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Title: Absolute Cavity Pyrgeometer (ACP) and InfraRed Integrating Sphere (IRIS) Comparisons for CIMO Meeting in the National Physical Laboratory (NPL), UK

Abstract

Results of four comparisons between NREL's ACPs and POMD's IRISs, and absolute atmospheric-longwave-irradiance versus the Irradiance measured by PIR with traceability to WISG.

Authors:
 [1]
  1. National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Publication Date:
Research Org.:
National Renewable Energy Lab. (NREL), Golden, CO (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
1408282
Report Number(s):
NREL/PR-1900-70458
DOE Contract Number:
AC36-08GO28308
Resource Type:
Conference
Resource Relation:
Conference: Presented at CIMO, 15-17 November 2017, London, United Kingdom
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION; ACP; IRIS; Pyrgeometer; absolute atmospheric longwave irradiance

Citation Formats

Reda, Ibrahim M. Absolute Cavity Pyrgeometer (ACP) and InfraRed Integrating Sphere (IRIS) Comparisons for CIMO Meeting in the National Physical Laboratory (NPL), UK. United States: N. p., 2017. Web.
Reda, Ibrahim M. Absolute Cavity Pyrgeometer (ACP) and InfraRed Integrating Sphere (IRIS) Comparisons for CIMO Meeting in the National Physical Laboratory (NPL), UK. United States.
Reda, Ibrahim M. Mon . "Absolute Cavity Pyrgeometer (ACP) and InfraRed Integrating Sphere (IRIS) Comparisons for CIMO Meeting in the National Physical Laboratory (NPL), UK". United States. doi:. https://www.osti.gov/servlets/purl/1408282.
@article{osti_1408282,
title = {Absolute Cavity Pyrgeometer (ACP) and InfraRed Integrating Sphere (IRIS) Comparisons for CIMO Meeting in the National Physical Laboratory (NPL), UK},
author = {Reda, Ibrahim M},
abstractNote = {Results of four comparisons between NREL's ACPs and POMD's IRISs, and absolute atmospheric-longwave-irradiance versus the Irradiance measured by PIR with traceability to WISG.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Nov 06 00:00:00 EST 2017},
month = {Mon Nov 06 00:00:00 EST 2017}
}

Conference:
Other availability
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  • Presenting results of five comparisons between ACPs and IRISs and the difference between the longwave irradiance measured by the ACPs and IRISs versus the average irradiance measured by the WISG. The process of CIMO recommendation to establish the world reference for measuring the atmospheric longwave irradiance with traceability to the International System of Units (SI) is also presented.
  • The ACP and IRIS are developed to establish a world reference for calibrating pyrgeometers with traceability to SI units. The two radiometers are unwindowed with negligible spectral dependence, and traceable to SI units through the temperature scale (ITS-90). The first outdoor comparison between the two designs was held from January 28 to February 8, 2013 at the Physikalisch-Metorologisches Observatorium Davos (PMOD). The difference between the irradiance measured by ACP and that of IRIS was within 1 W/m2. A difference of 5 W/m2 was observed between the irradiance measured by ACP&IRIS and that of the interim World Infrared Standard Group (WISG).
  • The Absolute Cavity Pyrgeometer (ACP) and InfraRed Integrating Sphere radiometer (IRIS) are developed to establish a world reference for calibrating pyrgeometers with traceability to SI units. The two radiometers are un-windowed with negligible spectral dependence, and traceable to SI units through the temperature scale (ITS-90). The second outdoor comparison between the two designs was held from September 30 to October 11, 2013 at the Physikalisch-Metorologisches Observatorium Davos (PMOD). The difference between the irradiance measured by ACP and that of the IRIS was within 1 W/m2 (3 IRISs: PMOD + Australia + Germany). From the first and second comparisons, a differencemore » of 4-6 W/m2 was observed between the irradiance measured by ACP&IRIS and that of the interim World Infrared Standard Group (WISG). This presentation includes results from the first and second comparison in an effort to establish the world reference for pyrgeometer calibrations, a key deliverable for the World Meteorological Organization (WMO), and the DOE-ASR.« less
  • Accurate and traceable atmospheric longwave irradiance measurements are required for understanding radiative impacts on the Earth's energy budget. The standard to which pyrgeometers are traceable is the interim World Infrared Standard Group (WISG), maintained in the Physikalisch-Meteorologisches Observatorium Davos (PMOD). The WISG consists of four pyrgeometers that were calibrated using Rolf Philipona's Absolute Sky-scanning Radiometer [1]. The Atmospheric Radiation Measurement (ARM) facility has recently adopted the WISG to maintain the traceability of the calibrations of all Eppley precision infrared radiometer (PIR) pyrgeometers. Subsequently, Julian Grobner [2] developed the infrared interferometer spectrometer and radiometer (IRIS) radiometer, and Ibrahim Reda [3] developedmore » the absolute cavity pyrgeometer (ACP). The ACP and IRIS were developed to establish a world reference for calibrating pyrgeometers with traceability to the International System of Units (SI). The two radiometers are unwindowed with negligible spectral dependence, and they are traceable to SI units through the temperature scale (ITS-90). The two instruments were compared directly to the WISG three times at PMOD and twice at the Southern Great Plains (SGP) facility to WISG-traceable pyrgeometers. The ACP and IRIS agreed within +/- 1 W/m2 to +/- 3 W/m2 in all comparisons, whereas the WISG references exhibit a 2-5 Wm2 low bias compared to the ACP/IRIS average, depending on the water vapor column, as noted in Grobner et al. [4]. Consequently, a case for changing the current WISG has been made by Grobner and Reda. However, during the five comparisons the column water vapor exceeded 8 mm. Therefore, it is recommended that more ACP and IRIS comparisons should be held under different environmental conditions and water vapor column content to better establish the traceability of these instruments to SI with established uncertainty.« less
  • Advancing climate change research requires accurate and traceable measurement of the atmospheric longwave irradiance. Current measurement capabilities are limited to an estimated uncertainty of larger than +/- 4 W/m2 using the interim World Infrared Standard Group (WISG). WISG is traceable to the Systeme international d'unites (SI) through blackbody calibrations. An Absolute Cavity Pyrgeometer (ACP) is being developed to measure absolute outdoor longwave irradiance with traceability to SI using the temperature scale (ITS-90) and the sky as the reference source, instead of a blackbody. The ACP was designed by NREL and optically characterized by the National Institute of Standards and Technologymore » (NIST). Under clear-sky and stable conditions, the responsivity of the ACP is determined by lowering the temperature of the cavity and calculating the rate of change of the thermopile output voltage versus the changing net irradiance. The absolute atmospheric longwave irradiance is then calculated with an uncertainty of +/- 3.96 W/m2 with traceability to SI. The measured irradiance by the ACP was compared with the irradiance measured by two pyrgeometers calibrated by the World Radiation Center with traceability to the WISG.« less