| DQR ID | Subject | Data Streams Affected |
|---|---|---|
| D031020.1 | SGP/SIRS/E1 - failed SIRS multiplexer | sgpsirsE1.00, sgpsirsE1.b1, sgpsirs20sE1.a0 |
| D031020.2 | SGP/SIRS/E9 - Possible instrument drift | sgpsirsE9.00, sgpsirsE9.b1, sgpsirs20sE9.a0 |
| D031118.1 | SGP/SIRS/E1 - Unknown - Downwelling shaded longwave measurement incorrect | sgpsirsE1.00, sgpsirsE1.b1, sgpsirs20sE1.a0 |
| D031124.8 | SGP/SIRS/E7 - Unknown problem with downwelling shortwave instrument (Eppley PSP) | sgpsirsE7.00, sgpsirsE7.b1, sgpsirs20sE7.a0 |
| D031208.6 | SGP/SIRS/E4 - Shadowband Misalignment | sgpsirsE4.00, sgpsirsE4.b1, sgpsirs20sE4.a0 |
| D040205.1 | SGP/SIRS/E1/E2/E3/E5/E8 - Snow on Radiometers | sgpsirsE1.00, sgpsirsE1.b1, sgpsirsE2.00, sgpsirsE2.b1, sgpsirsE3.00, sgpsirsE3.b1, sgpsirsE5.00, sgpsirsE5.b1, sgpsirsE8.00, sgpsirsE8.b1, sgpsirs20sE1.a0, sgpsirs20sE2.a0, sgpsirs20sE3.a0, sgpsirs20sE5.a0, sgpsirs20sE8.a0 |
| D040226.1 | SGP/SIRS/E9 - PSP dome contamination | sgpsirsE9.00, sgpsirsE9.b1, sgpsirs20sE9.a0 |
| D040226.2 | SGP/SIRS/E11 - PSP dome contamination | sgpsirsE11.00, sgpsirsE11.b1, sgpsirs20sE11.a0 |
| D040227.3 | SGP/SIRS/E2 - Reprocess: Incorrect shortwave radiometer calibration coefficients | sgpsirsE2.00, sgpsirsE2.b1 |
| D040320.1 | SGP/SIRS/E5 - anomalously low NIP readings | sgpsirsE5.00, sgpsirsE5.b1, sgpsirs20sE5.a0 |
| D040320.2 | SGP/SIRS/E8 - Possible Contamination of DS PSP instrument | sgpsirsE8.00, sgpsirsE8.b1, sgpsirs20sE8.a0 |
| D040405.2 | SGP/SIRS/E7 - PSP dome contamination | sgpsirsE7.b1, sgpsirs20sE7.a0 |
| D040420.2 | SGP/SIRS/E5 - Dirt on PSP Dome | sgpsirsE5.00, sgpsirsE5.b1, sgpsirs20sE5.a0 |
| D040621.3 | SGP/SIRS/E7 - Reprocess: Incorrect calibration coefficients applied to downwelling longwave | sgpsirsE7.00, sgpsirsE7.b1 |
| D040831.1 | SGP/SIRS/E1 - Reprocess: Incorrect shortwave radiometer calibration coefficients | sgpsirsE1.00, sgpsirsE1.b1 |
| D040831.2 | SGP/SIRS/E7 - Reprocess: Incorrect shortwave radiometer calibration coefficients | sgpsirsE7.00, sgpsirsE7.b1 |
| D040831.3 | SGP/SIRS/E8 - Reprocess: Incorrect shortwave radiometer calibration coefficients | sgpsirsE8.00, sgpsirsE8.b1 |
| D040831.4 | SGP/SIRS/E10 - Reprocess: Incorrect shortwave radiometer calibration coefficients | sgpsirsE10.00, sgpsirsE10.b1 |
| D040831.5 | SGP/SIRS/E11 - Reprocess: Incorrect shortwave radiometer calibration coefficients | sgpsirsE11.00, sgpsirsE11.b1 |
| D040903.1 | SGP/SIRS/E11 - Reprocess: Incorrect calibration coefficients applied to upwelling longwave | sgpsirsE11.00, sgpsirsE11.b1 |
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 10/14/2003 | 2023 | 10/21/2003 | 1930 |
| Subject: | SGP/SIRS/E1 - failed SIRS multiplexer |
| DataStreams: | sgpsirsE1.00, sgpsirsE1.b1, sgpsirs20sE1.a0 |
| Description: | Beginning 10/14, a failed multiplexer resulted in missing
downwelling shortwave data and downwelling and upwelling
longwave data which were much too low. The multiplexer
handles data for the longwave instruments (UIR and DIR)
case and dome temperatures as well as the downwelling shortwave
hemispheric instrument (DS). |
| Measurements: | sgpsirs20sE1.a0:
sgpsirsE1.b1:
sgpsirsE1.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 10/14/2003 | 00 | 10/21/2003 | 160 |
| Subject: | SGP/SIRS/E9 - Possible instrument drift |
| DataStreams: | sgpsirsE9.00, sgpsirsE9.b1, sgpsirs20sE9.a0 |
| Description: | Downwelling shortwave values were too low, dropping below -10 W/m^2
at night and reading 30-50 W/m^2 lower than DS calculated from
direct and diffuse measurements during the day. This problem became
more noticeable beginning on 10/14, when nighttime values began to
drop below -10 W/m^2 consistently. The problem was corrected with
the annual instrument changout on 10/23/03.
Although the downwelling shortwave instrument (DS) appears to be the
problem a more likely scenario is that the cable connections became
thermopile. The instrument changeout possibly reseated and corrected
any poor connections. |
| Measurements: | sgpsirs20sE9.a0:
sgpsirsE9.b1:
sgpsirsE9.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/11/2003 | 438 | 11/18/2003 | 220 |
| Subject: | SGP/SIRS/E1 - Unknown - Downwelling shaded longwave measurement incorrect |
| DataStreams: | sgpsirsE1.00, sgpsirsE1.b1, sgpsirs20sE1.a0 |
| Description: | Downwelling longwave values were very noisy and out of range
due to a missing PIR case temperature measurement. Faulty
wiring to the case temperature thermistor on the downwelling
longwave IR instrument (PIR) was the likely cause of
the problem.
On 11/18, the E1 tracker and associated instruments (direct
shortwave -NIP, hemispheric shaded shortwave -8-48 and
hemispheric shaded longwave - problem PIR) were moved to a new
tracker stand. Rewiring the instrument corrected the problem. |
| Measurements: | sgpsirs20sE1.a0:
sgpsirsE1.b1:
sgpsirsE1.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 11/21/2003 | 317 | 12/03/2003 | 00 |
| Subject: | SGP/SIRS/E7 - Unknown problem with downwelling shortwave instrument (Eppley PSP) |
| DataStreams: | sgpsirsE7.00, sgpsirsE7.b1, sgpsirs20sE7.a0 |
| Description: | Beginning around 0317 UTC, 11/21, downwelling shortwave values became anamolously high during the night, when they should have been around zero. Values returned to normal after SGP technicians reseated this instruments connections at 1215UTC 12/02/2003. The following day's data appeared normal. Appears that a poor connection was the culprit this time. |
| Measurements: | sgpsirs20sE7.a0:
sgpsirsE7.b1:
sgpsirsE7.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 12/04/2003 | 170 | 12/08/2003 | 120 |
| Subject: | SGP/SIRS/E4 - Shadowband Misalignment |
| DataStreams: | sgpsirsE4.00, sgpsirsE4.b1, sgpsirs20sE4.a0 |
| Description: | 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. |
| Measurements: | sgpsirsE4.00:
sgpsirsE4.b1:
sgpsirs20sE4.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/02/2004 | 120 | 02/02/2004 | 200 |
| Subject: | SGP/SIRS/E1/E2/E3/E5/E8 - Snow on Radiometers |
| DataStreams: | sgpsirsE1.00, sgpsirsE1.b1, sgpsirsE2.00, sgpsirsE2.b1, sgpsirsE3.00, sgpsirsE3.b1, sgpsirsE5.00, sgpsirsE5.b1, sgpsirsE8.00, sgpsirsE8.b1, sgpsirs20sE1.a0, sgpsirs20sE2.a0, sgpsirs20sE3.a0, sgpsirs20sE5.a0, sgpsirs20sE8.a0 |
| Description: | 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. |
| Measurements: | sgpsirs20sE1.a0:
sgpsirsE5.b1:
sgpsirsE3.00:
sgpsirsE8.00:
sgpsirs20sE5.a0:
sgpsirsE2.b1:
sgpsirsE1.b1:
sgpsirsE5.00:
sgpsirsE1.00:
sgpsirs20sE2.a0:
sgpsirsE2.00:
sgpsirs20sE3.a0:
sgpsirsE3.b1:
sgpsirs20sE8.a0:
sgpsirsE8.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/20/2004 | 160 | 02/23/2004 | 50 |
| Subject: | SGP/SIRS/E9 - PSP dome contamination |
| DataStreams: | sgpsirsE9.00, sgpsirsE9.b1, sgpsirs20sE9.a0 |
| Description: | Measured values of diffuse shortwave downwelling radiation fluctuated below derived values of downwelling shortwave radiation by 50 W/m^2 during the afternoon hours under clear conditions. SMOS precipitation and wind speed data reveals rain and wind the night before on 02/20/03 0100 GMT probably contaminated the PSP dome with dirt. Precipitation of .25mm on 02/23/04 0300 seems to have effectively cleared the PSP dome since PSP data on 02/24/04 compares correctly to direct and diffuse components. |
| Measurements: | sgpsirs20sE9.a0:
sgpsirsE9.b1:
sgpsirsE9.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/20/2004 | 150 | 03/01/2004 | 130 |
| Subject: | SGP/SIRS/E11 - PSP dome contamination |
| DataStreams: | sgpsirsE11.00, sgpsirsE11.b1, sgpsirs20sE11.a0 |
| Description: | Measured values of diffuse shortwave downwelling radiation fluctuated below derived values of downwelling shortwave radiation during the afternoon hours under clear conditions, probably due to a dirty PSP dome. SMOS precipitation and wind speed data reveal rain and wind on 02/19/03 at 2300 GMT probably contaminated the PSP dome with dirt. Precipitation of .4mm on 02/29/04 1400 seems to have effectively cleared the PSP dome since PSP data on 03/01/04 compares correctly to direct and diffuse components. |
| Measurements: | sgpsirsE11.b1:
sgpsirsE11.00:
sgpsirs20sE11.a0:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/12/2004 | 1612 | 03/25/2004 | 160 |
| Subject: | SGP/SIRS/E2 - Reprocess: Incorrect shortwave radiometer calibration coefficients |
| DataStreams: | sgpsirsE2.00, sgpsirsE2.b1 |
| Description: | During the pyrgeometer instrument (PIR) changout a datalogger program was loaded with incorrect calibration coefficients for the shortwave instruments. The affected measurements were : downwelling diffuse (DD), upwelling shortwave(US), direct normal (NIP) and downwelling shortwave(DS) Recalculate irradiances by determining original mV signal and reapplying the correct calibration coefficients. For each one minute irradiance value perform the following calculations by instrument: DD(corrected) = (DD/107.24)*118.11 US(corrected) = (US/113.19)*118.21 NIP(corrected)= (NIP/120.17)*119.08 DS(corrected) = (DS/118.46)*117.33 |
| Measurements: | sgpsirsE2.b1:
sgpsirsE2.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 03/17/2004 | 1843 | 03/28/2004 | 30 |
| Subject: | SGP/SIRS/E5 - anomalously low NIP readings |
| DataStreams: | sgpsirsE5.00, sgpsirsE5.b1, sgpsirs20sE5.a0 |
| Description: | 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. |
| Measurements: | sgpsirsE5.b1:
sgpsirs20sE5.a0:
sgpsirsE5.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 03/15/2004 | 150 | 03/31/2004 | 120 |
| Subject: | SGP/SIRS/E8 - Possible Contamination of DS PSP instrument |
| DataStreams: | sgpsirsE8.00, sgpsirsE8.b1, sgpsirs20sE8.a0 |
| Description: | Downwelling hemispheric shortwave values drop at about 1500 GMT under clear sky conditions, typically from about 14:00GMT to 16:00GMT. This may be due to a dirty PSP but maintenance on 03/23/04 18:11 GMT revealed no more than typical light dust. The problem was essentially undetectable by 03/31/04 12:00. The time of day that the problem exists appears to be an exagerated PSP cosine response. No obvious reason presents why the problem appeared and then disappeared within this two week period. |
| Measurements: | sgpsirsE8.00:
sgpsirs20sE8.a0:
sgpsirsE8.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 03/30/2004 | 1430 | 04/06/2004 | 210 |
| Subject: | SGP/SIRS/E7 - PSP dome contamination |
| DataStreams: | sgpsirsE7.b1, sgpsirs20sE7.a0 |
| Description: | Values of hemispheric downwelling shortwave radiation differed from derived values by 45 W/m^2 on 03/30 around 1430 GMT under clear sky conditions due to dirt on the dome. Maintenance reported cleaning heavy dust from dome on 04/06 2030 GMT. |
| Measurements: | sgpsirs20sE7.a0:
sgpsirsE7.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 04/11/2004 | 120 | 05/05/2004 | 1645 |
| Subject: | SGP/SIRS/E5 - Dirt on PSP Dome |
| DataStreams: | sgpsirsE5.00, sgpsirsE5.b1, sgpsirs20sE5.a0 |
| Description: | 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. |
| Measurements: | sgpsirsE5.b1:
sgpsirs20sE5.a0:
sgpsirsE5.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 04/20/2004 | 1825 | 06/29/2004 | 1915 |
| Subject: | SGP/SIRS/E7 - Reprocess: Incorrect calibration coefficients applied to downwelling |
| DataStreams: | sgpsirsE7.00, sgpsirsE7.b1 |
| Description: | While attempting to correct calibration coefficients (see D040831.2) a new
datalogger program was loaded which applied the wrong serial number and
calibration coefficients to the downwelling longwave measurement.
Recalculate data from the b1 datastream using the thermopile output, case and
dome temperatures following this procedure:
1) Obtain the following variables from the b1 datafile for each minute:
Td = inst_down_long_shaded_dome_temp[degK]
Tc = inst_down_long_shaded_case_temp[degK]
Wnet = down_long_netir[W/m2]
2) For each one minute data entry in b1 backout the thermopile voltage
V[uV] = Wnet/K1(wrongly applied DIR cal coeffs) =
down_long_netir[W/m2]/0.24764[W/m2/uV]
3) Apply for each one minute data entry:
Winc [W/m^2] = K0+K1*V+ K2*Sigma*Tr^4 + K3*Sigma*(Td^4 - Tr^4)
where,
Winc= incoming radiation [W/m2]
V = PIR thermopile voltage [uV]
K0 = offset W/m2 = -14.61
K1 = 1/Responsivity of TP [W/m2*uV] = .24832
K2 = case emittance w/ thermistor correction [unitless] = 1.028
K3 = thermal conductance between dome and receiver & therm. correction [unitless] =
-2.249
Sigma= 5.67 x 10^-8 [W/(sq mK^4)] = Stephan-Boltzman Constant
Td = PIR dome thermistor temperature [deg K]
Tr = Tc + 0.0007044 * V
where 7.044e-4 is empirically derived for an Eppley PIR
Tc = PIR case receiver temperature [deg K]
Other datastream corrections that use the DIR measurements will require
similar corrections.
See the following web site for additional information on the pyrgeometer
equations, specifically sections 2.1(Single Calibration Factor Approach)
and 2.2 (Four Coefficient Calibration Approach)
http://www.arm.gov/docs/instruments/static/pyrg.html |
| Measurements: | sgpsirsE7.b1:
sgpsirsE7.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/10/2004 | 2050 | 04/20/2004 | 2015 |
| Subject: | SGP/SIRS/E1 - Reprocess: Incorrect shortwave radiometer calibration coefficients |
| DataStreams: | sgpsirsE1.00, sgpsirsE1.b1 |
| Description: | During the pyrgeometer instrument (PIR) changout a datalogger program was loaded with incorrect calibration coefficients for the shortwave instruments. The affected measurements (instruments) were : downwelling diffuse (8-48), upwelling shortwave(PSP), direct normal (NIP) and downwelling shortwave (PSP) Recalculate irradiances by determining original mV signal and reapplying the correct calibration coefficients. For each one minute irradiance value perform the following calculations by instrument: DD(corrected) = (DD/107.24)*109.01 US(corrected) = (US/113.19)*111.47 NIP(corrected)= (NIP/120.17)*114.82 DS(corrected) = (DS/118.46)*116.51 |
| Measurements: | sgpsirsE1.b1:
sgpsirsE1.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/20/2004 | 1845 | 04/20/2004 | 1825 |
| Subject: | SGP/SIRS/E7 - Reprocess: Incorrect shortwave radiometer calibration coefficients |
| DataStreams: | sgpsirsE7.00, sgpsirsE7.b1 |
| Description: | During the pyrgeometer instrument (PIR) changout a datalogger program was loaded with incorrect calibration coefficients for the shortwave instruments. The affected measurements (instruments) were : downwelling diffuse (8-48), upwelling shortwave(PSP), direct normal (NIP) and downwelling shortwave (PSP) Recalculate irradiances by determining original mV signal and reapplying the correct calibration coefficients. For each one minute irradiance value perform the following calculations by instrument: DD(corrected) = (DD/107.24)*108.50 US(corrected) = (US/113.19)*110.10 NIP(corrected)= (NIP/120.17)*122.26 DS(corrected) = (DS/118.46)*122.56 |
| Measurements: | sgpsirsE7.b1:
sgpsirsE7.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/10/2004 | 1825 | 04/20/2004 | 1825 |
| Subject: | SGP/SIRS/E8 - Reprocess: Incorrect shortwave radiometer calibration coefficients |
| DataStreams: | sgpsirsE8.00, sgpsirsE8.b1 |
| Description: | During the pyrgeometer instrument (PIR) changeout a datalogger program was loaded with incorrect calibration coefficients for the shortwave instruments. The affected measurements (instruments) were: downwelling diffuse (8-48), upwelling shortwave (PSP), direct normal (NIP) and downwelling shortwave (PSP) Recalculate irradiances by determining original mV signal and reapplying the correct calibration coefficients. For each one minute irradiance value perform the following calculations by instrument: DD(corrected) = (DD/107.24)*116.37 US(corrected) = (US/113.19)*121.78 NIP(corrected)= (NIP/120.17)*122.47 DS(corrected) = (DS/118.46)*122.34 |
| Measurements: | sgpsirsE8.00:
sgpsirsE8.b1:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/20/2004 | 1630 | 04/21/2004 | 1425 |
| Subject: | SGP/SIRS/E10 - Reprocess: Incorrect shortwave radiometer calibration coefficients |
| DataStreams: | sgpsirsE10.00, sgpsirsE10.b1 |
| Description: | During the pyrgeometer instrument (PIR) changeout a datalogger program was loaded with incorrect calibration coefficients for the shortwave instruments. The affected measurements (instruments) were: downwelling diffuse (8-48), upwelling shortwave (PSP), direct normal (NIP) and downwelling shortwave (PSP) Recalculate irradiances by determining original mV signal and reapplying the correct calibration coefficients. For SGP/SIRS/E10 and each one minute irradiance value perform the following calculations by instrument: DD(corrected) = (DD/107.24)*114.63 US(corrected) = (US/113.19)*117.46 NIP(corrected)= (NIP/120.17)*119.26 DS(corrected) = (DS/118.46)*122.78 |
| Measurements: | sgpsirsE10.b1:
sgpsirsE10.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 02/17/2004 | 1741 | 05/05/2004 | 00 |
| Subject: | SGP/SIRS/E11 - Reprocess: Incorrect shortwave radiometer calibration coefficients |
| DataStreams: | sgpsirsE11.00, sgpsirsE11.b1 |
| Description: | During the pyrgeometer instrument (PIR) changeout a datalogger program was loaded with incorrect calibration coefficients for the shortwave instruments. The affected measurements (instruments) were: downwelling diffuse (8-48), upwelling shortwave (PSP), direct normal (NIP) and downwelling shortwave (PSP) Field tech reports the datalogger program was corrected on 4/27/04. Archive data review shows this was not the case and the corrected datalogger program was uploaded sometime late day 5/4/04. The end date for this DQR was chosen to be 5/5/04 0000 the first full day of the correct datalogger program. Recalculate irradiances by determining original mV signal and reapplying the correct calibration coefficients. For each one minute irradiance value perform the following calculations by instrument: DD(corrected) = (DD/107.24)*123.27 US(corrected) = (US/113.19)*127.75 NIP(corrected)= (NIP/120.17)*126.69 DS(corrected) = (DS/118.46)*126.56 |
| Measurements: | sgpsirsE11.b1:
sgpsirsE11.00:
|
| Start Date | Start Time | End Date | End Time |
|---|---|---|---|
| 05/04/2004 | 00 | 06/22/2004 | 1855 |
| Subject: | SGP/SIRS/E11 - Reprocess: Incorrect calibration coefficients applied to upwelling longwave |
| DataStreams: | sgpsirsE11.00, sgpsirsE11.b1 |
| Description: | While correcting calibration coefficients (see D040831.5) a new datalogger program was
loaded which applied the wrong serial number and calibration coefficients to the upwelling
longwave measurements.
For a PIR mounted in an upwelling measurement orientation (UIR), the
thermopile output is extremely low compared to a downwelling PIR (DIR).
In addition, the UIR case and dome temperature differences are much
smaller than a DIR. This results in the pyrgeometer receiver radiation
term, Wr (NREL/Hickey equation) or Wc (Albrecht/Cox equation), dominating
all other terms of the infrared radiant flux equation.
Since the receiver radiation term uses coefficients in both forms of
the pyrgeometer equations nearly equal to 1.0 +- <1% the result is a
measurement of incoming longwave radiant flux relatively insensitive
to the installed instrument - so long as it is an Eppley PIR.
Evaluation of the problem data shows the expected error of the data
(before correction) will be within 1% - less than the uncertainty of
the instrument (Eppley PIR greater of 5% or 5 W/m2)
To correct the one minute UIR data found in the raw or b1 datastream follow
this procedure:
1) Obtain the following variables from the b1 datafile for each minute:
Td = inst_up_long_dome_temp[degK]
Tc = inst_up_long_case_temp[degK]
Wnet = up_long_netir[W/m2]
2) For each one minute data entry in b1 backout the thermopile voltage
V[uV] = Wnet/K1(wrongly applied UIR cal coeffs) =
up_long_netir[W/m2]/0.24832[W/m2/uV]
3) Apply for each one minute data entry:
Winc [W/m^2] = K0+K1*V+ K2*Sigma*Tr^4 + K3*Sigma*(Td^4 - Tr^4)
where,
Winc= incoming radiation [W/m2]
V = PIR thermopile voltage [uV]
K0 = offset W/m2 = -6.93
K1 = 1/Responsivity of TP [W/m2*uV] = .24764
K2 = case emittance w/ thermistor correction [unitless] = 1.010
K3 = thermal conductance between dome and receiver & therm. correction [unitless] =
-3.886
Sigma= 5.67 x 10^-8 [W/(sq mK^4)] = Stephan-Boltzman Constant
Td = PIR dome thermistor temperature [deg K]
Tr = Tc + 0.0007044 * V
where 7.044e-4 is empirically derived for an Eppley PIR
Tc = PIR case receiver temperature [deg K]
Other datastream corrections that use the UIR measurements will require
similar corrections.
See the following web site for additional information on the pyrgeometer
equations, specifically sections 2.1(Single Calibration Factor Approach)
and 2.2 (Four Coefficient Calibration Approach)
http://www.arm.gov/docs/instruments/static/pyrg.html |
| Measurements: | sgpsirsE11.b1:
sgpsirsE11.00:
|