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.

• tkxc
• tipsky23
• tipsky31

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• 31tbsky
• 23tbsky

• Raw data stream - documentation not supported

• Total liquid water along LOS path(liq)
• 31.4 GHz sky brightness temperature(tbsky31)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Total water vapor along LOS path(vap)

• Raw data stream - documentation not supported

SGP/MWR/B1 - Spikes in sky temperature data

There are negative spikes in the sky temperature data, per Victor Morris.

• 23tbsky
• 31tbsky

• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• 31.4 GHz sky brightness temperature(tbsky31)

SGP/MWR/B1 - noisy data

The MWR exhibited occasional negative sky brightness temperatures that were resolved, 
after eliminating the instrument and communication lines as the source of the problem, by 
reformatting and reconfiguring the laptop computer.

• tkxc

• 23tbsky
• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• 31tbsky

• Total liquid water along LOS path(liq)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Total water vapor along LOS path(vap)
• 31.4 GHz sky brightness temperature(tbsky31)

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.

• Total water vapor along LOS path(vap)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Total liquid water along LOS path(liq)
• 31.4 GHz sky brightness temperature(tbsky31)

• Total liquid water along LOS path(liq)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Total water vapor along LOS path(vap)
• 31.4 GHz sky brightness temperature(tbsky31)

SGP/MWR/B1 - thermal instability

During periods of high ambient temperature, the instrument may have been thermally 
unstable.

• Total water vapor along LOS path(vap)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Total liquid water along LOS path(liq)
• 31.4 GHz sky brightness temperature(tbsky31)

• Total liquid water along LOS path(liq)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Total water vapor along LOS path(vap)
• 31.4 GHz sky brightness temperature(tbsky31)

SGP/MWR/B1/B4/B5 - Data dropouts due to serial comm problems

Conflicts between the drop shipper program and the
MWR operation program resulted in serial communication
problems which ultimately manifested as spikes and
dropouts in the data.

• actaz
• Total liquid water along LOS path(liq)
• actel
• Temperature, brightness, longwave(ir_temp)
• time_offset
• Total water vapor along LOS path(vap)
• wet_window
• 31tbsky
• 23tbsky
• base_time

• Temperature, brightness, longwave(ir_temp)
• base_time
• Total water vapor along LOS path(vap)
• 23tbsky
• actaz
• 31tbsky
• time_offset
• Total liquid water along LOS path(liq)
• wet_window
• actel

• wet_window
• Total water vapor along LOS path(vap)
• 23tbsky
• Total liquid water along LOS path(liq)
• time_offset
• Temperature, brightness, longwave(ir_temp)
• base_time
• actel
• actaz
• 31tbsky

SGP/MWR/B1 - Loss of thermal stabilization

Periodically during August and September 1995 all microwave radiometers
at the SGP CART generated error messages in the Site Operations Log
like:

  Time: Sat Aug 19 18:41:20 1995
  MWRLOS.C1, tkxc: Value above Maximum.

This indicates that the temperature of the microwave hardware
(specifically, the cross-coupler or "xc") exceeded its controlled
temperature (47-52 deg C) at which point it was no longer thermally
stabilized and the gain was uncontrolled.  During these periods which
typically last about 8 hours from about local noon until about sunset
the data behave anomalously and should be considered invalid.

Specifically the precipitable water vapor increases and the liquid
water path decreases (and becomes SIGNIFICANTLY NEGATIVE (-0.1 mm) on
clear sky days).  The RMS noise level in the data also increases
sharply.  The 'Tkxc' field appears ONLY in the a0-level data and does
NOT appear in either the a1 (mwrlos) or c1 (mwr5avg) files.  Therefore
THESE ANOMALOUS VALUES HAVE BEEN INCLUDED IN THE 5-MINUTE AVERAGES.

The microwave hardware is thermally stabilized to about +/- 0.1 deg C
by resistive heating.  When the internal temperature rises above the
set point the thermal stabilization of the instrument gain is lost.
>From an examination of the component temperature data it appears that
increasing the set point temperature to about 55 deg C (328 K) would
prevent a re-ocurrance of this problem at the SGP.  The manufacturer,
Radiometrics, concurs that raising the set point will fix this problem
and will not cause other problems.

I will have to carefully examine the MCTEX data to determine whether
this will be a problem for the TWP.  The manufacturer and I had
discussed this possibility prior to building the TWP MWRs (S/N 015,
016, and 017) and those instruments have set points above 50 deg C.
Note that MWR 018 has a set point near 52 deg C (like the TWP models)
but it still experienced a few loss-of-stabilization events.

Note that the instruments with the lowest set points had the most
loss-of-stabilization events.

• Total water vapor along LOS path(vap)
• 31tbsky
• Total liquid water along LOS path(liq)
• 23tbsky

• 23tbsky
• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• 31tbsky

• 23tbsky
• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)
• 31tbsky

SGP/MWR/B1 - Reprocess: Revised Retrieval Coefficients

IN THE BEGINNING (June 1992), the retrieval coefficients used to derive the precipitable 
water vapor (PWV) and liquid water path (LWP) from the MWR brightness temperatures were 
based on the Liebe and Layton (1987) water vapor and oxygen absorption model and the Grant 
(1957) liquid water absorption model.

Following the SHEBA experience, revised retrievals based on the more recent Rosenkranz 
(1998) water vapor and oxygen absorption models and the Liebe (1991) liquid waer absorption 
model were developed.  The Rosenkranz water vapor absorption model resulted a 2 percent 
increase in PWV relative to the earlier Liebe and Layton model.  The Liebe liquid water 
absorption model decreased the LWP by 10% relative to the Grant model.  However, the 
increased oxygen absorption caused a 0.02-0.03 mm (20-30 g/m2) reduction in LWP, which was 
particularly significant for low LWP conditions (i.e. thin clouds encountered at SHEBA).

Recently, it has been shown (Liljegren, Boukabara, Cady-Pereira, and Clough, TGARS v. 43, 
pp 1102-1108, 2005) that the half-width of the 22 GHz water vapor line from the HITRAN 
compilation, which is 5 percent smaller than the Liebe and Dillon (1969) half-width used in 
Rosenkranz (1998), provided a better fit to the microwave brightness temperature 
measurements at 5 frequencies in the range 22-30 GHz, and yielded more accurate retrievals. 
Accordingly, revised MWR retrieval coefficients have been developed using MONORTM, which 
utilizes the HITRAN compilation for its spectroscopic parameters.  These new retrievals 
provide 3 percent less PWV and 2.6 percent greater LWP than the previous retrievals based on 
Rosenkranz (1998).

Although the MWR data will be reprocessed to apply the new monortm-based retrievals, for 
most purposes it will be sufficient to correct the data using the following factors:

PWV_MONORTM = 0.9695 * PWV_ROSENKRANZ
LWP_MONORTM = 1.026  * LWP_ROSENKRANZ

The Rosenkranz-based retrieval coefficients became active at SGP.B1 20020412.1600.  The 
MONORTM-based retrieval coefficients became active at SGP.B1 20050624.2100.

Note: a reprocessing effort is already underway to apply the Rosenkranz-based retrieval 
coefficients to all MWR prior to April 2002.  An additional reprocessing task will be 
undertaken to apply the MONORTM retrieval to all MWR data when the first is completed.  Read 
reprocessing comments in the netcdf file header carefully to ensure you are aware which 
retrieval is in play.

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• vaptip
• liqtip

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

• mean_vap_mwr
• mean_liq_mwr

Reprocess: Effect of BBSS ground check on MWR tuning functions

Due to concern over the impact of the Ground Check (a one-point
	calibration applied to the Vaisala sonde prior to launch) on
	the MWR tuning functions, I have recalculated the tuning
	functions without the ground check.  The change in the tuning
	functions is slight and has only a very small (maximum of 1%)
	impact on the precipitable water vapor and cloud liquid water
	path values provided by the ARM microwave radiometers.

TUNING FUNCTIONS

	The tuning functions relate microwave brightness temperatures
	measured by the the radiometer to those computed from
	simultaneous radiosondes using a model of microwave radiation
	transfer.  The tuning functions are necessary to permit the use
	of the retrieval functions for precipitable water vapor and
	cloud liquid water which are based on the model calculations.
	The tuning functions are dependent only on the model; they are
	independent of the location and of the instrument (assuming it
	is properly calibrated).

METHODOLOGY

	Barry Lesht, the BBSS instrument mentor, provided me with 325
	soundings from the SGP central facility covering the period
	October 1992 - December 1993 from which he had removed the
	effect of the ground check.  For each of these soundings I
	computed the microwave brightness temperatures at the
	frequencies used by the ARM microwave radiometers.  Of these,
	91 were determined to have occured during periods when the sky
	was clear and horizontally homogeneous on the basis of the
	standard deviation of the measured brightness temperature of
	the liquid-sensitive channel of the radiometer being less than
	0.5 K for the period 10 minutes prior until 30 minutes
	subsequent to the sonde launch.  The mean of the brightness
	temperatures measured during this time period were then used in
	a linear regression to determine the intercept and slope of the
	tuning functions.

RESULTS:

	The new tuning functions are:
	
	23.8 GHz:  TB_model = 0.789 + 0.915 TB_measured  (R2 = 0.994)
	31.4 GHz:  TB_model = 1.142 + 0.910 TB_measured  (R2 = 0.988)
	
	These were applied to the MWR data acquired during the period
	October 1992 through December 1993 and compared with previous
	values.  Only for values of PWV > 3 cm was the effect of the
	new tuning functions as much as 1%.

	For the 91 clear-sky soundings, the RMS difference between the
	preciptable water vapor from the MWR and from the BBSS was 0.1
	cm; the mean difference was 0.00 cm.

	For 59 soundings during June 1993 (clear and cloudy sky), the
	mean difference in the PWV computed from the radiosondes (No
	ground check - ground check) was 0.05 cm; the RMS of the
	difference was 0.08 cm.

Other observations/measurements impacted by this problem: qmemwrlos

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

	1.  The new tuning functions were implemented on all SGP MWRs
	    on 5 Jan 1995.

	2.  The MWR data from Oct 92 - Dec 93 have been recalculated by
	    the mentor and are available from him (as ten-minute
	    averages in ASCII format) upon request.

	3.  A computer code has been provided by the mentor to the ARM
	    Experiment Center to duplicate this reprocessing, if the PRB
	    so desires.

• actaz
• time_offset
• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• wet_window
• lon
• 31tbsky
• 23tbsky
• base_time
• lat
• actel
• alt
• Temperature, brightness, longwave(ir_temp)

• Development data stream - documentation not supported

• Development data stream - documentation not supported

Precipitable Water Vapor (PWV) values at Hillsboro

DQR No:                               Platform: sgpmwrlos, sgp5mwravg

Subject: Precipitable Water Vapor (PWV) values at Hillsboro

Date Submitted:
Submitted By:    JIM LILJEGREN        _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:
    What level data: a0,a1,c1

    What location was the data collected at: SGP B1 (Hillsboro, KS)
 
    Period of time in question
        Begin Date  12/07/95   Time   03:00    (GMT)
        End Date    12/07/95   Time   16:00    (GMT)

        Begin Date  12/08/95   Time   20:00    (GMT)
        End Date    12/10/95   Time   06:00    (GMT)

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

The precipitable water vapor was negative which is unreasonable.  At the
same time the brightness temperature in the 23.8 GHz was less than that
in the 31.4 GHz for apparently clear skies.  This is also unreasonable.
The calibration needs to be checked and updated.

 
Other observations/measurements impacted by this problem:

none

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

Correct calibration.

Data Processing Notes                Date

• time_offset
• vap_sdev
• liq_sdev
• lon
• base_time
• tbsky31_sdev
• Total water vapor along LOS path(vap)
• tbsky23_sdev
• 31tbsky
• 23tbsky
• alt
• num_obs
• Total liquid water along LOS path(liq)
• lat
• water_flag_fraction

• actaz
• alt
• time_offset
• wet_window
• 23tbsky
• base_time
• Total liquid water along LOS path(liq)
• lon
• lat
• actel
• Temperature, brightness, longwave(ir_temp)
• Total water vapor along LOS path(vap)
• 31tbsky

• losn
• Temperature, brightness, longwave(ir_temp)
• 23unoise
• 23skyn
• 23bb
• 31bb
• base_time
• 31bbn
• 31sky
• tkbb
• lon
• actaz
• 23sky
• 23bbn
• lat
• 23tbsky
• actel
• tkxc
• time_offset
• 31unoise
• wet_window
• alt
• Total water vapor along LOS path(vap)
• 31tbsky
• Total liquid water along LOS path(liq)
• 31skyn

SGP/MWR/B1/B5 - Calibration questionable

At the present time, calibrations at B1 and B5 appear out of date.

SGP-B1 (Hillsboro, KS)
Precipitable vapor amounts occasionally negative - calibration needs to
be checked when sky becomes clear.  Data quality is questionable.

Precipitable vapor amounts about 0.6 cm less than integrated
soundings.


SGP-B5 (Morris, OK)
Data from this instrument are missing for 12-15 Jan.  Reason unknown.

Because precipitable vapor amount was negative during 7-8 Jan,
calibration is still suspect.  Liquid water path appears positive for
periods when sky is clear (positive bias).  Data quality is
questionable.

Precipitable vapor amounts 0.3-0.5 cm less than integrated soundings.

• actaz
• 23tbsky
• Total liquid water along LOS path(liq)
• actel
• Temperature, brightness, longwave(ir_temp)
• Total water vapor along LOS path(vap)
• 31tbsky

• losn
• Temperature, brightness, longwave(ir_temp)
• 23unoise
• 23skyn
• 23bb
• 31bb
• 31bbn
• 31sky
• tkbb
• actaz
• 23sky
• 23bbn
• actel
• tkxc
• 23tbsky
• 31unoise
• Total water vapor along LOS path(vap)
• 31tbsky
• Total liquid water along LOS path(liq)
• 31skyn

• Total liquid water along LOS path(liq)
• 31tbsky
• Temperature, brightness, longwave(ir_temp)
• 31unoise
• losn
• 23bbn
• 23sky
• tkbb
• actel
• actaz
• 31bbn
• 23unoise
• Total water vapor along LOS path(vap)
• 31skyn
• 23tbsky
• 23skyn
• tkxc
• 23bb
• 31sky
• 31bb

• Total water vapor along LOS path(vap)
• Temperature, brightness, longwave(ir_temp)
• actel
• actaz
• 23tbsky
• Total liquid water along LOS path(liq)
• 31tbsky

SGP/MWR/B1/B4/B5 - Reprocess: Error in MWR calibration

The effect of this error is small.  At most, it results in a bias of
about -0.015 cm in precipitable water vapor and -0.015 mm in liquid
water path during clear sky conditions.  The error is largest when the
brightness temperatures are small (i.e. clear skies and low PWV).

The error results from failing to correctly account for the effect of
the Teflon window covering the radiometer mirror.  Although the
contribution of the window is subtracted when the tip curve data are
reduced to determine the true zenith brightness temperature, it is not
added back in when the zenith brightness temperature is used to
calibrate the noise diode.  This would still not be a problem if the
contribution of the window where not subtracted (again) during zenith
line-of-sight (LOS) operations.  But it is and the net effect is to
subtract the contribution of the window twice.

The calibrations ('Noise Injection Temperatures') are off by a factor
of 1.00164 and 1.00217 for the 23.8 and 31.4 GHz frequencies,
respectively.

The magnitude of the error is equal to the emissivity of the window
multiplied by the difference between the brightness temperature and the
temperature of the window.  The latter is taken to be equal to the
temperature of the internal blackbody target (which is about 10 deg C
above ambient.)  The emissivity of the window is 0.00164 at 23.8 GHz
and 0.00217 at 31.4 GHz.  For a reference temperature of 292.6 K and
brightness temperatures of 32.3 and 20.8 K at 23.8 and 31.4 GHz
respectively, this amounts to errors of -0.43 and -0.59 K at the
respective frequencies.  The average PWV for this date (5 April 1995)
was 1.4 cm.

At higher levels of PWV and for cloudy conditions, the brightness
temperatures are higher and so the error is smaller.

I will adjust the calibrations of all SGP radiometers to account
for this problem by the end of tomorrow (4 April 1996).

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

SGP/MWR/B1/B4/B5 - Reprocess: MWR Tuning Functions

The 'tuning functions' used to adjust the equivalent brightness
temperatures (TBs) measured by the ARM microwave radiometers (MWRs) are
now believed to be both incorrect and unnecessary.  They should no longer
be used and the data (going back to 1992) that incorporated them should
be reprocessed.  By eliminating these tuning functions the radiometer
retrievals would be independent of the soundings.

BACKGROUND

A recent comparison by Barry Lesht (ANL) of the precipitable water
vapor (PWV) retrieved from the MWR-measured brightness temperatures
against PWV derived by integrating along the trajectory of radiosonde
ascents has revealed that the MWR values are about 90% of those derived
from the soundings.  This is directly attributable to the slope of the
tuning function for the vapor-sensing channel (23.8 GHz) of 0.915 which
is applied to the measured brightness temperatures prior to retrieval
of PWV.

The rationale behind the use of the tuning functions is that the
radiation model (Liebe 87), on which the retrieval is based, is
imperfect whereas the radiosondes represent 'ground truth.'  Thus the
observed brightness temperatures must be adjusted to match those
calculated with the model using co-located soundings so that the
retrieval yields precipitable vapor amounts that agree with the
soundings.

Tuning functions were developed for the present ARM MWRs using
co-located soundings launched between October 1992 and December 1993.
These were adjusted slightly in January 1995 to account for the effects
of the 1-point calibration check performed prior to launch (see DQR
P950110.1):

     23.8 GHz:  TB_model = 0.789 + 0.915 TB_measured  (R2 = 0.998)
     31.4 GHz:  TB_model = 1.142 + 0.910 TB_measured  (R2 = 0.984)

However, repeating this exercise for soundings launched during 1994 and
1995 (excepting those that were mis-calibrated by the manufacturer; see
D960229.1) it now appears that the model-calculated
brightness temperatures are in much closer agreement with the measured
values and that the tuning functions account more for variations in the
radiosonde calibration than for any deficiencies in the radiation
model.  

Consequently, it appears that the present tuning functions are
incorrect and bias the retrieved PWV low by 10%.  In addition, given
the present agreement between measured and modeled brightness
temperatures, the tuning functions are also unnecessary.

METHODOLOGY

Brightness temperatures measured with microwave radiometer (MWR) serial
number 10, which was deployed at the central facility in December 1993,
have been compared against calculations using measurements from the
co-located Balloon-Borne Sounding System (BBSS).  The results are
summarized in two tables.  In each table, the calibration dates of the
sondes and MWR are listed as well as the time period and number of
samples included in each regression.  Each MWR sample is a 40-minute
average, centered on the time of the sonde launch, of the microwave
brightness temperature.  In order to include only clear sky conditions,
samples for which the standard deviation of the liquid-sensing (31.4
GHz) channel exceeded 0.3 K were eliminated.  To assure that the water
vapor was reasonably homogeneous horizontally, samples for which the
standard deviation in the vapor-sensing (23.8 GHz) channel exceeded 0.4
K (in 1995) or 0.5 K (in 1994) were eliminated.  The 1994 threshold is
larger in order to increase the number of samples and reduce the
standard error in the results.

The microwave radiometer measurements used in this comparison have been
reprocessed to account for calibration changes and other problems (see
P940813.1)

                            TB vs PWV

The first table is a comparison of microwave brightness temperature
(TB_mwr) regressed against the precipitable water vapor (PWV) computed
by integrating along the trajectory of the radiosonde ascent.  The
sondes launched during May - December 1994 are compared against two
sets of MWR data; the first uses the May 1994 calibration, and the
second uses the calibration of July 1994.  A comparison is also made of
TB_model vs PWV ('Liebe87') for reference.

The intercepts indicate the contribution due to molecular oxygen (i.e.
the tail of the 60 GHz line) which is affected by temperature and
pressure.  Note that the 'Liebe87' intercepts vary seasonally as the
temperature changes.  Note also that the effect of MWR calibration
changes is most evident in the intercept: offsets of 1-2 K are
observed.  Because the MWR calibration values represent the slope of
the radiometer equation (see Appendix), the magnitude of the offset is
largest at 0 K (i.e. the intercept) and declines to zero at ambient
temperature (~290 K).

The slope of the regression is essentially unaffected by the MWR
calibration.  Variations in the slope of the regression correlate with
sonde calibration date.  The sondes calibrated in May 1994 or later
appear to yield much closer agreement between the measured brightness
temperatures and those calculated with the Liebe 87 model than those
calibrated in January 1994 or earlier, with which the present tuning
functions were developed.

TABLE 1.  Microwave brightness temperature vs. precipitable water vapor

Relationship:  TB_mwr (K) = intercept (K) + slope (K/cm) * PW_sonde (cm)
Standard Error of the intercepts and slopes are given in parentheses.

Date of   Date of  Period          ------ 23.8 GHz -----  ----- 31.4 GHz -----
Sonde Cal MWR tip  Covered    N    intercept   slope      intercept  slope

1991-93    92-93  Oct92-Dec93 91   6.7        14.7        8.1        5.3

1992,93   Dec 93  Jan-Feb 94  85   6.9(0.19)  15.8(0.26)  8.8(0.13)  5.6(0.17)
1992,93   Liebe87 Jan-Feb 94  85   6.5(0.02)  13.8(0.03)  8.9(0.07)  4.5(0.09)

 Jun 93   Dec 93      Apr 94  16  10.6(1.11)  14.8(0.55) 10.1(0.51)  5.6(0.25)
 Jun 93   Liebe87     Apr 94  16   6.9(0.05)  13.6(0.02)  8.1(0.09)  5.0(0.05)

1992,93   May 94  May-Jun 94  48   7.0(1.03)  14.9(0.45)  7.8(0.41)  5.7(0.17)
1992,93   Jul 94  May-Jun 94  48   5.1(1.03)  14.9(0.44)  6.6(0.39)  5.7(0.17)
1992,93   Liebe87 May-Jun 94  48   7.1(0.11)  13.5(0.05)  8.4(0.16)  4.9(0.07)

 Jan 94   Dec 93  Feb-May 94  95   7.6(0.27)  14.3(0.14)  8.5(0.15)  5.5(0.08)
 Jan 94   Liebe87 Feb-May 94  95   6.9(0.05)  13.6(0.02)  8.1(0.09)  5.0(0.05)

 May 94   May 94  Jun-Aug 94  78  12.3(1.04)  13.0(0.34) 11.0(0.39)  4.8(0.13)
 May 94   Jul 94  Jun-Aug 94  78  10.3(1.04)  13.1(0.34)  9.8(0.39)  4.8(0.13)
 May 94   Liebe87 Jun-Aug 94  78   7.8(0.22)  13.3(0.07)  8.6(0.29)  4.9(0.10)

 Jun 94   May 94  Jul-Dec 94  57   8.3(0.37)  13.6(0.21)  8.8(0.19)  5.2(0.11)
 Jun 94   Jul 94  Jul-Dec 94  57   6.4(0.37)  13.6(0.21)  7.7(0.18)  5.2(0.10)
 Jun 94   Liebe87 Jul-Dec 94  57   6.9(0.08)  13.5(0.04)  8.3(0.10)  4.9(0.06)

 Aug 94   May 94  Sep-Dec 94  90   7.4(0.15)  13.5(0.09)  8.8(0.11)  5.1(0.07)
 Aug 94   Jul 94  Sep-Dec 94  90   5.5(0.14)  13.6(0.09)  7.8(0.12)  5.0(0.07)
 Aug 94   Liebe87 Sep-Dec 94  90   6.8(0.05)  13.6(0.03)  8.6(0.09)  4.9(0.06)

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)

Loss of thermal stabilization

DQR No:                               Platform: sgpmwrlos, sgp5mwravg, 
                                                sgpqmemwrlos

Subject: Loss of thermal stabilization

Date Submitted:
Submitted By:    JIM LILJEGREN        _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:
      What level data: a0,a1,c1

    What location was the data collected at: SGP B1 (Hillsboro, KS)
                                             SGP B4 (Vici, OK)
                                             SGP B5 (Morris, OK)
                                             SGP B6 (Purcell, OK)
                                             SGP C1 (Lamont, OK) 

    Period of time in question  (see table below)

 Data should be labeled:
 ___  questionable                      ___  All data fields affected
 _X_  incorrect                         _X_  Only some data fields affected:
 ___  wrong calibration
 ___  others                                 "23tbsky","31tbsky","vap","liq"
 
 Discussion of Problem:

I pointed out in a previous DQR (P960405.1) that during August of 1994
and 1995 the microwave radiometers would lose thermal stabilization on
very hot, sunny days when the temperature in the radiometer enclosure
rose above the set point for thermal stabilization (~50 deg C).  Although
I had planned to travel to the SGP prior to August 1996 to adjust the
set points upward to prevent this problem from occuring this year, the
temperatures in July 1996 were hotter than in previous years and the
loss of stabilization problem occurred before I could make the needed
adjustment.

The purpose of this note is the identify the time periods for which
this problem occurred.  More specific information about the problem,
including how the problem is detected and its effect on the reported
values of integrated water vapor and integrated cloud liquid water are
provided in the earlier DQR.

It is useful to repeat here that when the thermal stabilization is
lost, the reported precipitable water vapor increases and the liquid
water path decreases (and becomes SIGNIFICANTLY NEGATIVE (-0.1 mm) on
clear sky days).  The RMS noise level in the data also increases
sharply.  THESE ANOMALOUS VALUES HAVE BEEN INCLUDED IN THE 5-MINUTE
AVERAGES.

LOCATION                BEGINNING DATE AND TIME    ENDING DATE AND TIME

C1 (Central Facility)  
                         1 July 96  18:25 GMT      2 July 96  02:00 GMT
                         2          16:45          3          02:30
                         3          17:40          4          02:15
                         4          15:50          4          17:10
                         5          17:00          6          03:30
                         6          16:00          7          03:00
                         7          20:20          8          01:30
                        18          20:00         18          23:45
                        19          18:30         20          01:20
                        20          19:45         21          02:25
                        21          17:00         22          02:20
                        22          19:30         23          23:00

B1 (Hillsboro, KS)
                         1 July 96  20:30          2 July 96  01:15
                         2          17:00          3          02:00
                        17          20:30         18          00:15
                        18          19:25         19          02:00
                        19          19:00         20          02:30
                        20          18:35         21          00:30
                        21          20:20         22          01:40
                        28          20:55         28          00:15

B4 (Vici, OK)            2 July 96  19:25          2 July 96  23:15
                         3          19:35          3          21:15
                         4          20:40          5          00:30
                         5          19:15          6          02:00
                         6          19:00          6          22:40
                         7          20:45          8          00:30
                        21          19:45         22          02:00

B5 (Morris, OK)
                         1 July 96  18:35          2 July 96  00:45
                         2          17:20          3          01:15
                         3          17:25          4          02:00
                         5          20:20          6          01:45
                         6          16:45          7          02:30
                         7          18:10          8          01:00
                        19          20:00         20          00:20
                        20          19:30         21          00:55
                        21          18:15         22          01:30
                        22          19:30         23          01:15
                        23          22:00         24          00:15

B6 (Purcell, OK)

                         1 July 96  20:15          2 July 96  00:10
                         2          18:40          3          00:05
                         3          20:40          4          00:35
                         4          20:15          5          00:10
                         5          19:45          6          01:15
                         6          19:10          7          01:40
                        19          21:30         19          23:00
                        20          20:15         21          00:05
                        21          21:45         22          01:00
                        22          21:45         23          00:00

Other observations/measurements impacted by this problem:

none

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

Flag with this comment.

• actaz
• time_offset
• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• wet_window
• lon
• 31tbsky
• 23tbsky
• base_time
• lat
• actel
• alt
• Temperature, brightness, longwave(ir_temp)

SGP/MWR/B1/B4/B5/B6/C1 - Thermal Stabilization Adjustment

In order to correct a thermal stabilization problem identified earlier
I adjusted the thermal set point of the microwave radiometers at the
SGP upward from 48-50 deg C to 55 deg C in early August 1996 according
to the schedule given below.

B6    5 August 1996
C1    6 August 1996
B1    7 August 1996
B5    8 August 1996

Subsequent to making this adjustment the MWRs were put in TIP mode to
check on whether the change in set point temperature affected their
calibration.  Because clear sky conditions were quite intermittent, it
is difficult to determine whether the substantial variability in the
tip data were attributable to the change in thermal set point.  The
instrument calibration was not altered in August.

Tip data were again collected with these instruments in September prior
to the beginning and at the close of the Water Vapor IOP.  For example,
the calibration of the instrument at the central facility (S/N 10)
derived from the September data was essentially the same as that
derived from calibration data acquired in February 1996.  Although this
would lead one to believe that altering the thermal set point did not
affect the instrument calibration, it may be that some transient effect
was induced.

In comparing soundings launched from the central facility with the
microwave radiometer there, I noticed that those sondes calibrated in
June 1996 consistently reported lower integrated water vapor than the
radiometer in July and September (during the IOP) but were in better
agreement with the radiometer for the two weeks period immediately
after the set point was adjusted.  I suspect that adjusting the thermal
set point may have temporarily increased the radiometer gain
(kelvins/volt) thereby lowering the measured brightness temperature and
the retrieved integrated water vapor.

It is not clear why a temporary change in gain should occur or even
whether it did.  But users of the data should be aware that the data
from the microwave radiometers at the SGP may be anomalous during
August 1996.

• 23tbsky
• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)
• 31tbsky

• 23tbsky
• Total water vapor along LOS path(vap)
• 31tbsky
• Total liquid water along LOS path(liq)

• 31tbsky
• Total water vapor along LOS path(vap)
• 23tbsky
• Total liquid water along LOS path(liq)

• 31.4 GHz sky brightness temperature(tbsky31)
• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)

• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)
• 31.4 GHz sky brightness temperature(tbsky31)

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)
• 23tbsky
• 31tbsky

• Total water vapor along LOS path(vap)
• 31tbsky
• 23tbsky
• Total liquid water along LOS path(liq)

• 31tbsky
• Total liquid water along LOS path(liq)
• 23tbsky
• Total water vapor along LOS path(vap)

• 23tbsky
• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• 31tbsky

• 23tbsky
• Total water vapor along LOS path(vap)
• 31tbsky
• Total liquid water along LOS path(liq)

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• 31tbsky
• 23tbsky

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• 31tbsky
• 23tbsky

• Total liquid water along LOS path(liq)
• 31tbsky
• Total water vapor along LOS path(vap)
• 23tbsky

• 31tbsky
• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)
• 23tbsky

• Total water vapor along LOS path(vap)
• 23tbsky
• Total liquid water along LOS path(liq)
• 31tbsky

• 23tbsky
• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)
• 31tbsky

Manually corrected error in header files

On 10/27/97 at 20:00 UTC, an error was made while remotely editing the
MWR configuration file.
This produced an error in the data file header which made the normal
processing programs fail. The problem was identified on 11/10/97.
The configuration file at BF1 was corrected on 11/11/97 at 19:40.
MWR.BBF5 wasremoved from service on
11/5/97 17:54. The configuration file at BF5 was corrected prior to 
reinstalling the MWR on 1/9/98.

The file headers of these data were reconstructed and the
data were delivered to the Archive on 11/26/97 for MWR.BF1
and on 12/3/97 for MWR.BF5.

This DQR is being filed to note that the headers were manually
recreated. The data should be unaffected.

This DQR is based on information obtained from Victor Morris
and Robin Perez.

• actaz
• alt
• time_offset
• base_time
• Total liquid water along LOS path(liq)
• lat
• actel
• Temperature, brightness, longwave(ir_temp)
• wet_window
• 23tbsky
• lon
• Total water vapor along LOS path(vap)
• 31tbsky

• losn
• Temperature, brightness, longwave(ir_temp)
• 23unoise
• 23bb
• 31bb
• base_time
• 31sky
• 23sky
• lat
• 23tbsky
• actel
• time_offset
• wet_window
• alt
• Total liquid water along LOS path(liq)
• 23skyn
• 31bbn
• tkbb
• lon
• actaz
• 23bbn
• tkxc
• 31unoise
• Total water vapor along LOS path(vap)
• 31tbsky
• 31skyn

• time_offset
• lat
• 31tipbb
• lon
• 23tipsky
• actaz
• tkxc
• tipn
• airm
• 23expave
• 23tbzenith
• 23r
• base_time
• 31tipskynd
• alt
• 23gain
• 31tbzenith
• Temperature, brightness, longwave(ir_temp)
• wet_window
• 31ndiode
• 23ndiode
• 31bb
• tkbb1
• tkbb2
• 31gain
• 31tipsky
• 31bbn
• 31r
• 23tipbb
• 31expave
• actel
• 23bb
• 23bbn
• 23tipskynd

• 31tbsky
• alt
• Temperature, brightness, longwave(ir_temp)
• losn
• 23sky
• actaz
• 23unoise
• base_time
• Total water vapor along LOS path(vap)
• time_offset
• 31skyn
• tkxc
• 23bb
• 31sky
• lon
• Total liquid water along LOS path(liq)
• 31unoise
• 23bbn
• tkbb
• actel
• 31bbn
• wet_window
• 23tbsky
• 23skyn
• lat
• 31bb

• wet_window
• Total water vapor along LOS path(vap)
• Temperature, brightness, longwave(ir_temp)
• actaz
• lat
• 23tbsky
• Total liquid water along LOS path(liq)
• alt
• 31tbsky
• lon
• time_offset
• actel
• base_time

SGP/MWR/B1/B4/B6/C1 - software change

The MWR operating software was changed on 12 October 1998 to provide additional 
functionality as described below. This change affects the format of the raw and ingested data. 
   
NEW FEATURES
1. Faster sampling rate
   
Standard line-of-sight (LOS) observations can now be acquired at 15-second intervals vs. 
20-second intervals previously. (The standard LOS cycle is comprised of one sky sample per 
blackbody sample and gain update.)
   
2. More flexible sampling strategy
   
Multiple sky observations can be acquired during a LOS cycle, up to 1024 per gain update. 
This permits sky samples to be acquired at intervals of 2.67 seconds for improved 
temporal resolution of cloud liquid water variations and better coordination with the millimeter 
cloud radar during IOPs.
   
3. Separation of zenith LOS observations from TIP data
   
When the radiometer is in TIP mode, the zenith LOS observations are now extracted, the PWV 
and LWP computed and reported separately in the output file. This eliminates the periods 
of missing LOS data during calibration checks/updates.
   
4. Automatic self-calibration
   
The software now permits the calibration to be updated at specified intervals or 
continuously. In the first case, LOS mode is automatically changed to TIP mode at user-specified 
intervals or whenever clear sky conditions occur, the tip data reduced, the calibration 
updated ,and the radiometer returned to LOS mode without operator intervention. In the 
second case, the radiometer is continuously is TIP mode until changed by the operator.
   
5. Graphical user display
   
The graphical display is comprised of a status display, a message display, a temperature 
plot, a plot of the retrieved PWV and LWP, and (in TIP mode) a plot of the latest tip 
curves.

Editor's Note: The SGP.C1 data were reprocessed in 2004 and enhancement #3 described above 
was applied to the data prior to Oct 1998.  The SGP.BF data are queued for reprocessing 
as well.

• tkair
• tnd23
• tknd
• tnd31

• tnd23
• tnd31
• tknd
• tkair

• tnd23I
• tnd31I

• tknd
• tkair
• tnd31
• tnd23

• tnd31
• tknd
• tnd23
• tkair

• tnd31
• tkair
• tknd
• tnd23

• tnd23I
• tnd31I

• tnd23I
• tnd31I

• tknd
• tnd31
• tnd23
• tkair

• tkair
• tnd23
• tnd31
• tknd

• tnd31
• tkair
• tnd23
• tknd

SGP/MWR/B1 out of calibration

A shift in the calibration of MWR/B1 occurred on 10 March 1998, 
apparently due to a power failure (see P980513.1). The calibration
was corrected on 19 May.

• actaz
• Total liquid water along LOS path(liq)
• lon
• lat
• alt
• actel
• Temperature, brightness, longwave(ir_temp)
• time_offset
• Total water vapor along LOS path(vap)
• wet_window
• 31tbsky
• 23tbsky
• base_time

• lon
• losn
• actaz
• Temperature, brightness, longwave(ir_temp)
• 23sky
• 23bbn
• lat
• 23tbsky
• actel
• tkxc
• 23unoise
• time_offset
• 31unoise
• 23skyn
• wet_window
• 23bb
• alt
• Total water vapor along LOS path(vap)
• 31tbsky
• 31bb
• base_time
• 31bbn
• 31sky
• Total liquid water along LOS path(liq)
• 31skyn
• tkbb

SGP/MWR/B1/B4/B5/B6/C1 - software upgrade (version 3.27)

At 00:00 GMT on 7 January version 3.27 of the MWR operating program was installed and made 
operational at the SGP central facility (C1).  No problems were noted over the next few 
days and the boundary facility MWRs (B1, B4, B5, B6) were upgraded at 20:00 GMT on 11 
January.  This version includes a beam width correction I developed as well as providing the 
capability to automatically level the elevation mirror (that is, to automatically detect 
and correct offsets in the elevation angle stepper motor position.)

On 12 January I discovered that the '486-based MWR computers at B1, B4 and B6 were not 
executing the system command to move and rename the data files so that the ARM data system 
could retrieve them.  Reducing the length of the storage arrays in the auto-leveling 
feature from 1000 to 250 resolved the problem.  This results in the auto-leveling being based 
on only 4 hours of clear sky data rather than 16 hours at B5 and C1.  This version of the 
program is 3.28. Version 3.27 (running at B5 and C1) can be installed if and when these 
computers are upgraded to Pentium-class machines.

The improvement in the quality of the tip curves resulting from the auto-leveling has been 
dramatic: differences in the brightness temperatures at 3 airmasses (19.5 and 160.5 
degrees) have been reduced from +/- 5 K to +/- 0.5 K.  The goodness-of-fit coefficient for 
the tip curves has improved from about 0.995 to over 0.998.  In order to take full 
advantage of this improvement to detect and reject cloudy tip curves, the minimum value of the 
goodness-of-fit coefficient for a valid tip curve has been increased from 0.995 to 0.998.

Editor's Note: The SGP.C1 data were reprocessed in 2004 to produce a common DOD for all 
time.  The 1996-1998 data reprocessing included beam width and mirror-leveling corrections, 
but the data prior to that range did not have these corrections applied.

• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)
• 31tbsky
• 23tbsky

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• 31tbsky
• 23tbsky

• 23tipsky
• 31tipsky

• 23tipsky
• 31tipsky

• Total water vapor along LOS path(vap)
• Total liquid water along LOS path(liq)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• 31.4 GHz sky brightness temperature(tbsky31)

• 31tipsky
• 23tipsky

• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Total liquid water along LOS path(liq)
• Total water vapor along LOS path(vap)
• 31.4 GHz sky brightness temperature(tbsky31)

• 31tipsky
• 23tipsky

• Total water vapor along LOS path(vap)
• 23tbsky
• 31tbsky
• Total liquid water along LOS path(liq)

• Total water vapor along LOS path(vap)
• 23tbsky
• Total liquid water along LOS path(liq)
• 31tbsky

SGP/MWR/B1/B4/B6 - Reprocess: Data Ingest Problem

The first version of the new ingest produced incorrect values of variables tbsky23 and 
ir_temp and global attribute elevation_angle. 
In evaluating this file, I found that tbsky23 is actually tnd31, ir_temp is 
noise_injection_temp_31, and elevation is '1079410688 deg' instead of 90. All other variables and 
global attributes are ok. 

Note, the SGP.C1 data were also originally affected by this problem, but they were 
subsequently reprocessed.  This DQR will be removed when the SGP.BF data have also been 
reprocessed.

• Temperature, brightness, longwave(ir_temp)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)

• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Temperature, brightness, longwave(ir_temp)

• Temperature, brightness, longwave(ir_temp)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)

• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Temperature, brightness, longwave(ir_temp)

• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)
• Temperature, brightness, longwave(ir_temp)

• Temperature, brightness, longwave(ir_temp)
• Radiation, longwave, brightness temperature, 23.8 GHz(tbsky23)

SGP/MWR/B1/B4/B5/B6 - data file split at 23:59

A problem with the MWR operating software has been corrected.  However, several files were 
generated that contain one record of data collected at midnight but labeled with the 
previous day's date.

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

• tnd31I
• tnd31
• tnd23
• actaz
• tkair
• tknd
• tnd_nom31
• bb23
• bb31
• tnd_nom23
• tc31
• tipsky23
• actel
• tkbb
• time_offset
• r31
• tc23
• r23
• tipsky31
• bbn31
• bbn23
• base_time
• tkxc
• tnd23I
• wet_window

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

• tknd
• tnd23
• bb31
• tnd31
• bb23
• tnd_nom31
• tc23
• wet_window
• actaz
• actel
• tc31
• base_time
• tipsky23
• r31
• tnd31I
• tkxc
• tipsky31
• bbn31
• tnd_nom23
• time_offset
• bbn23
• r23
• tkbb
• tkair
• tnd23I

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

• tknd
• r23
• r31
• base_time
• tnd_nom23
• tnd_nom31
• actel
• tkxc
• bbn23
• bbn31
• actaz
• time_offset
• tnd31I
• bb31
• tc23
• tkair
• tkbb
• bb23
• tipsky31
• tnd23I
• tipsky23
• tnd31
• wet_window
• tnd23
• tc31

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

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

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

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

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

• actel
• tc31
• tipsky31
• tnd_nom23
• tc23
• tipsky23
• actaz
• tkbb
• r31
• tkxc
• bb31
• tnd31I
• bb23
• wet_window
• tnd_nom31
• time_offset
• tnd31
• r23
• tnd23I
• base_time
• tnd23
• tkair
• bbn23
• bbn31
• tknd