SGP/SONDE/C1 - Possibly bad pressure sensor or operator data entry error

There is a discrepency between the surface pressure and temperature data entered by the 
operator and that recorded by the THWAPS.  Review of the raw data from the radiosonde shows 
that the pressure was periodically varying by as much as 12 hPa (~988 to 1000)in the 
time period before launch.  The operator entry of 998.2 is at the high end of this range - 
the concurrent THWAPS reading was about 988.4 at the low end.  The operator entered 
temperature 6.2 degC is considerably higher than the THWAPS value of 1.8.  The pre-flight log 
entry for this sounding is missing from the OMIS database.  If not for the extremely 
unstable pressure reading I would have assumed this was an operator error.  It will take some 
more research to figure out what is going on.

• Dewpoint Temperature(dp)
• Dry Bulb Temperature(tdry)
• lon
• Mean Wind Speed(wspd)
• base_time
• asc
• Pressure, atmospheric, constant value of model level, RUC model output(pres)
• Wind Direction(deg)
• Northward Wind Component(v_wind)
• lat
• time_offset
• alt
• wstat
• Humidity, relative(rh)
• Eastward Wind Component(u_wind)

SGP/SONDE/C1 - Surface pressure incorrect

I think the operator inadvdertently entered an incorrect surface pressure value.  The 
value entered is 988.8 hPa but the value shown in the raw data file at launch is 968.8.  As a 
result, the absolute altitudes in this sounding will be slightly incorrect as will be 
the ascent rate during the first 30 seconds of flight.

• alt
• asc

SGP/SONDE/C1 - Surface pressure bad and other data noisy

I was checking this sounding because the surface pressure entered by the operator was 
considerably higher than that recorded by the TWHAPS and SMOS.  I'm not sure why, but the 
pressure data are very noisy while the sonde is on the ground (which accounts for the 
incorrect surface pressure) and the RH data aloft do not look terrible but do not look great 
either.

• Dewpoint Temperature(dp)
• Dry Bulb Temperature(tdry)
• lon
• Mean Wind Speed(wspd)
• base_time
• asc
• Pressure, atmospheric, constant value of model level, RUC model output(pres)
• Wind Direction(deg)
• Northward Wind Component(v_wind)
• lat
• time_offset
• alt
• wstat
• Humidity, relative(rh)
• Eastward Wind Component(u_wind)

SGP/SONDE/C1 - Surface pressure incorrect

I think the operator inadvdertently typed an 89 instead of a 78 when entering the surface 
pressure value.  The value entered is 989.9 hPa but the value shown in the raw data file 
at launch is 978.9.  As a result, the absolute altitudes in this sounding will be 
slightly incorrect as will be the ascent rate during the first 30 seconds of flight.

• alt
• asc

SGP/SONDE/C1 - Surface pressure incorrect

I think the operator inadvdertently mistyped a digit when entering the surface pressure 
value.  The value entered is 975.6 hPa but the value shown in the raw data file at launch 
is 972.6.  As a result, the absolute altitudes in this sounding will be slightly incorrect 
as will be the ascent rate during the first 30 seconds of flight.

• alt
• asc

SGP/SONDE/C1 - Bad RH Data

The RH values below 6 km are incorrect.  The problem relates to a failure of the GC25 
ground check set used before this particular sounding.  The failure seems to have affected 
the sensor calibration with the effect that one of the two sensors was reading artificially 
high.  Because the internal processing software uses the highest of the two sensor 
readings, the bad sensor value is chosen whenever it is not heated.

• Dewpoint Temperature(dp)
• Humidity, relative(rh)

SGP/SONDE/C1 - Bad T/RH and surface P.

Apparently multiple failures.  The radiosonde temperature sensor broke on launch causing 
an approximate 35 degC negative offset and as a result, the RH is incorrect.  Furthermore, 
it appears that the pressure sensor was off by approximately 4 hPa, though this would 
not affect the altitude calculation, the absolute pressure is wrong.

• Dry Bulb Temperature(tdry)
• Humidity, relative(rh)
• Pressure, atmospheric, constant value of model level, RUC model output(pres)

SGP/SONDE/C1 - Temperature/RH incorrect

The temperature throughout this sounding is too high and as a result the RH values will be 
incorrect as well.  I'm not sure what is wrong here but the operators noted reasonable 
values (18.1 degC, 87%) in the log before launch.  Review of the raw data, however, shows 
the sonde reporting temperatures nearly 20 degC higher.  I suppose it is possible that 
the operator entered into the log the reference temperature from the GC25 ground check set 
rather than the temperature reported by the sonde - I can't think of any other 
explanation - there is no doubt that the temperature sensor on this sonde was bad.

• Humidity, relative(rh)
• Dry Bulb Temperature(tdry)

• Dry Bulb Temperature(tdry)
• Dewpoint Temperature(dp)
• Humidity, relative(rh)

SGP/SONDE/C1 - Bad RH Data

The RH values during this sounding oscillate between reasonable values and near-zero 
values.  The oscillation is due to failure of the RH sensor heating process.

• Dewpoint Temperature(dp)
• Humidity, relative(rh)

SGP/SONDE/C1 - Sonde RH values incorrect

RH values for all sondes launched during this time were incorrect due to a faulty Ground 
Check set which damaged or conditioned the RH sensor improperly.

• Dewpoint Temperature(dp)
• Humidity, relative(rh)

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.

• alt
• Dry Bulb Temperature(tdry)
• Dewpoint Temperature(dp)
• Humidity, relative(rh)
• Pressure, atmospheric, constant value of model level, RUC model output(pres)