Graphical Abstract
Takamura, T. and P. Khatri, 2021: Uncertainties in radiation measurement using a rotating shadow- band spectroradiometer. J. Meteor. Soc. Japan, 99, 1547-1561.
https://doi.org/10.2151/jmsj.2021-075
Graphical Abstract
Published
Plain Language Summary: A spectral radiometer with a shadow-band system can give two components simultaneously, direct (spDNI) and diffuse (spDHI), of solar radiation by using a combination of different band positions. These components estimated by a current analysis method have some errors due to imperfect correction of radiation shadowed by band. We discuss the errors using typical aerosol models under a realistic operational condition of the instrument. As a fundamental system error, it is clear that the valid range of the band angle is less than 72 deg within 2 % error in correction for a common setting of the instrument. And errors of optical depth ( τ ) as well as spDNI and spDHI are estimated, depending on their aerosol optical thickness (AOD).
Highlights:
- A correction coefficient 𝐶fwd for forward scattering shadowed by band is introduced and discussed under realistic atmospheric and instrumental conditions.
- Errors on spDNI, spDHI and t are estimated as a function of AOD using typical four aerosol models,Troposphere, Rural, Urban and Ocean. For example, one of simulated results shows that each error of these has about 5 %, -4 % and -5 %, respectively with AOD of 0.5 for Oceanic aerosol type.