SGP/ARSCL/C1 - ARSCL Cloud Bases and Low-level reflectivities

Prior to February 4, 2000, the ARSCL data set incorporated data from the
Beaufort Laser Ceilometer as one of its inputs.  Because of the BLC's
high spatial resolution, this data was often chosen by ARSCL as the
"CloudBaseBestEstimate" for boundary layer clouds. It was subsequently
determined that the BLC cloud base was biased, with the BLC reporting
cloud base heights that are 122 meters too high.

The bias error will be corrected when the entire ARSCL data set is
reprocessed as part of release_4.  (The release version number is included
the the netCDF global comments).   This reprocessing will also include a
small correction the the MMCR near-field reflectivities.  This correction
is less than 1 dB except for hydrometers within 200 meters of the surface.

Thanks to Roger Marchand for helping bracket this problem.

• LASER Cloud Base Height Best Estimate(CloudBaseBestEstimate)

• BLC/VCEIL Clothiaux et al. Algorithm Cloud Base Height(CloudBaseCeilometerCloth)
• Cloud, reflectivity, at altitude(Reflectivity)
• MMCR Reflectivity, Best estimate, Hydrometer(ReflectivityBestEstimate)
• BLC/VCEIL Standard Algorithm Cloud Base Height(CloudBaseCeilometerStd)
• LASER Cloud Base Height Best Estimate(CloudBaseBestEstimate)

• BLC/VCEIL Clothiaux et al. Algorithm Cloud Base Height(CloudBaseCeilometerCloth)
• BLC/VCEIL Standard Algorithm Cloud Base Height(CloudBaseCeilometerStd)

Reprocess: Jump in pressure value

DQR No:                               Platform:  sgpsondeB6

Subject:        Jump in pressure value B6 sounding 970404.1733

Date Submitted: 4/9/97
Submitted By:   Barry Lesht           _X_  Instrument Mentor
                                      ___  EST Member
                                      ___  Science Team Member
                                      ___  Other _____________________________
 
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at dqr@arm.gov.

Platform/Measurement: sgpsondewrpnb6/ (alt, asc, press)
    What level data: (raw,a0,a1,b1,c1 etc): all

    What location was the data collected at: SGP/BF6
 
    Period of time in question
        Begin Date  4/04/97    Time   17:33    (GMT)
        End Date               Time            (GMT)

 Data should be labeled:
 ___  questionable                      _X_  All data fields affected
 _X_  incorrect                         ___  Only some data fields affected
 ___  wrong calibration
 ___  others 
 
 Discussion of Problem:

The first pressure value reported by the radiosonde (t = 2 sec) is
879.2.  The surface pressure value was 962.1 hPa.  Either the pressure
sensor was jarred during launch or the system mis-identified the actual
launch start time.  Further clarification requires analysis of the raw
data which will take some time.  The altitude values for this sounding
will be incorrect.  The ascent rate values during the first 30 seconds
also will be wrong.  Because the system will reject samples with out
of bound ascent rates (i.e., during the first 30 seconds), the temperature
and rh values also will be incorrect (result of interpolation).  Relative
height values after 30 seconds should be okay.

 
Other observations/measurements impacted by this problem:


Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)

Flag data.

Data Processing Notes                Date

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

Reprocess: Jump in pressure value

DQR No:                               Platform:  sgpsondeB5

Subject:        Jump in pressure value B5 sounding 970405.2030

Date Submitted: 4/10/97
Submitted By:   Barry Lesht           _X_  Instrument Mentor
                                      ___  EST Member
                                      ___  Science Team Member
                                      ___  Other _____________________________
 
For questions or problems, please contact the ARM Experiment Center at
509-375-6898 or via email at dqr@arm.gov.

Platform/Measurement: sgpsondewrpnb5/ (alt, asc, press)
    What level data: (raw,a0,a1,b1,c1 etc): all

    What location was the data collected at: SGP/BF5
 
    Period of time in question
        Begin Date  4/5/97     Time   20:30    (GMT)
        End Date               Time            (GMT)

 Data should be labeled:
 ___  questionable                      _X_  All data fields affected
 _X_  incorrect                         ___  Only some data fields affected
 ___  wrong calibration
 ___  others 
 
 Discussion of Problem:

The first pressure value reported by the radiosonde (t = 2 sec) is
967.3.  The surface pressure value was 973.5 hPa.  This difference
is slightly greater than the expected (normal) change and may mean that
either the pressure sensor was jarred during launch or the system 
mis-identified the actual launch start time.  Further clarification requires 
analysis of the raw data which will take some time.  The altitude values 
for this sounding will be incorrect.  The ascent rate values during the 
first 30 seconds also will be wrong.  Because the system will reject 
samples with out of bound ascent rates (i.e., during the first 30 seconds), 
the temperature and rh values also will be incorrect (result of 
interpolation).  Relative height values after 30 seconds should be okay.

 
Other observations/measurements impacted by this problem:


Suggested Corrections of the Problem: (e.g. change calibration factor and
recompute, flag data with this comment, etc.)

Flag data.

Data Processing Notes                Date

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

Pressure jump at launch

The difference between the first pressure reported by the sonde after
launch (930.0) and that reported at the surface (935.7) is larger than
would be expected.  The altitude values for this sounding will be incorrect,
as will be the ascent rates for the first 30 seconds.  Some of the P, T, and
RH samples (most likely those nearest the ground) will be interpolated
values.

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

Pressure jump at launch

The difference between the first pressure value reported by the sonde
after launch (992.7) and the surface value entered by the operator (997.5)
is somewhat greater than would normally be expected.  This may indicate
jarring of the pressure sensor at launch or misidentification of the
start time by the system.  The altitude values in the file will be incorrect
as well be the ascent rate values during the first 30 seconds of the
sounding.

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

Pressure jump at launch

The difference between first pressure value reported by the radiosonde 
after launch (954.4) and the surface value entered by the operator (961.7)
is greater than expected , indicating that either ths sonde was jarred on 
launch or that the system mis-identified start time.

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