Field Notes

Twitchell Alfalfa: 2013-06-18 11:40:00 (DOY 169)
Author: Cove Sturtevant
Others:

Summary: Need better bracket for flux instrument pole. Changed 7550 time to ETC/GMT +8. Reinstalled the CNR1 to test alongside the NR01. Radiation readings looked good.

Twitchell Alfalfa
2013-06-18

I arrived at 11:40 PDT. It was sunny and windy, about 20 C. The alfalfa remains full and flowery, just above knee height. The spines on the sonic and 7500 did the trick, no birdie doo.

The pole with the sonic and 7500 was tilted to the east a few degrees off vertical. This is likely a result of the ad hoc wooden bracket used to secure the pole to the scaffold coupled with the need to grab the pole to stand on top of the scaffold and clean the 7500. I re-aligned the pole and tightened the bracket as much as possible. However, the pole is still easily pulled off of alignment. Until we can replace the wooden bracket with a metal one, take care to not use the pole to pull yourself up to the instruments.

I downloaded the GHG data and changed the time to ETC/GMT +8 at 10:59 PST. See Mayberry notes for explanation. I also checked to make sure that CO2 signal strength was being recorded. It was, along with Diagnostic Value #1. All towers with the 7550 now record these two values.

I downloaded MET data and radiation data. I reinstalled the CNR1 to test alongside the NR01 on the radiation boom and switched the program to the test program. All 4-band channels looked good before and after install, reading appropriate values. Im pretty sure of reason for the problem last time with the high readings on the longwave channels. I goofed and put the incoming shortwave channel of the CNR1 into the second COM channel on the multiplexor instead of the next channel. Doh. Thats why all the data coming off the radiation multiplexor had the pattern of incoming shortwave radiation. I think I can back out the original signals on most channels for the week of data mixup.

7500 readings:
CO2 = 395 ppm (same after cleaning)
H2O = 490 mmol m-3 (same after cleaning)
SS = 92.6% (93.5% after cleaning)
T = 21.7 C
p = 101.5 kPa
sos = 346.4 m s-1

MET looked good.

3 photos found

TA_autocam_20130619_0815.jpg ( 2013-06-19 08:15:01 ) Full size: 1920x1440
A lot of truck traffic on the road