NSA/METTWR/C2 - Tower Lowered

The tower was lowered to install the GroundMFR.  Data from the T/RH probes and the wind 
speed and direction sensors are not representative during the time period.

• Vector Averaged Wind Speed(WinSpeed_U_WVT)
• 5m Average Calculated Dew Point(DP5m_AVG)
• Arithmetic Mean Wind Speed(WinSpeed_S_WVT)
• Standard Deviation of Vector Averaged Wind Direction(WinDir_SDU_WVT)
• Vector Averaged Wind Direction(WinDir_DU_WVT)
• Standard Deviation of 5m Calculated Vapor Pressure(VP5m_STD)
• 2m Average Temperature(T2m_AVG)
• 5m Average Temperature(T5m_AVG)
• 5m Average Relative Humidity(RH5m_AVG)
• Standard Deviation of 5m Calculated Dew Point(DP5m_STD)
• 5m Average Calculated Vapor Pressure(VP5m_AVG)
• Standard Deviation of 5m Relative Humidity(RH5m_STD)
• 2m Average Calculated Vapor Pressure(VP2m_AVG)
• 2m Average Relative Humidity(RH2m_AVG)
• Standard Deviation of 2m Relative Humidity(RH2m_STD)
• Standard Deviation of 2m Calculated Dew Point(DP2m_STD)
• Standard Deviation of 2m Calculated Vapor Pressure(VP2m_STD)
• Standard Deviation of 5m Temperature(T5m_STD)
• 2m Average Calculated Dew Point(DP2m_AVG)
• Standard Deviation of 2m Temperature(T2m_STD)

NSA/METTWR/C2 - Incorrect Maximum for Precip Values

The max values for cumulative rain sum of 99 mm and the rain rate of 999 mm/hr are 
incorrect.  In communication with the manufacturer it has been found that the manual was in 
error.  The actual max values of the cumulative rain sum is 99.99 mm and the rain rate is 
999.99 mm/hr.

• Precipitation Rate(PCPRate)
• Cumulative Water Sum(CumH2O)

NSA/METTWR/C2 - CMH Data Missing During Calibration

The CMH was removed for it's bi-annual cleaning and calibration.

• Chilled Mirror Temperature(CMHTemp)
• Chilled Mirror Calculated Saturation Vapor Pressure(SatVPCMH)
• Chilled Mirror Calculated Vapor Pressure(VPCMH)
• Chilled Mirror Calculated Relative Humidity(CMHRH)
• Chilled Mirror Dew Point(CMHDP)

NSA/MWR/C2 - 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 NSA.C2 
20020418.1700.  The MONORTM-based retrieval coefficients became active 
at NSA.C2 20050629.0000.

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.

• Mean total liquid water amount along LOS path(liq)
• Mean total water vapor amount along LOS path(vap)

• Mean total liquid water amount along LOS path(liq)
• Mean total water vapor amount along LOS path(vap)

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

NSA/METTWR/C2 - Tower Lowered, Data Not Representative

The tower was lowered to remove equipment.  The data from the wind sensors and T/RH probes 
were not representative.

• Vector Averaged Wind Speed(WinSpeed_U_WVT)
• 5m Average Calculated Dew Point(DP5m_AVG)
• Arithmetic Mean Wind Speed(WinSpeed_S_WVT)
• Standard Deviation of Vector Averaged Wind Direction(WinDir_SDU_WVT)
• Vector Averaged Wind Direction(WinDir_DU_WVT)
• Standard Deviation of 5m Calculated Vapor Pressure(VP5m_STD)
• 2m Average Temperature(T2m_AVG)
• 5m Average Temperature(T5m_AVG)
• 5m Average Relative Humidity(RH5m_AVG)
• Standard Deviation of 5m Calculated Dew Point(DP5m_STD)
• 5m Average Calculated Vapor Pressure(VP5m_AVG)
• Standard Deviation of 5m Relative Humidity(RH5m_STD)
• 2m Average Calculated Vapor Pressure(VP2m_AVG)
• 2m Average Relative Humidity(RH2m_AVG)
• Standard Deviation of 2m Relative Humidity(RH2m_STD)
• Standard Deviation of 2m Calculated Dew Point(DP2m_STD)
• Standard Deviation of 2m Calculated Vapor Pressure(VP2m_STD)
• Standard Deviation of 5m Temperature(T5m_STD)
• 2m Average Calculated Dew Point(DP2m_AVG)
• Standard Deviation of 2m Temperature(T2m_STD)

NSA/MWR/C2 - MWR thermally unstable

Between 08/12 and 08/17 the instrument displayed some intermittent thermal instability. 
Measurement accuracy may be degraded during these time periods.

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

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

• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)

NSA/MWR/C2 - New software version (4.15) installed

A problem began with the installation of MWR.EXE version 4.12 in September 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 9/15/2005. As a consequence of this 
upgrade, the tip curve frequency increased. The tip cycle time decreased from ~60s to ~50s.

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

• 23.8 GHz blackbody+noise injection signal(bbn23)
• 31.4 GHz sky signal(tipsky31)
• Noise injection temp at nominal temperature at 31.4 GHz(tnd_nom31)
• Noise injection temp at 31.4 GHz adjusted to tkbb(tnd31)
• Noise injection temp at 31.4 GHz derived from this tip(tnd31I)
• Noise injection temp at 23.8 GHz derived from this tip(tnd23I)
• 31.4 GHz goodness-of-fit coefficient(r31)
• 31.8 GHz sky brightness temperature derived from tip curve(tbskytip31)
• Ambient temperature(tkair)
• 23.8 GHz sky brightness temperature derived from tip curve(tbskytip23)
• Total water vapor along zenith path using tip-derived brightness temperatures(vaptip)
• 23.8 GHz sky signal(tipsky23)
• Mixer kinetic (physical) temperature(tkxc)
• 31.4 GHz blackbody+noise injection signal(bbn31)
• 31.4 GHz Blackbody signal(bb31)
• Noise diode mount temperature(tknd)
• Temperature correction coefficient at 23.8 GHz(tc23)
• 23.8 GHz goodness-of-fit coefficient(r23)
• Blackbody kinetic temperature(tkbb)
• Noise injection temp at nominal temperature at 23.8 GHz(tnd_nom23)
• Noise injection temp at 23.8 GHz adjusted to tkbb(tnd23)
• Total liquid water along zenith path using tip-derived brightness temperatures(liqtip)
• 23.8 GHz Blackbody signal(bb23)
• Temperature correction coefficient at 31.4 GHz(tc31)

NSA/METTWR/C2 - Reprocess: Barometric Data Changed from hPa to kPa

Barometric pressure data was converted from hPa to kPa in order to standardize the 
measurement units among ARM sites and to conform to accepted standard units determined by the 
scientific community.

• Atmospheric Pressure(AtmPress)