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

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

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

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

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

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

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

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 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)
• Lower sensor, wind speed maximum(lo_spd_max)

• Wind #2 speed minimum(wind2_spd_min)
• Wind #2 speed arithmetic average(wind2_spd_arith_avg)
• Wind #2 speed vector average(wind2_spd_vec_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)

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

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

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

TWP/SMET/C1 - Missing data

Data are missing and unrecoverable.

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

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)