NSA/SKYRAD/C1 - direct normal pyhrheliometer (NIP)shaded by WWRp

Direct normal radiation values drop nearly to zero from about 1515 GMT - 1525 GMT from 
4/05 to 4/16 2004.  Field observation reveals the WWRp is shading the NIP instrument during 
this time.  This shading event was expected to occur several months after the soltice as 
well but archive data showed no shading on or around 8/30/2004.  The direct normal 
instrument was apparently only shaded during the time period noted.

• Raw data stream - documentation not supported

• Radiation, shortwave, direct normal irradiance, 1-min avg(short_direct_normal)
• short_direct_normal_std
• Shortwave Direct Normal Irradiance, Pyrheliometer, Minima(short_direct_normal_min)
• Shortwave Direct Normal Irradiance, Pyrheliometer, Maxima(short_direct_normal_max)

NSA/SKYRAD/C1 - itermittant IRT bias

A problem with the SKYRAD IRT that itermittantly produced a gradual increase in the sky 
temperature measurement then a sudden correction, as compared to AERI, appears to have been 
caused by a combination of a failing IR detector, a poor signal cable, a contaminated 
(with condensation or frost) mirror or lens, and low ambient temperatures. The positive 
bias was apparently not consistant in either frequency or duration but on days when the 
unusual behavior is observed, it usually occurred from about 00:00 to 06:00 local time. 

The instrument was repaired and recalibrated and the signal cable replaced.

• sky_ir_temp_min
• sky_ir_temp_std
• sky_ir_temp_max
• Temperature, Sky Infra-Red(sky_ir_temp)

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 - 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)