TWP/SONDE/C2  - Broken Temperature Sensor

The temperature sensors on these radiosondes broke at launch.  All
the temperature-related data are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

• Surface dew point temperature(dp)
• Dry bulb temperature(tdry)
• Relative humidity inside the instrument enclosure(rh)

TWP/SONDE/C2 - Bad RH Data (AIRS Validation Sonde)

The RH sensor heating circuit failed on this sonde.  This results in
oscillation of reported RH between reasonable values and values near zero.
This was an AIRS validation sounding.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

• Surface dew point temperature(dp)
• Relative humidity inside the instrument enclosure(rh)

TWP/SONDE/C2  - Failure of RH sensor

It appears that the RH sensor heating circuit failed during this sounding.  The RH 
oscillates rapidly between low (~0 %RH) and not so low (ambient %RH) and the oscillation seems 
to stop when the temperature is below ~35 degC.  According to Vaisala these are symptoms 
of failure in the ASIC (application specific integrated circuit) that controls the heating.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

• Surface dew point temperature(dp)
• Relative humidity inside the instrument enclosure(rh)

TWP/SONDE/C2 - Strange problem with data -

This is very strange.  The data has what appears to be a pressure jump at launch (from 
1007.2 to 956.5 hPa) but the sounding temperature and RH data clearly look to be 
interpolated between the surface and tropopause.  By examining the absolutely raw data, I found that 
the system assigned an elapsed time of 408 seconds (since system start up) to the launch 
point, but there is no raw data between 410 and 532 seconds.  The raw pressure value at 
410 seconds is 1007.6 hPa and that at 532 seconds is 40.9 hPa!  Unless this sounding was 
done by using a rocket-powered balloon (maybe even then), it would be impossible for the 
sonde to get to 40.9 hPa in 2 minutes.  Because the apparent gap is only two minutes, the 
system was able to interpolate but is not sophisticated enough to understand that the 
limits of the interpolation are unreasonable.

I can't imagine what went wrong - I've not seen anything like this before.

• null(Raw data stream - documentation not supported)

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

• null(Raw data stream - documentation not supported)

TWP/SONDE/C2 - RH sensor bad

It appears that the RH sensor heating circuits failed during these
soundings.  The RH oscillates rapidly between low (~0 %RH) and not
so low (ambient %RH) and the oscillation seems to stop when the
temperature is below ~35 degC.  According to Vaisala these are
symptoms of failure in the ASIC (application specific integrated
circuit) that controls the heating.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Broken temperature sensors

The temperature sensors on these radiosondes broke after launch.  All
temperature-related data are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

TWP/SONDE/C2  - Questionable rH data

It appears that the RH sensor heating circuit failed during this sounding.  The RH 
oscillates rapidly between low (~0 %RH) and not so low (ambient %RH) and the oscillation seems 
to stop when the temperature is below ~35 degC.  According to Vaisala these are symptoms 
of failure in the ASIC (application specific integrated circuit) that controls the heating.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2  - Bad RH sensor

It appears that the RH sensor heating circuit failed during this sounding.  The RH 
oscillates rapidly between low (~0 %RH) and not so low (ambient %RH) and the oscillation seems 
to stop when the temperature is below ~35 degC.  According to Vaisala these are symptoms 
of failure in the ASIC (application specific integrated circuit) that controls the heating.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Bad RH values aloft

It appears that the RH sensor heating circuit on this sonde failed about 24 minutes into 
the flight.  The RH values look reasonable, though somewhat noisy, from the surface to 
approximately 6.9 km (439 hPa) at which point they begin to oscillate between 0 and 100 %.  
This behavior stops when the sonde reaches approximately 11.5km (232 hPa) when the air 
temperature drops below -40 degC.  The oscillation stops at that point, though the RH 
remains higher than might be expected even under supersaturated conditions.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2  - RH sensor failure near surface

It appears that the RH sensor heating circuit failed during this sounding.  The RH 
oscillates rapidly between low (~0 %RH) and not so low (ambient %RH) and the oscillation seems 
to stop when the temperature is below ~35 degC.  According to Vaisala these are symptoms 
of failure in the ASIC (application specific integrated circuit) that controls the heating.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Operator used wrong calibration tape

It appears as though the opperator used the wrong calibration tape for this sounding.  The 
primary symptom is a jump in temperature from a surface value of 30.1 degC to the first 
value aloft of 61.0 degC.  Secondly, the recorded serial number for this sounding is 
Z1430179 which is the same serial number recorded for the previous sounding.

This problem points to three failures of procedure (I have notified TWP site ops by 
e-mail).  The first failure is using the wrong tape. The second failure is not checking the 
radiosonde values before launch which relates to the third failure of not entering the 
radiosonde values as the surface values of the sounding.

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

TWP/SONDE/C2  - RH sensor failure below 9km

It appears that the RH sensor heating circuit failed during this sounding.  The RH 
oscillates rapidly between low (~0 %RH) and not so low (ambient %RH) and the oscillation seems 
to stop when the temperature is below ~35 degC.  According to Vaisala these are symptoms 
of failure in the ASIC (application specific integrated circuit) that controls the heating.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Bad RH values aloft

It appears that the RH sensor heating circuit on these sondes failed after launch but 
resume proper operation when the ambient temperature dropped below ~40 degC.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/MWR/C2 - Heater problem

When the wiring of the air temperature sensor was checked the heater apparently began 
activating too often.

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

• Fraction of data in averaging interval with water on Teflon window(water_flag_fraction)

• Water on Teflon window (1=WET, 0=DRY)(wet_window)

TWP/MWR/C2 - Reprocessed: Revised Retrieval Coefficients

IN THE BEGINNING (June 1992), the retrieval coefficients used to derive the precipitable 
water vapor (PWV) and liquid water path (LWP) from the MWR brightness temperatures were 
based on the Liebe and Layton (1987) water vapor and oxygen absorption model and the Grant 
(1957) liquid water absorption model.

Following the SHEBA experience, revised retrievals based on the more recent Rosenkranz 
(1998) water vapor and oxygen absorption models and the Liebe (1991) liquid waer absorption 
model were developed.  The Rosenkranz water vapor absorption model resulted a 2 percent 
increase in PWV relative to the earlier Liebe and Layton model.  The Liebe liquid water 
absorption model decreased the LWP by 10% relative to the Grant model.  However, the 
increased oxygen absorption caused a 0.02-0.03 mm (20-30 g/m2) reduction in LWP, which was 
particularly significant for low LWP conditions (i.e. thin clouds encountered at SHEBA).

Recently, it has been shown (Liljegren, Boukabara, Cady-Pereira, and Clough, TGARS v. 43, 
pp 1102-1108, 2005) that the half-width of the 22 GHz water vapor line from the HITRAN 
compilation, which is 5 percent smaller than the Liebe and Dillon (1969) half-width used in 
Rosenkranz (1998), provided a better fit to the microwave brightness temperature 
measurements at 5 frequencies in the range 22-30 GHz, and yielded more accurate retrievals. 
Accordingly, revised MWR retrieval coefficients have been developed using MONORTM, which 
utilizes the HITRAN compilation for its spectroscopic parameters.  These new retrievals 
provide 3 percent less PWV and 2.6 percent greater LWP than the previous 
retrievals based on Rosenkranz (1998).

The Rosenkranz-based retrieval coefficients became active at TWP.C2 20020427.0600.  The 
MONORTM-based retrieval coefficients became active at TWP.C2 20050630.2100.

Note: The TWP.C2 data for 19981028-20050630 have been reprocessed to apply the 
MONORTM-based retrievals for all time.  The reprocessed data were archived 20061003.

• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)

• Ensemble average for MWR liquid in window centered about balloon release(mean_liq_mwr)
• Ensemble average for MWR vapor in window centered about balloon release(mean_vap_mwr)

• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)

TWP/SONDE/C2 - Bad RH sensor

It appears that the RH sensor heating circuit failed during this sounding.  The RH 
oscillates rapidly between low (~0 %RH) and not so low (ambient %RH) and the oscillation seems 
to stop when the temperature is below -50 degC.  According to Vaisala these are symptoms 
of failure in the ASIC (application specific integrated circuit) that controls the heating.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Broken temperature sensor

The temperature sensor on this radiosonde broke after launch.  All the temperature-related 
data are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

TWP/SONDE/C2  - Broken temperature sensor

The temperature sensor on this radiosonde broke after launch.  All the temperature-related 
data are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

TWP/SONDE/C2  - Broken temperature sensor

The temperature sensor on this radiosonde broke after launch.  All the temperature-related 
data are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

TWP/SONDE/C2  - Broken temperature sensor

The temperature sensor on this radiosonde broke after launch.  All the temperature-related 
data are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

TWP/SONDE/C2  - Bad RH in lower 8km

It appears that the RH sensor heating circuit failed during this sounding.  The RH 
oscillates rapidly between low (~0 %RH) and not so low (ambient %RH) and the oscillation seems 
to stop when the temperature is below ~35 degC.  According to Vaisala these are symptoms 
of failure in the ASIC (application specific integrated circuit) that controls the heating.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/MWR/C2 - Missing data

The heater blower assembly was causing the fuse to blow.  The instrument was taken offline 
until a replacement arrives.

• 31.4 GHz sky signal(sky31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Mixer kinetic (physical) temperature(tkxc)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Blackbody kinetic temperature(tkbb)
• lat(lat)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• 31.4 GHz blackbody(bb31)
• MWR column precipitable water vapor(vap)
• 23.8 GHz sky signal(sky23)
• Ambient temperature(tkair)
• IR Brightness Temperature(ir_temp)
• base time(base_time)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Averaged total liquid water along LOS path(liq)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• lon(lon)
• 23.8 GHz Blackbody signal(bb23)
• (tknd)
• Actual Azimuth(actaz)
• Time offset of tweaks from base_time(time_offset)
• Actual elevation angle(actel)
• Dummy altitude for Zeb(alt)
• Sky Infra-Red Temperature(sky_ir_temp)
• Temperature correction coefficient at 31.4 GHz(tc31)

• null(Raw data stream - documentation not supported)

• lat(lat)
• Standard deviation about the mean for the total water vapor amount(vap_sdev)
• lon(lon)
• Fraction of data in averaging interval with water on Teflon window(water_flag_fraction)
• Averaged total liquid water along LOS path(liq)
• Standard deviation about the mean for the 31.4 GHz sky brightness temperature(tbsky31_sdev)
• IR Brightness Temperature(ir_temp)
• Time offset of tweaks from base_time(time_offset)
• Number of data points averaged for 23tbsky, 31tbsky, vap & liq(num_obs)
• Standard deviation about the mean for the 23.8 GHz sky brightness temperature(tbsky23_sdev)
• Dummy altitude for Zeb(alt)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Number of points included in the ir_temp ensemble(num_obs_irt)
• base time(base_time)
• Standard deviation about the mean for the IR brightness temperature(ir_temp_sdev)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• MWR column precipitable water vapor(vap)
• Standard deviation about the mean for the total liquid water amount(liq_sdev)

• 31.4 GHz sky signal(tipsky31)
• lat(lat)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• 31.4 GHz goodness-of-fit coefficient(r31)
• Actual Azimuth(actaz)
• 23.8 GHz sky signal(tipsky23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz blackbody(bb31)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Ambient temperature(tkair)
• Dummy altitude for Zeb(alt)
• (tknd)
• base time(base_time)
• Blackbody kinetic temperature(tkbb)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• 23.8 GHz goodness-of-fit coefficient(r23)
• Time offset of tweaks from base_time(time_offset)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Actual elevation angle(actel)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• 23.8 GHz Blackbody signal(bb23)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• lon(lon)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Mixer kinetic (physical) temperature(tkxc)

TWP/SONDE/C2 - Surface Temperature Incorrect

The first two temperature values in the datafile are incorrect.  It appears that the 
observer mis-typed the surface temperature as -27 instead of +27.  The next value was 8 which 
is also incorrect and was caused by the system interpolating from the incorrect surface 
value and what the sonde temperature sensor was reading.

• Dry bulb temperature(tdry)

TWP/SONDE/C2 - Surface RH value incorrect

The surface RH value was incorrect.  It appears the observer mis-typed 70 instead of 80.  
This error also caused the dew point temperature to be incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Surface RH value incorrect

The surface RH was reproted as 78%.  The value should have been in the low 50's.  It 
appears the observer did not allow the sonde to equilibrate to ambient conditions before 
taking the reading.  This error also caused an incorrect dew point.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Surface RH Value incorrect

The surface value entered by the observers for RH (96%) is incorrect.  At the ascent time 
listed in the .ptu file the readings by the Sonde were around 65%.  This low RH value is 
supported by the nearby SMET tower RH reading of 71.8%.  This also caused the surface dew 
point to be incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Surface RH too high

The surface Rh was entered as 94%.  The ascent time has 72% and this value is supported by 
RH values from the nearby SMET system.  This error also will affect the dew point.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Broken temperature sensor at launch

Temperature sensor broken at launch.  All thermodynamic values are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)
• Wind Direction(deg)

TWP/SONDE/C2 - Broken temperature sensor at launch

The temperature sensor on this radiosonde broke after launch.  All the temperature-related 
data are incorrect.

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

TWP/SONDE/C2 - Failure of RH sensor

The RH sensor ASIC that controls the sensor heating failed.  As a result the RH at the 
beginning of the sounding oscillates between near-zero and ambient values.  The RH heating 
cycle stops when the ambient temperature reaches below -30 degC; above this level RH 
values should be valid.

• Relative humidity inside the instrument enclosure(rh)
• Surface dew point temperature(dp)