Results for “Shortwave spectral diffuse downwelling irradiance”

DOE OSTI2012

sashevis (b1)

The shortwave array spectroradiometer—hemispheric (SASHE) uses a hemispheric spectralon diffuser and rotating shadowband similar to the MFRSR and RSS instruments, so it also provides spectrally resolved, direct-normal, diffuse-horizontal, and total-horizontal irradiances, and can be calibrated in situ via Langley regression. The SASHE 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 spectral resolution is 2.4 nm for the ULS 2048 CCD and 6 nm for the NIR256-1.7. Like the SWS and SASZE, an external collector mounted outdoors is connected via fiber-optic cable to a pair of spectroradiometers housed indoors, so the entire spectral range is measured simultaneously for both spectroradiometers. For the typical shadowband measurement, the spectroradiometers are operated with one measurement per second, but the entire shadowband sequence takes about 20 seconds, so this is the measurement interval for the irradiances. The SASHE operating sequence is configurable and supports alternate programmed sequences as a function of solar zenith angle. For example, it currently employs different sequences for high sun angles, low sun angles, and twilight conditions when the sun is below the horizon but the sky is not yet fully dark. It also includes a mode where visible spectra are collected rapidly while the band is moved over a range of near-sun angles to characterize the forward-scattered radiation. The SASHE data are preliminarily calibrated through comparison with calibrated lamps. The accuracy of irradiance produced by the SASHE is expected to be better than ±5%, which includes calibration and instrument stability errors. Under suitably uniform atmospheric conditions, higher calibration accuracy and precisions (±1%) can be obtained when the responsivity is tied to the solar extraterrestrial irradiance via Langley regression plots. This approach is recommended when high-precision measurements of optical depth are required.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2012

sashemfr (b1)

The shortwave array spectroradiometer—hemispheric (SASHE) uses a hemispheric spectralon diffuser and rotating shadowband similar to the MFRSR and RSS instruments, so it also provides spectrally resolved, direct-normal, diffuse-horizontal, and total-horizontal irradiances, and can be calibrated in situ via Langley regression. The SASHE 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 spectral resolution is 2.4 nm for the ULS 2048 CCD and 6 nm for the NIR256-1.7. Like the SWS and SASZE, an external collector mounted outdoors is connected via fiber-optic cable to a pair of spectroradiometers housed indoors, so the entire spectral range is measured simultaneously for both spectroradiometers. For the typical shadowband measurement, the spectroradiometers are operated with one measurement per second, but the entire shadowband sequence takes about 20 seconds, so this is the measurement interval for the irradiances. The SASHE operating sequence is configurable and supports alternate programmed sequences as a function of solar zenith angle. For example, it currently employs different sequences for high sun angles, low sun angles, and twilight conditions when the sun is below the horizon but the sky is not yet fully dark. It also includes a mode where visible spectra are collected rapidly while the band is moved over a range of near-sun angles to characterize the forward-scattered radiation. The SASHE data are preliminarily calibrated through comparison with calibrated lamps. The accuracy of irradiance produced by the SASHE is expected to be better than ±5%, which includes calibration and instrument stability errors. Under suitably uniform atmospheric conditions, higher calibration accuracy and precisions (±1%) can be obtained when the responsivity is tied to the solar extraterrestrial irradiance via Langley regression plots. This approach is recommended when high-precision measurements of optical depth are required.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2012

sashenir (b1)

The shortwave array spectroradiometer—hemispheric (SASHE) uses a hemispheric spectralon diffuser and rotating shadowband similar to the MFRSR and RSS instruments, so it also provides spectrally resolved, direct-normal, diffuse-horizontal, and total-horizontal irradiances, and can be calibrated in situ via Langley regression. The SASHE 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 spectral resolution is 2.4 nm for the ULS 2048 CCD and 6 nm for the NIR256-1.7. Like the SWS and SASZE, an external collector mounted outdoors is connected via fiber-optic cable to a pair of spectroradiometers housed indoors, so the entire spectral range is measured simultaneously for both spectroradiometers. For the typical shadowband measurement, the spectroradiometers are operated with one measurement per second, but the entire shadowband sequence takes about 20 seconds, so this is the measurement interval for the irradiances. The SASHE operating sequence is configurable and supports alternate programmed sequences as a function of solar zenith angle. For example, it currently employs different sequences for high sun angles, low sun angles, and twilight conditions when the sun is below the horizon but the sky is not yet fully dark. It also includes a mode where visible spectra are collected rapidly while the band is moved over a range of near-sun angles to characterize the forward-scattered radiation. The SASHE data are preliminarily calibrated through comparison with calibrated lamps. The accuracy of irradiance produced by the SASHE is expected to be better than ±5%, which includes calibration and instrument stability errors. Under suitably uniform atmospheric conditions, higher calibration accuracy and precisions (±1%) can be obtained when the responsivity is tied to the solar extraterrestrial irradiance via Langley regression plots. This approach is recommended when high-precision measurements of optical depth are required.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2012

ARM: Pixels from SASHe corresponding to MFR radiometer wavelengths

Pixels from SASHe corresponding to MFR radiometer wavelengths

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2012

ARM: Shortwave Array Spectroradiometer-Hemispheric, Near-InfraRed channel

Shortwave Array Spectroradiometer-Hemispheric, Near-InfraRed channel

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2012

ARM: Shortwave Array Spectroradiometer-Hemispheric, VISible channel

Shortwave Array Spectroradiometer-Hemispheric, VISible channel

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2015

AWARE Shortwave Spectroradiometer Data

Shortwave spectral irradiance was measured at the West Antarctic Ice Sheet (WAIS) Divide Ice Camp as part of the ARM West Antarctic Radiation Experiment (AWARE). A Panalytical (Inc.) FieldSpec Pro Jr spectroradiometer belonging to Scripps Oceanography recorded downwelling spectral irradiance every minute covering the wavelength interval 350-2200 nm . Spectral resolution is 3 nm (10 nm) for wavelengths shorter (longer) than 1000 nm. Temporal coverage is nearly continuous between 8 December 2015 and 18 January 2016, with a few minutes of data missing during each day for data backup and optical collector hygiene. Spectral irradiances, particularly in the near infrared, are sensitive to cloud optical depth, thermodynamic phase, and effective particle size.

54 ENVIRONMENTAL SCIENCES↗

DOE OSTI2018

Radiometer for ACE-ENA

The broadband SPN total, zenith1, and zenith2 downwelling SW irradiances were corrected for tilt up to 10 degrees of tilt (per Long et al., 2010). For tilt greater than 10 degrees these values are set to ""bad"". No tilt correction has been applied to the MFR spectral data.

54 ENVIRONMENTAL SCIENCES↗

NASA NTRS1990

FIRE extended time/limited area observations at Palisades, New York

Downwelling shortwave and longwave irradiation are being continuously monitored at Palisades, New York as part of the First International Satellite Cloud Climatology Project (ISCCP) Regional Experiment (FIRE) Extended Time/Limited Area Initiative. In addition, fisheye (180 degree) sky photographs are taken at the times of NOAA 9 and LANDSAT satellite overpasses on select days, particularly when cirrus clouds are present. Measurements of incoming shortwave (0.28 to 2.80 microns) hemispheric and diffuse, hemispheric near infrared (0.7 to 2.80 microns), and downwelling hemispheric infrared (4.0 to 50.0 microns) irradiation have been made from a rooftop location on the grounds of the Lamont-Doherty Geological Observatory since December 1986. The three Eppley Precision Spectral Pyranometers and the Eppley Pyrgeometer used to measure these variables were calibrated with Colorado State University instruments at Madison, Wisconsin as part of the FIRE Intensive Laboratory. Pyrgeometer output contains an adjustment for body temperature but not for dome temperature. Data are transmitted to a Campbell CR-21 Digital Recorder, where one minute averages of ten second samples are stored and subsequently dumped to a cassette recorder. Using a Campbell C-20 Cassette Interface, these data are transferred to an Apple Macintosh computer for analysis and for archiving on floppy disks. In addition to the raw irradiances collected, variables derived from these data are generated and stored. These include: the ratio of near infrared irradiation to visible irradiation and the fraction of the full shortwave irradiation which is diffuse; and will soon include: shortwave transmissivity and optical depth in the shortwave. Sky photographs are taken with an Olympus OM2-N 35 mm camera and are timed to be coincident with overpassing NOAA and LANDSAT satellites. Palisades is within the field of view of the NOAA 9 daily in the middle to late afternoon. The satellite viewing angle is within 45 degrees of nadir over Palisades on approximately half of the passes.

Robinson, David A.↗

DOE OSTI2019