NSA/METTWR/C1 - Chilled Mirror transmit logic board chipset unsuited for Arctic 
temperatures

Data missing due to problems with manufacturer's transmit logic board chipset.  They were 
generic chips not rated for Arctic temperatures.

• SatVPCMH
• CMHDP
• CMHTemp
• CMHRH

NSA/METTWR/C1 - All 10m level Data Missing

After prolonged power outage and many power spikes during the outage all data from the 10m 
level are missing.  Blown fuse on the power supply was replaced once the temperatures 
warmed enough to allow the lowering of the tower carriages.

• Pressure, vapor, at 10-m height(VP10M_AVG)
• RH10M_STD
• T10M_STD
• Wind speed, mean, at 10-m height(WS10M_S_WVT)
• Wind direction, vector-averaged, at 10-m height(WD10M_DU_WVT)
• VP10M_STD
• DP10M_STD
• WD10M_SDU_WVT
• Temperature, dew point, average, at 10-m height(DP10M_AVG)
• Wind speed, vector-averaged, at 10-m height(WS10M_U_WVT)
• RefT10m_AVG
• Relative humidity, average, at 10-m height(RH10M_AVG)
• Temperature, air, average, at 10-m height(T10M_AVG)
• Volt10M_AVG

NSA/METTWR/C1 - 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.

• PcpRate
• CumH2O

NSA/METTWR/C1 - Data 1-minute behind

Data from the Barometer, Chilled Mirror Hygrometer and the Present Weather Sensor were 
one-minute behind due to timing problems collecting data from the Serial Data Multiplexer 
that handled these sensors.

• VPCMH
• PcpRate
• SatVPCMH
• CMHDP
• CumH2O
• CMHTemp
• PwCod1hr
• InstPwCod
• CumSnow
• PWSAlarm
• Visibility, 10 minute average(AvgVis10m)
• Pressure, atmospheric(AtmPress)
• Visibility, 1 minute average(AvgVis1mi)
• PwCod15mi
• CMHRH

NSA/METTWR/C1 - Reprocess: Wind direction data incorrect

Wind direction data is off by 30 degrees for all wind sensors.  The 40-m tower was 
misaligned to true north.

• Wind direction, vector-averaged, at 40-m height(WD40M_DU_WVT)
• Wind direction, vector-averaged, at 20-m height(WD20M_DU_WVT)
• Wind direction, vector-averaged, at 10-m height(WD10M_DU_WVT)
• SonicWD_DU_WVT
• Wind direction, vector-averaged, at 2-m height(WD2M_DU_WVT)

NSA/METTWR/C1 - 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.

• Pressure, atmospheric(AtmPress)

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.

• VPCMH
• CMHDP
• CMHTemp
• CMHRH

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.

• Wind direction, vector-averaged, at 40-m height(WD40M_DU_WVT)
• WD40M_SDU_WVT

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.

• DP20M_STD
• Temperature, dew point, average, at 20-m height(DP20M_AVG)
• Pressure, vapor, at 20-m height(VP20M_AVG)
• RH20M_STD
• Relative humidity, average, at 20-m height(RH20M_AVG)
• VP20M_STD

NSA/METTWR/C1 - 2m Wind Direction Sensor Freezing

The 2m wind direction was failing.  It began to exhibit instances of no movement 
suggesting it was frozen.  After some time it began to make erratic measurements compared to the 
co-located Ultrasonic and compared to the directions at the other levels.

• WD2M_SDU_WVT
• Wind direction, vector-averaged, at 2-m height(WD2M_DU_WVT)

NSA/METTWR/C1 - CMH Intake Fan Failure

The CMH intake fan failed causing the dew point and temp data to be incorrect.

If users need only T/RH and derived variables they can use the 2m data collected using the 
HMP-45D probes.  CMH data are unrecoverable.

• VPCMH
• SatVPCMH
• CMHDP
• CMHTemp
• CMHRH