TWP/SMET/C2 - Upper wind direction sensor failure

The upper wind direction sensor failed. Wind direction was reported at a near constant 
value of 69 degrees and was significantly different than the lower wind sensor's direction 
values. Sensor replaced.

• up_dir_vec_avg
• up_dir_sd

TWP/SMET/C2 - Upper wind direction sensor failure

After replacement on 03/03/2005 the upper wind direction sensor began reporting erroneous 
values again on 03/09/2005 becoming very apparent after 03/17/2005.  Wind speed data 
appears reasonable but the wind direction data do not agree well with the lower wind sensor.

• up_dir_vec_avg
• up_dir_sd

TWP/SMET/C2 - RH sensor failure

Relative humidity values were frequently over MAX value of 104% starting on 7/10/2005 
through end of period.  Sensor was replaced.

• relh_sd
• Relative humidity mean(relh_mean)

TWP/SMET/C2 - Instrument maintenance

Instrument calibration and testing were taking place for brief periods.

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

TWP/SMET/C2 - ORG data incorrect

Data from the ORG was incorrect due to heavy condensation on the lens.

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

TWP/SMET/C2 - Tower down for calibration activities

Tower lowered, wind vanes spun at different frequencies, and ORG tested with electronic 
rain.

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

TWP/SMET/C2 - Temp/RH probe failure

Temperature/RH probe failed and was replaced.

• vappress_sd
• relh_sd
• temp_sd
• Vapor pressure mean(vappress_mean)
• Relative humidity mean(relh_mean)
• Mean Air Temperature or Hardware Error(temp_mean)

TWP/SMET/C2 - Reprocess: Tipping bucket rain gauge added

A tipping bucket rain gauge was added to the TWP.C2 SMET suite of instruments on 20061129. 
Effective 20060926, two new variables (count and rain amount) were added to the end of 
the twpsmet60sC2.b1 datastream.  Between 9/26 and 11/29, the data for these two variables 
are filled with zeros.  Users should not use the data during this period as the zeros are 
not representative of the rain fall at the site.  When reprocessing of this datastream 
occurs these variables will be added for the 19981021-20060926 and data from 
19981021-20061129 will be filled with -9999 (missing).

• base_time

TWP/SMET/C2 - Barometer failure

The barometer began experiencing problems with noise resulting in incorrect data.  The 
problem becames worse over time; after 12/19/2006 @0151 GMT the barometer data is completely 
missing.  The barometer was replaced.

• Barometric Pressure(atmos_pressure)

TWP/SMET/C2 - Lower windspeed sensor questionable

Lower wind speed sensor had degraded bearings.  This sensor was reporting as much as 0.4 
m/s lower values than the upper sensors when the winds were 2 m/s or below.  The sensor 
was replaced.

• lo_spd_arith_avg
• lo_spd_min
• lo_spd_vec_avg
• lo_spd_max
• lo_spd_sd

TWP/SMET/C2 - Lower Wind Sensor Direction Incorrect

Wind directions between lower and upper anemometers were displaced by approximately 45 
degrees when a new sensor was installed to replace the failing lower winde sensor.  The new 
sensor direction data incorrect.

• lo_dir_vec_avg
• lo_dir_sd

TWP/SMET/C2 - Lower Wind Speed Data Suspect

The lower wind speed bearings appeared to be binding at speeds below 2 m/s as it did not 
compare well with the upper wind sensor.

• lo_spd_arith_avg
• lo_spd_min
• lo_spd_vec_avg
• lo_spd_max
• lo_spd_sd

TWP/SMET/C2 - 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.

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

TWP/SMET/C2 - ORG rainfall measurements too large

The ORG was collecting large amounts of rainfall compared to the co-located tipping bucket 
raingauge.  The cable was chewed by mice causing the wires to make contact 
intermittently mimicking rainfall.

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

TWP/SMET/C2 - 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.

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

TWP/SMET/C2 - ORG rainrate high due to calibration.

The rainrate from the ORG was high due to calibration.  This data is not real.

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

TWP/SMET/C2 - Barometer data incorrect

Beginning 05/20, atmos_pressure exceeded MAX between ~21:00 and 01:00 UTC on most days.  
The inlet tube was accidentally pinched in the door of the logger enclosure artificially 
increasing the atmospheric pressure during the listed times.  Only a few hours exceeded 
max limits.

• Barometric Pressure(atmos_pressure)

TWP/SMET/C2 - Induced wind speed when calm

The upper and lower wind sensors were not trending well at wind speed below 1 m/s.  Both 
sensors were showing values above 0m/s when calm.  The lightning protector was at fault 
resulting in an induced wind voltage during calm conditions.

Users should subtract any offset found (for example 0.19 m/s for upper wind speed) when 
the wind speeds are flat-lined.  The offset value was not consistent.

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

TWP/SMET/C2 - Tower Lowered for Maintenance

Data is suspect due to the tower being lowered.

• vappress_sd
• lo_spd_arith_avg
• relh_sd
• lo_spd_min
• lo_dir_vec_avg
• temp_sd
• up_dir_vec_avg
• lo_spd_vec_avg
• Vapor pressure mean(vappress_mean)
• up_spd_min
• up_dir_sd
• up_spd_max
• Mean Air Temperature or Hardware Error(temp_mean)
• up_spd_vec_avg
• lo_dir_sd
• Relative humidity mean(relh_mean)
• up_spd_arith_avg
• lo_spd_max
• up_spd_sd
• lo_spd_sd

TWP/SMET/C2 - Barometer failure

The atmos_pressure values were spiking high (up to 110 kPa) from 06:00 UTC on 02/04 until 
the data went missing at 10:44 UTC on 02/06 when the barometer failed completely.

Barometer replaced 2/23.

• Barometric Pressure(atmos_pressure)