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 arithmetic average(wind_spd_arith_avg)
• Wind speed arithmetic maximum(wind_spd_arith_max)
• Wind speed arithmetic minimum(wind_spd_arith_min)
• Vector-averaged Wind Speed(wind_spd_vec_avg)
• Wind speed arithmetic standard deviation(wind_spd_arith_sd)

HFE/AOS/M1 - PSAP data missing

The PSAP was disconnected during this time period.

• Absorption Coefficient Red, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_R_Dry_1um_PSAP3W_1)
• Aerosol light absorption coefficient, green channel, 10 um size cut(Ba_G_Dry_10um_PSAP1W_1)
• Absorption Coefficient Green, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_G_Dry_1um_PSAP3W_1)
• Absorption Coefficient Blue, corrected for flow and sample area, 3 wavelength
  PSAP, 1 um size cut(Ba_B_Dry_1um_PSAP3W_1)
• Absorption Coefficient Green, corrected for flow and sample area, 3 wavelength
  PSAP, 10 um size cut(Ba_G_Dry_10um_PSAP3W_1)
• Aerosol light absorption coefficient, green channel, 1 um size cut(Ba_G_Dry_1um_PSAP1W_1)
• Absorption Coefficient Blue, corrected for flow and sample area, 3 wavelength
  PSAP, 10 um size cut(Ba_B_Dry_10um_PSAP3W_1)
• Absorption Coefficient Red, corrected for flow and sample area, 3 wavelength
  PSAP, 10 um size cut(Ba_R_Dry_10um_PSAP3W_1)

HFE/SKYRAD/M1 - IRT bias

The sky temperatures exhibited a positive bias compared to AERI, especially when < 230K. 
This is indicative of an incorrect emissivity setting (to compensate for the gold mirror) 
or a poor calibration. A similar problem with the same instrument occurred during the FKB 
deployment that was attributed to water vapor.

• Sky Infra Red Temperature Minima(sky_ir_temp_min)
• Sky Infra-Red Temperature(sky_ir_temp)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)

HFE/MWRHF/M1 - Calibration updates

The MWRHF calibration algorithm updates the calibration parameters every time a new 
successful tip curve is acquired. 

This results in small jumps (1-2 K) in the brightness temperatures each time calibration 
is updated. During times of frequent calibrations the data appear discontinuous with short 
data segments interrupted by small jumps.

• Sky brightness temperature (150 GHz)(tbsky150)
• Sky brightness temperature (90 GHz)(tbsky90)

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.

• Barometric 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.

• 1 minute average water intensity(pwd_avg_H2O_int_1_min)
• 15 min present weather code(pwd_pw_code_15_min)
• Average 10 min visibility(pwd_avg_vis_10_min)
• Average 1 min visibility(pwd_avg_vis_1_min)
• 1 hour present weather code(pwd_pw_code_1_hr)
• Instantaneous present weather code(pwd_pw_code_inst)
• Cumulative water(pwd_cumul_water)
• Present weather detector error code(pwd_err_code)
• Present weather detector ID(pwd_id)
• Cumulative snow(pwd_cumul_snow)

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 arithmetic average(wind_spd_arith_avg)
• Wind speed arithmetic maximum(wind_spd_arith_max)
• Wind speed arithmetic minimum(wind_spd_arith_min)
• Vector-averaged Wind Speed(wind_spd_vec_avg)
• Wind speed arithmetic standard deviation(wind_spd_arith_sd)

HFE/MWRHF/M1 - Elevated noise in 150 GHz data

The noise level of the 150 GHz channel was about 4 times higher than expected, likely due 
to failure of the noise diode.  Disregard the 150 GHz data.

• Sky brightness temperature (150 GHz)(tbsky150)