TWP/SMET/C1 - Wind speed calibration errors

Wind speed calibration factors were reversed between wind speed sensors 1 (upper) and 2 
(lower). Results in less than 1% error, but correction factors may be used.

To correct wind speed #1 (upper) add 0.03 m/s.
To correct wind speed #2 (lower) subtract 0.03 m/s.

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

• Wind #2 speed arithmetic average(wind2_spd_arith_avg)
• Wind #1 speed maximum gust(wind1_spd_max_gust)
• Wind #1 speed vector average(wind1_spd_vec_avg)
• Wind #2 speed maximum(wind2_spd_max)
• Wind #1 speed arithmetic average(wind1_spd_arith_avg)
• Wind #2 speed minimum(wind2_spd_min)
• Wind #2 speed vector average(wind2_spd_vec_avg)
• Wind #1 speed standard deviation(wind1_spd_sd)
• Wind #1 speed minimum(wind1_spd_min)
• Wind #2 speed standard deviation(wind2_spd_sd)
• Wind #1 speed maximum(wind1_spd_max)
• Wind #2 speed maximum gust(wind2_spd_max_gust)

TWP/SMET/C1/C2 - Switch to new Data Header Formats not timely

On April 1, 2001 at 00:00:00 new data header with consistent variable naming conventions, 
etc were to be used for all sites, all data streams.  At the TWP sites the time of the 
movement to the new convention did not occur precisely at 00:00:00.  The following data 
files contain between 40 seconds and 20 minutes of data from 4/1/02 in the old format.  The 
delayed format change did not affect data quality in any way.

twpsmet60sC1.a1.20010401.000001.cdf
twpsmet60sC1.b1.20010401.000001.cdf
twpsmet60sC2.a1.20010401.000000.cdf
twpsmet60sC2.b1.20010401.000000.cdf

• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Upper sensor, wind speed minimum(up_spd_min)
• Upper sensor, wind speed maximum(up_spd_max)
• 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)
• Battery Voltage(internal_voltage)
• Barometric Pressure(atmos_pressure)
• Upper sensor, wind speed vector average(up_spd_vec_avg)
• Precipitation mean(precip_mean)
• base time(base_time)
• Logger panel temperature(logger_temp)
• Precipitation maximum(precip_max)
• lon(lon)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Precipitation standard deviation(precip_sd)
• Lower sensor, wind direction standard deviation(lo_dir_sd)
• precipitation minimum(precip_min)
• Vapor pressure standard deviation(vappress_sd)
• Vapor pressure mean(vappress_mean)
• Tipping bucket raingauge count total(tbrg_count_total)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• lat(lat)
• Time offset of tweaks from base_time(time_offset)
• Lower sensor, wind speed minimum(lo_spd_min)
• Tipping bucket raingauge total(tbrg_total)
• Lower sensor, wind speed maximum(lo_spd_max)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Upper sensor, wind direction standard deviation(up_dir_sd)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Dummy altitude for Zeb(alt)
• time(time)
• Mean Relative Humidity(relh_mean)
• Upper sensor, wind speed standard deviation(up_spd_sd)

• Upper sensor, wind direction standard deviation(up_dir_sd)
• Upper sensor, wind speed maximum(up_spd_max)
• Logger panel temperature(logger_temp)
• Time offset of tweaks from base_time(time_offset)
• Upper sensor, wind speed minimum(up_spd_min)
• Mean Air Temperature or Hardware Error(temp_mean)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Upper sensor, wind speed standard deviation(up_spd_sd)
• Tipping bucket raingauge count total(tbrg_count_total)
• lon(lon)
• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Precipitation maximum(precip_max)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Battery Voltage(internal_voltage)
• base time(base_time)
• Lower sensor, wind speed minimum(lo_spd_min)
• Mean Relative Humidity(relh_mean)
• Precipitation standard deviation(precip_sd)
• Tipping bucket raingauge total(tbrg_total)
• Std Dev of Air Temperature(temp_sd)
• Vapor pressure mean(vappress_mean)
• Upper sensor, wind speed vector average(up_spd_vec_avg)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• lat(lat)
• Lower sensor, wind speed maximum(lo_spd_max)
• Barometric Pressure(atmos_pressure)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• precipitation minimum(precip_min)
• time(time)
• Dummy altitude for Zeb(alt)
• Vapor pressure standard deviation(vappress_sd)
• Precipitation mean(precip_mean)
• Lower sensor, wind direction standard deviation(lo_dir_sd)

• Mean Air Temperature or Hardware Error(temp_mean)
• lat(lat)
• Wind #2 speed maximum gust(wind2_spd_max_gust)
• Vapor pressure standard deviation(vappress_sd)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Time offset of tweaks from base_time(time_offset)
• Vapor pressure mean(vappress_mean)
• Bit data. See details.(bit_data)
• Wind #2 speed arithmetic average(wind2_spd_arith_avg)
• Std Dev of Air Temperature(temp_sd)
• Battery Voltage(internal_voltage)
• Wind #2 speed maximum(wind2_spd_max)
• Wind #1 speed arithmetic average(wind1_spd_arith_avg)
• Dummy altitude for Zeb(alt)
• Wind #1 speed vector average(wind1_spd_vec_avg)
• Wind #2 speed vector average(wind2_spd_vec_avg)
• External voltage(external_voltage)
• Wind #1 speed minimum(wind1_spd_min)
• Wind #1 speed standard deviation(wind1_spd_sd)
• Wind #2 direction standard deviation(wind2_dir_sd)
• Temperature maximum(temp_max)
• Wind #1 direction vector average(wind1_dir_vec_avg)
• Barometric Pressure(atmos_pressure)
• Temperature minimum(temp_min)
• Wind #2 speed minimum(wind2_spd_min)
• lon(lon)
• Precipitation maximum(precip_max)
• Wind #1 speed maximum(wind1_spd_max)
• Precipitation mean(precip_mean)
• Precipitation standard deviation(precip_sd)
• Wind #1 speed maximum gust(wind1_spd_max_gust)
• precipitation minimum(precip_min)
• Logger panel temperature(logger_temp)
• Mean Relative Humidity(relh_mean)
• Relative humidity maximum(relh_max)
• Wind #2 speed standard deviation(wind2_spd_sd)
• Wind #2 direction vector average(wind2_dir_vec_avg)
• base time(base_time)
• Relative humidity minimum(relh_min)
• Wind #1 direction standard deviation(wind1_dir_sd)

• Precipitation mean(precip_mean)
• Wind #2 direction vector average(wind2_dir_vec_avg)
• Wind #2 speed standard deviation(wind2_spd_sd)
• Wind #2 speed maximum gust(wind2_spd_max_gust)
• Wind #2 speed vector average(wind2_spd_vec_avg)
• Std Dev of Air Temperature(temp_sd)
• Wind #1 direction vector average(wind1_dir_vec_avg)
• Precipitation standard deviation(precip_sd)
• Time offset of tweaks from base_time(time_offset)
• Temperature maximum(temp_max)
• Battery Voltage(internal_voltage)
• Wind #2 speed minimum(wind2_spd_min)
• Barometric Pressure(atmos_pressure)
• Vapor pressure standard deviation(vappress_sd)
• Relative humidity minimum(relh_min)
• Wind #2 speed arithmetic average(wind2_spd_arith_avg)
• lat(lat)
• Wind #1 speed arithmetic average(wind1_spd_arith_avg)
• precipitation minimum(precip_min)
• Temperature minimum(temp_min)
• Wind #2 speed maximum(wind2_spd_max)
• Dummy altitude for Zeb(alt)
• Bit data. See details.(bit_data)
• Wind #1 speed standard deviation(wind1_spd_sd)
• Logger panel temperature(logger_temp)
• Wind #1 direction standard deviation(wind1_dir_sd)
• base time(base_time)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Wind #1 speed vector average(wind1_spd_vec_avg)
• Mean Relative Humidity(relh_mean)
• Wind #1 speed maximum gust(wind1_spd_max_gust)
• Relative humidity maximum(relh_max)
• Wind #1 speed minimum(wind1_spd_min)
• lon(lon)
• Precipitation maximum(precip_max)
• Wind #2 direction standard deviation(wind2_dir_sd)
• Mean Air Temperature or Hardware Error(temp_mean)
• Wind #1 speed maximum(wind1_spd_max)
• Vapor pressure mean(vappress_mean)
• External voltage(external_voltage)

TWP/C1 - Incorrect elevation reported in Manus Data

(From Bill Clements) We have been using 6m MSL as the station
elevation of Momote (Manus).  This was based on information
posted near the station barometer in the Momote Weather Service
Office.  It turns out that the official WMO station elevation
for Momote is 4m MSL and the upper air elevation is 5m MSL.

All Manus instruments except the sonde station are at 4m MSL.
The sonde launching station is at 5m MSL.

• Dummy altitude for Zeb(alt)

• Dummy altitude for Zeb(alt)

• Dummy altitude for Zeb(alt)

• Dummy altitude for Zeb(alt)

• Dummy altitude for Zeb(alt)

TWP/SMET/C1 - Reprocess: Lower Wind Speed incorrect

The lower wind speed sensor (sensor #2) was reporting values 10 times above the actual 
value.  During an update to the logger configuration file the calibration multiplier was 
incorrectly entered.  The multiplier inserted was .97630 when it should have been .09763.  
This caused the readings from this sensor to be incorrect.

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

• Wind #2 speed arithmetic average(wind2_spd_arith_avg)
• Wind #2 speed standard deviation(wind2_spd_sd)
• Wind #2 speed maximum(wind2_spd_max)
• Wind #2 speed maximum gust(wind2_spd_max_gust)
• Wind #2 speed minimum(wind2_spd_min)
• Wind #2 speed vector average(wind2_spd_vec_avg)

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

TWP/SMET/C1 - Incorrect rainrate equation used

There are two different Optical Raingages in use at the TWP sites.  The incorrect equation 
was used at this site.  The incorrect equation is (25*(V^1.87)) - 0.15.
The correct equation is (20*(V^2)) - 0.05.  The correct equation was installed.

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

TWP/SMET/C1 - 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.  New loggers were installed 03/09/2004 @ 2243 GMT.

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

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 speed maximum(up_spd_max)
• Upper sensor, wind speed standard deviation(up_spd_sd)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• 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)

TWP/SMET/C1 - 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.

• Barometric Pressure(atmos_pressure)

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/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 speed maximum(up_spd_max)
• Upper sensor, wind speed standard deviation(up_spd_sd)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• 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)

TWP/SMET/C1 - 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 are reprocessing the data to remove these small 
values and are adjusting the collection program to remove them before ingest.

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

TWP/SMET/C1 - ORG Precip Data Incorrect

Moisture intrusion into the sensor body allowed condensation on the lens of the ORG.  
Continual and long-term precipitation was reported during this time.

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

TWP/SMET/C1 - Missing data

Data are missing and unrecoverable.

• Upper sensor, wind direction standard deviation(up_dir_sd)
• Lower sensor, wind speed vector average(lo_spd_vec_avg)
• Upper sensor, wind speed maximum(up_spd_max)
• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Logger panel temperature(logger_temp)
• Upper sensor, wind direction vector average(up_dir_vec_avg)
• Precipitation maximum(precip_max)
• Time offset of tweaks from base_time(time_offset)
• Upper sensor, wind speed minimum(up_spd_min)
• Mean Air Temperature or Hardware Error(temp_mean)
• precipitation minimum(precip_min)
• time(time)
• Std Dev of Relative Humidity or Hardware Error Code(relh_sd)
• Battery Voltage(internal_voltage)
• lat(lat)
• Dummy altitude for Zeb(alt)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• base time(base_time)
• Lower sensor, wind speed maximum(lo_spd_max)
• Lower sensor, wind speed minimum(lo_spd_min)
• Mean Relative Humidity(relh_mean)
• Vapor pressure standard deviation(vappress_sd)
• Upper sensor, wind speed standard deviation(up_spd_sd)
• Tipping bucket raingauge count total(tbrg_count_total)
• Barometric Pressure(atmos_pressure)
• Upper sensor, wind speed arithmetic average(up_spd_arith_avg)
• Precipitation standard deviation(precip_sd)
• Tipping bucket raingauge total(tbrg_total)
• Std Dev of Air Temperature(temp_sd)
• Precipitation mean(precip_mean)
• Lower sensor, wind speed arithmetic average(lo_spd_arith_avg)
• lon(lon)
• Lower sensor, wind direction standard deviation(lo_dir_sd)
• Vapor pressure mean(vappress_mean)
• Upper sensor, wind speed vector average(up_spd_vec_avg)

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

TWP/SMET/C1 - Optical Rain Gage Inoperative

Beginning on 02/07/2009, the trending between the TBRG and ORG began to look poor, one 
recording precip when the other was not and vice versa.  After a while the ORG quit 
registering any precip at all.  ORG was replaced.

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

TWP/SMET/C1 - Surface pressure spike

A spike occured in the surface pressure.  The reported pressure rose as
high as 1300 hPa but returned to normal levels after 15 minutes.

• Barometric Pressure(atmos_pressure)