| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D010423.14 | SGP/SIRS/E13 - Diffuse Pyranometer Thermal Offsets | sgpsirsE13.a0, sgpsirsE13.a1 |
| D030917.17 | SGP/SIRS/E13 - Missing data due to Ice storm and clock problems | sgpsirsE13.00, sgpsirsE13.a2, sgpsirsE13.b1, sgpsirs20sE13.a0, sgpsirs60sE13.a1, sgp1swfanalsirs1longE13.c1, sgp15swfanalsirs1longE13.c1 |
| D040907.1 | SGP/SIRS/C1/E13 - Incorrect calibration coefficients | sgpsirsC1.00, sgpsirsC1.b1, sgpsirsE13.00, sgpsirsE13.b1, sgpsirs20sC1.a0, sgpsirs20sE13.a0 |
| D050206.3 | SGP/SIRS/E13 - Monthly Report | sgpsirsE13.b1 |
| D050601.1 | SGP/SIRS/E13 - Reprocess: incorrect calibrations | sgpsirsE13.00, sgpsirsE13.b1, sgpsirs20sE13.a0 |
| D060630.21 | SGP/SIRS/E13 - Reprocessed: Longwave Calibration error | sgpsirsE13.b1 |
| D970927.1 | SIRS NIPs affected by condensation at E8, E11, E13, & E15 | sgpsirsE8.a1, sgpsirsE11.a1, sgpsirsE13.a1, sgpsirsE15.a1 |
| D980224.1 | Reference Broadband Shortwave Data at SGP Central Cluster during Fall IOP '97 | sgpbsrnC1.00, sgpbsrnC1.a0, sgpbsrnC1.a1, sgpsirsE13.a0, sgpsirsE13.a1, sgpsirosE13.00, sgpsirosE13.a1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 08/29/1997 | 0421 | 02/22/2001 | 2021 |
| Subject: | SGP/SIRS/E13 - Diffuse Pyranometer Thermal Offsets |
| DataStreams: | sgpsirsE13.a0, sgpsirsE13.a1 |
| Description: | Broadband downwelling shortwave diffuse (sky) irradiance measurements available from SIRS during the period of this Data Quality Report (DQR), require adjustment for thermal offsets. These thermal, or ?zero? offsets refer to the generally reduced output signals from a shaded pyranometer due to the exchange of longwave (infrared) irradiance between the single black thermopile detector, the protective glass domes surrounding the detector, and the atmosphere. Originally considered an acceptable nighttime response of thermopile-type pyranometers, the generally negative bias is now recognized to significantly effect the accuracy of SIRS diffuse irradiance data during daylight periods. Studies of the Eppley Laboratory, Inc. Model PSP (Precision Spectral Pyranometer), used for the SIRS measurements of diffuse irradiance, suggest the thermal offset correction can range from near 0 to as much as 30 Watts per square meter, depending on the coincident net longwave, or infrared irradiance [1, 2]. Under very clear-sky conditions, the diffuse irradiance from a shaded PSP can be less than the minimum physical limit defined by radiative transfer model estimates based only on Rayleigh scattering effects. A correction method has been developed for adjusting SIRS diffuse irradiance data [3]. The resulting Value Added Product (VAP) will be applied to SIRS data for the period of this DQR. The VAP will not be applied to SIROS data collected before the instrument platform was converted to SIRS. Additionally, the Model PSP radiometer has been replaced by a Model 8-48 which uses a black and white thermopile detector known to reduce the thermal offset errors to less than 2 Watts per square meter [3]. The radiometer replacement at this SIRS location was completed on the ending date of this DQR. References: 1. Gulbrandsen, A., 1978: On the use of pyranometers in the study of spectral solar radiation and atmospheric aerosols. J. Appl. Meteorol., 17, 899-904. 2. Cess, R. D., X. Jing, T. Qian, and M. Sun, 1999: Validation strategies applied to the measurement of total, direct and diffuse shortwave radiation at the surface. J. Geophys. Res. 3. Dutton, E.G., J. Michalsky, T. Stoffel, B. Forgan, J. Hickey, D. Nelson, T. Alberta, and I. Reda, 2001: Measurement of Broadband Diffuse Solar Irradiance Using Current Commercial Instrumentation With a Correction for Thermal Offset Errors. J. Atmos. Oceanic Tech. Vol 18, No. 3, 297-314. (March 2001) |
| Measurements: | sgpsirsE13.a0:
sgpsirsE13.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 03/09/2002 | 2006 | 03/10/2002 | 1902 |
| 03/13/2002 | 1806 | 03/14/2002 | 1607 |
| Subject: | SGP/SIRS/E13 - Missing data due to Ice storm and clock problems |
| DataStreams: | sgpsirsE13.00, sgpsirsE13.a2, sgpsirsE13.b1, sgpsirs20sE13.a0, sgpsirs60sE13.a1, sgp1swfanalsirs1longE13.c1, sgp15swfanalsirs1longE13.c1 |
| Description: | Data are missing due to power failures caused by an ice storm and resulting system/instrument clock problems. |
| Measurements: | sgpsirsE13.b1:
sgpsirs60sE13.a1:
sgpsirsE13.a2:
sgpsirs20sE13.a0:
sgp15swfanalsirs1longE13.c1:
sgp1swfanalsirs1longE13.c1:
sgpsirsE13.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 08/27/2004 | 1830 | 09/07/2004 | 2130 |
| Subject: | SGP/SIRS/C1/E13 - Incorrect calibration coefficients |
| DataStreams: | sgpsirsC1.00, sgpsirsC1.b1, sgpsirsE13.00, sgpsirsE13.b1, sgpsirs20sC1.a0, sgpsirs20sE13.a0 |
| Description: | After the DIR changeout on 8/27, the DLH measurements at the central facility vary significantly between pyrgeometers by as much as 65 Wm^(-2). It was discovered that the two downwelling pyrgeometers destined for C1 and E13 may have been swapped during installation. The instrument mentor is unsure of applied calibration coefficients during this DQR's time period. Backing out new downwelling longwave irradiances would be difficult in this case. Fortunately, the problem period is less than a fortnight. |
| Measurements: | sgpsirsE13.b1:
sgpsirsC1.b1:
sgpsirsC1.00:
sgpsirs20sE13.a0:
sgpsirs20sC1.a0:
sgpsirsE13.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/01/2004 | 0000 | 01/01/2005 | 0000 |
| Subject: | SGP/SIRS/E13 - Monthly Report |
| DataStreams: | sgpsirsE13.b1 |
| Description: | :Data quality this site-month is good. The offset for the Global PSP is about -7 W/m^2. The dominant problem here is the daytime 3 component problem. Direct and Diffuse are always too high and Global is too low. The problem occurs around the time that the testing regime switches from twilight to daytime testing regimes or from daytime to twilight. The flags occur in significant numbers on the 1st - 5th, 7th - 20th, 24th - 28th, 30th, and 31st. The failures vary in magnitude and duration. The worst flags for a particular respect to this problem. Global goes below daytime empirical limits on both the 5th and 6th for substantial periods of time. Diffuse also goes below daytime empirical limits on the 6th in the afternoon. Upwelling Longwave is below empirical limits on the 24th. This may not be a problem, as many sites exhibited the same problem on the same night. Exceptionally cold temperatures may be the cause. |
| Measurements: | sgpsirsE13.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 05/25/2005 | 1409 | 06/02/2005 | 2205 |
| Subject: | SGP/SIRS/E13 - Reprocess: incorrect calibrations |
| DataStreams: | sgpsirsE13.00, sgpsirsE13.b1, sgpsirs20sE13.a0 |
| Description: | After a long data gap on 5/25/2005, presumably a power outage, the following datastreams
were showing incorrect values as well as incorrect calibration coefficients in the
datalogger program:
down_long_hemisp_shaded (downwelling PIR instrument)
up_long_hemisp (upwelling PIR instrument)
short_direct_normal (NIP instrument)
The SIRS.E13 datalogger was power cycled (6/2/2005 2200GMT) and the correct program loaded
into the SIRS datalogger and storage module.
The data during this time range can be recalibrated as follows:
First divide value by incorrectly applied cal coeff (first number) then multiply by
correct cal coeff (second number)
short_direct_normal 120.28 124.58
up_long_netir 0.2386 0.2595
down_long_netir 0.3052 0.2304
Reapply cal coeffs below using up_long_netIR(uV), inst_up_long_dome_temp(K),
inst_up_long_dome_temp(K) using procedure described in SIRS instrument manual.
up_long_hemisp
k0 -18.3400 W/m^2\n,
k1 0.2595 W/(m^2*uV)\n,
k2 1.0380 unitless\n,
k3 -2.7420 unitless\n,
kr 0.0007044 K/uV\n,
Reapply cal coeffs below using down_long_netIR(uV),inst_down_long_dome_temp
(K),inst_down_long_dome_temp(K).
down_long_hemisp_shaded
k0 -11.6300 W/m^2\n,
k1 0.2304 W/(m^2*uV)\n,
k2 1.0190 unitless\n,
k3 -2.4230 unitless\n,
kr 0.0007044 K/uV\n, |
| Measurements: | sgpsirsE13.b1:
sgpsirs20sE13.a0:
sgpsirsE13.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/11/2003 | 1935 | 02/16/2006 | 1905 |
| Subject: | SGP/SIRS/E13 - Reprocessed: Longwave Calibration error |
| DataStreams: | sgpsirsE13.b1 |
| Description: | Modified pyrgeometer calibration procedures were implemented beginning in December 2003. These modified procedures introduced a calibration bias in the longwave data. The previous procedures were re-implemented at all sites between December 2005 and February 2006 to restore proper calibrations. The data collected while the incorrect procedures were in place have been reprocessed to remove the calibration bias. The reprocessed 60 second averaged data are based on 3 instantaneous 20 second data records rather than on 60 1 second instantaneous data records. Still, these data are considered far superior to the originally processed data. The reprocessed data were archived in October 2006. |
| Measurements: | sgpsirsE13.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 09/26/1997 | 1230 | 09/26/1997 | 1330 |
| 09/26/1997 | 1230 | 09/26/1997 | 1345 |
| 09/26/1997 | 1230 | 09/26/1997 | 1415 |
| Subject: | SIRS NIPs affected by condensation at E8, E11, E13, & E15 |
| DataStreams: | sgpsirsE8.a1, sgpsirsE11.a1, sgpsirsE13.a1, sgpsirsE15.a1 |
| Description: | Comparison of data from the unshaded PSP to that derived from the 'direct + diffuse' (NIP + shaded PSP) indicated low values of the 'direct+diffuse' combination starting at sunrise and lasting for about an hour at E8, E11, E13 and E15. Futher examination revealed that the NIPs were reading low and were likely affected by condensation during this brief period. Weather conditions were foggy over the area early that morning, and fog quickly dissipated after sunrise. |
| Measurements: | sgpsirsE8.a1:
sgpsirsE13.a1:
sgpsirsE11.a1:
sgpsirsE15.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 09/17/1997 | 0000 | 10/03/1997 | 2359 |
| Subject: | Reference Broadband Shortwave Data at SGP Central Cluster during Fall IOP '97 |
| DataStreams: | sgpbsrnC1.00, sgpbsrnC1.a0, sgpbsrnC1.a1, sgpsirsE13.a0, sgpsirsE13.a1, sgpsirosE13.00, sgpsirosE13.a1 |
| Description: | This is a recommendation for the best available broadband shortwave data from the SGP Central Cluster (Lamont, OK) during the Combined Fall IOP, 15 Sept - 5 Oct 1997. Data available from the SGP Radiometer Calibration Facility (RCF) has lower measurement uncertainties than similar measurements from the C1, E-13, and BSRN/BRS platforms. The RCF data were collected using the same Broadband Outdoor Radiometer CALibration (BORCAL) system used for routine calibration of pyranometers and pyrheliometers at the RCF. The data are available for 30-second interval. Direct normal irradiance measurements from a windowed RCF Absolute Cavity Radiometer during the IOP is considered more accurate (+/- 0.5%) than the Normal Incidence Pyrheliometers (NIP) at the Central Cluster (+/- 2%). The Automated Hickey-Frieden cavity radiometer is electrically self-calibrating and provides reference standard data suitable for the calibration of the NIPs used at all the CART sites. Diffuse horizontal irradiance is available as the average of two Eppley Precision Spectral Pyranometers and is considered slightly more accurate than the downwelling diffuse (DD) data from the Central Cluster instruments. The RCF data will have periodic gaps during the electrical calibration intervals (about 6-10 minutes, 4 or 5 times per day). The reference global horizontal (or Downwelling Shortwave - DS) has been computed from the measured direct normal and diffuse components: DS = NIP x Cos(Z) + DD, where, Z = solar zenith angle. All RCF data collected during the IOP are on the ARM IOP Web page (iop.archive.arm.gov/arm-iop). with other data from the Fall97 shortwave IOP. Additional corrections to the diffuse data may be possible after researching PSP nighttime offsets. Data from C1, E-13, and BSRN/BRS platforms during the SW-IOP '97 are still being investigated. |
| Measurements: | sgpbsrnC1.a0:
sgpsirsE13.a0:
sgpsirsE13.a1:
sgpbsrnC1.00:
sgpbsrnC1.a1:
sgpsirosE13.a1:
sgpsirosE13.00:
|