solar tracker inoperative

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.

the solar tracker was fixed  on 97/03/06 at about 1500 GMT - case dismissed!

the calibration problem with either the diffuse pyranometer and/or the
total downward pyranometer has not been resolved as of 97/03/10

• lon(lon)
• Ventilated Pyrgeometer Dome Temperature(down_long_dome_temp)
• Downwelling Longwave Diffuse Hemispheric Irradiance, Ventilated Pyrgeometer(down_long_diffuse_hemisp)
• Data Logger Temperature(logger_temp)
• Diffuse Hemispheric Irradiance, MFRSR(diffuse_hemisp_narrowband)
• Thermistor Excitation Voltage, Data Logger(therm_volt)
• Down-welling unshaded pyranometer voltage(down_short_hemisp)
• Ventilated Pyrgeometer Case Temperature(down_long_case_temp)
• Direct Normal Irradiance, MFRSR(direct_norm_broadband)
• 25 meter Longwave Case Temperature, Pyrgeometer(up_long_case_temp)
• 10 meter Longwave Dome Temperature, Pyrgeometer(up_long_dome_temp)
• Flag fields with *2 returned from callang(flag_ln_error1-24)
• Data logger supply voltage(logger_volt)
• base time in epoch(base_time)
• Direct Normal Irradiance, NIMFR(direct_norm_narrowband)
• Flag fields with *4 returned from callang(flag_nighttime1-24)
• Time offset from base_time(time_offset)
• MFRSR channels(channel)
• -180.0 - +180.0(alt)
• Flag fields with *3 returned from callang(flag_zero_cosine1-24)
• North Latitude(lat)
• Shortwave direct normal irradiance, pyrheliometer(short_direct_normal)
• Flag fields with *1 returned from callang(flag_zero_divisor1-24)
• Hemispheric broadband irradiance(hemisp_broadband)
• Downwelling Shortwave Diffuse Hemispheric Irradiance, Ventilated Pyranometer(down_short_diffuse_hemisp)
• 25 meter Upwelling Shortwave Hemispheric Irradiance, Pyranometer(up_short_hemisp)
• Diffuse Hemispheric Broadband Irradiance, offset corrected(diffuse_hemisp_broadband)
• 10 meter Upwelling Longwave Hemispheric Irradiance, Pyrgeometer(up_long_hemisp)
• MFRSR Detector Temperature(mfrsr_temp)
• Hemispheric Irradiance, MFRSR(hemisp_narrowband)