Field Notes

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Tonzi: 2005-02-17 09:00:00 (DOY 48)
Author: Ted Hehn
Others:

JD-48-50

Weather Clear and sunny at 09:00 turning to fog by 09:15 All vegetation covered with heavy dew and ground is wet with standing water. Grass about 2" tall with clump grasses 6" tall. I have not seen the ground cover this full at Vaira since I arrived in 2001. Mr. Tonzi noted that the Canadian Thistle was growing and that is unusual.

Tonzi Ranch:
Thurs 14:16 soil co2 profile system CR23x5 (SN2299) has lithium battery at 2.529 volts and was last calibrated in 1999

The soil co2 values on the CO2E1-4 are reading 0.00000 indicating Low Voltage Drop Out by the solar regulator. CO2W1-4 have values.

Remove fuse from battery to reset regulator to perform diagnostics.

CO2E1 = 2.36% DRO, 6.2 volts measured at the logger input, 20ma/250ohm, voltage output = 12.0, sn Z2720014, 1% fullscale
CO2E2 = 2.93%, 6.2 volts measured at the logger input, 20ma/250ohm, sn Z2720011, 1%FS
CO2E3 = 2.85%, 6.2 volts measured at the logger input, 20ma/250ohm, sn Z2720012, 1%FS
CO2E4 = 6670ppm , 1%FS

Pull profile probe 1 (2cm) out of ground and response falls to 380 ppm in atmosphere

Remove probe 4 (16 cm) some moisture on the outer body but dry inside the Teflon filter and in the cell. Response falls to 160ppm in atmosphere.

Remove probe 3 (8cm) at 330ppm in atmosphere,

Remove probe 2 (4cm) falls to 350ppm in atmosphere.

Move to CO2West

CO2W1 3440ppm, sn X4840007, 1%FS, 2cm, atmosphere 380-390ppm
CO2W2 = 3660ppm, sn X1920001, 1%FS, 8cm, atmosphere 350-400ppm
CO2W3 = 1.0%, sn X1520002, 2%FS, 16cm, atmosphere 0.16-0.17% 1600-1700ppm
CO2W4 = 0.55%, sn Y0710013, 3%FS, 4cm, atmosphere 0.04% = 400ppm

16:31 Tower cr23x6 precip multiplier set to 0.0254 I thought I had changed this on 27Jan05 but did not.
See the following:
Teds_site_Log_27Jan05.doc
Teds_site_Log_27Jan05_Addendum_17Feb05.doc

Perform 10 tip check yields 0.254 which indicates the unit is working properly but with the incorrect multiplier.

Change precip multiplier from 0.0254 to 0.254 and perform 10 tip check yielding a value of 2.54 which is correct.

Install LI820 and zero and span

Friday
11:00 floor JD 49
flux system in LVDO overnight until 05:30 when it powered up.

Tower
11:04 Co2 profile system has all 4 ports open and this should not be
Data from CR23x7 indicate that the data logging stopped after the 05:00hr reset and the logger locked up in its last mode with all 4 ports open. These ports are open for the last few minutes of every half hour.

Climb tower and install keyboard on cr10x7 and press *0 to compile and run program and logger begins to function at beginning of next full half hour.

Remove fast acting 2.5 amp fuse from co2 profile pump dc/dc converter and install 4 amp slo-blo fuse.

11:42 floor
CR23x6 has bogus values for T & RH readings replace this unit next trip

Soil CO2 profile system east array is in LVDO status while the west array is functional. West array has slightly larger solar panels. Consequently I removed the data logger from the 24 volt batteries and installed a new battery and solar panel to run only the data logger. This may help and it may not. It was the only thing I could do at the time with the materials I had on site. Also reset the angle of the solar panels to 60 degree to face the sun. They were set for Dec22 at 70 degree.

Reset regulator and soil profile system starts functioning
3 of 4 values at east array are again over-ranged 1.59%, 2.32% , 1.82% this indicates that the probes do not have a full scale output high enough to measure the concentrations that we are experiencing. Nothing else is wrong with the system other than there is not enough solar radiation to continuously power the systems.

West array
CO2W1 = 5500ppm
CO2W2 = 1.39%
CO2W3 = 3.18%
CO2W4= 0.60%
Probes 2&3 are over-ranged

Regarding the tower co2 profile system.
The facts:
2.5 amp pump motor DC/DC converter fuses are being blown.
When this occurs the LI800 locks up at 1000ppm
CR10x7 locks up and will not function until the program is recompiled or reloaded.
During Dec- Feb the battery voltage will become depleted over the course of a night

My hypothesis:
At the 05:00hr reset when the power is restored the depleted battery voltage requires an increased current draw (P=IV) that blows the fuse on the DC/DC converter but not the 2 amp fuse on the motor itself. During this high current draw the battery voltage is drawn lower than what the CR10x requires to start up and compile the program so it returns to its last known configuration before the power reset and does not compile and run the program.

When a fuse blows an arc is created whose voltage can exceed 35KV and this high voltage spike causes the LI800 to lock up.

I removed the programming for the 05:00hr reset from the CR23x6 logger.

On my next visit I will install a 5 second delay regulator on the cr10x7 so that it is not trying to power up during times high inrush current and low voltage. I will also install 16 volt Zener diode on the power input leads and on the signal output leads of the LI800 to act as transient voltage suppression.

I setup the failed LI800 from the tower in the lab and the source lamp on the optical bench was not blinking and all attempts to span the device failed.

While still powered up I removed the source lamp PC board from the optical bench by removing the 4 larger screws from the PC board. During the removal process the light came on. I put the unit back together and zero and span procedures went smoothly.

Field Data

No tank data

No TZ Well data found

No TZ Moisture Point data found

No VR Moisture Point data found

No TZ grass heigth found

No VR grass heigth found

No TZ Tree DBH found

No water potential data found

No TZ Grass Biomass data found

No TZ OakLeaves Biomass data found

No TZ PineNeedles Biomass data found