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Characterization of Thermal Parameters for Improving Pyranometer and Pyrgeometer MeasurementsSince the introduction of thermopile, pyranometers (solar, e.g., 0.3-3.0 micrometers) and pyrgeometers (terrestrial, e.g., 4-50 micrometers) have become instruments commonly used for measuring the broadband hemispherical irradiances at the surface in a long-term, monitoring mode for decades. These commercially available radiometers have been manufactured in several countries such as from the United States, Asia, and Europe, and are generally reliable and economical. These worldwide distributions of surface measurements become even more important in the era of Earth remote sensing in studying climate change. However, recent studies from field campaigns have pointed out that erroneous factors (e.g., temperature gradients between the filter dome and detector, emissivity of the thermopile) are responsible for the unacceptable level of uncertainty (e.g., 20 W m(exp -2)). Using a newly developed instrument of Quantum Well Infrared Photodetector (QWTP), we have characterized the brightness temperature fields of pyranometers and pyrgeometers under various sky conditions. The QWIP is based on the superlattice (GaAs/AlGaAs) technology and has a noise equivalent temperature (NEAT) less than 0.1 K. The quality of pyranometer and pyrgeometer measure- ments can be improved largely by applying proper knowledge of the thermal parameters affecting the operation of the thermopile systems. Data correction procedure and algorithm will be presented and discussed.
Document ID
20000074256
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Tsay, Si-Chee
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Jhabvala, Murzy D.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Ji, Qiang
(Science Systems and Applications, Inc. United States)
Rapshun, David
(Raytheon STX Corp. United States)
Shu, Peter K.
(NASA Goddard Space Flight Center Greenbelt, MD United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 2000
Subject Category
Instrumentation And Photography
Meeting Information
Meeting: Remote Sensing of Environment
Location: Cape Town
Country: South Africa
Start Date: March 27, 2000
End Date: March 31, 2000
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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