NSA/GNDRAD/C2 - Upwelling PIR measurement - spikes in thermopile signal

ULH measurements have many spikes at this site.  On 2/03, the anomalous spikes become 
frequent and are very noticeable from 0027 - 0445 UTC.  Negative and positive spikes occur on 
seemingly random days until 5/27/2004.  Extensive troublshooting could not resolve 
problem, including a datalogger changout on 4/22.  Problem seems to have resolved itself with 
the last spikes occuring on 5/27/2004 approximately 1500GMT.  No problems with upwelling 
PIR noise are evident up until and after the conversion from Zeno to Campbell dataloggers 
on 11/22/2004.

review upwelling PIR (ULH) data before using.

• Upwelling Longwave Hemispheric Irradiance, Pyrgeometer, Minima(up_long_hemisp_min)
• 10 meter Upwelling Longwave Hemispheric Irradiance, Pyrgeometer(up_long_hemisp)
• PIR1 minimum(pir1_min)
• Upwelling longwave hemispheric irradiance, pyrgeometer, maxima(up_long_hemisp_max)
• Upwelling (10 meter) Longwave Hemispheric Irradiance, Ventilated Pyrgeometer,
  Standard Deviation(up_long_hemisp_std)
• PIR1 unshaded standard deviation(pir1_sd)
• PIR1 unshaded maximum(pir1_max)
• PIR1 mean(pir1_mean)

• Instantaneous PIR1 uncorrected irradiance(pir1_voltage)
• Instantaneous Upwelling Pyrgeometer Thermopile Pyrgeometer(inst_up_long_hemisp_tp)

• (Raw data stream - documentation not supported)