| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D010423.6 | SGP/SIRS/E5 - Diffuse Pyranometer Thermal Offsets | sgpsirsE5.a0, sgpsirsE5.a1 |
| D010423.7 | SGP/SIRS/E6 - Diffuse Pyranometer Thermal Offsets | sgpsirsE6.a0, sgpsirsE6.a1 |
| D010423.8 | SGP/SIRS/E7 - Diffuse Pyranometer Thermal Offsets | sgpsirsE7.a0, sgpsirsE7.a1 |
| D031110.1 | SGP/SIRS/E5 - | sgpsirsE5.a0, sgpsirsE5.a1 |
| D031110.2 | SGP/SIRS/E6 | sgpsirsE6.a0, sgpsirsE6.a1 |
| D031110.3 | SGP/SIRS/E7 - | sgpsirsE7.a0, sgpsirsE7.a1 |
| D031110.4 | SGP/SIRS/E7 | sgpsirsE7.a0, sgpsirsE7.a1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/18/1997 | 0142 | 02/14/2001 | 1945 |
| Subject: | SGP/SIRS/E5 - Diffuse Pyranometer Thermal Offsets |
| DataStreams: | sgpsirsE5.a0, sgpsirsE5.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 Additionally, the Model PSP radiometer has been replaced by a Model 8-48 which uses a black and white thermopile detector known to reduce the thermal offset errors to less than 2 Watts per square meter [3].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: | sgpsirsE5.a1:
sgpsirsE5.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/05/1997 | 0000 | 02/15/2001 | 1530 |
| Subject: | SGP/SIRS/E6 - Diffuse Pyranometer Thermal Offsets |
| DataStreams: | sgpsirsE6.a0, sgpsirsE6.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: | sgpsirsE6.a0:
sgpsirsE6.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 10/31/1997 | 0227 | 02/13/2001 | 1925 |
| Subject: | SGP/SIRS/E7 - Diffuse Pyranometer Thermal Offsets |
| DataStreams: | sgpsirsE7.a0, sgpsirsE7.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: | sgpsirsE7.a1:
sgpsirsE7.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/01/2000 | 0000 | 02/01/2000 | 0000 |
| Subject: | SGP/SIRS/E5 - |
| DataStreams: | sgpsirsE5.a0, sgpsirsE5.a1 |
| Description: | Data quality this month is pretty good, with some exceptions. Nighttime offsets in the Downwelling pyranometer (DS) average about -4 W/m^2 for the month as does the Downwelling Diffuse pyranometer (DD). There are moderate inconsistencies between the Global (DS), Direct (NIP) and Diffuse (DD) the DD and NIP are too high and the DS is too low. There is moderate inconsistencies between the DS, NIP, and DD components in the middle of the day on the 4th and 5th. In both cases the DS is too low and the DD and NIP are too high. It looks like the DS is bad on the 4th but it can't be determined what causes it. Site ops were there on the 5th doing data collection, so that is a possible contributor to the discrepincies of that day. It could also be caused by the use of a constant pyranometer responsivity for all solar zenith angles, or the switchover from probable factor in the error. It should also be noted that the calibration factors for the PSP's have a tolerance of plus or minus 5% and the NIP has a tolerance of plus or minus 3%. Upwelling Longwave goes below empirical limits on the 4th from 11:00 to 15:00 GMT and on the 31st from 02:00 to 12:00 GMT. The winter Longwave empirical limit of 250 W/m^2 is currently under further review. (A reading of 250 W/m^2 suggests a temperature between 5 and 20 degrees Fahrenheit.) DS goes below daytime empirical limits on the local evening of the 8th and DS and DD go below daytime empirical limits in the morning of the third. NIP goes above its nightitme empirical limit on the 31st before sunrise. Something happens with the Upwelling Shortwave (US) on the 3rd and 27th where it exceeds its daytime empirical limit. Snowy conditions is the likely cause. US also dips belows its nighttime empirical limit for short durations on the local nights of the 15th, 22nd, and the 30th. |
| Measurements: | sgpsirsE5.a1:
sgpsirsE5.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/01/2000 | 0000 | 02/01/2000 | 0000 |
| Subject: | SGP/SIRS/E6 |
| DataStreams: | sgpsirsE6.a0, sgpsirsE6.a1 |
| Description: | Data quality this month is pretty good, with some exceptions. Nighttime offsets in the Downwelling Diffuse pyranometer (DD) average about -6 W/m^2 and about -5 W/m^2 in the Global (DS) for the month. The Direct (NIP) nighttime offset is anywhere from 0 to 10 W/m^2 or more during the month. The NIP data exceed its empirical limits on the local nights (after sunset) of the 7th, 11th, 20th, 23rd, 25th, 28th, 29th, and 30th consequently triggering yellow flags in the longwave. The longwave data look to be OK during these instances but data quality cannot be ascertained. NIP also exceeds daytime empirical limits on the 4th and 7th. DD goes below nighttime empirical limits on the 2nd and local 19th for short time periods. Global dips below daytime empirical limits on the 3rd and 8th. There are moderate inconsistencies between the Global (DS), Direct (NIP) and Diffuse (DD) are too high and the DS is too low. This could be caused by the use of a constant pyranometer responsivity for all solar zenith angles, or the switchover from probable factor in the error. It should also be noted that the calibration factors for the PSP's have a tolerance of plus or minus 5% and the NIP has a tolerance of plus or minus 3%. |
| Measurements: | sgpsirsE6.a0:
sgpsirsE6.a1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/01/2000 | 0000 | 02/01/2000 | 0000 |
| Subject: | SGP/SIRS/E7 - |
| DataStreams: | sgpsirsE7.a0, sgpsirsE7.a1 |
| Description: | Data quality this site-month is good (other than at the begining where the sun tracker was not aligned properly. See the additional DQR.) Global (DS) and Diffuse (DD) have nighttime offsets of about -4 W/m^2. There are some daytime empirical limit problems on some of the overcast days. DS alone sinks below daytime empirical limits on the 8th, 16th, and 27th. For all three occurances it is below empirical limits for less than an hour. Both DS and DD go below empirical limits on the 3rd and 19th. They go below daytime empirical limits Longwave also dips below empirical limits on the 31st from 11:15 to 14:00 GMT. The winter Longwave empirical limit of 250 W/m^2 is currently under further review. (A reading of 250 W/m^2 suggests a temperature between 5 and 20 degrees Fahrenheit.) Upwelling Shortwave (US) dips belows its nighttime empirical limit for short durations on the local nights of the 15th, 22nd, and the 2nd. |
| Measurements: | sgpsirsE7.a1:
sgpsirsE7.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 01/01/2000 | 0000 | 01/04/2000 | 2010 |
| Subject: | SGP/SIRS/E7 |
| DataStreams: | sgpsirsE7.a0, sgpsirsE7.a1 |
| Description: | Site ops said the tracker was off .3 degrees through this period. |
| Measurements: | sgpsirsE7.a1:
sgpsirsE7.a0:
|