Coronavirus Information for the UC San Diego Community

Our leaders are working closely with federal and state officials to ensure your ongoing safety at the university. Stay up to date with the latest developments. Learn more.

A review of protocols for fiducial reference measurements of downwelling irradiance for the validation of satellite remote sensing data over water

TitleA review of protocols for fiducial reference measurements of downwelling irradiance for the validation of satellite remote sensing data over water
Publication TypeJournal Article
Year of Publication2019
AuthorsRuddick K.G, Voss K., Banks A.C, Boss E., Castagna A., Frouin R., Hieronymi M., Jamet C., Johnson B.C, Kuusk J., Lee Z., Ondrusek M., Vabson V., Vendt R.
Volume11
Date Published2019/08
Type of ArticleReview
Accession NumberWOS:000482442800006
Keywordscalibration; downwelling irradiance; Fiducial Reference; measurements; network; ocean-color; radiation; radiometer; reflectance; Remote sensing; satellite validation; solar irradiance; spectrometer; surface; system; water reflectance
Abstract

This paper reviews the state of the art of protocols for the measurement of downwelling irradiance in the context of Fiducial Reference Measurements (FRM) of water reflectance for satellite validation. The measurement of water reflectance requires the measurement of water-leaving radiance and downwelling irradiance just above water. For the latter, there are four generic families of method, using: (1) an above-water upward-pointing irradiance sensor; (2) an above-water downward-pointing radiance sensor and a reflective plaque; (3) a Sun-pointing radiance sensor (sunphotometer); or (4) an underwater upward-pointing irradiance sensor deployed at different depths. Each method-except for the fourth, which is considered obsolete for the measurement of above-water downwelling irradiance-is described generically in the FRM context with reference to the measurement equation, documented implementations, and the intra-method diversity of deployment platform and practice. Ideal measurement conditions are stated, practical recommendations are provided on best practice, and guidelines for estimating the measurement uncertainty are provided for each protocol-related component of the measurement uncertainty budget. The state of the art for the measurement of downwelling irradiance is summarized, future perspectives are outlined, and key debates such as the use of reflectance plaques with calibrated or uncalibrated radiometers are presented. This review is based on the practice and studies of the aquatic optics community and the validation of water reflectance, but is also relevant to land radiation monitoring and the validation of satellite-derived land surface reflectance.

DOI10.3390/rs11151742
Student Publication: 
No