SGP/MFR10M/C1 - Head temperature problems

Head temperature control was not functioning during the specified period.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• Cosine of Solar Zenith Angle(cosine_solar_zenith_angle)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)

SGP/MFR10M/C1 - Artifact in data

A cable was hanging under the instrument and was in the field of view of the instrument. 
This resulted in some erroneous increases in the data, frequently around 22GMT. These 
increases are likely from specular reflections off the cable.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Dummy altitude for Zeb(alt)
• Time offset of tweaks from base_time(time_offset)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• base time(base_time)
• lon(lon)
• lat(lat)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• Cosine of Solar Zenith Angle(cosine_solar_zenith_angle)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• Data Logger Supply Voltage(logger_volt)

• lat(lat)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• Time offset of tweaks from base_time(time_offset)
• Data Logger Supply Voltage(logger_volt)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• base time(base_time)
• Detector Temperature(head_temp)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• lon(lon)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• Dummy altitude for Zeb(alt)

SGP/MFR10M/C1 - Data discontinuities

There is a discontinuity in the data (all channels) just after 1500 UTC on June 27, 2003 
and again, just before 1930 UTC on Jan 20, 2005.  There is nothing unusual in the temp or 
volt data.

At these times the tower was lowered for cleaning so the initial assumption was the 
instrument was dirty, and a cleaning resulted in the discontinuity.  This theory doesn't hold 
up well though as the tower is lowered for instrument cleaning regularly and these are the 
only two times in the past few years that a discontinuity coinciding with a lowering of 
the tower has resulted.  

Also, down pointing instruments are also not prone to collecting dust and dirt.  This 
instrument is located on the E13 SIRS tower and the down pointing PSP does not show a 
discontinuity at either time, which further discounts the dirty instrument theory.  Site 
operations were asked to check the instrument mount to see if it was loose possibly causing the 
instrument to change its position, and they reported that the mount seemed secure and 
stable.  So as of now, the cause of this issue is a mystery.

Compare with other down pointing instruments to help ascertain if data on one side of the 
discontinuity or the other are "better."  Perform an error analysis to determine if this 
would introduce a significant error in the role the data stream plays in a user's research.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)

SGP/MFR10M/C1 - Dip in data at solar noon

On clear days there is a dip in the data (all channels) at solar noon that is more 
pronounced during the winter months.  While we currently don't know the cause of this dip, we 
believe it is related to reflections off the tower pole.  The working theory says at solar 
noon the north-south crossbar shades the tower pole cutting off reflections into the 
detector.  If true, this means data on either side of the dip are being enhanced by 
reflections and the data within the dip are actually "correct."  An experiment is being planned 
for next fall that will wrap the upper portion of the tower in a non-reflecting cloth.  
This should determine if the dip is related to reflections from the tower pole.

Since at this point we don't know if the dip consists of bad or good data, users should be 
aware there is a problem and treat all the data as suspect.  It should noted that the 
magnitude of the problem is relatively small, likely no greater than 2.5%, so the dataset 
as whole is probably still useful as is for most users.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)

SGP/MFR10M/C1 - Missing data

Data are missing and unrecoverable.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Dummy altitude for Zeb(alt)
• Time offset of tweaks from base_time(time_offset)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• base time(base_time)
• lon(lon)
• lat(lat)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• Cosine of Solar Zenith Angle(cosine_solar_zenith_angle)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• Data Logger Supply Voltage(logger_volt)

• lat(lat)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• Time offset of tweaks from base_time(time_offset)
• Data Logger Supply Voltage(logger_volt)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• base time(base_time)
• Detector Temperature(head_temp)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• lon(lon)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• Dummy altitude for Zeb(alt)

SGP/MFR10M/C1 - Heater failure

The heater stopped working on 20090517.  Maintenance on 20090520 seemed to resolve the 
problem, but the heater failed again on 5/24.  Additional maintenance on 20090610 seems to 
have resolved the issue.

The instrument is designed to operate with a head temp of around 40 deg C.  As the head 
was at ambient temp during the period covered by this DQR, the mentor suggests looking at 
the 25m MFR if one is interested in these data.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)

SGP/MFR10M/C1 - Tower lowered for maintenance

The 10-m tower at the central facility central cluster was lowered
by site operations personnel for maintenance and repair activities.  
During this time interval, the multifilter radiometer on the tower 
had a field of view that were altered, possibly to include some sky 
radiation.  Data from this sensor should not be included in any 
analyses, for the specified time interval and location.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)

SGP/MFR10M/C1 - New datalogger PROM

The sgpmfr10m datalogger had its PROM upgraded during a visit by the instrument mentors. 
The new PROM is Version 13 with the capability of operating the MFR heater without a 
shadowband motor attached to the MFR head. No operating changes resulted from this upgrade.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• Cosine of Solar Zenith Angle(cosine_solar_zenith_angle)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)

SGP/MFR10m/C1 - Small intermittent time stamp error

The internal code that runs the MFR data logger had a bug that occasionally caused the 
time stamp associated with the data to be slightly in error.  This error is thought to be 
very small (say less than 30 seconds) and very infrequent.  (Unfortunately, we cannot give 
firm estimates of the magnitude and frequency of the error).

Also, the upwelling MFR measurements were contaminated by electrical noise originating 
from the heater contained in the sensor head.  During the time the sensor head was polled by 
the data logger, the heater would strobe "on and off", and the noise caused by this 
strobing could greatly contaminate the data.  Some of the data is so contaminated that it is 
virtually useless.   

After 96/03/27 these problems were corrected.  Those who use the data before this time 
should realize that the time stamp for each record of data might be slightly in error, and 
the data could be very noisy due to the heater switching on and off.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Time offset of tweaks from base_time(time_offset)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• base time(base_time)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• Cosine of Solar Zenith Angle(cosine_solar_zenith_angle)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Data Logger Supply Voltage(logger_volt)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• Time offset of tweaks from base_time(time_offset)
• Data Logger Supply Voltage(logger_volt)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• base time(base_time)
• Detector Temperature(head_temp)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)

SGP/MFR10M/C1 - Corrupt or truncated data

On about 96/08/18, the data logger board for the downlooking 10m MFR was modified to test 
an upgrade.  Unfortunately this upgrade did not work as planned, and some data was either 
corrupted or truncated.  You can't miss the corrupted data (from which you can infer 
albedos much greater than one!).  The truncated data is truncated in time, by which we mean 
that only a half day's worth of data was collected.  The daily time span of these 
truncated data is from midnight to about 1 PM (local time). At about 96/10/03, these problems 
were corrected.

Note:  The "begin date" given for this DQR may be off a day or two, so beware.

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• Cosine of Solar Zenith Angle(cosine_solar_zenith_angle)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)

• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 3(up_hemisp_narrowband_filter3)
• Broadband Upwelling Hemispheric Irradiance, Uncalibrated Silicon Detector,
  GNDMFR(up_hemisp_broadband)
• Data Logger Supply Voltage(logger_volt)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 5(up_hemisp_narrowband_filter5)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 2(up_hemisp_narrowband_filter2)
• Detector Temperature(head_temp)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 6(up_hemisp_narrowband_filter6)
• Fields flagged by callang: 0 = No Flag\n,(callang_flags)
• 25 meter Upwelling Hemispheric Irradiance, Filter 1(up_hemisp_narrowband_filter1)
• 25 meter Upwelling Narrowband Hemispheric Irradiance, Filter 4(up_hemisp_narrowband_filter4)

SGP/MFR10M/C1 - Head heater not working

On 19990415, the tower upon which the 10-m MFR was mounted was dismantled and replaced 
with a so-called "tippy tower".  After the 10-m MFR was reinstalled on the new tower, the 
mfr head heater did not work, or worked intermittently (at best).  A new mfr head was 
installed on 99.09.02 and that solved the problem.  

Data was collected from the old head in the morning up to the time it was replaced.  Once 
the new head was installed, data collection resumed.  There's a gap of about an hour 
between the time the old head was removed and the new head was installed.  If we try to gauge 
how well the old head was calibrated by comparing the two segments of data (old head, 
new head) it appears as if the old head remained in a good state of calibration even though 
the head heater was not working.

• Detector Temperature(head_temp)

• Detector Temperature(head_temp)