Specifications and performance of UV rotating shadowband spectroradiometer (UV-RSS)

The UV rotating shadowband spectroradiometer (UV-RSS) is capable of measuring direct, diffuse and total horizontal irradiances simultaneously with spectral resolution of 0.25- 0.45 nm in the 290-380 nm range. It is based on a two-prism spectrograph that has very high out-of-band rejection of 2*10-6) as defined by the 325 nm HeCd laser line. Without moving parts, the radiometric stability is limited by the stability of the diffuser throughput and the stability of the cooled CCD. The wavelength stability is maintained by temperature control of the fused silica prisms and air pressure in the spectrograph. The current signal-to- noise ratio allows optical depth retrievals in the 305-360 nm range at mid latitudes in summer for typical ozone loading of 300 DU. This signal-to-noise can be increased by a factor of 5 within a one-minute shadowbanding cycle by means of multiple exposures. The UV-RSS permits ozone retrieval from diffuse irradiance using the DOAS method or from direct irradiance via Langley regression. Either method is robust as the UV-RSS provides 205 pixels of data within 310-330 nm range.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.