¶ Shortwave Array Spectroradiometer-Zenith (SASZE)
¶ Instrument Description
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 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. The SASZE measures sky radiance throughout the day including throughout twilight before the sun has risen and after it has set. The SASZE rack with spectroradiometers and data acquisition system is located within a temperature-controlled building isolated from the elements.
- For more information see the SASZE Instrument web page.
¶ Additional Information
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, validation/comparison with SGP surface remote sensors and future cloud IOP campaigns, multivariate analysis to derive information content in hyper spectral data sets and to improve cloud retrieval algorithm development, and compare with radiative transfer models for testing and validating retrieval procedures.
- For more information see the Radiation Information Page.
¶ Expected Operations
SGP
- Data is not available overnight.
- There are typically various DQO flags throughout the day when data falls below specified limits.
- Chiller and collector dewpoints missing various times throughout the day.
- Zenith radiance missing all day.
AMF1
- Data is not available overnight.
- There are typically various DQO flags throughout the day when data falls below specified limits.
- Mio tepmperatures fall below valid minimum all day.
- Zenith radiance missing all day.
¶ Plots
filter_bands
- These two plots compare the visible zenith radiance (black) against the NFOV (green). This data comes from the filter bands data stream.
- These plots are recorded at 673nm and 870nm.
- There is no NFOV at SGP, so these plots do not exist there.
sas_spectra
- These are plots of wavelength spectra for the visible (top) and near infrared (bottom) during the day.
- Vertical banding (as seen here) correlates with cloud cover.
- On clear days the plots should be ovular with the peak wavelengths at solar noon.
zenir_hour_spectra
- This is a plot of the near-IR wavelength range vs spectral zenith irradiance measured each hour.
zevis_hour_spectra
- This is a plot of the visible wavelength range vs spectral zenith irradiance measured each hour.
diagnostic_temp
- Plots of the collection, chiller, and avantes diagnositc temperatures.
- The avantes diagnostic temperature is comprised of a bench temperature (blue), ad temperature (green), saszevis bench temperature (brown), and saszevis ad temperature (purple).
mio_temperatures
- Plot of the multi-IO temperature trh (green) and mems (blue).
diagnostic_rh
- Plot of the spectrometer chiller internal RH (green) and the mulit-IO RH (blue).
diagnostic_dewpoint
- Plots of the chiller dewpoint and collector internal dewpoint.
collector_tilt
- Plot of the collector Y tilt (green) and X tilt (blue).
- Plots of the collector X and Y tilts standard deviation.
¶ Site-Specific Information
The SASZE is currently located at the SGP Central Facility and AMF1. All locations operate similarly.
¶ Known Issues
¶ Known Behaviors
List of known issues for this instrument that MAY NOT need to be mentioned in your DQA's:
Document some here
¶ Past Problems
List of past problems for this instrument that DO need to be mentioned in your DQA's:
Poor comparison with NFOV
- At times the SASZE records far less zenith radiance and struggles to compare with the NFOV. This only occurs at AMF1 as there is not NFOV at SGP.
Missing filter bands data
- At times the visible filter bands data goes missing showing a blank comparison against the NFOV. It also will show only the NIR plots in the sas_spectra and hour_spectra.
