Blog from July, 2008

The pam towers for configuration 3 are now setup. Tomorrow we will mark them for height measurents.

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 position.  Good winds at this location are bit restricted due to the config#3 towers that Steve has erected, but should give us some idea.  Changes done 0915-0930.

6t - I've removed this transducer and placed it inside my CHATS sensor tube which is now in buried in the ground near the middle of the horizontal array and covered with a space blanket.  The + side is connected to the AHATS reference system and the - side is connected to the reference volume inside this tube. Changes done 0940-1020.  Note that the AHATS reference system was open to the world a couple of times during this work.

NOTE THAT THIS DESTROYS THE AHATS p' ARRAY, since no center sensor at either height.  I think these tests are worth it, though.

Last night about 10pm, upwind's serial boards crashed again.  "adn/aup" worked, but crashed again after ~10min.  I "reboot"ed from the apartments and got it working.  However, the usbdrive wasn't working this morning, so it probably died in the reboot.  About 9:30 this morning, I cycled power on upwind and all seems well at the moment.

We would change this serial board, but it isn't clear to us which board to swap with.

We lost data from the serial boards in both profile and upwind last night.

profile died at 20:20 local and upwind at 03:05.  Both were restarted with "adn" and "aup" at 09:43.

Sorry it took so long to fix this.

 I guess we now should take seriously the "To Do" task of swapping profile's serial board!

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 guess 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.  I believe that this is consistent with the sequence of operations (from Khuong) when the cylinder was reburied (hole dug Fri AM, old hold dug up Fri AM, cylinder moved to new hole Fri AM, pressure lines sealed & checked Sat AM, hole backfilled and space blanket added Sat AM).  Although Pref is now 14mb lower than P, this is well within the 150mb range of the 202BGs, so I'm not excessively concerned.  We'll keep on monitoring this signal.

 
2. I've now looked at selected pressure spectra from two periods, one in config#1 and one in config#2. The two periods have spectra that are quite similar to each other and the 3 sensors I've looked at also are similar to each other.  However, these spectra are completely different than those seen in CHATS.  CHATS p spectra followed f^-5/3 reasonably well from a peak more-or-less at 0.1Hz until a digitizing white noise floor at ~7Hz.  The amplitude of the noise was about 2.5e-6 (mb^2).

Here, we are seeing a nice peak at about 0.02 Hz, but with a roll-off that goes more like f^-3.5 and thus intersects the noise floor (of about 2.5e-7 mb^2) at a frequency of only about 1Hz.  It is gratifying that the noise floor is lower (given all the hard work on our counter boards), though I thought we would gain more than this factor of 3 (the square root of 2.5e-6/2.5e-7).  The amplitude of the signal at 0.01 Hz is actually about the same as the CHATS cases but, with this sharper roll-off at high frequencies, there is a lot less energy at, say, 1 Hz.

I don't understand the sharper roll-off.  At first, I thought that the low frequencies might be contaminated by tower wakes in our configuration #2, but I would have expected energy at high frequencies as well and I see the same roll-off in configuration #1 data.  However, I can't see how filtering like f^2 (the approximate difference between -5/3 and -3.5) could be caused by a physical process (say, too small tubing).  My best guess is that it is a signal processing artifact, though I can't imagine what.  The cut-off frequency of such a filter would be about 0.1 Hz (10 s period).

I don't know at the moment what the calibration code is doing.  Since the variables "pper" and "p" are almost perfectly correlated, I'm assuming that the temperature correction, if it is being applied, is quite small (at least at these frequencies).  In any case, since this "filtering" appears in "pper", I'm assuming that it hasn't been introduced by post-processing. 

Did anyone else look at pressure spectra before I arrived?  If so, did you see similar behavior??

I might try changing the sample-side tubing on one of the transducers, in a long-shot attempt to figure this out, but otherwise I'm stumped.

I got the following replies from Tom and Gordon: 

Steve:

Perhaps you have already considered the averaging of the counter board output.  It is
counting for approximately 0.1 second, which is applying a low-pass filter equal to
sin/x where x = 2/pi*f*dt/2 and dt=0.1 sec.  This does not nearly correspond to the
attenuation you are seeing at high frequencies.  At the Nyquist frequency, 5 Hz, the
attenuation is 0.637 (0.405 for the power spectrum: a rough anti-aliasing filter) and at
1 Hz the attenuation is 0.984 (0.968).

Still not much help.  It is perhaps worth noting this in the logbook for future users of
the pressure data.

Tom 

We can alter that averaging period.  It is the NumPulses parameter in the XML,
currently set to 3000 for pressures and 10,000 for temperatures.

Gordon

My status reports have noted issues with 4u and 8m.

8m: By just playing with offsets, I'm able to get better looking profiles by adding 0.3 m/s to dat("u").  As yet, I have no justification for doing this.  Tom wondered about flow distortion around the etherant, but this seems only a remote possiblity after looking at it today.  The next step would be to move the etherant.

4u: At 09:10 on 20 July, tc on this jumps by 0.25 degC.  I can see no evidence of a similar step in any of the wind components.  Tom confirmed that an upwind sensor might have been "bumped" by a ladder at this time, but his recollection was that it was one at the southwest end, whereas 4u would be at the northeast end.  I don't see any reason for further action with 4u.

Steve, Kuong, and I moved the upwind tripods from their config1 to config3 positions.  During the period ~0845-0930 we walked in front of the config2 towers to avoid doubling the length of carry.  Unfortunately, there were some good winds during this period.  I'll reduce our unstable data inventory by about an hour when considering when to change.

AHATS daily status 7/22/08

Staff: Semmer, Oncley, Knguyen, Tudor with ISS
Temps: 92F/57F yesterday

For more details, see the ahats logbook at https://wiki.ucar.edu/display/ahatslogbook

Good wind direction: Now have almost 26 hours of data (10 unstable, 16 stable)
in this configuration.  We're already half way!

Local data storage: (all now quite low)
------------------
upwind:/dev/sda1 57685532 3898500 53787032 7% /var/tmp/usbdisk
downwind1:/dev/sda1 57685532 4346968 53338564 8% /var/tmp/usbdisk
downwind2:/dev/sda1 57685532 5086676 52598856 9% /var/tmp/usbdisk
profile:/dev/sda1 57685532 3163852 54521680 5% /var/tmp/usbdisk
pressure1:/dev/sda1 3940812 651032 3289780 17% /var/tmp/usbdisk
pressure2:/dev/sda1 3940812 645516 3295296 16% /var/tmp/usbdisk

aster:/dev/sdb1 721075720 248687612 472388108 35% /media/isff2
isff:/dev/sdb1  961432072 374897584 586534488  39% /media/isff3

replacement for isff3 should be at Hanford by now.

Pressure:
--------
(+/- = ~1 std deviation among variables at the same height)

The spectra I looked at yesterday were strange.  I have to look at more
examples to figure out what is wrong.  It could simply be turbulent wakes
in this configuration.
p: ok, +/- 0.03 mb
p'p': ok, +/- 0.001 mb^2
w'p': ok, +/- 0.002 m/s mb
t: 6b&6t are outliers by 5degC during day, others +/- 1.5 degC
(may be orientation of sun shields?)
Pref: still steadily drifting low, though a bit of a diurnal cycle now.
(might be cooling of the reservoir)
now 14mb below ambient.

Profile: [,select.p]
--------

T: ok
RH: 4m RH swapped, but left cap on!  Now ok?
P: okay

diag: ok
samples.sonic: ok
spd: ok?, 8m generally lower than 7m (sensors are in correct position)
dir: ok
w: ok
tc: ok, 8m low by ~0.3 degC?
w'w': ok
u*: ok
sigma_w/u*: ok (1.3 at night)
w'tc': ok
h2o: ok?, 2 g/m^3 offset from dat("Q"), except in afternoon.  (Does a light
leak help??)
w'h2o': ok, 0.03 m/s g/m^3 at midday
co2: ok, 15 mmol/m^3
w'co2': ok, -0.01 m/s mmo/m^3 at midday

Upwind (hts=3.3): [,select.u]
----------------

diag: ok
samples.sonic: ok
spd: ok, +/- 10 cm/s
dir: ok, mean offsets of up to 13deg -- need to enter new Vazimuths??
w: ok, +/- 5 cm/s
tc:  ok, +/- 0.2 deg,
w'w': ok, +/- 0.005 m^2/s^2  (30 min avg for second moments)
u*: ok,  +/- 3 cm/s, imaginary during light winds this afternoon
sigma_w/u*: ok (1.3 at night)
w'tc': ok, +/- 0.01 m/s degC
tc'tc': ok, +/- 0.05 degC^2

Downwind Lower (hts=3.3): [,select.b]
------------------------

diag: ok
samples.sonic: ok
spd: ok, +/- 30 cm/s
dir: ok, +/- 3 deg
w: ok, +/- 15 cm/s [need to check tilt angles]
tc:  ok, +/- 0.2 deg
w'w': ok, +/- 0.01 m^2/s^2  (30 min avg for second moments)
u*: ok,  +/- 2 cm/s, some imaginary mid-day
sigma_w/u*: ok (1.3 at night)
w'tc': ok, +/- 0.02 m/s degC
tc'tc': ok, +/- 0.05 degC^2

Downwind Upper (hts=4.3): [,select.t]
------------------------

diag: ok
samples.sonic: ok
spd: ok, +/- 10 cm/s, 3t lower by 20cm/s
dir: ok, +/- 2 deg, 3t now outlier
w: ok, +/- 5 cm/s, 5t&6t outliers
tc:  ok, +/- 0.2 degC, offsets up to 0.6 degC
w'w': ok, +/- 0.01 m^2/s^2  (30 min avg for second moments)
u*: ok,  +/- 2 cm/s, again imaginaries
sigma_w/u*: ok (1.3 at night)
w'tc': ok, +/- 0.005 m/s degC
tc'tc': ok, +/- 0.05 degC^2

----------------------------------------------------------------

To check the 8m speeds being low, we checked the physical serial numbers on the tower.  They are:

 These are exactly as recorded in the file sonics/sonic.configs.

The 4m TRH, on profile, was replaced this morning. The RH of sensor 8 was ready a little low compared to the other TRHs. Sensor 8  was replaced with sensor 10.

UPDATE: It appears the protective cover was left on the sensor. The humidity is ready too high! It was removed at about 14:00.  However, the RH from this position is still a bit low!

I've just added a few commands/aliases to make my life easier:

sshp, sshd1, sshd2, sshu, sshp1, sshp1 all ssh to the various adams

ds is data_stats (on aster)

rs is the shortcut rs that Gordon had on the adams, with a required second argument of the adam name

lsu does "df  | grep usb" on all of the adams and lists aster's usb disk as well

My daily status is in $ISFF/projects/AHATS/logbook/template.

A list of S+ commands used to generate the daily status is in $ISFF/projects/AHATS/S/daily.qq.

AHATS daily status 7/21/08

Staff: Semmer, Oncley, Knguyen, Tudor with ISS
Horst has just left for a well-deserved break...
Max temp: only 89F and min 59F yesterday! (with broken clouds)

- An extension of AHATS operations for 6 additional days has been approved.
- As of 16:00 yesterday afternoon, we are now in configuration #2.

For more details, see the ahats logbook at https://wiki.ucar.edu/display/ahatslogbook

Good wind direction: Winds turned perfect at 10pm last night, so we now
are in a 13-hour period of good data (obviously both stable and unstable).

Local data storage: (all now quite low)
------------------
root@upwind root# df | grep usb
/dev/sda1             57685532   2453532  55232000   4% /var/tmp/usbdisk
root@downwind1 root# df | grep usb
/dev/sda1             57685532   2745012  54940520   5% /var/tmp/usbdisk
root@downwind2 root# df | grep usb
/dev/sda1             57685532   3164908  54520624   5% /var/tmp/usbdisk
root@profile root# df | grep usb
/dev/sda1             57685532   2109752  55575780   4% /var/tmp/usbdisk
root@pressure1 root# df | grep usb
/dev/sda1              3940812    317660   3623152   8% /var/tmp/usbdisk
root@pressure2 root# df | grep usb
/dev/sda1              3940812    312264   3628548   8% /var/tmp/usbdisk
aster: df | grep isff2
/dev/sdb1            721075720 242010508 479065212  34% /media/isff2
isff: df | grep isff3
/dev/sdb1            961432072 367926356 593505716  39% /media/isff3

Pressure:
--------
Has been running since late 19 Jul. when set into configuration #2
(+/- = ~1 std deviation among variables at the same height)

9t connector in box loosened -- fixed yesterday afternoon,
p: ok, +/- 0.03 mb
p'p': ok, +/- 0.001 mb^2
w'p': ok, +/- 0.002 m/s mb
t: 6b&6t are outliers by 5degC now, others +/- 1.5 degC
Pref: now steadily drifting low -- might be cooling of the reservoir
(which was reburied Sat morning -- 2 days ago), but looks strange.
now 11mb below ambient.

Profile: [,select.p]
--------
Has been running since late 18 Jul. when set into configuration #2

diag: ok, recent spikes on 13b when Y-cable added to 3m profile
samples.sonic: ok
T: ok
RH: 4m is low by up to 2% RH -- we'll swap in a spare
P: okay

spd: ok?, 8m generally lower than 7m
dir: ok
w: ok
tc: ok, 8m low by ~0.3 degC?
w'w': ok
u*: ok
sigma_w/u*: ok (1.3 at night)
w'tc': ok
h2o: now okay after swapping Li7500s, offset of ~1.3 from dat("Q")
w'h2o': ok, 0.02 m/s g/m^3 at midday
co2: ok, 15 mmol/m^3
w'co2': ok, -0.01 m/s mmo/m^3 at midday

Upwind (hts=3.3): [,select.u]
----------------
Has been running since late 18 Jul. when set into configuration #2

Sonics were moved in height yesterday morning.
diag: ok, spikes during move
samples.sonic: ok, drops during move
spd: ok, +/- 10 cm/s, suggestion of systematic differences
dir: ok, mean offsets of up to 13deg -- need to enter new Vazimuths??
w: ok, +/- 5 cm/s
tc:  ok, +/- 0.2 deg, 4u changed offset by ~0.3degC since move -- perhaps
it got bumped?
w'w': ok, +/- 0.005 m^2/s^2  (30 min avg for second moments)
u*: ok,  +/- 3 cm/s
sigma_w/u*: ok (1.3 at night)
w'tc': ok, +/- 0.01 m/s degC, again systematic??
tc'tc': ok, +/- 0.05 degC^2, again systematic??

Downwind Lower (hts=3.3): [,select.b]
------------------------
Has been running since mid 20 Jul. when set into configuration #2

diag: ok
samples.sonic: ok
spd: ok, +/- 30 cm/s
dir: ok, +/- 3 deg, offsets now smaller than config #1??
w: ok, +/- 15 cm/s, now larger deviations and systematic negative bias,
consistent with being on horizontal array now, droop ~2 deg
tc:  ok, +/- 0.2 deg
w'w': ok, +/- 0.01 m^2/s^2  (30 min avg for second moments)
u*: ok,  +/- 2 cm/s
sigma_w/u*: ok (1.3 at night)
w'tc': ok, +/- 0.02 m/s degC
tc'tc': ok, +/- 0.05 degC^2

Downwind Upper (hts=4.3): [,select.t]
------------------------
Has been running since mid 19 Jul. when set into configuration #2

diag: ok
samples.sonic: ok
spd: ok, +/- 10 cm/s
dir: ok, +/- 2 deg; more consistent now that on the horiz array, 6t at one
extreme
w: ok, +/- 5 cm/s
tc:  ok, +/- 0.2 deg
w'w': ok, +/- 0.01 m^2/s^2  (30 min avg for second moments)
u*: ok,  +/- 2 cm/s
sigma_w/u*: ok (1.3 at night)
w'tc': ok, +/- 0.005 m/s degC
tc'tc': ok, +/- 0.05 degC^2

----------------------------------------------------------------

We just swapped Li7500s with our spare (1164) and data are now coming in.  This unit is just sitting on the ground at the moment.  We will move it up soon.

The old unit (1167) was burning ADAM front panel fuses.

P.S. Steve S. mounted it at about 11:30am.

P.P.S. In the trailer, 1167 works fine.  Perhaps the whole problem is just the ADAM fuse -- it should be 3A since the Li7500 is supposed to go up to 30W during start-up.  We'll check what is in there now.

P.P.P.S! The h2o values appeared high for the first couple of hours, but by about 13:00 they agreed within 0.5 g/m3 of dat("Q").  Assume that co2 is off for the first 2 hours as well.

After the reconfiguration, pressure 9t was bad.  Steve fixed the serial input cable for 9t in pressure 2 to make better contact with the RJ45 connector.  This was completed around 16:00 PDT, July 20.

The 3m profile sonic is doing double duty as a profile sonic and also sonic 13b in the horizontal array.  Steve made a y cable to connect this sonic to both profile S2 and downwind2 S10.

11/23/09, TWH: It appears from the 5-minute covars that the connection of the 3m profile sonic to Serial channel 10 on the downwind2 adam was made around 09:30 on July 21.