SGP/EBBR/E9 - Malfunctioning Wind Dir Sensor, Incorrect SM2 Results

It has been reported previously that a malfunction of the wind direction
sensor resulting in zero or 135 degree outputs can cause the soil moisture
#2 sensor to read offscale.  The two sensors are attached to a multiplexer
pair.  The manufacturer of the multiplexer and data acquisition system have
not been able to explain how our instrument configuration can cause this
effect.  Shortly after 0030 GMT on August 20, 1994 significant rainfall
occurred, being reflected in more than a doubling of soil moisture within
an hour.  During the time period listed above, the wind direction sensor
mulfunctioned (apparently caused by water in the wind direction sensor
electronics), causing the following data fields to be incorrect:

5 minute:  res_ws, wind_d, sigma_wd

15 minute: mv_wind_dir

30 minute: res_ws, wind_d, sigma_wd.

During part of the listed period, Soil Moisture #2 was also incorrect,
being offscale; during those times the following 30 minute data is also
incorrect:

30 minute: sm2, c_shf2, ave_shf, cs2, ces2, g2, h, e.

The calculations of e and h can be recomputed by using the four sets of
soil sensors that were not malfunctioning, or by substituting a SM2 value
of approximately 25.5.  The equations for the recalculation are not 
included here.

• Wind direction vector mean standard deviation(wdir_vec_std)
• Wind direction vector mean(wdir_vec_mean)
• Wind speed vector mean(wspd_vec_mean)

• Wind direction vector mean (mV)(wdir_vec_mean_mv)

• Wind direction vector mean(wdir_vec_mean)
• Wind direction vector mean standard deviation(wdir_vec_std)
• Wind speed vector mean(wspd_vec_mean)