SGP/QCRAD/E2 - Tracker inoperative

Solar tracker inoperative. Described in instrument DQR D970310.1.

From about 97/02/20 to 97/03/06 (1500 GMT) the solar tracker was inoperative
at site E2.  We cannot pin down the exact starting time of this failure
because of cloudy conditions around 97/02/20.  The failure becomes obvious
during clear skis at which time the NIP reads zero (i.e., it isn't pointed
at the sun) and the downward diffuse radiation is too large (because the
diffuse pyranometer is not being shaded).  97/03/03 was a particularly 
clear day and the diffuse pyranometer reads almost the same as the total
downward pyranometer.  The fact that they don't read exactly the same - the
discrepency is about 75 W/m^2 at solar noon - is indicative of a large sensor
calibration problem.  This large calibration error is NOT typical of ARM 
data, rather it is peculiar to this site.

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• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)

• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)

• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)

• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)