The shortwave array spectroradiometer—zenith (SASZE) measures the zenith sky shortwave radiance over the spectral range from the near infrared to the ultraviolet.
The SASZE measures sky radiance throughout the day, including twilight before sunrise and after sunset. The SASZE rack with spectroradiometers and data acquisition system is located in a temperature-controlled building isolated from the elements. The SAS measurements can be used to:
- Retrieve cloud optical depth, particle size, and cloud water path.
- Test the cloud optical depth retrieval for overcast and broken cloud fields.
- Validate/compare with Southern Great Plains site surface remote sensors and future cloud field campaigns.
- Perform multivariate analysis to derive information content in hyper-spectral data sets and to improve cloud retrieval algorithm development.
- Compare with radiative transfer models for testing and validating retrieval procedures.
The SASZE incorporates two Avantes fiber-coupled spectroradiometers (Avaspec ULS 2048 CCD and Avaspec NIR256-1.7) for visible and near-infrared detection in the wavelength range 350-1700 nm. The sampling frequency is 1 Hz.
The spectral resolution is 2.4 nm for the ULS 2048 CCD and 6 nm for the NIR256-1.7. The light collector has a narrow-field-of-view (1° full-angle) collimator at the front end of a high-grade fiber optic cable.