DQR ID | Subject | Data Streams Affected |
---|---|---|
D010423.4 | SGP/SIRS/E3 - Diffuse Pyranometer Thermal Offsets | sgpsirsE3.a0, sgpsirsE3.a1 |
D010423.5 | SGP/SIRS/E4 - Diffuse Pyranometer Thermal Offsets | sgpsirsE4.a0, sgpsirsE4.a1 |
D031107.1 | SGP/SIRS/E3 | sgpsirsE3.a0, sgpsirsE3.a1 |
D031107.2 | SGP/SIRS/E4 | sgpsirsE4.a0, sgpsirsE4.a1 |
D031107.3 | SGP/SIRS/E4 - | sgpsirsE4.a0, sgpsirsE4.a1 |
D040712.1 | SGP/SIRS/E24 - NIP shaded near sunrise | sgpsirsE24.a2, sgpsirs20sE24.a0, sgpsirs60sE24.a1 |
D040712.2 | SGP/SIRS/E24 - NIP shaded near sunrise | sgpsirsE24.a2, sgpsirsE24.b1, sgpsirs20sE24.a0, sgpsirs60sE24.a1 |
Start Date | Start Time | End Date | End Time |
---|---|---|---|
11/04/1997 | 0000 | 02/14/2001 | 1930 |
Subject: | SGP/SIRS/E3 - Diffuse Pyranometer Thermal Offsets |
DataStreams: | sgpsirsE3.a0, sgpsirsE3.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 Additionally, the Model PSP radiometer has been replaced by a Model 8-48 which uses a black and white thermopile detector known to reduce the thermal offset errors to less than 2 Watts per square meter [3].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: | sgpsirsE3.a1:
sgpsirsE3.a0:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
11/10/1997 | 1202 | 02/14/2001 | 1510 |
Subject: | SGP/SIRS/E4 - Diffuse Pyranometer Thermal Offsets |
DataStreams: | sgpsirsE4.a0, sgpsirsE4.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: | sgpsirsE4.a1:
sgpsirsE4.a0:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
01/01/2000 | 0000 | 02/01/2000 | 0000 |
Subject: | SGP/SIRS/E3 |
DataStreams: | sgpsirsE3.a0, sgpsirsE3.a1 |
Description: | Data this site-month is good except for Global (DS), which is pretty bad. DS goes below empirical limits every single night of the month. Its nighttime offset average is about -11 W/m^2. DS also dipped below daytime empirical limits intermittently throughout the day on the 3rd, 8th, and 9th and on the morning of the 17th. There is also a noticeable but unascertainable daytime offset in the DS which becomes evident when the NIP is near zero. Diffuse (DD) also goes below empirical limits on the morning of the 9th. The DD nighttime offset is about -5 W/m^2. 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 daylight to twilight SERI QC testing regimes. The daytime negative offset in the DS PSP is also a 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 the empirical limits on the local nights of the 23rd and 30th (24th and 31st GMT) for extended periods of time. 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.) |
Measurements: | sgpsirsE3.a1:
sgpsirsE3.a0:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
01/01/2000 | 0000 | 01/05/2000 | 1650 |
01/06/2000 | 0000 | 01/19/2000 | 1750 |
01/20/2000 | 0000 | 01/31/2000 | 1800 |
Subject: | SGP/SIRS/E4 |
DataStreams: | sgpsirsE4.a0, sgpsirsE4.a1 |
Description: | Direct too low by visual inspection and Diffuse too high. Downwelling and upwelling IR, global and upwelling shortwave all indicate clear or mostly clear sky conditions during daylight hours, yet direct is near zero. Probable cause: sun tracker failure. There was a couple of ultimately futile attempts to fix the problem on the 5th and 19th. |
Measurements: | sgpsirsE4.a1:
sgpsirsE4.a0:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
01/01/2000 | 0000 | 02/01/2000 | 0000 |
Subject: | SGP/SIRS/E4 - |
DataStreams: | sgpsirsE4.a0, sgpsirsE4.a1 |
Description: | Data quality this site-month is terrible. This is due to the repeated failure of the sun tracker. The longwave looks good and there are no notable problems for those 2 parameters. Global (DS) has a nighttime offset of about -4 W/m^2. DS data look good. Disregard the three component test flags for DS. Something happens with the Upwelling Shortwave (US) on the 3rd where it exceeds its daytime empirical limit. Snowy conditions is the likely cause. US also dips below its nighttime empirical limit on the local night of the 15th after sunset. |
Measurements: | sgpsirsE4.a1:
sgpsirsE4.a0:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
04/08/2001 | 1200 | 05/20/2001 | 1300 |
07/26/2001 | 1300 | 09/06/2001 | 1200 |
Subject: | SGP/SIRS/E24 - NIP shaded near sunrise |
DataStreams: | sgpsirsE24.a2, sgpsirs20sE24.a0, sgpsirs60sE24.a1 |
Description: | The NIP is shaded by the EF laptop computer enclosure near sunrise during parts of the Spring and Summer. This has occurred from 04/08 to 05/20 and from 07/26 to 09/06 every year since 2001 and will occur during these date ranges in the future as well. The shading occurs for a few minutes each day between 1200 and 1300 GMT depending on the time of the year. For the early dates, shading occurs a little after 1200 GMT and by 05/20 shading happens nearer to 1300 GMT. In late July the shading occurs near 1300 GMT and closer to 1200 GMT by 09/06. |
Measurements: | sgpsirsE24.a2:
sgpsirs60sE24.a1:
sgpsirs20sE24.a0:
|
Start Date | Start Time | End Date | End Time |
---|---|---|---|
04/08/2002 | 1200 | 05/20/2002 | 1300 |
07/26/2002 | 1300 | 09/06/2002 | 1200 |
04/08/2003 | 1200 | 04/16/2003 | 1300 |
Subject: | SGP/SIRS/E24 - NIP shaded near sunrise |
DataStreams: | sgpsirsE24.a2, sgpsirsE24.b1, sgpsirs20sE24.a0, sgpsirs60sE24.a1 |
Description: | The NIP is shaded by the EF laptop computer enclosure near sunrise during parts of the Spring and Summer. This has occurred from 04/08 to 05/20 and from 07/26 to 09/06 every year since 2001 and will occur during these date ranges in the future as well. The shading occurs for a few minutes each day between 1200 and 1300 GMT depending on the time of the year. For the early dates, shading occurs a little after 1200 GMT and by 05/20 shading happens nearer to 1300 GMT. In late July the shading occurs near 1300 GMT and closer to 1200 GMT by 09/06. |
Measurements: | sgpsirsE24.a2:
sgpsirs60sE24.a1:
sgpsirsE24.b1:
sgpsirs20sE24.a0:
|