to revive SPN1.near (for second time)
To dos:
- Take gravimetric soil samples (now have all necessary equipment)
- Measure guy wire tensions
Sensor status:
T/RH: ok. RH.20m.rim is high by about 3%; RH.40m.near is high by about 1%. Not worth chasing.
P: ok
csat u,v: ok
csat ldiag: ok
csat w, tc: ok
kh2o: ok. One event about 1630 yesterday -- a bug?
motes: ok. SPN1.near died last night (just like the previous night), but revived by cycling power.
Wetness: ok.
radiation: Rsw.in MUCH better after cleaning; still odd SPN1.flr midday and at local sunrise
Tsoil: ok
Gsoil: ok
Qsoil: Still need to recalibrate far and flr.
Cvsoil: ok. Fixed range issue on Vpile.off.
2D sonic: ok
About 21:30, lost SPN1 data from near -- about the same time as the outage last night. Hard to believe that the connector slipped again at just this time. Vmote had decreased the entire day, but still was 12.4V at last report. Unlike last night, the mote isn't sending reset messages. Like last night, it doesn't respond to commands. Guess we'll take a look at it first thing tomorrow morning (about 9AM).