SGP/SONDE/C1 - Bad temperature in SGP/CF sounding 20020108:0528

Temperature values in this sounding went from 3.5 degC at the surface to
-33.3 degC at the next sample.  It appears that all the remaining
temperature values have an approximate -35 degC offset.  The pressure
and RH values appear reasonable.

• Dry bulb temperature(tdry)
• Surface dew point temperature(dp)

• Surface dew point temperature(dp)
• Dry bulb temperature(tdry)

SGP/SONDE/C1 - CF sounding 20020522:1130 bad temperature/RH

It appears that the sonde sensor boom was damaged upon launch.  The result
is that no RH data are reported and the reported temperature is something on
the order of 60 degC too low.

• Dry bulb temperature(tdry)
• Dummy altitude for Zeb(alt)
• Relative humidity inside the instrument enclosure(rh)
• Ascent Rate(asc)
• Surface dew point temperature(dp)

• Surface dew point temperature(dp)
• Dry bulb temperature(tdry)
• Relative humidity inside the instrument enclosure(rh)
• Ascent Rate(asc)
• Dummy altitude for Zeb(alt)

SGP/SONDE/C1 - Bad T/RH data in CF sounding 20020523:1129

It appears that the sensor boom was damaged shortly after launch.  The
temperature reading jumps -60 degC and the RH goes to 0.

• Dry bulb temperature(tdry)
• Dummy altitude for Zeb(alt)
• Relative humidity inside the instrument enclosure(rh)
• Ascent Rate(asc)
• Surface dew point temperature(dp)

• Surface dew point temperature(dp)
• Dry bulb temperature(tdry)
• Relative humidity inside the instrument enclosure(rh)
• Ascent Rate(asc)
• Dummy altitude for Zeb(alt)

SGP/SONDE/C1 - CF sounding 20020609:0229 bad temp/rh/etc

The temperature and RH for this sounding look bad, either because of
interference from another sonde or because the temperature sensor was
broken on launch.  The sounding terminated early in any event.

• Dry bulb temperature(tdry)
• Dummy altitude for Zeb(alt)
• Relative humidity inside the instrument enclosure(rh)
• Ascent Rate(asc)
• Surface dew point temperature(dp)

• Surface dew point temperature(dp)
• Dry bulb temperature(tdry)
• Relative humidity inside the instrument enclosure(rh)
• Ascent Rate(asc)
• Dummy altitude for Zeb(alt)

SGP/SONDE/C1 - Incorrect Surface Pressure

It appears that the operator made a typographical error when entering the
surface pressure.  The file has 987.0 hPa and it probably should be 978.0
which would be consistent with the first sample provided by the radiosonde
(977.3 hPa), the surface pressures recorded for the adjacent soundings, and
the THWAPS pressure.

Because the sounding altitude is calculated assuming the surface pressure
is correct, the altitude values for the entire flight and the ascent rate 
values for the first 30 seconds of the sounding will be incorrect.

• Dummy altitude for Zeb(alt)
• Ascent Rate(asc)

• Ascent Rate(asc)
• Dummy altitude for Zeb(alt)

SGP/SONDE/C1 - Bad Temperature Sensor

It appears that the temperature sensor broke shortly after launch.  As a
result, the temperature and dewpoint values are incorrect.

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

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

SGP/SONDE/C1 - Temperature sensor failure

Temperature sensor broke at launch.  All temperature-related variables
are incorrect.

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

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

• Integrated vapor column from sonde using MWR Instrument Performance Model (IPM)(integ_vap_sonde)
• Integrated vapor column from sonde using a direct calculation (external from the
  IPM)(integ_vap_sonde_direct)

SGP/SONDE/C1 - Bad Temperature Sensor

It appears that the temperature sensor broke upon launch and therefore the reported 
temperature is approximately 40 degC too low.

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

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

• Integrated vapor column from sonde using MWR Instrument Performance Model (IPM)(integ_vap_sonde)

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)

SGP/SONDE/C1 - Bad Temperature Sensor

It appears that the temperature sensor broke shortly after launch. Temperatures are offset 
by approxmiately (but not constantly) 40 degC.

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

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

• Integrated vapor column from sonde using MWR Instrument Performance Model (IPM)(integ_vap_sonde)

• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)

Bad temperature sensor

It appears that the temperture sensor broke a few seconds into flight.  This results in an 
unreasonably low temperature for the rest of the flight.  For some reason, the rh values 
also go missing shortly after launch.  Only the wind and pressure data are reliable.

• Dummy altitude for Zeb(alt)
• Surface dew point temperature(dp)
• Dry bulb temperature(tdry)
• Relative humidity inside the instrument enclosure(rh)
• Ascent Rate(asc)

• Surface dew point temperature(dp)
• Relative humidity inside the instrument enclosure(rh)
• Ascent Rate(asc)
• Dry bulb temperature(tdry)
• Dummy altitude for Zeb(alt)

• Dummy altitude for Zeb(alt)
• Relative humidity inside the instrument enclosure(rh)
• Dry bulb temperature(tdry)

SGP/SONDE/C1 - Questionable RH: CF sounding 11/13/2002:2044

The RH data in this sounding is erratic between 2km and 10 km, oscillating between 
reasonable values (~40%RH) and zero.  I certainly doubt that this is a real, heretofore 
unreported, atmospheric phenomenon so I have to conclude that something is probably wrong with 
the sensor.  I have not seen this behavior before.  One would have to look at the 
absolutely raw RH data to explore further.

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

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

SGP/SONDE/C1 - Contaminated by interference

These three soundings are contaminated by interference from another radiosonde.  It is not 
clear why; this doesn't usually happen at the CF where the operators are very 
experienced and frequency separation is not usually a problem.

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

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

• null(Raw data stream - documentation not supported)

SGP/SONDE/C1 - Interference CF sounding 20021120:0225

Like several soundings on 11/19, this sounding was affected by interference from another 
radiosonde.

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

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

• null(Raw data stream - documentation not supported)

SGP/SONDE/C1 - Questionable RH CF sounding 0211211:1130

The RH samples in this sounding oscillate between reasonable values (60-80%) and zero.  
This may be a problem with the RH sensor or the software that alternates between the heated 
and non-heated RH elements.  In either case, the reported values are questionable.  More 
investigation of the raw binary data would be required to diagnose further.

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

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

SGP/MWR/C1 - Intermittent Negative Sky Brightness Temperatures

Several related and recurring problems with the SGP MWRs have been
reported dating back to 1999.  These problems were due to the
occurrence of blackbody signals (in counts) that were half of those
expected. The symptoms included noisy data (especially at Purcell),
spikes in the data (especially at Vici), negative brightness
temperatures, and apparent loss of serial communication between the
computer and the radiometer, which results in a self-termination of the
MWR program (especially at the CF).

Because these all initially appeared to be hardware-related problems,
the instrument mentor and SGP site operations personnel (1) repeatedly
cleaned and replaced the fiber optic comm. components, (2) swapped
radiometers, (3) sent radiometers back to Radiometrics for evaluation
(which has not revealed any instrument problems), and (4) reconfigured
the computer's operating system.  Despite several attempts to isolate
and correct it, the problem persisted.

It became apparent that some component of the Windows98 configuration
conflicted with the DOS-based MWR program or affected the serial port
or the contents of the serial port buffer. This problem was finally
corrected by upgrading the MWR software with a new Windows-compatible
program.

• Averaged total liquid water along LOS path(liq)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 31.4 GHz(tbsky31)

• Sky brightness temperature at 31.4 GHz(tbsky31)
• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 23.8 GHz(tbsky23)

• Sky brightness temperature at 23.8 GHz(tbsky23)
• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 31.4 GHz(tbsky31)

• MWR column precipitable water vapor(vap)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Averaged total liquid water along LOS path(liq)

SGP/MWR/C1 - REPROCESS - 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).

Although the MWR data will be reprocessed to apply the new monortm-based retrievals, for 
most purposes it will be sufficient to correct the data using the following factors:

PWV_MONORTM = 0.9695 * PWV_ROSENKRANZ
LWP_MONORTM = 1.026  * LWP_ROSENKRANZ

The Rosenkranz-based retrieval coefficients became active as follows (BCR 456):
SGP/C1 (Lamont)     4/16/2002, 2000
SGP/B1 (Hillsboro)  4/12/2002, 1600
SGP/B4 (Vici)       4/15/2002, 2300
SGP/B5 (Morris)     4/15/2002, 2300
SGP/B6 (Purcell)    4/16/2002, 2200
SGP/E14(Lamont)     4/16/2002, 0000
NSA/C1 (Barrow)     4/25/2002, 1900 
NSA/C2 (Atqasuk)    4/18/2002, 1700
TWP/C1 (Manus)      5/04/2002, 0200
TWP/C2 (Nauru)      4/27/2002, 0600
TWP/C3 (Darwin)     inception

The MONORTM-based retrieval coefficients became active as follows (BCR 984):

SGP/C1 (Lamont)     6/28/2005, 2300
SGP/B1 (Hillsboro)  6/24/2005, 2100
SGP/B4 (Vici)       6/24/2005, 2100
SGP/B5 (Morris)     6/24/2005, 2100
SGP/B6 (Purcell)    6/24/2005, 1942
SGP/E14(Lamont)     6/28/2005, 2300
NSA/C1 (Barrow)     6/29/2005, 0000 
NSA/C2 (Atqasuk)    6/29/2005, 0000
TWP/C1 (Manus)      6/30/2005, 2100
TWP/C2 (Nauru)      6/30/2005, 2100
TWP/C3 (Darwin)     6/30/2005, 2100
PYE/M1 (Pt. Reyes)  4/08/2005, 1900**

** At Pt. Reyes, the original retrieval coefficients implemented in March 2005 were based 
on a version of the Rosenkranz model that had been modified to use the HITRAN half-width 
at 22 GHz and to be consistent with the water vapor continuum in MONORTM.  These 
retrievals yield nearly identical results to the MONORTM retrievals.  Therefore the Pt. Reyes 
data prior to 4/08/2005 may not require reprocessing.

• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)

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

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

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

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

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

SGP/SONDE/C1 - Increased precision for alt, dp, pres, rh, tdry

The output precision of the following variables was increased 20060928

alt  changed from 1m to 0.1m
dp   changed from 0.1degC to 0.01degC
pres changed from 0.1 hPa to 0.01 hPa
RH   changed from 1%RH to 0.01%RH
tdry changed from .1degC to 0.01degC

Note that the increase in precision does not necessarily imply an increase in accuracy.  
Users are cautioned to continue to use their best scientific judgement when using these or 
any other data.

• Surface dew point temperature(dp)
• Dry bulb temperature(tdry)
• Relative humidity inside the instrument enclosure(rh)
• Retrieved pressure profile(pres)
• Dummy altitude for Zeb(alt)