GRW/VCEIL/M1 - Receiver failure

The AMF VCEIL had lower-than-normal laser transmitter power, ~84%, so the instrument was 
replaced with a spare on 4/22. The spare VCEIL had just been repaired but began to display 
receiver failure warnings.

Diagnostic information was sent to Vaisala and we discussed either replacing the receiver 
with the one from the original VCEIL (with the degraded transmitter) or replacing the 
transmitter in the original VCEIL with the one from the spare. Vaisala recommended the 
latter because the original VCEIL is a much newer unit.

On 5/16, the site operator replaced the transmitter in the original VCEIL with the one 
from the spare, realigned the optics, recalibrated the laser, and put the instrument back 
into service, successfully correcting the problem.

The data during this period were intermittently incorrect, containing warning flags and 
alarms and unreasonable cloud base heights.

• Vertical visibility(vertical_visibility)
• Lowest cloud base height detected.(first_cbh)
• background_light
• Backscatter(backscatter)
• Third cloud base height(third_cbh)
• Second lowest cloud base height(second_cbh)
• alt_highest_signal

GRW/MWR/M1 - Loose mirror

The data from the MWR were suspicious and became progressively worse. The problem was 
traced back to the fact that the screw that keeps the mirror in place had become loose and 
the mirror was freely rotating. 

The mirror was tightened on 6/9/2009, however the measurements were noisy until 6/16, when 
the instrument was rebooted and all the connections checked. 

Measurements between 5/1 and 6/9 should not be used. Data between 6/9 and 6/16 are usable, 
although they are very noisy.

• vaptip
• bb31
• tbsky23tip
• bbn23
• bbn31
• tbsky31tip
• tipsky23
• bb23
• tipsky31
• liqtip

• sky23
• bbn23
• Total water vapor along LOS path(vap)
• bbn31
• Total liquid water along LOS path(liq)
• sky31
• 31.4 GHz sky brightness temperature(tbsky31)
• bb31
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• bb23

GRW/SONDE/M1 - Wind data missing

A GPS problem associated with Vaisala BBSS ground station software issues caused the 
ground stations to enter into an error state when using GPS wind finding. In some instances, 
the flight was aborted due to the error state and no data was collected.  A workaround was 
developed to allow sondes to be launched without collecting wind data.

• Northward Wind Component(v_wind)
• Eastward Wind Component(u_wind)
• wstat
• Mean Wind Speed(wspd)

GRW/VCEIL/M1 - Reprocess: Incorrect serial_number and sum_backscatter fields

Attribute serial_number: In most cases, this field is not representative of the actual 
serial number of the instrument because the value did not change when an instrument changed 
locations or was replaced with a spare.
   
Variable sum_backscatter: An out-of-range condition for the "sum of detected and 
normalized backscatter" was reported as 0 instead of missing (-9999). The valid range is 0 - 
0.0999 /srad.

• sum_backscatter

GRW/MWR/M1 - Reprocess: Biased LWP retrievals-Updated retrieval coefficients

Retrieval coefficients were updated to screen for some bad soundings

• liqtip

• Total liquid water along LOS path(liq)

GRW/MWR/M1 - Incorrect ambient temperature

The ambient temperature readings are incorrect.  Problem appeared to have started around 
10:48 GMT on 02/09, but was not really noticeable until slightly after 11 GMT, when tkair 
values dipped considerably.  

The dewblower was replaced on 2/11 and temperature readings returned to normal.

• tkair

• tkair

GRW/MWR/M1 - Incorrect instrument computer set-up

Starting late on 07/11 the instrument began to have very brief (< 1 min) data outages 
every few hours.  By 07/12 data had become noticeably incorrect, particularly the PWV, LWP, 
TB23, and TB31.  At ~17 Z on 0713 the missing data / no data available flags became more 
frequent.

The problem was identified as improper settings of the instrument computer and was solved 
on 8/9.

• tnd_nom31
• vaptip
• tnd31I
• r23
• tc23
• tbsky23tip
• tnd_nom23
• tbsky31tip
• tc31
• tnd23I
• r31
• tnd31
• tnd23
• liqtip

• Total water vapor along LOS path(vap)
• tnd31
• Total liquid water along LOS path(liq)
• tnd23
• tnd_nom31
• 31.4 GHz sky brightness temperature(tbsky31)
• tnd_nom23
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• tc23
• tc31

GRW/MWR/M1 - Erratic brightness temperature

Around 12 Z on 7/20 both the PWV and 23.8 GHz brightness temp values began to diverge from 
those of the MWRP. By 7/22 both the LWP and 31.4 GHz brightness temp had followed suit. 
At 0600 Z on 7/22 multiple (10-20), brief (<=1 min) data outages began appearing hourly.  
The problem persisted intermittently until 8/9.

On 8/9, changes in the settings of the computer restored the proper functionality of the 
MWR software.

• tnd_nom31
• vaptip
• tnd31I
• tc23
• tbsky23tip
• tnd_nom23
• tbsky31tip
• tc31
• tnd23I
• tnd31
• tnd23
• liqtip

• Total water vapor along LOS path(vap)
• tnd31
• Total liquid water along LOS path(liq)
• tnd23
• tnd_nom31
• 31.4 GHz sky brightness temperature(tbsky31)
• tnd_nom23
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• tc23
• tc31

GRW/MWR/M1 - Missing data

Data are missing and unrecoverable.

• vaptip
• tc23
• bbn23
• wet_window
• tnd_nom23
• tbsky31tip
• time
• tipsky31
• actel
• bb31
• tbsky23tip
• tc31
• r31
• tnd31
• tipsky23
• bb23
• tkbb
• tkxc
• time_offset
• tknd
• r23
• actaz
• base_time
• tnd23
• tkair
• alt
• lat
• tnd_nom31
• tnd31I
• bbn31
• tnd23I
• lon
• liqtip

• IR Brightness Temperature(sky_ir_temp)
• tnd31
• bbn31
• lon
• time
• bb23
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• tc23
• base_time
• alt
• tkbb
• sky31
• bb31
• tc31
• sky23
• wet_window
• tknd
• Total liquid water along LOS path(liq)
• tnd_nom31
• tkxc
• tkair
• tnd_nom23
• bbn23
• Total water vapor along LOS path(vap)
• tnd23
• lat
• 31.4 GHz sky brightness temperature(tbsky31)
• time_offset

GRW/MWRHF/M1 - Incorrect surface temp and RH

The surface temperature and surface relative humidity did not compare well with the 
co-located MET system.   The temperature was not too different than the MET system, but trended 
differently.  The MWRHF RH values were often 20% or greater different and trended 
inversely.

• Temperature, air(temp)
• Humidity, relative(rh)