HFE/MET/M1 -  Wind speed data contain offset due to induced voltage

The marine model of the RM Young wind sensor needs twisted pair shielded cable.  The 
manufacturer did not originally supply the pigtail with twisted pair shielded cable.  Use of 
twisted pair shielded cable for the rest of the cable run to the logger was also not 
specified.  This caused an induced voltage in the wind speed line from the wind direction 
excitation.  The induced voltage varied from sensor to sensor and probably changed anytime 
the cable was replaced or parts of the wind sensor were repaired or replaced. The induced 
voltage has been seen to vary from 0.15 m/s to as much as 1.08 m/s.

• Wind speed vector mean(wspd_vec_mean)
• Wind speed, lower, 1-min avg(wspd_arith_mean)

HFE/MET/M1 - Intermittent barometer failure

Intermittent barometer failure occurred throughout the deployment.  We were unable to 
pinpoint the cause of the failure.  Typically one or two minutes of missing data occurred 
every few days.

Since pressure data is typically invariant over 1 minute, linear interpolation should be 
fine to fill in missing data.

• Atmospheric pressure(atmos_pressure)

HFE/MET/M1 - Intermittent PWD data

The Present Weather Detector had intermittent missing values throughout this deployment.  
Missing values occurred almost everyday, usually just one or two minutes per day.

• pwd_pw_code_15min
• pwd_cumul_rain
• PWD 1 minute mean visibility(pwd_mean_vis_1min)
• PWD 1 minute mean precipitation rate(pwd_precip_rate_mean_1min)
• pwd_err_code
• PWD 10 minute mean visibility(pwd_mean_vis_10min)
• pwd_pw_code_inst
• pwd_pw_code_1hr

HFE/MET/M1 - ORG measuring ice crystals or fog

The ORG was measuring consistent values for long periods of time.  Typically this is 
indicative of fog, ice crystals in the air or poor performance of the lens heaters.

• ORG precipitation rate mean(org_precip_rate_mean)

HFE/MET/M1 - Induced voltage on wind speed sensor cable

The cable for the wind monitor is not a twisted pair shielded cable.  This caused an 
induced voltage on the wind sensor wires from the wind direction measurement excitation 
voltage.  A small offset is added into the wind speeds.  This value varies.  Most frequently 
the values of 0.49, 0.588 and 0.686 m/s were added into the wind speed.  On 11/27/2008 the 
value jumped to 0.98 m/s for most of the day.

• Wind speed vector mean(wspd_vec_mean)
• Wind speed, lower, 1-min avg(wspd_arith_mean)

HFE/MET/M1 - Precipitation data bias

Mounting of the optical rain gauge and present weather sensor on cross-arms affixed to the 
meteorological tower introduced a precipitation rate bias. Precipitation data at this 
site should be used with caution.

• pwd_cumul_rain
• ORG precipitation rate mean(org_precip_rate_mean)
• PWD 1 minute mean precipitation rate(pwd_precip_rate_mean_1min)