Field Notes
<--2001-05-25 09:30:00 | 2001-06-01 15:08:00-->Other sites visited today: Tonzi
Vaira: 2001-05-31 09:00:00 (DOY 151)
Author: Dennis Baldocchi
Others: Ted Hehn, LiuKang
Summary: Extreme heat killed grass & also caused malfunction in LI 6400; drought effect on oaks uses more air than usual from tank; T/Rh is aspirated.
| 5/31/01 Dennis, Ted, Liukang Where: Tonzi/Vaira Ranches Who: Baldocchi, Hehn, Xu When: May 31, 2001, D151 Conditions. Record heat. High for the day reached 40 C and soil temperatures near the surface were 54 C. The grass is dead, but the trees seem to be functioning. Our goal for the day was to inspect the new set up, take A-Ci curves and leaf water potential. The extreme heat played havec on the LI 6400 so only 2 samples were taken. Leaf temperature was 30 C plus. We also had problems with leaf water potential. In the morning, were consistant at about -23 bars, but on inspection, weird things were happening. After hitting the high mark, I'd drop the pressure and the leaf would keep exuding water. I would finally drop the pressure to about -10 bars and work back up, with a new set point at about -16bars. In the afternoon, we tried to read values on Nancy's trees, but we could not get the Pbomb higher than -29 with no response. The tank was filled with a new tank, yet in the field at start it only read about 1400 psi. The strong drought effect on oaks uses much more air than crops and temperate forests. Ted will bring a big tank to the field. ~1000 Checking out the Tonzi floor system. The signals looked good. We were able to read md9s 2 through 5, but not six. When I tried to add the 6th md9, that on the tower, we lost communications with all the other systems. Ted had to reset the whole software system after trying to debug hardware problems, which were non existant. We also need a new Task to read the md9 for the tower. Signals on the sensors look fine. The floor system did not get back in operation until about 1400. Then we also swapped irgas and installed number 41. Climbed the tower and inspected the flux system. The sonic system had not been re-elevated. We elevated it around 1100. Then made a measurement of its height. The height from the ground to the base of the sonic was 22.75 m. The sonic and the LICOR were about 0.75 m apart with the licor not on the extender. This is ok. Kristensen shows that it is better to have an open path sensor below the sonic. I felt the lateral separation distance was rather large. I had Ted move them closer. They are now about 0.25 m apart, but we need to remeasure everything. Also in moving the sensors together, Ted had to move the orientation. Now North is pointing 53 degrees East of North. This change needs to be put in the code. We also need another clamp on the sonic pole for stability and safety. The net radiometer is extended nicely from the tower. But because this is a savanna and the tower was placed in the open for the guys, the net does not see any trees. It is mostly seeing bare red dirt below. We need to consider this fact during any attempt to close or test energy balance closure. Overall the landscape has a nice flat and extended forest. A fair number of pines are noticable to the North east. The T/Rh system is aspriated, but with the 0.1 amp fan. This is probably ok ,as it is windier on the tower. Lab tests did show in a calm room that the 0.5 amp fan did not work as well as the 0.5 amp, but we need to conserver power. The rain gauge is on the floor met tower near the tree. It needs to be moved to the tower for better exposure. Data was downloaded from the flux systems. The battery on the pc died, so we could not download tower met data. 1500 At Vaira ranch. Down loaded data, took down the Net radiation calibration system. We also need to work up relations with long wave radiation, since that is a 4 stream system. We need to decide if we should run that system full time for model purpose and long wave radiation inputs and parameterization. Turned on the ventilation fan on the T/Rh sensor. Temperature dropped from about 41.1 to 39.6 C. A substantial drop. We should be generating enough power that the current draw from the fan should not be a problem during the summer. Ted todos: 1. Aspirator, floor T/RH, Tonzi 2. Move precip sensor to Tower 3. Fix soil moisture at Vaira and install repaired sensor 4. tap extra holes on sonic mount so alignment has more flexibility. We want to guage height and orientation, to the sensor is put back in the same place everytime it is moved. 5. 0.1 amp fans for aspirators 6. insulation/reflectix on CR 10 and Cr 23x boxes 7. check and fix md9 #6. 8. Put gillsonic program with fixed disk drive reading on other systems 9. check clock on Rnet data logger |
Field Data
No tank data
No VR 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
Tree DBH
| Date | Tag# | Reading (mm) |
|---|
No water potential data found
No VR Grass Biomass data found
No VR OakLeaves Biomass data found
No VR PineNeedles Biomass data found
0 photos found
9 sets found
16 VR_met graphs found
2 VR_flux graphs found
No data found for VR_soilco2.
No data found for VR_pond.
Can't check TZVR_mixed
No data found for VR_fd.
No data found for VR_processed.
No data found for VR_arable.
No data found for VR_soilvue.