- 118: Sensor Array, Site , Mon 25-Jun-2001 09:58:50 MDT, Towers a and b: sonic heights and tower spacing and azimuth
To my embarrassment, Jan notes that the sonic heights and tower spacings
for towers a and b are mostly missing from the logbook. I looked
through the scraps of paper that were used to note things in the field
and only find one note from Don Lenschow recording sonic heights on
9/24/00 (array 4), see below.
Sonic heights
-------------
The intent was for the sonic heights on towers a and b to match those
on the other sonic towers, so they presumably were:
z.d z.s
(m) (m)
Array 1 3.45 6.90
Array 2 4.33 8.66
Array 3 8.66 4.33
Array 4 4.15 5.15 but see the following note
Logbook entry #90 notes that the PAM masts did not allow the sonics in
Array 4 to be precisely mounted at the intended heights because of
interference with gussets, etc. This should not have been a problem
with Arrays 1-3, because the sonics in the s and d arrays (with the
exception of tower 0) were also mounted on PAM masts. The heights
for Array 4 were (found in both the logbook and Don's field notes):
a 4.13 and 5.05 m
b 4.13 and 5.02 m
Note that the sonic heights for towers a and b were simply measured
from the local ground surface. The heights were not determined
relative to the other towers using the theodolite as was done for
towers 0-9. That degree of precision was thought to be unnecessary for
the intended purpose of the data from towers a and b.
Tower spacing
-------------
The intention was for the tower spacing to equal the span of the d
array, 8*S.d. Thus these presumably were
S.d a/b spacing
Array 1 3.350 26.8 m
Array 2 2.167 17.3 m
Array 3 2.167 17.3 m
Array 4 0.500 17.3 m see following note
Note that array 4 does not follow the original design. It was decided
in the field that 8*0.5m = 4m was unreasonably close, so the towers
were left in the same location as for arrays 2-4. Thus my recollection
is that there was only one change in the location of towers a and b.
The change in spacing between arrays 1 and 2 is supported by the
following from logbook entry 39, dated Sunday, Sept 10:
"The towers were reconfigured starting with tower 1 and proceeding to
tower 9, then tower 0, and finally towers a and b. By the end of
Friday we had completed towers 1-7. On Saturday morning we completed
towers 8-9 and tower 0, finishing about noon.
On Saturday afternoon we completed towers a and b, finishing
tower a about 3 pm PDT and tower b about 4 pm PDT."
It should not have taken another hour to "complete" tower b unless the
tower was actually moved.
It also makes sense that no change of towers a and b occurred between
arrays 2 and 3 because the sonic spacing in the d array was not changed,
only the height of the d array changed. Thus the only real ambiguity
is the spacing between a and b for array 1 and then arrays 2-4.
Azimuth of tower line
---------------------
The azimuth of the line between towers a and b was only measured twice,
consistent with my recollection that there was only one change in their
location, between arrays 1 and 2. Note that tower b was nominally NW
of tower a (logbook #29)
a/b alignment logbook date
Array 1 135 deg 53' 25" 29 9/4/00
Array 2 135 deg 36' 28" 39 9/11/00
- 115: Sensor Array, Site , Thu 30-Nov-2000 12:06:41 MST, sonic heights and spacing
Following is a summary of the sonic heights and spacings for all arrays.
The filter designation refers to the array (1-4) and the 5 (s) or 9 (d)
sonic crosswind line.
height(m)
----------------
filter nominal measured spacing (m)
-------------------------------------------
1d 3 3.45 3.35
1s 6 6.90 6.70
2d 4 4.33 2.167
2s 8 8.66 4.33
3d 8 8.66 2.167
3s 4 4.33 1.05
4d 4 4.15 0.50
4s 5 5.15 0.625
These dimensions are contained in a file
$ASTER/projects/SGS00/sonics/dim.array:
# SGS array dimensions
#
# sonic height, z, and spacing, S, in meters
# for both (d)ouble and (s)ingle filter arrays
#
#Date Time z.d S.d z.s S.s
# (GMT)
# Array #1
2000 Sep 01 00:00 3.45 3.35 6.90 6.70
# array #2
2000 Sep 09 18:00 4.33 2.167 8.66 4.33
# array #3
2000 Sep 16 00:25 8.66 2.167 4.33 1.05
# array #4
2000 Sep 25 00:00 4.15 0.50 5.15 0.625
- 90: Sensor Array, Site , Sat 23-Sep-2000 11:31:36 PDT, Array geometry, array #4
In preparation for changing from array 3 to array 4, John Militzer and
I placed a reference height mark on tower 0 and on the two supporting
towers for array 4, using the theodolite in a transit mode.
This new mark is 5.5 cm above the mark for array 1. Since the height
mark for array 1 is 1.62m above the surface, this new mark is
assumed to be 1.675m above the surface.
Next, we measured the heights of the two horizontal towers to be
used to support the sonics in array 4. On the NE leg of array 4,
the heights of the two horizontal towers are (we measured the heights
to each of the two legs of each horizontal tower where they were
attached to the vertical towers):
(256 + 244)/2 - 10 cm = 240 cm + 1.675 m = 4.075 m
and
(356 + 344)/2 - 10 cm = 340 cm + 1.675 m = 5.075 m
On the SW leg of array 4, the heights of the two horizontal towers are:
(258 + 245)/2 - 10 cm = 241.5 cm + 1.675 m = 4.09 m
(358 + 345)/2 - 10 cm = 341.5 cm + 1.675 m = 5.09 m
Thus the heights of the CSAT sonics are 4.08 m + 5cm = 4.13 m and 5.13 m*
*Note that I mistakenly added 5 cm to the height of the middle of the
horizontal ASTER towers and the middle of the ASTER yokes on tower
zero. I should have added this dimension to height of the top of
the booms. The booms are 1.5 in x 1.5 in, and thus the true height
of the sonics on towers s0-s1, d0-d1 is higher by 0.75 in = 1.9 cm
or 4.15 m and 5.15 m.
The sonics on towers a and b were placed at the following heights
relative to the local surface. The height of the 5m sonics are
slightly lower than s0-s5 because of interference with the gussets
on the PAM mast:
A 4.13 m 5.05 m
B 4.13 m 5.02 m
The upper sonic on tower B is S/N NUW5.
The serial numbers and cosmos channel numbers of the CSAT sonics are:
sonic S/N channel
d0 * 200
d1 325 207
d2 364 208
d3 374 209
d4 367 210
d5 251 211
d6 376 212
d7 333 213
d8 290 214
d9 379 215
s0 * 201
s1 326 203
s2 373 204
s3 250 202
s4 375 205
s5 378 206
*unchanged from array 3
On Sept 29, 08:45 PDT, I measured the alignment of array 4 with the
theodolite. It is 45 deg 46'45" = 45.78 deg.
11/28/00:
I appear to have forgotten to note the sonic spacing. The spacing of
the d array at a nominal height of 4 m was 0.5 m and the spacing of the
s array at a nominal height of 5 m was 0.625 m. twh
- 66: Sensor Array, Site , Fri 15-Sep-2000 18:04:34 PDT, Changed from Array 2 to Array 3 today
Today, September 15, we changed from array 2 to array 3
between 1225 PDT and 1725 PDT. The new array has the
9-sonic, double filter array at the 8.66 m height with a
spacing of 2.167 m and the 5-sonic, single filter array
at the 4.33 m height with a spacing of 1.08 m on towers
4-6. Three of the 4.33 m sonics (S2,S3,S4) are mounted
on tower 5 and their actual spacing is 0.5*2.09 m =
1.05 m, not 1.08 m. Note that the booms on these three
sonics are also perhaps 5 cm shorter than the other booms!
I confirmed the shorter length of the triple boom. These booms
measure 138 cm between the mounting bolt for the sonic and the
mounting bolt for the boom to the yoke on the mast. The other
booms are 143 cm long.
The sonic serial numbers and cosmos channels are:
Tower serial number cosmos channel
-------------- --------------
4.33 m 8.66 m 4.33 m 8.66 m
0 422 423 200 201
1 290 203
2 333 204
3 251 206
4 376 378 207 202
5 379 205
5 375 250 208 209
5 367 211
6 374 373 210 214
7 326 212
8 364 213
9 325 215
- 39: Sensor Array, Site , Sun 10-Sep-2000 08:17:25 PDT, Reconfigured sonics to array 2
On Friday morning, September 8, we started reconfiguring the
sonics from array 1 to array 2. Array 2 has a PAM tower spacing
of 2.167 m and sonics heights of 4.33 m (double filter array of 9
sonics) and 8.66 m (single filter array of 5 sonics with 4.33 m spacing).
The PAM masts were located by stretching a string along the ground
that followed the line of the previous array and marking the line
at intervals of 2.167 m. We then used a plumb bob hanging from
the bolt connecting the PAM mast to the tripod to locate the center
of each tripod. We oriented the tripod by aligning the back leg
with a truck parked 1550 m to the NW of the array. We parked
the truck about 3.5 m west of the previous location to account for
the shrinkage of the tower 1-9 array from 26.8 m to 17.33 m.
The sonic heights were determined by again using the theodolite,
locked into a horizontal orientation to place marks on the towers
at the same geopotential height. This new mark was 5.4 cm below the
previous mark for array #1. The old mark was interpreted to be
1.62 m, so the new mark is interpreted to be 1.56 m (1.62m - 0.054m).
The towers were reconfigured starting with tower 1 and proceeding to
tower 9, then tower 0, and finally towers a and b. By the end of
Friday we had completed towers 1-7. On Saturday morning we completed
towers 8-9 and tower 0, finishing about noon.
On Saturday afternoon we completed towers a and b, finishing
tower a about 3 pm PDT and tower b about 4 pm PDT.
The masts on towers 1-9 were again oriented using the truck as a
reference. On tower 2 there was insufficient leeway to complete the
orientation and the sonic is pointed to a spot about 20 m west
of the truck. This orientation was completed about 11 am PDT,
September 9.
On September 11, Peter Sullivan and I measured the array azimuths.
The SGS array was measured at 0950 PDT to be 225 deg 15' 50".
The AB array was measured at 1035 PDT to be 135 deg 36' 28"
- 19: Sensor Array, Site , Thu 31-Aug-2000 07:42:44 PDT, Array 1 geometry; sonic S/Ns
The PAM stations for Array #1 have a spacing of 3.35 m and the
normal to the array is at azimuth 315 deg 10 minutes.
This measurement was made around 0900 PDT, Sept 4, using the
sun angles for year 1900 rather than year 2000. The correction
is +18' for a final angle of 315 deg 28' = 315.47 deg.
On Sept 29, 09:00 PDT, I remeasured this angle using the stakes
that were used to align array. The angle was 45 deg 9'.
A reference surface for setting the heights of the sonics was
determined by using the theodolite to mark a common height on
the nine PAM masts and on the reference ASTER tower. The
heights of this mark above the local surface at the PAM masts
were:
1.63 m
1.63 m
1.61 m
1.63 m
1.66 m
1.61 m
1.58 m
1.62 m
1.61 m
for an average height of 1.62 m. The sonics were placed at a height
of 3.45 m (!) above the surface by measuring 1.78 m from this mark to the
tops of the booms. The center of the CSAT sonic array is another 5 cm
above the top of the boom.
Note that, after determining this reference height and marking it on the
masts, some of the PAM masts were moved up slightly to allow them
to be reoriented. When we changed arrays on September 8, we measured
a new reference mark with the theodolite. Following are the differences
between the two reference heights. Since the height of the ASTER tower 0
was not changed, the change in the heights of the PAM masts is the
difference between dz at the PAM masts and dz at the ASTER tower.
The biggest change appears to be 8.0 - 5.4 = 2.6 cm.
tower dz (cm)
0 5.4
1 5.8
2 8.0
3 6.8
4 (mark on plate, which did not get moved with the mast)
5 6.2
6 6.6
7 7.1
8 5.9
9 6.3
The second sonic is at a height of 3.45 m above the lower sonic, or
6.90 m above the surface.
The length of the CSAT booms is 143 cm, measured between the mounting
bolt for the sonic and the bolt used to attach the boom to the yoke
on the mast.
Going from NE to SW, the CSAT sonics are
CSAT S/N Cosmos serial channel
-------------- ---------------------
Tower 3.45 m 6.90 m 3.45 m 6.90 m
9 364 325 214 215
8 367 213
7 373 326 211 212
6 374 210
5 375 250 208 209
4 376 207
3 378 251 205 206
2 379 204
1 333 290 202 203
0 422 423 200 201
The lower sonics on the PAM towers were aligned using a telescope
attached to a flat reference surface. That surface was mated to
the side of the CSAT junction box at the rear of each array and
the pam mast was rotated until the telescope lined up with a truck
parked at azimuth 315 deg 10 min at a distance of 1550 m.
The upper sonics were aligned roughly by orienting their booms paralled
to the lower sonic boom on the same tower.
The UW sonics on towers a and b (the Taylor's hypothesis array, with
tower b upwind of tower a) are:
3.45m 6.90m
a UW#6
b uw#3 uw#5*
*read on September 26