Design and development of a portable tuneable radiation source from UV to IR for in situ calibration of radiometers measuring atmospheric aerosol properties.

Abstract We present the results of development of a portable tuneable radiation source (TuPS II) covering the broad spectral range from 300 nm up to 1700 nm. It was developed to provide SI-traceable in-situ calibration of bandpass functions of radiometers measuring both sky radiance and sky irradiance in the surface-based remote sensing networks for column integrated atmospheric aerosol properties. The TuPS II provides quasi-monochromatic radiation with spectral bandwidth smaller than 0.2 nm and central wavelength uncertainty lower than 0.05 nm for a specified number of aerosol wavelength bands ranging from to 300 nm to 1700 nm. In its design it represents an evolution with extended spectral capabilities of the TuPS (Smid, M. et al., 2021) that was successfully used to characterize Dobson spectrophotometers in the UV spectral range.