SGP/MWR/B1 - occasional negative brightness temperatures

Occasional spikes in the MWR data were observed. Inspection of
the data indicates that these are due to spikes in the gain that result from
either unrealistically low values of the blackbody target temperature (~150 K) or
unrealistically low values of the microwave signal counts when viewing the
blackbody target. Unrealistically low values of the mixer temperature have also been
observed.

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

• 23.8 GHz sky brightness temperature(23tbsky)
• MWR column precipitable water vapor(vap)
• Averaged total liquid water along LOS path(liq)
• 31.4 GHz sky brightness temperature(31tbsky)

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

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

• 23.8 GHz sky signal(tipsky23)
• 31.4 GHz sky signal(tipsky31)
• Mixer kinetic (physical) temperature(tkxc)

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)
• Mean 23.8 GHz sky brightness temperature(tbsky23)
• MWR column precipitable water vapor(vap)
• Mean 31.4 GHz sky brightness temperature(tbsky31)

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

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

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

SGP/MWR/B1 - 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.

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

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

SGP/MWR/B4 - 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)
• Mean 31.4 GHz sky brightness temperature(tbsky31)
• Mean 23.8 GHz sky brightness temperature(tbsky23)
• MWR column precipitable water vapor(vap)

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

SGP/MWR/B5 - 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.

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

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

SGP/MWR/B6 - 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.

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

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

SGP/MWR/B1  - min/max/delta values incorrect

The values of valid_min, valid_max, and valid_delta for fields tkxc and tknd were 
incorrect. They should be 303, 333, and 0.5 K, respectively.

• (tknd)
• Mixer kinetic (physical) temperature(tkxc)

SGP/MWR/B4  - min/max/delta values incorrect

The values of valid_min, valid_max, and valid_delta for fields tkxc and tknd were 
incorrect. They should be 303, 333, and 0.5 K, respectively.

• Mixer kinetic (physical) temperature(tkxc)
• (tknd)

SGP/MWR/B5  - min/max/delta values incorrect

The values of valid_min, valid_max, and valid_delta for fields tkxc and tknd were 
incorrect. They should be 303, 333, and 0.5 K, respectively.

• (tknd)
• Mixer kinetic (physical) temperature(tkxc)

SGP/MWR/B6  - min/max/delta values incorrect

The values of valid_min, valid_max, and valid_delta for fields tkxc and tknd were 
incorrect. They should be 303, 333, and 0.5 K, respectively.

• Mixer kinetic (physical) temperature(tkxc)
• (tknd)

SGP/AERI/C1 - Metadata errors

The latitude, longitude and altitude of the AERI
were incorrectly entered into the ARM database.  
The correct location of the SGP.C1 AERI is:
   Lat: 36.606N
   Lon: 97.485W
   Alt:    316m

• lat(lat)
• Dummy altitude for Zeb(alt)
• lon(lon)

• MFRSR channels(channel)
• Dummy altitude for Zeb(alt)
• lon(lon)

• lon(lon)
• Dummy altitude for Zeb(alt)
• lat(lat)

• Dummy altitude for Zeb(alt)
• lat(lat)
• lon(lon)

• lat(lat)
• lon(lon)
• Dummy altitude for Zeb(alt)

• lat(lat)
• Dummy altitude for Zeb(alt)
• lon(lon)

• lon(lon)
• Dummy altitude for Zeb(alt)
• lat(lat)

• Dummy altitude for Zeb(alt)
• lat(lat)
• lon(lon)

• lon(lon)
• Dummy altitude for Zeb(alt)
• lat(lat)

• Dummy altitude for Zeb(alt)
• lat(lat)
• lon(lon)

SGP/AERI/B1 - Increased radiative uncertainty during hot summer afternoons

The ambient temperature of the AERI enclosures at the boundary facilities
often exceeded 308 K during hot summer afternoons.  This threshold marked
the maximum end of the "acceptable" range of temperatures that the 
ambient blackbody should maintain.  The issue is that if the hot 
blackbody and ambient blackbody temperatures are too close together, then 
the radiative calibration becomes more uncertain.  It should be noted 
that the hot blackbody's temperature is maintained at roughly 333 K.  

Using the calibration equation, an uncertainty analysis was performed
to see how much "additional" uncertainty resulted in the AERI
observations when the ambient temperature was between 308-315 K (315 K
was the maximum temperature that the ambient blackbody reached during
the summer).  The analysis compared the radiative uncertainties from the
Hillsboro (B1) AERI (chosen at random) with the AERI-01 at the SGP/CF
over a 5-year period.  Plot1 (below) shows the time-series of ambient
blackbody temperatures for the two instruments, along with histograms to
show the distribution of the temperatures.  The boundary facility
instrument did suffer from higher temperatures in the summer
time periods.  Plot2 (bleow) shows the relative radiative uncertainty
for each instrument.  The CF instrument has a maximum radiative
uncertainty of around 0.18% during the summer, while the BF instrument's
maximum radiative uncertainty is about 0.25%.  This plot demonstrates
that the radiative uncertainty is significantly larger for the BF
instrument in the summer relative to the CF instrument.  However, the
absolute radiative accuracy for the AERI is specified to be better than
1% of the ambient radiance, and both the CF and the BF AERIs are well
within this uncertainty.  

In short, there is significantly higher radiative uncertainty in the
BF AERIs during the hot summer afternoons, but the uncertainty is well
within the specified accuracy of the instrument.

plot1:  aeri_abb_temp.lamont_hillsboro.png 

plot2:  aeri_relative_error.lamont_hillsboro.png 

• Mean of radiance spectra ensemble(mean_rad)

• Mean of radiance spectra ensemble(mean_rad)

SGP/AERI/B4 - Increased radiative uncertainty during hot summer afternoons

The ambient temperature of the AERI enclosures at the boundary facilities
often exceeded 308 K during hot summer afternoons.  This threshold marked
the maximum end of the "acceptable" range of temperatures that the 
ambient blackbody should maintain.  The issue is that if the hot 
blackbody and ambient blackbody temperatures are too close together, then 
the radiative calibration becomes more uncertain.  It should be noted 
that the hot blackbody's temperature is maintained at roughly 333 K.  

Using the calibration equation, an uncertainty analysis was performed
to see how much "additional" uncertainty resulted in the AERI
observations when the ambient temperature was between 308-315 K (315 K
was the maximum temperature that the ambient blackbody reached during
the summer).  The analysis compared the radiative uncertainties from the
Hillsboro (B1) AERI (chosen at random) with the AERI-01 at the SGP/CF
over a 5-year period.  Plot1 (below) shows the time-series of ambient
blackbody temperatures for the two instruments, along with histograms to
show the distribution of the temperatures.  The boundary facility
instrument did suffer from higher temperatures in the summer
time periods.  Plot2 (bleow) shows the relative radiative uncertainty
for each instrument.  The CF instrument has a maximum radiative
uncertainty of around 0.18% during the summer, while the BF instrument's
maximum radiative uncertainty is about 0.25%.  This plot demonstrates
that the radiative uncertainty is significantly larger for the BF
instrument in the summer relative to the CF instrument.  However, the
absolute radiative accuracy for the AERI is specified to be better than
1% of the ambient radiance, and both the CF and the BF AERIs are well
within this uncertainty.  

In short, there is significantly higher radiative uncertainty in the
BF AERIs during the hot summer afternoons, but the uncertainty is well
within the specified accuracy of the instrument.

plot1:  aeri_abb_temp.lamont_hillsboro.png 

plot2:  aeri_relative_error.lamont_hillsboro.png 

• Mean of radiance spectra ensemble(mean_rad)

• Mean of radiance spectra ensemble(mean_rad)

SGP/AERI/B5 - Increased radiative uncertainty during hot summer afternoons

The ambient temperature of the AERI enclosures at the boundary facilities
often exceeded 308 K during hot summer afternoons.  This threshold marked
the maximum end of the "acceptable" range of temperatures that the 
ambient blackbody should maintain.  The issue is that if the hot 
blackbody and ambient blackbody temperatures are too close together, then 
the radiative calibration becomes more uncertain.  It should be noted 
that the hot blackbody's temperature is maintained at roughly 333 K.  

Using the calibration equation, an uncertainty analysis was performed
to see how much "additional" uncertainty resulted in the AERI
observations when the ambient temperature was between 308-315 K (315 K
was the maximum temperature that the ambient blackbody reached during
the summer).  The analysis compared the radiative uncertainties from the
Hillsboro (B1) AERI (chosen at random) with the AERI-01 at the SGP/CF
over a 5-year period.  Plot1 (below) shows the time-series of ambient
blackbody temperatures for the two instruments, along with histograms to
show the distribution of the temperatures.  The boundary facility
instrument did suffer from higher temperatures in the summer
time periods.  Plot2 (bleow) shows the relative radiative uncertainty
for each instrument.  The CF instrument has a maximum radiative
uncertainty of around 0.18% during the summer, while the BF instrument's
maximum radiative uncertainty is about 0.25%.  This plot demonstrates
that the radiative uncertainty is significantly larger for the BF
instrument in the summer relative to the CF instrument.  However, the
absolute radiative accuracy for the AERI is specified to be better than
1% of the ambient radiance, and both the CF and the BF AERIs are well
within this uncertainty.  

In short, there is significantly higher radiative uncertainty in the
BF AERIs during the hot summer afternoons, but the uncertainty is well
within the specified accuracy of the instrument.

plot1:  aeri_abb_temp.lamont_hillsboro.png 

plot2:  aeri_relative_error.lamont_hillsboro.png 

• Mean of radiance spectra ensemble(mean_rad)

• Mean of radiance spectra ensemble(mean_rad)

SGP/AERI/B6 - Increased radiative uncertainty during hot summer afternoons

The ambient temperature of the AERI enclosures at the boundary facilities
often exceeded 308 K during hot summer afternoons.  This threshold marked
the maximum end of the "acceptable" range of temperatures that the 
ambient blackbody should maintain.  The issue is that if the hot 
blackbody and ambient blackbody temperatures are too close together, then 
the radiative calibration becomes more uncertain.  It should be noted 
that the hot blackbody's temperature is maintained at roughly 333 K.  

Using the calibration equation, an uncertainty analysis was performed
to see how much "additional" uncertainty resulted in the AERI
observations when the ambient temperature was between 308-315 K (315 K
was the maximum temperature that the ambient blackbody reached during
the summer).  The analysis compared the radiative uncertainties from the
Hillsboro (B1) AERI (chosen at random) with the AERI-01 at the SGP/CF
over a 5-year period.  Plot1 (below) shows the time-series of ambient
blackbody temperatures for the two instruments, along with histograms to
show the distribution of the temperatures.  The boundary facility
instrument did suffer from higher temperatures in the summer
time periods.  Plot2 (bleow) shows the relative radiative uncertainty
for each instrument.  The CF instrument has a maximum radiative
uncertainty of around 0.18% during the summer, while the BF instrument's
maximum radiative uncertainty is about 0.25%.  This plot demonstrates
that the radiative uncertainty is significantly larger for the BF
instrument in the summer relative to the CF instrument.  However, the
absolute radiative accuracy for the AERI is specified to be better than
1% of the ambient radiance, and both the CF and the BF AERIs are well
within this uncertainty.  

In short, there is significantly higher radiative uncertainty in the
BF AERIs during the hot summer afternoons, but the uncertainty is well
within the specified accuracy of the instrument.

plot1:  aeri_abb_temp.lamont_hillsboro.png 

plot2:  aeri_relative_error.lamont_hillsboro.png 

• Mean of radiance spectra ensemble(mean_rad)

• Mean of radiance spectra ensemble(mean_rad)

SGP/AERI/C1 - Data Reprocessed to correct laser wavenumber

SGP.C1 AERI data from 20000302-20020510 have been reprocessed
to correct for the spectral calibration; i.e., to correct the
laser wavenumber.  These data are now available from the ARM
Archive.

Data users who retrieved the previous version of this data from 
the archive should consider the following graphic to gauge the
impact the correction might have on their analyses.


vlaser_correction_example.png  

Note: only the ch1 and ch2 data were reprocessed; the summary
data have not been recomputed.  The summary data typically
are 5 to 25 cm-1 spectral averages of the ch1 and ch2 data,
and the effect of the spectral calibration on these averages
should be negligible.

• Mean of radiance spectra ensemble(mean_rad)

• Mean of radiance spectra ensemble(mean_rad)