NSA/METTWR/C1 - CMH Sensor Calibrated Incorrectly

The CMH temp and DP were higher than the co-located T/RH probe at the 2m level.  An 
incorrect calibration along with a failing thermistor caused the readings to be incorrect for 
both measured values Temp and Dew Point.

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

NSA/METTWR/C1 - 40m wind sensor heater failure

The 40m wind direction became frozen at times.  The values from the sensor were flat-lined 
(stdev = 0) much of the time and did not match sensors from other levels.

• 40m Vector Averaged Wind Direction(WD40M_DU_WVT)
• Standard Deviation of 40m Vector Averaged Wind Direction(WD40M_SDU_WVT)

NSA/METTWR/C1 - 40m Wind Direction Data Suspect

The 40m wind direction data was suspect due to icing on the vane or a failing shafter 
heater or a combination of both.  The affected data can be easily seen on comparison plots 
with other levels data or by checking the standard deviation of the 40m wind direction.  
Any standard deviation of less than 0.10 degrees for the 40m level suggest a sluggish/ice 
affected sensor.

• 40m Vector Averaged Wind Direction(WD40M_DU_WVT)
• Standard Deviation of 40m Vector Averaged Wind Direction(WD40M_SDU_WVT)

NSA/METTWR/C1 - PWS Data Questionable

There was a degradation in the PWS lenses.  New lenses were installed on 08/28/2007 but a 
proper calibration was not conducted until 10/10/2007.  Data  during the listed time 
period should be used with caution.

• 15 minute Present Weather Code(PwCod15mi)
• 1 minute Average Visibility(AvgVis1mi)
• Instant Present Weather Code(InstPwCod)
• 1 hour Present Weather Code(PwCod1hr)
• Cumulative Snow Sum(CumSnow)
• 10 minute Average Visibility(AvgVis10m)
• Precipitation Rate(PcpRate)
• Cumulative Water Sum(CumH2O)
• Present Weather Sensor Alarm(PWSAlarm)

NSA/METTWR/C1 - 20m RH Data Questionable

The 20m RH data was questionable at times.  When the data appeared to be poor was when the 
2m and 20m agreed better than the 20m and the 40m and/or 10m.

• Standard Deviation of 20m Calculated Dew Point(DP20M_STD)
• Standard Deviation of 20m Calculated Vapor Pressure(VP20M_STD)
• Standard Deviation of 20m Relative Humidity(RH20M_STD)
• 20m Average Relative Humidity(RH20M_AVG)
• 20m Average Calculated Vapor Pressure(VP20M_AVG)
• 20m Average Calculated Dew Point(DP20M_AVG)