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Influence of cosine corrector and UAS platform dynamics on airborne spectral irradiance measurements


Bendig, J and Gautam, D and Malenovsky, Z and Lucieer, A, Influence of cosine corrector and UAS platform dynamics on airborne spectral irradiance measurements, Proceedings from the Geoscience and Remote Sensing, IEEE International Symposium, 22-27 July 2018, Valencia, Spain, pp. 8826-8829. ISBN 9781538671504 (In Press) [Refereed Conference Paper]

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Measuring solar-induced chlorophyll fluorescence from smallsized Unmanned Aircraft Systems (UAS) can potentially fill the scaling gap between ground-based and airborne/spaceborne observations. These measurements require well calibrated, high-spectral resolution spectroradiometers and precise measurements of vegetation radiance and incoming solar irradiance. Here we present a system equipped with a spectroradiometer with a split optical path that measures incoming irradiance through a cosine corrector/diffuser. The objectives of this study are to characterise cosine corrected solar irradiance measurements with regard to sensor homogeneity and possible offset from an ideal cosine response. We further suggest a methodology to calculate a corrected zenith angle that accounts for changing sensor orientation due to pitch, roll and heading of the UAS platform during flight. We found that the cosine corrector is sufficiently homogeneous, thus measurements are independent of UAS heading. The response follows the cosine law for zenith angles, however, the sensor significantly underestimated irradiance for zenith angles >10◦ , with overall cosine errors ranging from 0.991 to 1.229. Yet, typical in-flight platform pitch and roll angles produce a zenith angle offset of up to 6 ◦ in low wind conditions. Cosine sensor measurements corrected for the zenith angle offset and the cosine error resulted in a 1.7 % change in irradiance.

Item Details

Item Type:Refereed Conference Paper
Keywords:pectroradiometer, solar-induced chloro- phyll fluorescence, unmanned aircraft system, sun zenith an- gle, irradiance cosine corrector
Research Division:Engineering
Research Group:Geomatic Engineering
Research Field:Photogrammetry and Remote Sensing
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in Technology
UTAS Author:Bendig, J (Ms Juliane Bendig)
UTAS Author:Gautam, D (Mr Deepak Gautam)
UTAS Author:Malenovsky, Z (Dr Zbynek Malenovsky)
UTAS Author:Lucieer, A (Professor Arko Lucieer)
ID Code:127581
Year Published:In Press
Funding Support:Australian Research Council (FT160100477)
Deposited By:Geography and Spatial Science
Deposited On:2018-08-03
Last Modified:2019-06-11

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