Perdigão-ISFS Data Report

Sonic Anemometers


In order to report winds in geographic coordinates, the orientation of the instrument needs to be known.  As part of their total survey of Perdigão instrumentation, DTU used their multistation to measure 4 points on each anemometer's mounting boom to determine azimuth, pitch, roll, and height of the instrument.  These are documented in the Sensor Coordinates spreadsheet.  A later tilt correction analysis may be performed to use the pitch and roll information, but we start out here using just the azimuth information.  

By agreement of the PIs, the masts were to be constructed with one face roughly parallel to the local height contour (which usually was preferred anyway for mast guying) and the anemometer boom to be mounted on this face, pointing up-valley (approximately SE).  This was done to minimize distortion of the flow by the mast for winds perpendicular to the ridge lines (of most interest to the project) and also capture down-valley flow.  Of course, the local slope direction varied over the domain, resulting in boom angles between 111 to 166 degrees.  Also, local obstacles (trees and mast-mounted solar panels) sometimes interfered with this location for the anemometer.  In these cases, the anemometer boom was set to point down-valley (180 degrees from the nominal orientation).  

With the measured boom azimuth, the orientation of the CSAT3A anemometers is known since the anemometer head is rigidly attached to the boom.  Also, the CSAT3 heads were attached in a captive manner, though the amount had +/-1 degree of "play".  This effect was not measured and has been ignored in the definition of the boom angles.  In one case, 10m.tse12, the anemometer head was found during tear-down to have been hit by a branch and was skewed by an estimated 20 degrees.  This will take further examination to determine when this event (or events) occurred.

The other anemometer types -- Metek, Gill, and RMYoung -- were mounted either on vertical post or round plate that allowed the anemometer head to rotate with respect to the boom.  Field staff attempted to align these sensors by eye in a consistent manner, but (unmeasured) errors of perhaps 2 degrees may be present.  The Meteks were mounted so that the black arrows on the side of the head base were pointing towards the mast, with this side of the base parallel to the boom.  The Gills were mounted so that the N indication on the head was aligned with the boom, pointing towards the mast.  The RMYoungs mostly were mounted with the connector box at the base of the head mostly pointed towards the mast (and the face of the box's lid perpendicular to the boom).  However, some RMYoungs mounted in the first set-up period may have had the connector box facing out (180 degrees from the others).  Since not all of these cases were documented, we will determine them both from mast photos (most sites were documented during tear-down) and by noting which sites were set up early (e.g. rne02, rne01, rsw01, rsw02).


[insert results of temperature chamber tests]


NCAR's standard Temperature/Relative Humidity sensors were deployed on all of the tall masts for the entire project.  During the IOP, another 9 sensors were deployed on the shorter masts along the NW transect.  Due to the clamping system that was used, it was possible for water to collect in the booms near the connector, that eventually caused failure of some of the sensors.  We also found that some sensors just stopped for reasons that weren't clear.  In these cases, the data are missing.  Hopefully, most were serviced or replaced without too much data loss.

Fan Operation

In addition to total TRH failures, the fan controller electronics (and possibly also the fan itself) died, again presumably due to water infiltration.  In most cases, the sensor was revived by changing the wiring to bypass the electronics board, allowing the sensor to operate but giving no feedback on fan operation.  [Here we should generate a table of which sensors were bypassed and when, and then look at the data to identify periods when the fan actually had failed.]


Pre- and post-calibrations were done on every sensor in the EOL Calibration Laboratory. [These cals are available -- need to summarize or make a table to list any issues] 



9? Vaisala PTB220s were deployed.  They operated normally. [true?  Also, check calibrations.]


The 4 NCAR nanobarometers were deployed as microbarographs.  They operated normally.  [true?  Also, check calibrations.]


These were supplied by Cornell University and used at 4 locations as microbarographs.  Data from the sensor at rsw03 were found to have picked up excessive noise due to the long analog cable that was used, which will limit the utility of its data.  Unfortunately, this noise was not detected until after the field program.  Otherwise, they operated normally. [true?]


NR01 integrated radiometers were used at 13? sites, mounted on booms extending from near the top of the masts.  They were never cleaned, though rain during the first half of the IOP probably reduced dust/pollen build-up.  For this reason, each sensor was tested upon return to Boulder after the experiment.  [refer to Wiki? description of the results]

Another issue with the tower-mounted NR01s was that many had solar panels (also mounted on the south sides of the towers) in the field of view.  [need to quantify this effect]

Another 3 sites each had a set of 4-component radiometers mounted on our "darkhorses".  Again, these were not cleaned.  [They have not yet been tested.]


Soil sensors were deployed at 16? sites.  All behaved as expected. [true?]


[need to fix negative offscale values] [still need to do post-cals]


[refer to gravimetric test results]