Field Notes
<--2002-04-03 14:26:00 | 2002-04-11 09:30:00-->Other sites visited today: Vaira
Tonzi/Vaira: 2002-04-04 10:00:00 (DOY 94)
Author: Dennis Baldocchi
Others: Ted, ESB
Summary: Cross compared HMP45s - okay, swapped IRGAs at Tower and Vaira, bird spikes on 7500s, removed orange fence around Floor, Moved Floor IRGA closer to sonic
| Day: April 4, 2002, D94 Who: ddb, th, esb Where: Tonzi Ranch Arrived around 10:00. Very cloudy and remained cloudy all day. Cool temperatures, around 14 C and light winds. The trees have leafed out and Mr. Tonzi says they leafed out about a week ago. The grass is very green. Mr Tonzi said the grazing pressure on the ranch is about 48 head. The flux systems are looking good. The site is getting cleaned up and fenced off with zappers. Each data logger has its own small panel and battery, separate from the flux system for constant met data acquisition and for controlling the flux pcs. Ted said the LICOR on the Tower had not been hooked up correctly and we lost a very important week of data across the deciduous leaf out transition. I cannot stress enough that whenever we are at the ranches please check and double check that the computers are running when you leave. Also ensure that the computers are logging real and correct data; I normally write down the voltages of the w,u,v,T, Q and C to ensure this action. Whenever a LICOR is switched double check that the voltages are on-scale. Rebooting is probably a work. We’ve lost too much data this spring with solar panels, diskette in drives and missing irga issues. I want to get refunded so I’d like to reduce our amount of missing data from now on, so please, please double check instruments. 10:30. Read the values on the moisture point soil moisture sensors. Voltage of electronics was 12.8 volts. Data have been entered on the spreadsheet on Syrah. The Tonzi ranch is wetter than the Vaira ranch and the soil is saturated at 45-60 cm. Plenty of early water available for the trees. Calibrated the Vaisala T/RH sensors at all three stations. This is something we need to do periodically to ensure the quality of the instruments. We have our lab standard, which is the digital system in the lab. To perform the comparison we need to remove the instrument and insert the lab standard in the aspirator. One gets grossly different values if one does not aspirate the standard. Also note it takes about 2 to 3 minutes to reach an equilibrium. Floor system agrees with the standard with the specifications of the instruments and imperfect sampling procedure. Field sensor: Tair: 13.8 C, RH: 76.5% Lab Standard: Tair: 13.5 C, RH: 76.8% Checked output on the forest floor met systems. The data looked good. All sensors were operating and in range. Pressure was 99.5 kPa, voltages of the soil moisture sensors were on the order of 0.8 volts We removed the orange fence around the forest floor met system. Ted has installed a zapper fence around the tower complex. The system is much cleaner and the sensors are not affected by the fence now, if it did create a small microclimate. I would like to move the net radiometer at the floor and put under the trees more, but the wires are short. At present the radiometer sees trees to the north but its southern exposure is very open to the sun and sky. Noted that the line radiometer is starting to have grass grow over it. 12:00 Downloaded data from the Tower Flux system Swapped IRGAs on the tower system. sn 0041 came down and sn 0065 went up. (after discussing the LICOR installations with LX this am, it seems that sn 0073 was taken off the tower last week and installed at the floor system. Calibrated the T/RH sensor on top of the tower Vaisala Std: Tair: 14.0C, RH: 73.9% Field Vaisala: Tair: 14.1 C, RH: 74.0% The standard and field sensor agree within specs! Battery volts 13.5 Solar panel generating 4.0 amp Load 0.8 amp Batt volt on CR23x, 12.5 volts Finished tower work around 13:09. We had a short on the battery as Ted hooked up the ground to the battery system. He noted that we should look for ground loops and offsets in the radiometers after this point. The pc was hung up for another hour and was re-booted and back on line after 14:00. 13:45 Downloaded data from the floor PC. Downloaded Nancy’s data in the CR21x5.dat format. The file was about 5M. I did not rename her old file, so data will be continued to be added to it. Was not sure what to do with that data. LX says rename it with that day and the pc will create another file. Will do next time. The forest floor flux and met systems checked out. Ted had put the Licor on an inclination. It was about 40 cm from the sonic center. Since we are near the floor and close to the ground I move the orientation and now the Licor is about 30 cm from the sonic center. Took Dendrometer readings. Data are added to the spread sheet. Noted significant expansion. So with my aging eyes I think I was reading them correctly! Only missed one tree at the north end. Took reading of grass height. 7.00 +/- 2.28 cm was the height. Took samples of leaf area. Took samples of leaves from trees for C/N and d13C analysis. 15:30 At Vaira Ranch Ted had downloaded data in the am Calibrated the T/RH. Found the filter on the T/RH to be dirty. It needs cleaning! Vaisala Std: Tair: 14.1 C, RH: 72.7% Field T/RH: Tair: 13.8 C, RH: 76.7% The air temperature is not off much, but the humidity is off by 4%. This sensor has been in the field for over a year. Swapped Licors at the site. sn 0035 came off and sn 0065 went on. We need to have uniform and quick release screws on all LICOR boxes. The one at Vaira needed a hex Allen wrench and ironically NONE of the Allen wrenches in the tool box worked! Took awhile to make the change. We put the bird protection device on the LICORs. I am worried though that we may squeeze the head too much and damage the LICOR. I’ve asked Ted to devise another method. Please be careful taking and putting these devices on and off. We probably should dispense with them in the future until a new make is produced. Took grass height samples, 10.95 +/- 4.22 cm, 19 samples Took soil moisture samples Took LAI samples, 3 Left the site at 17:30. Saw 6 Turkeys on the ranch. A fantastic site. Wish I had the camera. Overall it was a wonderful day, the ecosystem is functioning nicely and we are getting high quality data. As for analysis this was a very diffuse uniform day. It may be nice for testing some model results. |
0 photos found
16 sets found
No data found for TZ_Fenergy.
11 TZ_tmet graphs found
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3 TZ_mixed graphs found
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8 TZ_fmet graphs found
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2 TZ_sm graphs found
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1 TZ_met graphs found
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