TWP/SMET/C1 - Poor Performing Sensor

On 4/23/2004 condensation was found inside the target area of the ORG lens. A spare was 
sent and installed but did not solve the problem of high background voltage values causing 
rainrate values to be recorded during no rainfall.  Values range anywhere from 0.06 to 
0.12 mm/hr.  

A new Optical Rain Gage was installed on 01/19/2005 @ 13:30 GMT alleviating the high 
background voltage values that lead to consistent rainfall rates of around 0.11 to 0.15 mm/hr 
on a consistent basis.  

The formula used to calculate rainfall rates from the new Optical Rain Gage is:  RR 
(mm/hr) = 25(V^1.87) - 0.15.

Older model formula = 20(V^2) - 0.05

The two formulas result in comparable data.

• Precipitation mean(precip_mean)
• Precipitation maximum(precip_max)
• Precipitation standard deviation(precip_sd)
• precipitation minimum(precip_min)

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.

• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Upper sensor, wind direction standard deviation(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.

• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Upper sensor, wind direction standard deviation(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.

• Mean Relative Humidity(relh_mean)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)

TWP/SMET/C2 - Instrument maintenance

Instrument calibration and testing were taking place for brief periods.

• Mean Relative Humidity(relh_mean)
• Upper sensor, wind speed minimum(up_spd_min)
• Mean Air Temperature or Hardware Error(temp_mean)
• Upper sensor, wind speed maximum(up_spd_max)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Upper sensor, wind direction standard deviation(up_dir_sd)
• Upper sensor, wind speed vector average(up_spd_vec_avg)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind speed maximum(lo_spd_max)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Upper sensor, wind speed standard deviation(up_spd_sd)
• precipitation minimum(precip_min)
• Tipping bucket raingauge count total(tbrg_count_total)
• Vapor pressure mean(vappress_mean)
• Lower sensor, wind speed minimum(lo_spd_min)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Std Dev of Air Temperature(temp_sd)
• Tipping bucket raingauge total(tbrg_total)
• Barometric Pressure(atmos_pressure)
• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Vapor pressure standard deviation(vappress_sd)
• Precipitation maximum(precip_max)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Precipitation mean(precip_mean)
• Lower sensor, wind direction standard deviation(lo_dir_sd)
• Precipitation standard deviation(precip_sd)

TWP/SMET/C2 - ORG data incorrect

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

• Precipitation maximum(precip_max)
• Precipitation mean(precip_mean)
• precipitation minimum(precip_min)
• Precipitation standard deviation(precip_sd)

TWP/SMET/C1 - Upper wind sensor failure

The upper wind speed sensor was binding at low wind speeds.  Comparison to the lower wind 
sensor showed that the upper sensor flat-lines for long periods of time.  The upper 
anemometer was replaced.

• Upper sensor, wind direction standard deviation(up_dir_sd)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Upper sensor, wind speed maximum(up_spd_max)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Upper sensor, wind speed vector average(up_spd_vec_avg)
• Upper sensor, wind speed minimum(up_spd_min)
• Upper sensor, wind speed standard deviation(up_spd_sd)

TWP/SMET/C2 - Temp/RH probe failure

Temperature/RH probe failed and was replaced.

• Mean Relative Humidity(relh_mean)
• Mean Air Temperature or Hardware Error(temp_mean)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Std Dev of Air Temperature(temp_sd)
• Vapor pressure standard deviation(vappress_sd)
• Vapor pressure mean(vappress_mean)

TWP/SMET/C1 - Reprocess: Tipping bucket rain gauge added

A tipping bucket rain gauge was added to the TWP.C1 SMET suite of instruments on 20061017. 
 Effective 20060926, two new variables (count and rain amount) were added to the end of 
the twpsmet60sC1.b1 datastream.  Between 9/26 and 10/17, 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 19961009-20060926 and data from 
19961009-20061017 will be filled with -9999 (missing).

• base time(base_time)

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(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/C1 - Upper winds failure

The upper wind instrument was inoperative resulting in constant wind direction and speed.  
A failed cable was replaced.

• Upper sensor, wind direction standard deviation(up_dir_sd)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Upper sensor, wind speed maximum(up_spd_max)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Upper sensor, wind speed vector average(up_spd_vec_avg)
• Upper sensor, wind speed minimum(up_spd_min)
• Upper sensor, wind speed standard deviation(up_spd_sd)

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.

• Lower sensor, wind speed minimum(lo_spd_min)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind speed maximum(lo_spd_max)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Lower sensor, wind speed standard deviation(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.

• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Lower sensor, wind direction standard deviation(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.

• Lower sensor, wind speed minimum(lo_spd_min)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind speed maximum(lo_spd_max)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Lower sensor, wind speed standard deviation(lo_spd_sd)

TWP/SMET/C1 - 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.

• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Upper sensor, wind speed maximum(up_spd_max)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Lower sensor, wind speed minimum(lo_spd_min)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Upper sensor, wind speed vector average(up_spd_vec_avg)
• Upper sensor, wind speed minimum(up_spd_min)
• Upper sensor, wind speed standard deviation(up_spd_sd)
• Lower sensor, wind speed maximum(lo_spd_max)

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.

• Upper sensor, wind speed vector average(up_spd_vec_avg)
• Upper sensor, wind speed minimum(up_spd_min)
• Lower sensor, wind speed minimum(lo_spd_min)
• Upper sensor, wind speed maximum(up_spd_max)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind speed maximum(lo_spd_max)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Upper sensor, wind speed standard deviation(up_spd_sd)