Determination Of The Thermal Offset Of The Eppley Precision Spectral Pyranometer

Simple item page
dc.contributor.authorHaeffelin, M.en
dc.contributor.authorKato, S.en
dc.contributor.authorSmith, A. M.en
dc.contributor.authorRutledge, C. K.en
dc.contributor.authorCharlock, T. P.en
dc.contributor.authorMahan, J. Roberten
dc.contributor.departmentMechanical Engineeringen
dc.date.accessed2014-02-24en
dc.date.accessioned2014-04-04T15:12:14Zen
dc.date.available2014-04-04T15:12:14Zen
dc.date.issued2001-10-01en
dc.description.abstractEppley's precision spectral pyranometer (PSP) is used in networks around the world to measure down-welling diffuse and global solar irradiance at the surface of the Earth. In recent years several studies have shown significant discrepancy between irradiances measured by pyranometers and those computed by atmospheric radiative transfer models. Pyranometer measurements have been questioned because observed diffuse irradiances sometimes are below theoretical minimum values for a pure molecular atmosphere, and at night the instruments of ten produce nonzero signals ranging between +5 and -10 W m(-2). We install thermistor sondes in the body of a PSP as well as on its inner dome to monitor the temperature gradients within the instrument, and we operate a pyrgeometer (PIR) instrument side by side with the PSP. We derive a relationship between the PSP output and thermal radiative exchange by the dome and the detector and a relationship between the PSP output and the PIR thermopile output (net-IR). We determine the true PSP offset by quickly capping the instrument at set time intervals. For a ventilated and shaded PSP, the thermal offset can reach -15 W m(-2) under clear skies, whereas it remains close to zero for low overcast clouds. We estimate the PSP thermal offset by two methods: (1) using the PSP temperatures and (2) using the PIR net-IR signal. The offset computed from the PSP temperatures yields a reliable estimate of the true offset (+/-1 W m(-2)). The offset computed from net-IR is consistent with the true offset at night and under overcast skies but predicts only part of the true range under clear skies. (C) 2001 Optical Society of America.en
dc.format.mimetypeapplication/pdfen
dc.identifier.citationMartial Haeffelin, Seiji Kato, Amie M. Smith, C. Ken Rutledge, Thomas P. Charlock, and J. Robert Mahan, "Determination of the Thermal Offset of the Eppley Precision Spectral Pyranometer," Appl. Opt. 40, 472-484 (2001). doi: 10.1364/ao.40.000472en
dc.identifier.doihttps://doi.org/10.1364/ao.40.000472en
dc.identifier.issn1559-128Xen
dc.identifier.urihttp://hdl.handle.net/10919/46887en
dc.identifier.urlhttp://www.opticsinfobase.org/ao/abstract.cfm?URI=ao-40-4-472en
dc.language.isoen_USen
dc.publisherOptical Society of Americaen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectSurface shortwave irradianceen
dc.subjectRadiationen
dc.subjectAtmosphereen
dc.subjectScatteringen
dc.titleDetermination Of The Thermal Offset Of The Eppley Precision Spectral Pyranometeren
dc.title.serialApplied Opticsen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
ao-40-4-472.pdf
Size:
856.08 KB
Format:
Adobe Portable Document Format
Description:
Main article
Download

Collections

Scholarly Works, Mechanical Engineering