PYE/SKYRAD/M1 - Reprocessed: IRT configuration and calibration

The configuration of the IRT was inadvertently set to default and the program of the data 
loggers were changed to that used at TWP.C3.  This caused the calibration of the data to 
be wrong. It was corrected by reconfiguring the IRT and changing the conversion factors 
in the data logger program.

These data have been reprocessed to apply correct calibrations and the reprocessed data 
were archived in February, 2007.

• Sky Infra Red Temperature Minima(sky_ir_temp_min)
• Sky Infra Red Temperature Maxima(sky_ir_temp_max)
• Standard Deviation of Sky Infra Red Temperature(sky_ir_temp_std)
• Sky Infra-Red Temperature(sky_ir_temp)

• null(Raw data stream - documentation not supported)

• Instantaneous Sky/Cloud Infrared(inst_sky_ir_signal)

PYE/MWR/M1 - tipping angles

Obstacles above the horizon were in the field of view of the MWR at the lowest tipping 
elevation angle of 19.5 degrees. The AOS stack to the north and trees to the south affected 
the tip scan measurements at 3 airmasses. This problem was corrected by removing 
observations at the lowest angle from the MWR tip configuration.

• 23.8 GHz sky brightness temperature derived from tip curve(tbsky23tip)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• Temperature correction coefficient at 23.8 GHz(tc23)

PYE/MWR/M1 - Reprocessed: 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 water 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).

At Point Reyes, the original coefficients implemented in March 2005 were based on a 
version of the Rosenkranz model that had been modified to use the HITRAN half-width at 22 GHz 
and to be consistent with the water vapor continuum in MONORTM.  These retrievals yielded 
nearly identical results to the MONORTM retrievals.

The MONORTM-based retrieval coefficients became active at PYE.M1 20050506.

Note: The PYE.M1 MWRLOS data for 20050201-20050506 have been reprocessed
to apply the MONORTM-based retrievals for all time. The reprocessed data
were archived in April 2007.  The TIP data have not been reprocessed.

• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)

• Averaged total liquid water along LOS path(liq)
• MWR column precipitable water vapor(vap)

PYE/MWR/M1 - Reprocessed: Calibration corrected

On May 28 1:30 GMT the NFOV radiometer was placed in the field of view of the MWR tip 
calibration. Almost immediately calibration of the MWR was compromised resulting in incorrect 
brightness temperatures and overestimation of both PWV and LWP. 

On July 15 the NFOV radiometer was moved away from the MWR and the instantaneous 
calibration values jumped back to normal. The median values returned to normal on July 17 around 
2100.

The LOS data were reprocessed using interpolated values for the calibration coefficients.  
The reprocessed data are available from the ARM Archive effective December 7, 2005.  
NOTE: the format of the reprocessed data are slightly different than the format of the 
original data and the data available before and after the reprocessed data period.  The 
quality of the data are not affected, just the format.

The MWRTIP data can not be reprocessed and should be used with caution.

• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• 31.4 GHz sky signal(tipsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• 23.8 GHz goodness-of-fit coefficient(r23)
• 23.8 GHz sky signal(tipsky23)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz goodness-of-fit coefficient(r31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Temperature correction coefficient at 23.8 GHz(tc23)

• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Averaged total liquid water along LOS path(liq)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• 31.4 GHz sky signal(sky31)
• 23.8 GHz sky signal(sky23)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• MWR column precipitable water vapor(vap)

PYE/NFOV/M1 - Intermittent missing data

During the Pt Reyes deployment of the NFOV, the instrument experienced intermittent data 
gaps due to communications problems.  Data gaps occurred for the following date ranges:
20050718-20050723
20050727-20050730
20050803-20050804
20050813-20050816
20050820-20050822
20050826-20050827
20050830-20050902
20050908-20050910

• null(Raw data stream - documentation not supported)

• Calibrated Zenith Radiance, 870 nm(radiance_870nm)
• Tube Temperature(tube_temp)
• Raw counts from instrument before calibration, 673 nm(raw_counts_673nm)
• time(time)
• Cosine of Solar Zenith Angle(cosine_solar_zenith_angle)
• Raw counts from instrument before calibration, 870 nm(raw_counts_870nm)
• base time(base_time)
• Calibrated Zenith Radiance, 673 nm(radiance_673nm)
• Detector Temperature(head_temp)
• Time offset of tweaks from base_time(time_offset)

PYE/NFOV/M1 - Intermittent data gaps

Intermittent data collection of the NFOV.  Data collection not successful regularly during 
day light hours but generally caught up during the nighttime hours.  Occasionally the 
system stopped collecting altogether and a reboot of the network components was required to 
restart collection. Data gaps are largest 18 through 23 of July and 27 through 30 July.

• null(Raw data stream - documentation not supported)

• Tube Temperature(tube_temp)
• Calibrated Zenith Radiance, 870 nm(radiance_870nm)
• Dummy altitude for Zeb(alt)
• lat(lat)
• Cosine of Solar Zenith Angle(cosine_solar_zenith_angle)
• base time(base_time)
• lon(lon)
• Time offset of tweaks from base_time(time_offset)
• Raw counts from instrument before calibration, 673 nm(raw_counts_673nm)
• time(time)
• Raw counts from instrument before calibration, 870 nm(raw_counts_870nm)
• Calibrated Zenith Radiance, 673 nm(radiance_673nm)
• Detector Temperature(head_temp)

PYE/MWR/M1 - New software version (4.15) installed

A problem began with the installation of MWR.EXE version 4.12 in July 2002. The software 
had been upgraded from a "DOS" to a "Windows"-compiled program to address an earlier 
problem.  The software upgrade corrected the earlier problem but introduced a new one that 
caused line-of-sight observing cycles to be skipped, a 15% reduction in the number of tip 
curves, and saturation of CPU usage. Software versions 4.13 and 4.14 also produced these 
problems.

The new MWR software, version 4.15, was installed on 9/13/2005. As a consequence of this 
upgrade, the tip curve frequency increased. The tip cycle time decreased from ~60s to ~50s.

• 23.8 GHz sky brightness temperature derived from tip curve(tbsky23tip)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• 31.4 GHz sky signal(tipsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Blackbody kinetic temperature(tkbb)
• Ambient temperature(tkair)
• (tknd)
• 31.4 GHz blackbody(bb31)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• 23.8 GHz Blackbody signal(bb23)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• 31.4 GHz sky brightness temperature derived from tip curve(tbsky31tip)
• 23.8 GHz sky signal(tipsky23)
• 23.8 GHz goodness-of-fit coefficient(r23)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Mixer kinetic (physical) temperature(tkxc)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz goodness-of-fit coefficient(r31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 31.4 GHz blac2body+noise injection signal(bbn31)

• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• 31.4 GHz blac2body+noise injection signal(bbn31)
• Temperature correction coefficient at 23.8 GHz(tc23)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Averaged total liquid water along LOS path(liq)
• Mixer kinetic (physical) temperature(tkxc)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• 31.4 GHz blackbody(bb31)
• Sky brightness temperature at 23.8 GHz(tbsky23)
• 31.4 GHz sky signal(sky31)
• 23.8 GHz sky signal(sky23)
• Ambient temperature(tkair)
• 23.8 GHz Blackbody signal(bb23)
• 23.8 GHz blackbody+noise injection signal(bbn23)
• (tknd)
• Sky brightness temperature at 31.4 GHz(tbsky31)
• Temperature correction coefficient at 31.4 GHz(tc31)
• Sky Infra-Red Temperature(sky_ir_temp)
• Blackbody kinetic temperature(tkbb)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• MWR column precipitable water vapor(vap)