Recent Updates about the Absolute Cavity Pyrgeometer (ACP), InfraRed Integrating Sphere (IRIS), and Atmospheric Emitted Radiance Interferometer (AERI) Comparisons

Ibrahim Reda, Julian Gröbner, and Dave TurnerBSRN 2018 WorkshopJuly 19, 2018

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Overview

• Results of five comparisons between ACPs and IRISs.• Difference between the longwave irradiance

measured by the ACPs and IRISs versus the irradiance measured by the WISG.

• The longwave irradiance measured by the ACPs, IRISs, and AERI versus the irradiance measured by the WISG.

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Results of First Comparison between ACPs and IRISs-Davos

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0:00:00 0:28:48 0:57:36 1:26:24 1:55:12 2:24:00 2:52:48 3:21:36 3:50:24

Irrad

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Time

Average Irradiance of Two IRISs&ACP95F3 or 96F3 versus the WISG Average Irradiance at night on Feb. 5, 2013

(~8 mm H2O vapor column)

Av IRISs&ACP95F3 Av IRISs&ACP96F3 WISG

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Results of Second Comparison between ACPs and IRISs-Davos

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0:00:15 0:25:15 1:14:08 19:00:24 20:22:26 20:47:26 21:27:29 21:52:29 22:46:19 23:11:19 23:51:15

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Average Irradiance of Two IRISs&ACP96F3 versus the WISG Average Irradiance on Oct. 2&3, 2013(~15 mm H2O vapor column)

Av IRISs&ACP96F3 WISG

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Results of Third Comparison between ACPs and IRISs-Davos

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18:41:31 20:47:31 22:07:31 22:57:31 23:47:31 0:37:31 1:27:31 2:17:31 3:07:31 19:13:31 21:32:31 22:22:31 23:12:31

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Average Irradiance of Four IRISs&ACP95F3 or ACP96F3 versus the WISG Average From September 28 to October 16, 2015

(~10 mm H2O vapor column)

AV IRISs&ACP96F3 AV IRISs&ACP95F3 WISG

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Results of Fourth Comparison between ACPs and IRISs-SGP-Phase 1

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20:51:42 23:21:32 2:19:53 22:13:49 0:50:32 3:28:56 18:38:31 23:11:46 1:50:41 4:26:47

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CST

Average of Three IRISs & Two ACPs Versus PIR-31197F3 with traceability to WISG on October 16, 17, 18, 24, 25, 26, 2017

AV IRISs&ACPs WISG

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Results of Fifth Comparison between ACPs and IRISs-SGP-Phase 2

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0:00:24 0:29:24 0:54:54 1:20:54 2:13:17 2:49:17 3:52:03 4:30:03 5:16:03 6:05:28

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Average of Three IRISs and Two ACPs Versus PIR-30475F3 with traceability to WISG on November 28, 2017

Average ACPs&IRISs WISG

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Summary of the Five comparisons

W/m2 First Second Third Fourth Fifth

Average difference between ACPs&IRISs 0.10 0.31 -1.17 -1.58 -1.77

StDev of Difference 0.08 0.65 0.70 1.15 0.88

Difference within 95% 0.19 1.34 1.82 2.79 2.50

Average of ACPs&IRISs - WISG 3.93 6.14 3.82 3.50 6.50

StDev of Difference 0.97 0.76 0.67 0.81 0.66

Difference within 95% 4.38 6.33 4.05 3.86 6.63

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Results of Comparison between ACPs, IRISs, and AERI at SGP

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Results of Comparison between ACPs, IRISs, and AERI at SGP

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Results of Comparison between ACPs, IRISs, and AERI at SGP

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Results of Comparison between ACPs, IRISs, and AERI at SGP

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Results of Comparison between ACPs, IRISs, and AERI at SGP

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Results of Comparison between ACPs, IRISs, and AERI at SGP

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Water Vapor effect on Irradiance difference (WISG minus IRIS) at PMOD

Results

Average Offset (IWV>10) -4.1 ± 1.5 Wm-2

Gradient (IWV<10) -0.45 ± 0.1 Wm-2mm-1IWV

WISG 1 WISG 2 WISG 3

WISG 4

Night averages

IRIS u95

From J. Gröbner et al., JGR, 2014

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• The difference between the irradiance measuredby the ACPs, IRISs, and AERI varied from 0.2W/m2 to 2.5 W/m2 based on the atmosphericconditions, which is within the stateduncertainties of ±3 W/m2.

• The irradiance measured by the WISG is lowerthan the average irradiance measured by ACPsand IRISs, magnitude of the difference variedfrom 4.4 W/m2 to 6.6 W/m2 depending on theintegrated water vapor.

Conclusion

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WMO CIMO Task Team on Radiation References

• The first session of the World Meteorological Organization (WMO) Commission for Instruments and Methods of Observation Commission (CIMO) Task Team on Radiation References (TT) was held in the National Physical Laboratory (NPL) from November 15 to 17, 2017 in Teddington, United Kingdom.• The meeting focused on the traceability of terrestrial radiation measurements. It reviewed and evaluated recent developments of reference instruments for terrestrial radiation, and developed recommendations to the attention of CIMO on the appropriateness, requirements and timeliness for a possible future modification of the current reference.• Relevant recommendations from the TT will be submitted to the CIMO MG (26-29 March 2018), and most likely to CIMO-17 session (12-16 October 2018, Amsterdam) for endorsement. The report of the TT meeting will encompass all the recommendations.

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Newton’s Apple Tree in National Physical Laboratory, UK, London-November 2017

Nigel, Reda, Isabelle, Bruce, Julian, Peter, Alison, Nozumo

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

www.nrel.gov

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiencyand Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Thank YouContact :Ibrahim Reda Ibrahim.Reda@nrel.gov

This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by U.S. Department of Energy Office of Energy Efficiency and Renewable Energy. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.

NREL/PR-1900-71819