SGP/SIRS/E3 - Degraded upwelling longwave data

Upwelling longwave values had been showing spikes in the late evening beginning around 
7/5. On 7/16/03 technicians found a rodent nest and cables chewed at pivot point of 
upwelling instrument tower.  Only the upwelling longwave (UIR) instrument case temperature was 
affected but this degrades all of the UIR longwave irradiance measurement. Both UIR and US 
cables replaced on 7/30/03 1600 GMT which fixed the problem.

• Raw data stream - documentation not supported

SGP/SIRS/E5 - Downwelling direct normal (NIP) reporting low

There were large differences between the measured downwelling 
              shortwave (DS) and the downwelling shortwave calculated from direct 
              (NIP) and diffuse (DD) readings.  It appears that the direct normal 
              shortwave readings were much too low, particularly on 7/14 and 7/15. 
              It appears that the diffuse instrument was being shaded properly, but 
              the NIP was not tracking the sun. 

              The problem was corrected during the preventative maintenance visit on 
              7/16/03 at 1840GMT.  The technician reported doing the quarterly 
              connection corrosion checks and ventilator fan cleaning, the NIP was 
              described as having "dry-light dust" on the window, no mention of 
              tracker alignment was made.  Although uncertain, a bad connection at 
              some point in the instrument wiring was likely to blame and was 
              eliminated during the corrosion inspection process.

• Raw data stream - documentation not supported

SGP/SIRS/E4 - Shadowband Misalignment

The solar tracker failed on 12/4, resulting in bad direct and 
               diffuse measurements. The tracker started working again on 12/8 
               without Ops intervention.  Technician maintenance checks on 12/3
               and 12/17 reported correct tracker operation.

• Raw data stream - documentation not supported

SGP/SIRS/E1/E2/E3/E5/E8 - Snow on Radiometers

A large discrepancy between the measured values of downwelling hemispheric shortwave 
radiation and the derived values occurred on 2/02 at the listed sites.  The difference is on 
the order of 200 Wm^(-2) at E2 and to a lesser extent at the other affected stations.  
This problem most likely resulted from a previous day or night snow/ice accumulation on 
the Direct(NIP), Downwelling Sortwave(PSP) and/or  Downwelling Diffuse(8-48) instruments.  
During the morning hours of 02/02, Approx 1300-2000GMT, snow/ice was covering one or more 
of these three instruments resulting in faulty readings and incorrect derived 
downwelling shortwave values as well.  Instrument readings indicate the problem resolved itself 
later in the day through normal meltoff.

• Raw data stream - documentation not supported

• Raw data stream - documentation not supported

SGP/SIRS/E5 - anomalously low NIP readings

Direct normal (NIP instrument) irradiance readings fall anomalously on 3/17 18:43GMT to 
less than half the expected values during clear sky conditions.  NIP readings returned to 
normal on 3/28/04 12:00. Maintenance on 3/29/04 19:48 revealed no unusual contaminents. 
Precipitation on 3/27 (measured by the SMOS system) probably cleared the NIP window of 
contaminents before scheduled maintenance.

• Raw data stream - documentation not supported

SGP/SIRS/E5 - Dirt on PSP Dome

The PSP dome was dirty.  The magnitude of differences from derived 
             vs. measured values of downwelling shortwave were about 75 W/m^2. 
             Preventative maintenance on 4/21 cleaned instruments but they 
             became dirty again immediately afterward and continued to be
             so until the next PM on 5/5.

• Raw data stream - documentation not supported

SGP/SIRS/E4 - Dirt on Dome

The downwelling shortwave hemispheric radiation data are suspect.  The PSP dome appears to 
have been very dirty, especially during times when the sun angles were low.

• Raw data stream - documentation not supported

SGP/SIRS/E5 - Dirty radiometers

Snow or heavy dirt may have been covering one side of the PSP or 8-48 domes. The start of 
the problem coincides with a preciption event.  We may assume that the offending 
substance was snow and it melted by 1/30/2007.  PM after this time reports dry-light dust on 
radiometers.

• Raw data stream - documentation not supported

SGP/SIRS/C1/E1/E10/E11/E12/E13/E15/E16/E18/E19/E2/E20/E21/E22/E24/E25/E27/E3/E4/E5/E6/E7/E8/E9 - Ice

Ice storms affected the SGP central and extended facilities starting Dec 10 0000GMT to 
mid/late December. Each facility was affected at various times and degrees dependant on 
elevation, latitude and whether power failed for short or extended periods of time.  By 
December 15th most ice had melted from the radiometers at all the faclities but power outages 
and tracker failures persisted at some stations.

• Raw data stream - documentation not supported

• Raw data stream - documentation not supported

• Raw data stream - documentation not supported

SGP/SIRS/E5 - Incorrect Calibration Coefficient

When instruments were changed out on 6/25 the UIR (up_long_hemisp measurement) S/N and cal 
coefficient reverted to a previous UIR instrument that was damaged and removed on 
12/28/2007. The UIR S/N should be 31637F3 with corresponding cal K=.2526 instead of applied 
value of K=.2571. 
However, for the PIR longwave instrument in this inverted position (UIR) the K1 term 
contributes approximately 0-7% of the total upwelling longwave signal throughout the day, or 
about 0-30 W/m2.  The cal coefficient is too high by approximately 2%. Thus, the UIR data, 
as is, ranges from 0 to .6 W/m2 too low since this term is always negative.  The 
uncertainty of this instrument is approximately +-10 W/m2 with respect to the WSIG. Reprocessing 
is not recommended.

• Raw data stream - documentation not supported

SGP/SIRS/E4 - Tracker malfunction

Tracker failure resulted in incorrect tracked data.

• Raw data stream - documentation not supported