TWP/SMET/C3 - Lower wind direction sensor misaligned

The lower wind direction sensor (sensor #2) was misaligned and off by 15 degrees.

• wind2_dir_sd
• Wind #2 direction vector average(wind2_dir_vec_avg)

• lo_dir_sd
• lo_dir_vec_avg

TWP/SMET/C3 - Intermittent Pressure Sensor Failure

The Barometric Pressure sensor was intermittently failing at TWP site C3 Darwin.  At times 
there were large pressure fluctuations occurring on the order of 24 mb in a few minutes. 
 Times of large pressure fluctuations are readily apparent in the data.  At these times 
the data should be carefully analyzed before determining it's usefulness.  In between the 
periods of large fluctuations the readings appear to be stable.  It is still suggested 
that independent pressure data be obtained for comparison before use.

• Atmospheric pressure(atmos_pressure)

• Atmospheric pressure(atmos_pressure)

TWP/SMET/C3 - Data reported at 15sec rather than 60s intervals

Data in these data streams should be reported at 60sec intervals, but
the logger program running during this time had the interval set to
15s.  Users will have to average the 15sec data to get 60sec data.

• Wind #1 speed arithmetic average(wind1_spd_arith_avg)
• Wind #2 speed maximum gust(wind2_spd_max_gust)
• Wind #2 speed maximum(wind2_spd_max)
• wind2_spd_sd
• Wind #1 speed maximum gust(wind1_spd_max_gust)
• Precipitation mean(precip_mean)
• time_offset
• vappress_sd
• Wind #1 speed minimum(wind1_spd_min)
• wind1_dir_sd
• Temperature maximum(temp_max)
• logger_temp
• wind2_dir_sd
• Wind #2 speed vector average(wind2_spd_vec_avg)
• internal_voltage
• bit_data
• Wind #2 speed minimum(wind2_spd_min)
• Precipitation maximum(precip_max)
• Wind #1 speed vector average(wind1_spd_vec_avg)
• Atmospheric pressure(atmos_pressure)
• Relative humidity maximum(relh_max)
• Relative humidity minimum(relh_min)
• Vapor pressure mean(vappress_mean)
• temp_sd
• Temperature minimum(temp_min)
• relh_sd
• Wind #1 direction vector average(wind1_dir_vec_avg)
• external_voltage
• Precipitation minimum(precip_min)
• Temperature mean(temp_mean)
• Wind #2 direction vector average(wind2_dir_vec_avg)
• Wind #2 speed arithmetic average(wind2_spd_arith_avg)
• wind1_spd_sd
• Relative humidity mean(relh_mean)
• precip_sd
• Wind #1 speed maximum(wind1_spd_max)

• lo_dir_sd
• Vapor pressure mean(vappress_mean)
• logger_temp
• up_spd_max
• up_spd_min
• precip_sd
• lo_spd_min
• temp_sd
• relh_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• lo_dir_vec_avg
• up_spd_sd
• lo_spd_arith_avg
• tbrg_total
• Temperature mean(temp_mean)
• Precipitation mean(precip_mean)
• up_dir_vec_avg
• tbrg_count_total
• time_offset
• Relative humidity mean(relh_mean)
• lo_spd_vec_avg
• lo_spd_sd
• Atmospheric pressure(atmos_pressure)
• up_spd_arith_avg
• lo_spd_max
• vappress_sd
• up_spd_vec_avg
• up_dir_sd
• time
• internal_voltage

TWP/SMET/C3 - Rain blocked pressure port

Atmospheric pressure values were suspect due to anomolous readings during heavy rain 
events.  Suspect blockage of port due to rainfall.  New logger and enclosure corrected problem.

• Atmospheric pressure(atmos_pressure)

TWP/SMET/C3 - Negative rainfall rates

Due to limitations of the Zeno dataloggers all voltage measurements
from the optical rain gauge (ORG) were converted to rainfall rates. 
This resulted in negative values for rain rates.  Any value below
0.10 mm/hr should be considered to be 0 mm/hr.  New dataloggers 
alleviated this problem.

• precip_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• Precipitation mean(precip_mean)

TWP/SMET/C3 - Data non-representative

Tower mast was lowered for inspection.  Data during this time is non-representative.

• lo_dir_sd
• tbrg_count_total
• Vapor pressure mean(vappress_mean)
• Relative humidity mean(relh_mean)
• up_spd_max
• up_spd_min
• lo_spd_sd
• lo_spd_vec_avg
• precip_sd
• lo_spd_min
• Atmospheric pressure(atmos_pressure)
• temp_sd
• up_spd_arith_avg
• lo_spd_max
• vappress_sd
• relh_sd
• up_spd_vec_avg
• up_dir_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• up_spd_sd
• lo_dir_vec_avg
• lo_spd_arith_avg
• tbrg_total
• Temperature mean(temp_mean)
• Precipitation mean(precip_mean)
• up_dir_vec_avg

TWP/SMET/C3 - Lower wind direction sensor failure

The lower wind direction sensor failed on 4/14 and disagrees significantly with the upper 
wind direction sensor.  The lower wind sensor reports a constant value around 0-15 
degrees since it failed.  Testing showed that excitation channel two on the logger was the 
problem.  Logger was replaced by spare.

• lo_dir_sd
• lo_dir_vec_avg

TWP/SMET/C3 - Data not representative

Tower was lowered for radiometer change and characterization. Data are not representative 
of local conditions.

• lo_dir_sd
• tbrg_count_total
• Vapor pressure mean(vappress_mean)
• Relative humidity mean(relh_mean)
• up_spd_max
• up_spd_min
• lo_spd_sd
• lo_spd_vec_avg
• precip_sd
• lo_spd_min
• Atmospheric pressure(atmos_pressure)
• temp_sd
• up_spd_arith_avg
• lo_spd_max
• vappress_sd
• relh_sd
• up_spd_vec_avg
• up_dir_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• up_spd_sd
• lo_dir_vec_avg
• lo_spd_arith_avg
• tbrg_total
• Temperature mean(temp_mean)
• Precipitation mean(precip_mean)
• up_dir_vec_avg

TWP/SMET/C3 - Upper wind sensor failure

A lightning strike destroyed the upper wind sensor.

• up_spd_vec_avg
• up_dir_sd
• up_spd_max
• up_spd_min
• up_spd_sd
• up_spd_arith_avg
• up_dir_vec_avg

TWP/SMET/C3 - RH Values Artificially High

Lightning strike caused RH readings to be higher than reasonable (130%).

• relh_sd
• Vapor pressure mean(vappress_mean)
• vappress_sd
• Relative humidity mean(relh_mean)

TWP/SMET/C3 - Instrument failure

A lightning strike caused a failure in the ORG.  Rainfall was being continually recorded.

• precip_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• Precipitation mean(precip_mean)

TWP/SMET/C3 - ORG data noisy due to degraded ground

SMET Rain Data began to be noisy during December 2005 and the problem slowly became worse 
over time so that in February 2006 the ORG was reporting with a constant background value 
of around 0.10 mm/hr rain rate.  ORG voltage showed a near constant value above the 85mV 
threshold.  The ground for the ORG had become degraded and was lost due to corrosion.

• precip_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• Precipitation mean(precip_mean)

TWP/SMET/C3 - Reprocessed: Lower windspeed sensor calibration error

The lower anemometer was replaced but the calibration coefficients were not changed during 
this period.  The data were reprocessed to apply the correct calibrations and the 
reprocessed data were archived in August 2008.

• lo_spd_vec_avg
• lo_spd_sd
• lo_spd_min
• lo_spd_arith_avg
• lo_spd_max

TWP/SMET/C3 - Data not representative

The Anemometer readings were incorrect due to the tower being lowered for maintenance.

• lo_spd_sd
• lo_spd_vec_avg
• lo_spd_min
• lo_dir_sd
• up_spd_arith_avg
• lo_spd_max
• up_spd_vec_avg
• up_dir_sd
• up_spd_max
• up_spd_sd
• up_spd_min
• lo_dir_vec_avg
• lo_spd_arith_avg
• up_dir_vec_avg

TWP/SMET/C3 - Reprocess: Barometric pressure units change

Barometric pressure data during this time period is reported in hPa.  After this time, the 
data have been converted to kPa to standardize the measurement units among ARM sites and 
to conform to accepted standard units determined by the scientific community.

• Atmospheric pressure(atmos_pressure)

TWP/SMET/C3 - Reprocess: Tipping bucket rain gauge added

A tipping bucket rain gauge was added to the SMET suite of instruments effective 20060926. 
 Two new variables (count and rain amount) were added at the end of the twpsmet60sC1.b1 
datastream.  When reprocessing of this datastream occurs these variables will be added 
with -9999 (missing) as the value for dates prior to gauge installation.

• base_time

TWP/SMET/C3 - Barometer Data Incorrect

The barometer data was incorrect or missing due to water intrusion.

• Atmospheric pressure(atmos_pressure)

TWP/SMET/C3 - Water in enclosure

Data became erratic and unreasonable after water intrusion into the enclosure.

• relh_sd
• precip_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• temp_sd
• Vapor pressure mean(vappress_mean)
• Precipitation mean(precip_mean)
• Temperature mean(temp_mean)
• vappress_sd
• Relative humidity mean(relh_mean)

TWP/SMET/C3 - Upper wind speed artificially slow

The upper wind measurement was consistently slower by around 0.5 - 1 m/s than the lower 
wind measurement.  The bearings on the upper wind measurement were binding.

• up_spd_vec_avg
• up_spd_max
• up_spd_min
• up_spd_sd
• up_spd_arith_avg

TWP/SMET/C3 - ORG overestimated rainfall

Optical rain gauge (ORG) measured approximately 10mm higher than two co-located tipping 
bucket rain gauges and a co-located disdrometer.  The ORG is typically higher but usually 
not by an order of magnitude.

• precip_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• Precipitation mean(precip_mean)

TWP/SMET/C3 - Upper Wind Sensor Data Questionable

The wind_up vs. wind_low wind directions diverged, with the differences between the two 
eventually reached 45 degrees. The Upper sensor was found to be mis-aligned and loose.

• up_spd_vec_avg
• up_spd_max
• up_spd_min
• up_spd_sd
• up_spd_arith_avg

TWP/SMET/C3 - Reprocess: ORG Data has very small rainrate values

The ORG data is collected via analog signal and not digital.  Therefore, we
continuously collect data even when no rain is occurring.  We also capture small events 
such as leaves, large bugs, dust, etc blowing through the measurement path.  Because this 
discrete event occurs quickly the value is usually captured for 1 or 2 seconds.  This 
value is then averaged to the minute producing rainrate on the order of .009 mm/hr or less.  

These values are not indicative of rain and should be removed from the record or summing 
over long periods can bias the climate record.  We will reprocess the data to remove these 
small values.

• precip_sd
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• Precipitation mean(precip_mean)

TWP/SMET/C3 - Lower Wind Direction Intermittently Wrong

The lower wind sensor cabling had a problem causing an intermittent connection for the 
wind direction data.

• lo_dir_sd
• lo_dir_vec_avg

TWP/SMET/C3 - Upper wind speed data incorrect

Beginning on 07/08, the upper wind sensor started reporting significantly lower wind 
speeds than the lower wind sensor.  The cable connections weather proofing failed allowing 
corrosion to occur and increasing he resistance of the cables.  This in turn lowered the 
wind speeds artificially.

• up_spd_vec_avg
• up_spd_max
• up_spd_min
• up_spd_sd
• up_spd_arith_avg

TWP/SMET/C3 - Missing data

Data are missing and unrecoverable.

• alt
• lo_dir_sd
• lon
• base_time
• tbrg_count_total
• time_offset
• Vapor pressure mean(vappress_mean)
• Relative humidity mean(relh_mean)
• logger_temp
• up_spd_max
• up_spd_min
• lo_spd_vec_avg
• lo_spd_sd
• precip_sd
• lo_spd_min
• Atmospheric pressure(atmos_pressure)
• temp_sd
• lat
• up_spd_arith_avg
• lo_spd_max
• vappress_sd
• up_spd_vec_avg
• relh_sd
• up_dir_sd
• time
• Precipitation maximum(precip_max)
• Precipitation minimum(precip_min)
• internal_voltage
• lo_dir_vec_avg
• up_spd_sd
• lo_spd_arith_avg
• tbrg_total
• Temperature mean(temp_mean)
• Precipitation mean(precip_mean)
• up_dir_vec_avg

TWP/SMET/C3 - 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.

• up_spd_vec_avg
• lo_spd_vec_avg
• lo_spd_sd
• lo_spd_min
• up_spd_max
• up_spd_min
• up_spd_sd
• lo_spd_arith_avg
• up_spd_arith_avg
• lo_spd_max

TWP/SMET/C3 - Reprocess: Station Pressure values reported in hPa instead of kPa.

An incorrect program was entered into the datalogger.  This program did not convert the 
station pressure from hPa to kPa.  This made the values larger by a factor of 10 and caused 
the QC bit to be tripped.

• Atmospheric pressure(atmos_pressure)

TWP/SMET/C3 - Reprocess: Temperature data biased low

Due to a datalogger problem, the temperature data were biased low by 2.13 degrees C.

The data will be reprocessed.

• temp_sd
• Temperature mean(temp_mean)

TWP/SMET/C3 - Reprocess: Temperature Biased low by 1.06 Degrees

The temperature of the SMET system was biased low by 1.06 Deg C due to a non-precision 
resistor being used int he measurement circuit.  The data will be reprocessed.  Saturation 
Vapor pressure and Vapor pressure will have to be reprocessed also.

Add 1.06 degrees to the temperature data.  

Correct Sat Vap Press using the Buck approximation:
   Es = 6.1121exp((17.502*T)/(240.97 + T) 
where T is the temperature in C.  

Correct Vapor pressure using: E = (RH*Es)/100

• temp_sd
• Vapor pressure mean(vappress_mean)
• Temperature mean(temp_mean)
• vappress_sd

TWP/SMET/C3 - Tower Lowered for Maintenance

The tower was lowered for annual anemometer changes.  The wind data is suspect.

• lo_spd_sd
• lo_spd_vec_avg
• lo_spd_min
• lo_dir_sd
• up_spd_arith_avg
• lo_spd_max
• up_spd_vec_avg
• up_dir_sd
• up_spd_max
• up_spd_sd
• up_spd_min
• lo_dir_vec_avg
• lo_spd_arith_avg
• up_dir_vec_avg