FLATLAND96: HYGRO Messages: 17 Entries..

Station 2 Visit: 22:20-23:35, 96/06/28, JD180


TRH Fan Replaced
	This station had been having high temps.  I found the fan was dead, and
	wouldn't come back.  This is the same site where similar problems
	occurred earlier.  I replaced the fan in the beehive....what a nuisance
	to do.

EVE Not talking
	I never got the Compaq to cooperate with EVE.  It would see the EVE's
	messages but apparently never got a xmt through.  This had happened
	quite a bit previously, all over, and had been attributed to low/hot
	battery in the Compaq.  Even after powering down the Compaq for awhile
	and using the battery cable Matt sent, and recycling the Compaq, i 
	still never go into EVE.  I didn't have a gender change to try the RJ45
	direct console connection.
	NOTE: that this station has been having Freewave difficulty as well, but
	i think that's related to the lowered antenna at the base and a
	different radio xmit characteristics table than normal being used with
	these new replacement units.

Station 3 Visit:   20:25-21:45Z, 96/06/28, JD180

TRH inner shield had dropped down about 1.5" since yesterday's visit.
I removed the shield and pushed it back as best i could, but it needs to have
larger screws put in the stripped housing.

The TRH inner shield tube was inserted fully so that no air could flow between
it and the outter tube.  The configuration was corrected, but there may have
been a small influence on the readings possibly, i.e. slightly too warm.

		visit time: 17:00 - 17:30 GMT

  I did a temperature IC using the ASSMAN. The data
was recorded on the compact pc. Overall the temperature
was about 0.2 degrees high and the humidity was around 3%
high compared to the ASSMAN.

		visit time: 18:00 - 18:30 GMT

  I did a temperature IC using the ASSMAN. The data
was recorded on the compact pc. Overall the temperature
was about 0.3 degrees high and the humidity was around 1.5%
high compared to the ASSMAN.

		visit time: 14:00 - 14:30 GMT

  Temperature IC showed similar results as ICs at
stations 2 and 3. The temperature was about .25C high
and rh was .6% high.

  The robins at the nest are getting mad about our
unschedule visits!

Matt noticed yesterday that the fan wasn't going on this sensor - it had a
corroded (and now broken) lead.  We just replaced the fan.

P.S. fun.Tddiff.plot() shows that the fan died about 10Z on 23 July, so it
was bad (with readings high by about 1.5 C) for about 3 days.

I have been a bit worried that the Tddiff plots for the last 2 nights show
station 2 not reversing sign, as it did earlier and as the other stations
are continuing to do.  Yesterday, Erik and I visited the site (while taking
pictures).  We opened up the hygro and cleaned out a few bits of biota,
but it appeared to be okay.  We reinstalled it, but also broke the top couple
of feet of the 4 corn plants which had grown up around the sensor in order
to give it some air flow.  This doesn't seem to have affected the data last
night.

At 1730 local powered down TRH at station 1 and cleaned and inspected
housing. Restarted.

The experiment with the Trh having the filter off only caused the temperature 
difference to be worse.  Last night the offset was about 8 degC.  Worse than 
the previous value of 5 degC.

Swapped the 50Y probe in the Trh sensor.  Old unit was #15, new was #12.  Put 
in new calibration values for probe.  Replaced dessicant.  Temp values rose and came back in line with other sensors at night.

the bph's at station 2 & 3 were moved down to the trh levels at 16:35 & 16:55
respectively. this was down to compare bandpass and hygrothermometer per
Steve Semmer.

the bph was moved to the trh level at 16:20 today

                                   FLAT96
 9/04/96                           Assman ICs                           Page   1


                         Sample                            --Trh Sensor-  ----Assman Data------
Site#   Date      Time   Time    Trh ID  Press   Samples  Tdry    Rh      Tdry    Twet    rh      Comments
-----   --------  -----  ------- ------  -----   -------  ------  ------  ------  ------  ------  ---------------------------------------------------

  1      7/05/96  14:17  14:46        1   992.2      10    25.03    39.6   24.75   15.94    39.2
  1      7/13/96  19:01  19:04        1   986.2      10    27.65    44.3   27.10   18.51    43.5
  1      7/19/96  21:49  22:02        1   988.0       4    30.01    70.6   30.00   25.95    72.6
  1      7/25/96  20:40  20:55        1   991.1       7    24.78    63.9   24.84   19.90    63.5  ok
  1      7/30/96  20:22  20:46        1   990.1      10    26.13    69.9   25.76   21.61    69.6  station temp may be high due to close person
  1      8/04/96  18:35  18:57        1   993.9       5    27.02    68.3   27.19   23.08    70.6
  1      8/09/96  16:32  16:49        1   997.6       9    26.11    53.2   26.15   18.79    49.4  temp cllose, but rh a bit high
  1      8/14/96  17:22  17:44        1   993.3       9    27.93    66.4   27.79   22.89    65.9
  1      8/19/96  19:11  19:31        1   996.2       9    29.53    70.2   29.25   24.96    70.6  nice averages


  2      7/04/96  16:51  17:24        3   991.4      15    24.21    35.1   23.93   14.24    33.0
  2      7/13/96  16:33  17:23        3   986.8      10    27.74    49.6   27.35   19.59    48.4  cloud during samples 3-9
  2      7/19/96  21:15  21:29        3   987.6       4    30.83    63.9   30.60   24.48    60.6
  2      7/25/96  19:22  19:46        3   991.5       7    24.89    61.5   24.71   19.31    60.4  ok--done during variable clouds
  2      7/30/96  19:23  19:51        3   990.2      10    24.87    67.7   24.56   19.91    65.3  sun/cloud mix, hygro sees leaves (reflected
                                                                                                  radiation?)
  2      8/04/96  17:56  18:16        3   994.6       9    27.93    69.5   27.62   22.94    67.2
  2      8/09/96  15:56  16:11        3   998.0       9    26.16    52.3   25.89   18.74    50.4  ok
  2      8/14/96  16:16  16:50        3   994.0       9    28.06    64.3   27.86   22.52    63.2
  2      8/19/96  16:28  16:48        3   997.0       9    28.69    73.8   28.37   24.60    73.5  temp a bit high, rh good


  3      7/04/96  18:10  18:30        2   991.0      15    25.28    26.3   25.01   13.51    24.7
  3      7/13/96  17:49  17:54        2   986.9      10    27.41    45.5   27.41   18.67    43.0  sun increased during samples
  3      7/19/96  20:40  20:57        2   988.0       4    32.53    56.4   32.33   24.85    54.5
  3      7/25/96  18:06  18:32        2   991.5       6    25.38    61.2   24.42   19.18    61.2  ok-- tried to hold assman into wind hanging from
                                                                                                  xarm
  3      7/26/96  15:51  16:13        2   997.0      10    23.79    65.9   23.62   18.88    63.9  new fan instaled
  3      7/30/96  18:33  19:02        2   990.1      12    24.42    70.9   24.23   20.00    68.0  cloudy at end
  3      8/04/96  17:17  17:38        2   994.4       9    27.84    68.0   27.45   22.56    65.8  rh a bit  high
  3      8/09/96  15:17  15:36        2   998.0       9    24.64    57.6   24.43   18.22    54.7  a bit high but not bad
  3      8/14/96  20:18  20:34        2   991.9      10    29.08    59.1   28.96   22.48    61.5  OK
  3      8/19/96  17:10  17:28        2   996.6       9    28.44    74.2   28.31   24.57    73.7  good IC

  During the operation period of FLATLAND96, routine intercomparison tests were 
conducted between the hygrothermometers and an ASSMAN psychrometer. A typical
test took place in the early afternoon consisting of 10 data points collected
over a 5 minute period.

  The ASSMAN IC plot shows the difference between the ASSMAN and each
hygrothermometer. The positive mean error value for the temperature difference
is due to the radiation affects on the hygrothermometer shield. The humidity
errors are within a 2% window.

STATION			   TRH - ASSMAN
		temperature (C)		humidity (%)
PAM 1		  0.15			  0.2
PAM 2		  0.28			  1.7
PAM 3		  0.18			  1.4

  

GENERAL:
  At the end of operations, the BPH instrument was moved down to the
height of the TRH to allow for a side-by-side comparison. Data were collected
over a 24 hour period. It should be pointed out that the data from station
1 was collected approximately 24 hours after station 2 and 3. In general,
the side-by-side test highlighted the radiation problem with the TRH
shield and the effects of contamination on the humidity transducer.

TEMEPRATURE:
  Graphics TCOMP PLOT shows a comparison of the temperature response of
the two instruments over time along with the net radiation response. The
affects of solar radiation on the TRH shield are quite obvious from
17:00 to 01:00 GMT. The dramatic change, in station 3, from 23:00 to
2:00 GMT is believe to related to the crop conditions. The instruments
at stations 1 and 2 were in the upper leafs of the corn where the radiation
affects were not as great as at station 3 where the sensors were fully
exposed. At night time, the temperature differences should have approached
zero assuming the calibrations were correct. As can be seen in the plot,
the data did not support this concept. The post project check did show
a mean error of -0.18 C in the TRH temperature sensor at station 3.
This would change the mean error of station 3 to -0.11 C. At this time
nothing has been found to explain the results at station 2.

RELATIVE HUMIDITY:
  Graphics RHCOMP PLOT is a difference plot between the TRH and BPH with
respect to humidity. What immediately jumps out is the difference in the
response of station 1 compared to stations 2 and 3. The environment the
sensors were exposed to can not be the cause because stations 1 and 2
were located in the same environment. Another possible cause was the data
acquisition systems used to collect the BandPass data. The BandPass instruments,
at stations 2 and 3, were interfaced to the older ATI sonics. A check of the
A/D system of the sonics did not explain the difference. A third possible
cause is the calibration of the sensors.
  The post calibration check of the sensors can be seen in POSTCAL PLOT.
An important aspect of this plot is the response of the BPH sensors compared
to the TRH. This difference is due to the BPH humidity transducers being
directly exposed to the atmosphere while the TRH transducers were protected
by a filter. This was confirmed by cleaning the BPH transducers and repeating
the test in the humidity chamber. A second factor in this plot was the
difference in the response of BPH sensor between station 1 and stations 2 and 3.
This difference may explain the issue brought out in RHCOMP PLOT.
  To explore this assumption, a simple linear correction was computed for
each individual sensor using the data from POSTCAL PLOT. The fit was
applied only from 60% to 90% representing the range of data collected
during the field side-by-side check (note: it was assumed that the 90%
point for stat1 - BPH was a bad data point and was therefore not used
in the fit for this sensor). The correction fits were applied to the field
data and plotted. RHCOR PLOT shows the results. Station 1 shows little change
as we would hope. Station 2 shows an improvement in the slope of the data and
a offset in the mean error. There is a significant change in the offset
of station 3 and a small improvement in the slope.