Date: Fri, 29 Mar 2024 03:19:58 -0600 (MDT)
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Of course, I now think that many pressure spikes are now real events (e.g. =
dust devils). However, I've seen other spikes (mostly upwards) that a=
ren't real. Further tracking finds that most are (only?) spikes in th=
e Paro's temperature measurement. These spikes are always positive. &=
nbsp;During 10 Aug, most of these were with t.8b, however I also see them o=
n 5b, 9b, 10b, 7t, and 8t. These are not exclusively on pressure2, no=
r are they all the channels on pressure2. Also,=E2=80=A6
To follow-up on the leak check yesterday (which showed a slow leak), I repe=
ated this test today: 1033 P=3D1004.88 (pinched off) 1034 unpinched Pref (s=
o I could read pressure easily) P=3D1007.29 1037 installed tee, P=3D1007.32=
1038 blew in, P=3D 1029 dropping 1039 pinched entire array, P=3D1025 still=
dropping 1041 tighten tee, P=3D1021.5 still dropping 1043 pinched off 11b =
P=3D1018.9, still dropping ~1100-1113 reseated both reservoir endcaps with =
more Teflon tape and plumbers' grease.=E2=80=A6
between 1440 - 1522, Khoung tried the pinch test again, removing all of the=
array of tubing. During this test, the overall noise in p[ref].11b w=
as significantly less, indicating that part (but not all) of the p' problem=
s still are tubing related. At 1525, he sucked on the reservoir and reconne=
cted the (entire) tubing. It appears that the tubing has a leak with =
a time constant of about 10min. This was actually desirable(!), but i=
ndicates that we still have some sleuthing to do.
Still trying to work several problems: P.0m is only 1Hz, only about same re=
solution as Pref, so not much help monitoring Pref after all. Thus, c=
hange back to monitor Pref with 11b's 202BG Data from P.0m yesterday showed=
Pref fluctuations. Try to damp these by removing potential leak (old=
capillary leak) and add more steel wool.=E2=80=A6
At 1512, I pinched off the entire reference pressure tubing so that both Pr=
ef and P.0m measured just the reference volume. (It turned out that P=
.0m's RS232 connector fell off, so we didn't get data from it for any of th=
ese tests .) At 1618, I opened the above, but pinched off lines to only con=
nect 6b. At ~1745, I opened the above connecting the entire tubing system, =
but pinched off Pref (after reconnecting the P.0m signal).=E2=80=A6
pressure1 pressure2 w302859 w302821 w302828 w302829 w302832 w302826 w302871=
w302874 w302835 w302842 This is the list with viper on the top and the pow=
er supply on the bottom. Also see https://wiki.ucar.edu/display/=
ahatslogbook/2008/07/17/GPIO+boards+in+pressure+systems https://wiki.ucar.e=
du/display/ahatslogbook/2008/07/17/GPIO+boards+in+pressure+systems
I notice in the p' time series a drop of pressure at 1323 this afternoon.&n=
bsp; This looks like the signature of a dust devil to me (and I saw one ear=
lier today near the trailer).
To further diagnose the p' system, I've been wanting to set up an independe=
nt system like CHATS. Now that John has brought out another pressure =
sensor, we made the following changes between 1030-1200: - Installed the ca=
l-lab field reference Paro 760 to measure Pref (in lieu of the 14th 202BG).=
Added it to profile:ttyS17 as P.0m. - Changed the 14th 202BG (still =
known as p.11b.4.8m) to measure just like CHATS, between the Bedard port th=
rough the hose and the CHATS reference.=E2=80=A6
All of the reference line tubing was insulated between 0800-0840 this morni=
ng. Based on one spectrum, it doesn't look like this has made much of a dif=
ference. Does this mean <yet> something else is going on to cau=
se these Pref fluctuations? Tonight we should receive another Pref sensor.&=
nbsp; Tomorrow I intend to use it as the new Pref sensor and configure my c=
urrent Pref sensor (the 11b 202BG) exactly as done in CHATS.</yet>=E2=
=80=A6
After discussions with John Wyngaard over the last 2 days (and a wake-up ca=
ll this morning), we decided to try to lower at least the high frequency fl=
uctuations in Pref by trying to add a sleeve around the tubing. John =
had the great idea to use foam pipe insulation. We found some in Hanf=
ord and added it to the horizontal sections of the array when it was down f=
or sonic leveling today. Unfortunately, I had only purchased enough f=
or a test this morning,=E2=80=A6
Here is an example from yesterday (1700-1730) of spectra (top panel) and co=
spsectra (bottom). The black line in the top panel is the spectrum of=
just the reference pressure (not connected to the atmosphere in any way).&=
nbsp; The red lines are all the sensors at 5m. Low frequencies in the=
reference pressure are due to drift in the CHATS reference volume due to c=
hanging soil temperature. Note that the signal-to-noise ratio from 0.=
01 to 1 Hz is on the order of one. (Actually,=E2=80=A6
At my request, Steve just pinched closed the leak I added yesterday to the =
AHATS pressure reference system. I hadn't seen much reduction of the =
high frequency temperature fluctuations in the Pref signal since this leak =
was introduced. (Though it definitely had an affect on the low freque=
ncies, where P and Pref were perfectly correlated. This was done about 10:1=
1am.
From about 1635-1735 I reconfigured pressure yet again. (See 11b sign=
al for exact times.) - 11b transducer removed and inserted into the CHATS s=
ystem (which was buried yet again) to monitor Pref (in parallel with the Va=
isala PTB220). - a leak installed into the far end of the AHATS reservoir (=
black tube). About 4m of the 1/16" line is attached, mostly coiled up=
in the ground, but the open end is exposed. We'll see what <this> lo=
oks like...
We built a 26-liter volume out of 2 5' lengths of 4" ABS pipe, stuffed it w=
ith steel wool and buried it in the ground (after checking that there were =
no leaks). We disinterred the N2 cylinder. After the usual 2 ho=
urs, Pref has settled down. I <do> think the signal is better b=
ehaved than for any of the other volumes, however there still are fluctuati=
ons that are larger than the static pressure signal (by about an order of m=
agnitude in the power spectra between 0.01 and 1.0 Hz).</do>=E2=80=A6
The results of this morning's tests indicate that the "medium frequency" si=
gnals we've been seeing in the pressure spectra are from the reference!&nbs=
p; This may be caused by convection in the cylinder that Jim Wilczak warned=
us about. Since we don't have a perfect alternative at the moment, w=
e've just plumbed all the references to the CHATS reference. Unfortun=
ately, we had to disinter and rebury this reference in order to connect to =
it. 6b and 6t are now returned to their original configurations.=E2=80=A6
To diagnose our strange p' spectra problem, I've made 2 changes: 6b - the +=
side is now plumbed through the CHATS garden hose to the Bedard quad-disk-=
probe, which I've lashed to the top of the tripod in the middle pitchfork p=
osition. Good winds at this location are bit restricted due to the co=
nfig#3 towers that Steve has erected, but should give us some idea. C=
hanges done 0915-0930.=E2=80=A6
Okay, I've been looking at pressure data and I can't figure out some things=
: 1. The reference pressure is slowly ramping away from P. My best gu=
ess is that the soil surrounding the reservoir is actually cooling now that=
it has the space blanket on top of it, thus making the pressure go down.&n=
bsp; I believe that this is consistent with the sequence of operations (fro=
m Khuong) when the cylinder was reburied (hole dug Fri AM, old hold dug up =
Fri AM, cylinder moved to new hole Fri AM,=E2=80=A6
Tom said to note that, upon tear-down of configuration #1 (wide array), the=
pressure ports appeared to swivel a bit on the 1/4" bolt securing them to =
the booms. Thus, the separation vector between the ports and sonic ar=
rays could be different. The bolts were tightened by inserting a wash=
er in configuration #2. (comment entered by Steve Oncley, but page was logg=
ed in as Gordon -- now I know better...)
These are the serial numbers of the Diamond GPIO-MM-12 cards used in each p=
ressure system, along with the clock rates that were determined for each ca=
rd. Following the tables is a discussion of the clock rate calibratio=
n procedure. Plots of the clock calibrations are viewable as attachments, u=
nder the Tools menu. Pressure1 board SN corrected clock rate (Hz) 0 302859 =
20,000,292.73 1 302828 20,000,450.67 2 302832 20,000,284.66 3 302871 20,000=
,072.66 4 302835 20,000,242.=E2=80=A6
The output message from the ambient pressure was changed to 3 decimal place=
s like the pressure reference. This occurred at 15:20 local time.
The output format of the pressure sensor attached to the pressure reference=
tank was changed to 1/1000. Also the running average was changed to 30 sec=
onds to provide better resolution. The output rate was left at 1 second. UP=
DATE: The averaging was set back to 1 second since we can average the data =
in post processing.
Steve completed sealing the fast pressure lines July 11 at 10:30 am PDT.&nb=
sp; He used teeny cable ties on all the junctions. The system p=
assed an over-pressure leakdown test by maintaining a constant pressure. A =
separate test was done on the reference tank. It also had a leak at the jun=
ction to the tank. This was fixed at 12:00 noon.
A pressure check was done after modifying 4 sensors. There was improvement =
but the leak still existed. Decided to go back to square one by checking th=
e Vaisala line. It was ok. Leakage started as soon as we added the first "T=
" junction. Further tests showed that the leak could be stopped by adding p=
anduit ties at each junction (3 ties per T). This requires very small ties =
so an order to Digikey was placed. Should have the ties by tomorrow noon.
After getting the wireless link from downwind2 and profile going this morni=
ng we did not realize that pressure1 was also down. It was restarted late t=
his afternoon. Note by Gordon: this system was still configured to use dhcp=
- and it lost its lease when the etherants were down. Fixed.
A variety of pressure tests were conducted on the pressure lines. Th first =
was a check of the reference cell. There appeared to be a very slow leak. T=
he main line was tested a major leak was found. It was at the end of the li=
ne where a tee was instead of a straight coupler. This was fixed around 2:3=
0 pm.; We will see what happens over the next few hours.
The interface board being used for 11B had a bad RJ45 connector. This was f=
ixed and the board was installed at Pressure2. PARO 11B was attached and da=
ta looks good. This occurred around 10:00am local.
A modified interface board for 11B, Pressure2, was added this morning=
. Based on Gordon's data_dump function the pressure and temperature data lo=
oked good with little noise.
In order to investigate whether the reference pressure system is working co=
rrectly, the Vaisala barometer was removed from the profile tower and=
installed next to the reference pressure tank. It is connected to th=
e reference tube via a 1/16 inch T connector near where the line goes under=
ground to the tank. The barometer data cable is connnected to ttyS17 =
on downwind2. The pressure variable is called Pref. The data ap=
pears at 18:22 PDT, Jul 8. So,=E2=80=A6
Yesterday, July 6, in the afternoon we installed the pressure1 system, with=
the altered interface cards, and mounted the Paroscientific units on the m=
asts. Data from pressure1 appears at 15:30 PDT. All frequency c=
ounts look good. The units serviced by pressure1 are 3b,4b,5b,5t,6b,6=
t and 7t.
No data was being sent from pressure2, and local storage was not being writ=
ten to. System was up, could log in over the network, and the dsm pro=
cess was running. data quit at 12:26 UTC, Jul 1. Restarted it w=
ith adn/aup at 13:26 UTC.
Chenning and Khuong working on the pressure measurement system at these tim=
es: June 27, 2008: Morning. Hung the horizo=
ntal pressure reference line. 4:45-5:15 PM. Worki=
ng on the 1/4 in tubing, connecting them to the pressure transducers.  =
;June 28, 2008 9:00-11:00am. Put 1/16 in couplers to the tran=
sducers on the lower array. The tubing on the transducer is hard and the co=
upler cannot be inserted directly, a heat gun was used to melt the tubing i=
n order to insert the coupler.=E2=80=A6
Specific Sonic Locations; Wide Array: Note: Sensors shown in table organize=
d from Southwest end of array to the Northeast end of the array. UpWind Arr=
ay of PAM tripods (spacing nominally 4m, array line parallel to and 16m NW =
from 'downwind'). SW  =
; NE horiz index 11 10 9 8 7 6 5 4 3 3.2m sonic s/n 1122 1123 1121 673 1119=
674 677 536 539 upwind serial port 11 10 9 8 7 6 5 2 1 DownWind Array of P=
AM tripods (spacing nominally 4m).=E2=80=A6
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