TWP/C2/SMET - Pressure sensitivity to rain

The pressure behaves anomalously during rain events - even very mild
ones.  Normally, the pressure undergoes a smooth semi-diurnal
oscillation with little higher frequency variability.  However, during
and shortly after rain events, the pressure signal exhibits abrupt
changes - this sort of behavior has occasionally been observed at
Manus but not with the regularity seen here.  Examples of this
behaviour occur on (date in the form YYYYMMDD):

19981212
19981215
19981216
19981217
19981223
19981224
19981225
19981230
19981231

• Barometric Pressure(atmos_pressure)
• Vapor pressure standard deviation(vappress_sd)
• Vapor pressure mean(vappress_mean)

• Vapor pressure standard deviation(vappress_sd)
• Vapor pressure mean(vappress_mean)
• Barometric Pressure(atmos_pressure)

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/SMET/C2 - Upper wind sensor failed

The upper wind speed sensor failed.  Wind speeds were reported as 0 m/s and wind direction 
data was not in agreement with the lower wind sensor. Anemometer was replaced.

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

TWP/SMET/C2 - Lower wind sensor failure

The lower wind sensor failed.  Wind direction showed little or no variation, unlike the 
co-located/upper sensor.  This caused depressed wind speed values as the sensor was not 
rotating properly to orient itself parallel to the wind stream.  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)
• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Lower sensor, wind direction standard deviation(lo_dir_sd)

TWP/SMET/C2 - connection and timing issues with new logger

Atmospheric pressure data are intermittent during this time period due to connection 
problems and program timing issues with new logger installation.  Data resumed normal 
operations after this time period.

• Barometric Pressure(atmos_pressure)

TWP/SMET/C2 - 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.

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

TWP/SMET/C2 - 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 maximum(precip_max)
• Precipitation mean(precip_mean)
• precipitation minimum(precip_min)
• Precipitation standard deviation(precip_sd)

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/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/C2 - 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/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/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/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 maximum(precip_max)
• Precipitation mean(precip_mean)
• precipitation minimum(precip_min)
• Precipitation standard deviation(precip_sd)

TWP/SMET/C2 - Missing data

Data are missing and unrecoverable.

• 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)
• base time(base_time)
• 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)
• lon(lon)
• Lower sensor, wind speed maximum(lo_spd_max)
• Logger panel temperature(logger_temp)
• Lower sensor, wind speed standard deviation(lo_spd_sd)
• Time offset of tweaks from base_time(time_offset)
• 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)
• Battery Voltage(internal_voltage)
• 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)
• Barometric Pressure(atmos_pressure)
• Tipping bucket raingauge total(tbrg_total)
• Lower sensor, wind direction vector average(lo_dir_vec_avg)
• Dummy altitude for Zeb(alt)
• Vapor pressure standard deviation(vappress_sd)
• time(time)
• lat(lat)
• 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 - 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)

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