TWP/C2/Sonde Missing Data

There were no sondes launced during this period because there was
no helium on site and the hydrogen generator was not working.  The
hydrogen generator was repaired and launches resumed.

• null(Raw data stream - documentation not supported)

• base time(base_time)
• lon(lon)
• Wind Direction(deg)
• Ascent Rate(asc)
• Mean Wind Speed(wspd)
• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)
• Wind Status(wstat)
• Dummy altitude for Zeb(alt)
• lat(lat)
• Retrieved pressure profile(pres)
• Time offset of tweaks from base_time(time_offset)

• null(Raw data stream - documentation not supported)

• Dry bulb temperature(tdry)
• Time offset of tweaks from base_time(time_offset)
• U-component(u_wind)
• lon(lon)
• lat(lat)
• Relative humidity inside the instrument enclosure(rh)
• Retrieved pressure profile(pres)
• Ascent Rate(asc)
• Wind Direction(deg)
• Surface dew point temperature(dp)
• Dummy altitude for Zeb(alt)
• Wind Status(wstat)
• base time(base_time)
• Mean Wind Speed(wspd)
• V-component(v_wind)

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/SONDE/C2 - Missing Winds

About half of the soundings in November-December exhibited drop-outs
in the winds.  These dropouts were typically over a depth of 1-2 km.
Sometimes the dropout occurred at the surface, sometimes at the top of
the sounding and sometimes in the middle.  These gaps occurred on:

19981126
19981129
19981206
19981209
19981210
19981211
19981212
19981221
19981222

• Mean Wind Speed(wspd)

• U-component(u_wind)
• Mean Wind Speed(wspd)
• V-component(v_wind)

TWP/C2/Balloon Soundings: Missing Flights

No sondes were launched during this period for reasons unknown.

• base time(base_time)
• lon(lon)
• Wind Direction(deg)
• Ascent Rate(asc)
• Mean Wind Speed(wspd)
• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)
• Wind Status(wstat)
• Dummy altitude for Zeb(alt)
• lat(lat)
• Retrieved pressure profile(pres)
• Time offset of tweaks from base_time(time_offset)

• Dry bulb temperature(tdry)
• Time offset of tweaks from base_time(time_offset)
• U-component(u_wind)
• lon(lon)
• lat(lat)
• Relative humidity inside the instrument enclosure(rh)
• Retrieved pressure profile(pres)
• Ascent Rate(asc)
• Wind Direction(deg)
• Surface dew point temperature(dp)
• Dummy altitude for Zeb(alt)
• Wind Status(wstat)
• base time(base_time)
• Mean Wind Speed(wspd)
• V-component(v_wind)

TWP/C2  Installation

The Nauru ARCS was installed during the period September-November
1998.  Data were being collected by the end of October, but for the
first several weeks of November, the site was undergoing considerable
change, so data from that period should be used with caution.  The
official site dedication occured on November 20.  Most on-site
activity ended following the dedication so we will consider November
20 to be the beginning of the Nauru operations.  The last members of
the installation team left Nauru on November 24.

• base time(base_time)
• lon(lon)
• Wind Direction(deg)
• Ascent Rate(asc)
• Mean Wind Speed(wspd)
• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)
• Wind Status(wstat)
• Dummy altitude for Zeb(alt)
• lat(lat)
• Retrieved pressure profile(pres)
• Time offset of tweaks from base_time(time_offset)

• null(Raw data stream - documentation not supported)

• Dry bulb temperature(tdry)
• Time offset of tweaks from base_time(time_offset)
• U-component(u_wind)
• lon(lon)
• lat(lat)
• Relative humidity inside the instrument enclosure(rh)
• Retrieved pressure profile(pres)
• Ascent Rate(asc)
• Wind Direction(deg)
• Surface dew point temperature(dp)
• Dummy altitude for Zeb(alt)
• Wind Status(wstat)
• base time(base_time)
• Mean Wind Speed(wspd)
• V-component(v_wind)

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 - 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 - 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)