Pyranometer Thermal Offset: Measurement and Analysis

G. Sanchez Department of Physics, University of Extremadura, Badajoz, Spain

Search for other papers by G. Sanchez in
Current site
Google Scholar
PubMed
Close
,
A. Serrano Department of Physics, University of Extremadura, Badajoz, Spain

Search for other papers by A. Serrano in
Current site
Google Scholar
PubMed
Close
,
M. L. Cancillo Department of Physics, University of Extremadura, Badajoz, Spain

Search for other papers by M. L. Cancillo in
Current site
Google Scholar
PubMed
Close
, and
J. A. Garcia Department of Physics, University of Extremadura, Badajoz, Spain

Search for other papers by J. A. Garcia in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The reliable estimation of the radiative forcing and trends in radiation requires very accurate measurements of global and diffuse solar irradiance at the earth’s surface. To improve measurement accuracy, error sources such as the pyranometer thermal offset should be thoroughly evaluated. This study focuses on the measurement and analysis of this effect in a widely used type of pyranometer. For this aim, a methodology based on capping the pyranometer has been used and different criteria for determining the thermal offset have been applied and compared. The thermal offset of unventilated pyranometers for global and diffuse irradiance has been measured under a wide range of cloud, ambient temperature, wind speed, and radiation conditions. Significant differences in absolute values and variability have been observed between daytime and nighttime, advising against correcting the thermal offset effect based only on nighttime values. Notable differences in the thermal offset between cloudy and cloud-free conditions have been also observed. The main results show that the ambient temperature, the radiation, and its direct/diffuse partitioning are the variables more related to the daytime thermal offset.

Corresponding author address: Guadalupe Sanchez Hernandez, Department of Physics, University of Extremadura, Avenida de Elvas s/n, 06071 Badajoz, Spain. E-mail: guadalupesh@unex.es

Abstract

The reliable estimation of the radiative forcing and trends in radiation requires very accurate measurements of global and diffuse solar irradiance at the earth’s surface. To improve measurement accuracy, error sources such as the pyranometer thermal offset should be thoroughly evaluated. This study focuses on the measurement and analysis of this effect in a widely used type of pyranometer. For this aim, a methodology based on capping the pyranometer has been used and different criteria for determining the thermal offset have been applied and compared. The thermal offset of unventilated pyranometers for global and diffuse irradiance has been measured under a wide range of cloud, ambient temperature, wind speed, and radiation conditions. Significant differences in absolute values and variability have been observed between daytime and nighttime, advising against correcting the thermal offset effect based only on nighttime values. Notable differences in the thermal offset between cloudy and cloud-free conditions have been also observed. The main results show that the ambient temperature, the radiation, and its direct/diffuse partitioning are the variables more related to the daytime thermal offset.

Corresponding author address: Guadalupe Sanchez Hernandez, Department of Physics, University of Extremadura, Avenida de Elvas s/n, 06071 Badajoz, Spain. E-mail: guadalupesh@unex.es
Save
  • Bush, B. C., Valero F. P. J. , and Simpson A. S. , 2000: Characterization of thermal effects in pyranometers: A data correction algorithm for improved measurement of surface insolation. J. Atmos. Oceanic Technol., 17, 165175, doi:10.1175/1520-0426(2000)017<0165:COTEIP>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Carlund, T., 2013: Baltic region pyrheliometer comparison 2012: 21 May–1 June 2012, Norrköping, Sweden, World Meteorological Organization Rep., Instruments and Observing Methods Rep. 112, 40 pp.

  • Cess, R. D., Qian T. , and Sun M. , 2000: Consistency tests applied to the measurement of total, direct, and diffuse shortwave radiation at the surface. J. Geophys. Res., 105, 24 881–24 887, doi:10.1029/2000JD900402.

    • Search Google Scholar
    • Export Citation
  • Dutton, E. G., Michalsky J. J. , Stoffel T. , Forgan B. W. , Hickey J. , Nelson D. W. , Alberta T. L. , and Reda I. , 2001: Measurement of broadband diffuse solar irradiance using current commercial instrumentation with a correction for thermal offset errors. J. Atmos. Oceanic Technol., 18, 297314, doi:10.1175/1520-0426(2001)018<0297:MOBDSI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Garratt, J. R., 1994: Incoming shortwave fluxes at the surface—A comparison of GCM results with observations. J. Climate, 7, 7280, doi:10.1175/1520-0442(1994)007<0072:ISFATS>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Gulbrandsen, A., 1978: On the use of pyranometers in the study of spectral solar radiation and atmospheric aerosols. J. Appl. Meteor., 17, 899904, doi:10.1175/1520-0450(1978)017<0899:OTUOPI>2.0.CO;2.

    • Search Google Scholar
    • Export Citation
  • Haeffelin, M., Kato S. , Smith A. M. , Rutledge C. K. , Charlock T. P. , and Mahan J. R. , 2001: Determination of the thermal offset of the Eppley precision spectral pyranometer. Appl. Opt., 40, 472484, doi:10.1364/AO.40.000472.

    • Search Google Scholar
    • Export Citation
  • Halthore, R. N., Nemesure S. , Schwartz S. E. , Irme D. G. , Berk A. , Dutton E. G. , and Bergin M. H. , 1998: Models overestimate diffuse clear-sky surface irradiance: A case for excess atmospheric absorption. Geophys. Res. Lett., 25, 35913594, doi:10.1029/98GL52809.

    • Search Google Scholar
    • Export Citation
  • Ji, Q., and Tsay S.-C. , 2010: A novel nonintrusive method to resolve the thermal dome effect of pyranometers: Instrumentation and observational basis. J. Geophys. Res., 115, D00K21, doi:10.1029/2009JD013483.

    • Search Google Scholar
    • Export Citation
  • Kato, S., Ackerman T. P. , Clothiaux E. E. , Mather J. H. , Mace G. G. , Wesely M. L. , Murcray F. , and Michalsky J. , 1997: Uncertainties in modeled and measured clear-sky surface shortwave irradiance. J. Geophys. Res., 102, 25 88125 898, doi:10.1029/97JD01841.

    • Search Google Scholar
    • Export Citation
  • Kipp and Zonen, 2000: Instruction manual for CM11 and CM14 pyranometer/albedometer, version 0805, 62 pp. [Available online at http://www.kippzonen.com/Download/48/CM-11-Pyranometer-CM-14-Albedometer-Manual.]

  • Kipp and Zonen, 2003: Instruction manual for CG1 and CG2 pyrgeometer and net pyrgeometer, version 0204, 63 pp. [Available online at http://www.kippzonen.com/Download/31/CG-1-CG-2-Pyrgeometers-Manual.]

  • Long, C. N., Younkin K. , Gaustad K. L. , and Augustine J. A. , 2003: An improvement daylight correction for IR loss in ARM diffuse SW measurements. Proceedings of the Thirteenth Atmospheric Radiation Measurement Science Team Meeting, D. A. Carrothers, Ed., U.S. Department of Energy, 1–8.

  • Michalsky, J. J., and Coauthors, 2005: Toward the development of a diffuse horizontal shortwave irradiance working standard. J. Geophys. Res., 110, D06107, doi:10.1029/2004JD005265.

    • Search Google Scholar
    • Export Citation
  • Pachauri, R. K., and Reisinger A. , Eds., 2007: Climate Change 2007: Synthesis Report. Cambridge University Press, 104 pp.

  • Patsalides, M., and Coauthors, 2007: The effect of solar irradiance on the power quality behaviour of grid connected photovoltaic systems. Proc. Int. Conf. on Renewable Energy and Power Quality (ICREPQ’07), Seville, Spain, EA4EPQ, 284. [Available online at http://www.icrepq.com/icrepq07/284-patsalides.pdf.]

  • Patsalides, M., Stavrou A. , Efthymiou V. , and Georghiou G. E. , 2012: Towards the establishment of maximum PV generation limits due to power quality constraints. Int. J. Electr. Power Energy Syst., 42, 285298, doi:10.1016/j.ijepes.2012.03.043.

    • Search Google Scholar
    • Export Citation
  • Philipona, R., 2002: Underestimation of solar global and diffuse radiation measured at Earth’s surface. J. Geophys. Res., 107, 4654, doi:10.1029/2002JD002396.

    • Search Google Scholar
    • Export Citation
  • Reda, I., Stoffel T. , and Myers D. , 2003: A method to calibrate a solar pyranometer for measuring reference diffuse irradiance. Sol. Energy, 74, 103112, doi:10.1016/S0038-092X(03)00124-5.

    • Search Google Scholar
    • Export Citation
  • Smith, A. M., 1999: Prediction and measurement of thermal exchange within pyranometers. M.S. thesis, Dept. of Mechanical Engineering, Virginia Polytechnic Institute and State University, 64 pp.

  • Valero, F. P., and Bush B. C. , 1999: Measured and calculated clear-sky solar radiative fluxes during the Subsonic Aircraft Contrail and Cloud Effects Special Study (SUCCESS). J. Geophys. Res., 104, 27 38727 398, doi:10.1029/1999JD900947.

    • Search Google Scholar
    • Export Citation
  • Vignola, F., Long C. N. , and Reda I. , 2007: Evaluation of methods to correct for IR loss in Eppley PSP diffuse measurements. Optical Modeling and Measurements for Solar Energy Systems, D. R. Myers, Ed., International Society for Optical Engineering (SPIE Proceedings, Vol. 6652), 66520A, doi:10.1117/12.73447.

  • Vignola, F., Long C. N. , and Reda I. , 2008: Modeling IR radiative loss from Eppley PSP Pyranometers. Optical Modeling and Measurements for Solar Energy Systems II, B. K. Tsai, Ed., International Society for Optical Engineering (SPIE Proceedings, Vol. 7046), 70460E, doi:10.1117/12.796457.

  • Vignola, F., Long C. N. , and Reda I. , 2009: Testing a model of IR radiative losses. Optical Modeling and Measurements for Solar Energy Systems III, B. K. Tsai, Ed., International Society for Optical Engineering (SPIE Proceedings, Vol. 7410), 741003, doi:10.1117/12.826325.

  • Wardle, D. I., and Coauthors, 1996: Improved measurements of solar irradiance by means of detailed pyranometer characterisation. Int. Energy Agency Rep. IEA-SHCP-9C-2, 364 pp.

  • Wild, M., 2005: Solar radiation budgets in atmospheric model intercomparison from a surface perspective. Geophys. Res. Lett., 32, L07704, doi:10.1029/2005GL022421.

    • Search Google Scholar
    • Export Citation
  • Wild, M., 2009: Global dimming and brightening: a review. J. Geophys. Res., 114, D00D16, doi:10.1029/2008JD011470.

  • Wild, M., Ohmura A. , Gilgen H. , Roeckner E. , Giorgetta M. , and Morcrette J. J. , 1998: The disposition of radiative energy in the global climate system: GCM-calculated versus observational estimates. Climate Dyn., 14, 853886, doi:10.1007/s003820050260.

    • Search Google Scholar
    • Export Citation
  • Wild, M., and Coauthors, 2005: From dimming to brightening: Decadal changes in surface solar radiation. Science, 308, 847850, doi:10.1126/science.1103215.

    • Search Google Scholar
    • Export Citation
  • Wild, M., Folini D. , Schar C. , Loeb N. , Dutton E. G. , and Konig-Langlo G. , 2013: The global energy balance from a surface perspective. Climate Dyn., 40, 31073134, doi:10.1007/s00382-012-1569-8.

    • Search Google Scholar
    • Export Citation
  • WMO, 2008: Guide to meteorological instruments and methods of observation. 7th ed. No. 8, Secretariat of the World Meteorological Organization, 681 pp.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 1087 284 25
PDF Downloads 965 257 26