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)