Blog

The config3 transition yesterday went:

1. Move the east horiz array up 3 slots.   (This measured at ~4.87m for the top of 5b's boom to the base plate.) [started ~0600]

2. Move the west horiz array up 3 slots.

3. Move 6t and 6b up.

4. Move 12b up.

5. Move 5.5m and 4.3m up to ~5.8m and ~4.8m (also T/RHs) [done by 0830]

6. Tear-down upwind and move to staggered upwind, sequence 11u -> 3u [done by 1230]

7. Remove upwind bases [1530-1630] 

When we started to build config 3, we measured 3.254m from the config 3 reference line  to the top of 5b's boom (of course, after raising it to its position).  New measurements for other sensors:

6t: 3.252m

6b: 3.250m

12b: 3.275m

(I didn't record new measurements of the 2 profile sensors.)

All of the upwind sensors were set to 3.261 = 3.254+0.7 to the top of the clamp +/-1mm.

P.S. The reference height mark #3 is 15.2cm below the mark for #2. 

P.P.S. Some spacings:

5t  133.4cm  6t  127.4cm  7t

5b 133.7cm  6b  127.8cm  7b

11b 128.3cm  12b  132.0cm  13b

Tom asked us to remeasure heights of the config2 upwind array as we tore it down yesterday:

There were some stray marks on the towers.  I wouldn't rule out the possibility that we chose the wrong reference line on some of the towers (note the the marks ended up underneath the masts sometimes).  In particular, I wonder if 6u's measurement was wrong.

Also note that we ended up measuring to the top of the clamp, rather than the top of the boom since this was much easier to get to.  The values above all have had an additional 0.7cm subtracted to compensate for this. 

P.S. On x-spacing:

Distance from end of boom bracket to center of PAM (square) mast, which was aligned to stakes: 12.4cm 

Distance from end of boom bracket to center of horiz array base plate, which was aligned to stakes: ~9cm

Distance between upwind stake line and horiz array stake line: was supposed to be 5.16m.

Distance between end of boom bracket to center of sonic arrays: ~177.7cm [but should be the same for either upwind or horiz array]

Thus, distance between upwind sensors and horiz array sensors: 5.16m + 12.4cm - 9cm = 5.13m.

Note that config 3 x-spacing should be the same. 

We changed from config 2 to config 3 between 0600-1230 today.  There still are a few PAM tripod bases left from config 3, so the surface is rougher than it should be.  We'll remove them this afternoon after a well-deserved lunch!

 P.S. John Wyngaard and Roger Wakimoto are now here as well.

I've looked a bit at the data from the 8m sonic.  I plotted u,v,w components from 7m&8m as a function of wind direction.  If the etherant were causing flow distortion, I would expect a signature that depends on wind direction.  I also would expect vertical velocity to have a negative bias for winds into the array.  What I see is u.8m being lower than u.7m, v.8m being equal to v.7m, and w.8m being higher than w.7m, all independent of wind direction.  Thus, I do not believe that the etherant is the source of the low winds at 8m that we've been seeing.

The next step is to replace this sonic.

During the last 10 minutes, we swapped Pocketecs on upwind, downwind1, pressure2, and pressure1 (in that order).  Obviously, there

will be brief data outages.

The pocketec units from profile and downwind2 were changed at about 12:45 local.

upwind stayed up with no hiccups overnight using the spare Viper board.  Hopefully it is now fixed...

AHATS daily status 7/27/08

Staff: Semmer, Oncley, Nguyen, Tudor with ISS
Cohn visited yesterday.
Temps: 103F/66F yesterday

Again, a bi-daily report.  Yesterday played with the pressure
system some more.  Also have had upwind crashes every night.

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

Good wind direction: The standard function reports 53 hours (23
unstable, 30 stable) in this configuration, all but 3 segments shorter
than 2.5 hours.  Note that our longest segment changed from 820 min
to 650 min now that I've entered boom angles -- a big change for only
a few degrees of reorientation!  However we have had some sensors and
data systems down so the actual numbers would be lower.

Local data storage: (we're getting ready to download these)
------------------
upwind:/dev/sda1 57685532 8441508 49244024 15% /var/tmp/usbdisk
downwind1:/dev/sda1 57685532 11579060 46106472 20% /var/tmp/usbdisk
downwind2:/dev/sda1 57685532 13765456 43920076 24% /var/tmp/usbdisk
profile:/dev/sda1 57685532 7746824 49938708 13% /var/tmp/usbdisk
pressure1:/dev/sda1 3940812 2157556 1783256 55% /var/tmp/usbdisk
pressure2:/dev/sda1 3940812 2045904 1894908 52% /var/tmp/usbdisk

aster:/dev/sdb1 721075720 277274000 443801720 39% /media/isff2
isff:/dev/sdc1 1922890480 403213996 1421999280  23% /media/isff15

The isff3 backup disk should now be back in Colorado via Steve Cohn.

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

We've made lots of adjustments to the pressure system over the past few
days to improve the spectra.   We're now using a 25 liter reservoir
that we built from ABS pipe and stuffed with steel wool.  However,
variation of the reference pressure (presumably due to tubing temperature
changes) still is about 3 times the variation of the static pressure.
We sacrificed the sensor at 11b to have it measure the reference pressure
so that we might be able to recover this signal.
p: ok, +/- 0.03 mb [still]
p'p': ok, +/- 0.001 mb^2
w'p': ok, +/- 0.002 m/s mb
t: 6b&6t are outliers by 3degC during day, others +/- 1.5 degC
Pref: ok -- has moved a lot during several changes

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

T: ok
RH: sensor that is now at 5.5m is strange, but we're going to live with it.
P: okay

diag: ok
samples.sonic: ok
spd: ok?, 8m still lower than 7m sometimes.  We'll change 8m out during
the next configuration switch.
dir: ok
w: ok
tc: ok, 8m low by ~0.3 degC? (related to the speeds being low as well?)
w'w': ok
u*: ok, some imaginary values with light winds
sigma_w/u*: ok (1.3 at night)
w'tc': ok
h2o: normal, 2 g/m^3 offset from dat("Q"), except in afternoon.
w'h2o': ok, 0.03 m/s g/m^3 at midday
co2: ok, 15-20 mmol/m^3 (some nights have large values, some don't [last
night]).  Presumably related to shallow nocturnal boundary layers,
but I haven't gone through the sodar data yet.
w'co2': ok, -0.01 m/s mmo/m^3 at midday

Upwind (hts=3.3): [,select.u]
----------------
Has crashed each of the last 5 nights at about 10pm.  Last night stayed
down due to a certain SE trying to help.  We've replaced the Viper CPU
board so hopefully it will work tonight.

diag: ok
samples.sonic: ?????ok
spd: ok, +/- 20 cm/s
dir: ok, angles much better now that they have been shot
w: ok, +/- 5 cm/s
tc:  ok, +/- 0.2 deg, biases somewhat larger
w'w': ok, +/- 0.005 m^2/s^2  (30 min avg for second moments)
u*: ok,  +/- 2 cm/s, again some imaginary values
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, +/- 20 cm/s
dir: ok, +/- 3 deg
w: ok, +/- 15 cm/s [need to check tilt angles].  Most negative.
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, +/- 0.01 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, better now with boom angles shot
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

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

The wide array downwind tripods were dis-assembled this morning.

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 frequencies, where P and Pref were perfectly correlated.

This was done about 10:11am. 

upwind now has the Viper board from spare and has just been restarted.  Also the Ethernet cable was changed to a different port on the hub located in downwind2. We'll see whether it stays up tonight!

upwind serial boards crashed again about 9:30pm last night.  I noted that there were long ping times to it, though Gordon believes that this is just a symptom of a generally sick adam.  Gordon actually tried to download a fix about 11pm that ended up crashing the adam.

We drove out about 8am this morning and got it running again by cycling power.

Steve and Gordon are now configuring "spare" in preparation for swapping it with upwind.

I note that winds were too much to the south all last night, so we didn't miss much data. 

From about 1635-1735 I reconfigured pressure yet again.  (See 11b signal for exact times.)

- 11b transducer removed and inserted into the CHATS system (which was buried yet again) to monitor Pref (in parallel with the Vaisala 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> looks like... 

Tom asked that we measure the crosswind spacings between the Rohn towers.  I think these are what he wanted:

5t  1.327m  6t  1.279m 7t

5u 1.325m  6u 1.282m 7b

11b 1.283 12b 1.283m 13b

Steve Cohn and I just shot boom angles for config#2.  A few notes:

- We were standing upwind of the sonics near the berm from about 12:00-13:30 doing this, during a period when the winds were good. A critical investigator may want to remove these data. 

- Where there are 2 values, Cohn's are listed second (no reflection on him or his measurements)

- 3u and 8u are not misprints--they really did look quite different

- 5t was behind 5u's PAM mast, but I think I got a good reading by centering the visible outside of the "claws".

P.S. Today (the following morning) I've entered all of the Oncley angles -131.7 degrees into each of the cal_files in boom_normal.  We'll see if the wind azimuths start falling into place.

A new set of angles shot by Semmer on 7/28.

 cal: entry in calibration file = measured magnetic azimuth - 131.7

The horizontal plane marks were put on the tower structures this morning.