SGP/SONDE/C1 - Mixed use of RS92-SGP and RS92-KL radiosondes

Because of a manufacturer's production problem, we will be using both RS92-SGP (GPS 
windfinding and RS92-KL (Loran windfinding) radiosondes at the SGP/CF starting February 10, 
2006.  The radiosonde type used for the each sounding may be determined by looking the 
metadata variable "launch_status" in the netCDF data files.

• lon(lon)
• U-component(u_wind)
• Mean Wind Speed(wspd)
• V-component(v_wind)
• lat(lat)
• Wind Direction(deg)
• Wind Status(wstat)

SGP/SONDE/C1 - No Wind/Lat/Lon Data in Sonde Files

The wind finding hardware failed so that no wind or latitude/longitude data was collected 
on the launches for these days.

• lon(lon)
• U-component(u_wind)
• Mean Wind Speed(wspd)
• V-component(v_wind)
• lat(lat)
• Wind Status(wstat)

SGP/MWR/C1 - Spikes in ambient temperature readings

There are intermittent spikes in the Tkair temperature (T ~ 400 K). On 7/28 the sensor 
was cleaned and the instrument power cycled following a power outage. Readings came back to 
normal.

• Ambient temperature(tkair)

• Ambient temperature(tkair)

SGP/MWR/C1 - Missing data

Data are missing because of a SW problem

• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz blackbody(bb31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• (tknd)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Actual elevation angle(actel)
• Blackbody kinetic temperature(tkbb)
• 23.8 GHz Blackbody signal(bb23)
• Temperature correction coefficient at 23.8 GHz(tc23)
• lat(lat)
• Ambient temperature(tkair)
• Mixer kinetic (physical) temperature(tkxc)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Dummy altitude for Zeb(alt)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• 31.4 GHz sky signal(tipsky31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Actual Azimuth(actaz)
• base time(base_time)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• lon(lon)
• 23.8 GHz sky signal(tipsky23)
• Time offset of tweaks from base_time(time_offset)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)
• 31.4 GHz goodness-of-fit coefficient(r31)
• 23.8 GHz sky brightness temperature derived from tip curve(tbsky23tip)
• 23.8 GHz goodness-of-fit coefficient(r23)

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

SGP/SONDE/C1 - RH values offset due to error in ground check

Background: After installation of the latest software update , we began performing formal 
ground checks on RS92 radiosondes.  By comparing the
radiosonde readings with reference values in a controlled environment, the
ground check is intended to ensure that the radiosonde sensors are in
calibration before launch.  The radisonde values during the ground check
process are recorded automatically; the reference values are entered by the
operator.  If the radiosonde readings vary from the reference values, the
system 'corrects' the radiosonde values.  In the case of RH, the correction
is applied as an offset (true RH = indicated RH + correction).

Problem: Some operators misunderstood the ground-check procedure and entered the 
radiosonde values of RH rather than the reference value (assumed 0%RH), thus, some soundings done 
during this period have RH values that are different from what they would be if the 
ground check procedure had been done correctly.

Consequence:  Because the RH corrections generally are small (averaging
about 0.5% RH) and the precision of the reported RH data during this time
period is 1% RH, some values will not be affected at all; others will be off by about 1% 
RH (still within the stated accuracy of the sensor). 
Furthermore, because entering the radiosonde value as the reference value
results in a near zero 'correction,' one may view these soundings as being
done without the ground check correction.  Also note that the dew point
value will be suspect as well.

I am attaching below a listing of the soundings that were affected during the indicated 
time period.  Users can see the magnitude of the problem and choose whether or not to apply 
an offset in RH.  Note that application of the offset to the processed RH data (in the 
netCDF file) will not have the same effect of applying the correction to the absolutely 
raw data (before processing), but the differences should be insignificant.  Also note that 
the corrections for each sounding are included in the netCDF header information.  These 
attributes are named 'humidity_correction' and 'humidity_correction_2'.  The values of RH 
indicated by the radiosonde while it is in the ground check set are in attributes 
'humidity_gc_sonde' and 'humidity_gc_sonde_2.'  There is an RH reading for each of the two RH 
sensors used in the RS92 radiosonde.

Here is the list - RH1 and RH2 are the radiosonde readings in the ground
check set.  Ref is the reference value entered by the operator.  The
correcte reference value should be 0%.  To obtain an approximation to the RH value that 
would have been recorded if the ground check had been done
properly, subtract the Ref value from the indicated RH.

 YYYYMMDD  HHMM  SerialN      RH1     RH2     Ref
 20060827  2332  B2624322    1.00    1.00    1.00
 20060828  1731  B2634078    1.00    1.00    1.00
 20060828  2332  B2624380    3.00    3.00    2.00
 20060909  2331  B2615266    1.00    1.00    1.00
 20060915  1759  B2914012    1.00    1.00    1.00
 20060919  2350  B2825128    1.00    1.00    1.00
 20060920  1800  B2825088    1.00    1.00    1.00
 20060920  2346  B2815633    1.00    1.00    1.00
 20060921  1728  B2834732    1.30    1.30    1.30
 20060921  2330  B2825042    1.50    1.50    1.50
 20060922  0527  B2825043    1.70    1.80    1.70
 20060922  1128  B2825031    1.60    1.50    1.60
 20060922  1729  B2834437    1.50    1.50    1.50
 20060922  2330  B2825040    0.40    0.50    0.50
 20060923  0529  B2834733    0.30    0.30    0.30
 20060923  1128  B2825026    0.40    0.40    0.40
 20060923  1729  B2825064    0.60    0.70    0.60
 20060923  2330  B2825041    0.40    0.50    0.50
 20060924  0529  B2825039    0.30    0.30    0.30
 20060924  1729  B2825025    0.20    0.30    0.20
 20060924  2329  B2825032    0.30    0.40    0.40
 20060925  0529  B2824234    0.20    0.30    0.20

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

• 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)

SGP/SONDE/C1 - RH Sensor failure

The differences between the two RH sensors on this sonde are unreasonably high (~20%).  As 
a result the reported RH values oscillate by this amount during the times the sensors 
are alternately heated.  After the heating stops, the reported RH comes from the sensor 
reading the higher value.  There is no way of knowing if this is the correct value.

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

SGP/MWR/C1 - Instrument testing

On 11/28 the insrument was removed and taken inside for testing

• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz blackbody(bb31)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• (tknd)
• Water on Teflon window (1=WET, 0=DRY)(wet_window)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Actual elevation angle(actel)
• Blackbody kinetic temperature(tkbb)
• 23.8 GHz Blackbody signal(bb23)
• Temperature correction coefficient at 23.8 GHz(tc23)
• lat(lat)
• Ambient temperature(tkair)
• Mixer kinetic (physical) temperature(tkxc)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• Dummy altitude for Zeb(alt)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• 31.4 GHz sky signal(tipsky31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Actual Azimuth(actaz)
• base time(base_time)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• lon(lon)
• 23.8 GHz sky signal(tipsky23)
• Time offset of tweaks from base_time(time_offset)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)
• 31.4 GHz goodness-of-fit coefficient(r31)
• 23.8 GHz sky brightness temperature derived from tip curve(tbsky23tip)
• 23.8 GHz goodness-of-fit coefficient(r23)

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

• Raw data stream - documentation not supported(Raw data stream - documentation not supported)

SGP/MWR/C1/E14 - Freezing rain-Incorrect rain flag

Between 01/12 and 01/15 brightness temperatures show high values (Tb > 100 K) indicative 
of rain, however the wet_window flag is 0 (indicative of no rain). During that time there 
where freezing conditions with ice pellets that were not detected by the sensor. The high 
brightness temperatures may be due to melting ice on the window.

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

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

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

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

SGP/MWR/C1 - Noisy data

Since 7/14 the MWR is experiencing intermittent periods of increased noise. The cause for 
this is under investigation.

• 31.4 GHz blac2body+noise injection signal(bbn31)
• 31.4 GHz blackbody(bb31)
• 23.8 GHz sky signal(tipsky23)
• 31.4 GHz sky signal(tipsky31)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)
• 23.8 GHz sky brightness temperature derived from tip curve(tbsky23tip)
• 23.8 GHz Blackbody signal(bb23)

• Mean 31.4 GHz sky brightness temperature(tbsky31)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 31.4 GHz sky signal(sky31)
• Averaged total liquid water along LOS path(liq)
• 31.4 GHz blackbody(bb31)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• MWR column precipitable water vapor(vap)
• 23.8 GHz Blackbody signal(bb23)
• Mean 23.8 GHz sky brightness temperature(tbsky23)
• 23.8 GHz sky signal(sky23)