Realization of the new national primary scale of spectral radiance and spectral irradiance

2013 ◽  
Author(s):  
Cai-hong Dai ◽  
Zhifeng Wu ◽  
Jia-lin Yu
Keyword(s):  
Spectral Irradiance ◽  
Spectral Radiance ◽  
Primary Scale

scholarly journals Radiometric calibration of a non-imaging airborne spectrometer to measure the Greenland ice sheet surface

2019 ◽  
Vol 12 (3) ◽  
pp. 1913-1933
Author(s):  
Christopher J. Crawford ◽  
Jeannette van den Bosch ◽  
Kelly M. Brunt ◽  
Milton G. Hom ◽  
John W. Cooper ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Spectral Response ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Spectral Irradiance ◽  
Spectral Radiance ◽  
Landsat 8 ◽  
Radiometric Calibration ◽  
Bare Rock ◽  
Sheet Surface

Abstract. Methods to radiometrically calibrate a non-imaging airborne visible-to-shortwave infrared (VSWIR) spectrometer to measure the Greenland ice sheet surface are presented. Airborne VSWIR measurement performance for bright Greenland ice and dark bare rock/soil targets is compared against the MODerate resolution atmospheric TRANsmission (MODTRAN®) radiative transfer code (version 6.0), and a coincident Landsat 8 Operational Land Imager (OLI) acquisition on 29 July 2015 during an in-flight radiometric calibration experiment. Airborne remote sensing flights were carried out in northwestern Greenland in preparation for the Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) laser altimeter mission. A total of nine science flights were conducted over the Greenland ice sheet, sea ice, and open-ocean water. The campaign's primary purpose was to correlate green laser pulse penetration into snow and ice with spectroscopic-derived surface properties. An experimental airborne instrument configuration that included a nadir-viewing (looking downward at the surface) non-imaging Analytical Spectral Devices (ASD) Inc. spectrometer that measured upwelling VSWIR (0.35 to 2.5 µm) spectral radiance (Wm-2sr-1µm-1) in the two-color Slope Imaging Multi-polarization Photon-Counting Lidar's (SIMPL) ground instantaneous field of view, and a zenith-viewing (looking upward at the sky) ASD spectrometer that measured VSWIR spectral irradiance (W m−2 nm−1) was flown. National Institute of Standards and Technology (NIST) traceable radiometric calibration procedures for laboratory, in-flight, and field environments are described in detail to achieve a targeted VSWIR measurement requirement of within 5 % to support calibration/validation efforts and remote sensing algorithm development. Our MODTRAN predictions for the 29 July flight line over dark and bright targets indicate that the airborne nadir-viewing spectrometer spectral radiance measurement uncertainty was between 0.6 % and 4.7 % for VSWIR wavelengths (0.4 to 2.0 µm) with atmospheric transmittance greater than 80 %. MODTRAN predictions for Landsat 8 OLI relative spectral response functions suggest that OLI is measuring 6 % to 16 % more top-of-atmosphere (TOA) spectral radiance from the Greenland ice sheet surface than was predicted using apparent reflectance spectra from the nadir-viewing spectrometer. While more investigation is required to convert airborne VSWIR spectral radiance into atmospherically corrected airborne surface reflectance, it is expected that airborne science flight data products will contribute to spectroscopic determination of Greenland ice sheet surface optical properties to improve understanding of their potential influence on ICESat-2 measurements.

scholarly journals Research note: Calculating spectral irradiance indoors

2016 ◽  
Vol 49 (1) ◽  
pp. 122-127 ◽  
Author(s):  
S Bará ◽  
J Escofet
Keyword(s):  
Quantitative Description ◽  
Spectral Composition ◽  
Integral Form ◽  
Observation Point ◽  
Spectral Irradiance ◽  
Spectral Radiance ◽  
Source Spectrum ◽  
Secondary Source ◽  
Light Sources ◽  
Multiple Reflections

The spectral composition of the light that reaches any indoor work plane depends on the characteristics of the light sources and the spectral reflectances of the surrounding surfaces due to the multiple reflections experienced by the light rays along their paths from the source to the observation point. We show that in indoor spaces, the source and surface radiances must obey a definite self-consistent relationship derived from the fact that each illuminated surface point acts as a secondary source of light. It is then established that the spectral irradiance on any plane is linearly dependent on the spectral radiance of the light source. The explicit integral form of this relationship provides a theoretical framework for a quantitative description of the surface effects. Additionally, under very general assumptions, we show that the spectral irradiance can be computed from the spectral flux of the source through a simple multiplication by a wavelength-dependent function. This function, with units of inverse surface (1/m2), provides a convenient way for evaluating the effects that arbitrary changes in the source spectrum will produce on the spectral irradiance at the indoor point under study.

scholarly journals Radiometric calibration of a non-imaging airborne spectrometer to measure the Greenland Ice Sheet surface

2018 ◽  
Author(s):  
Christopher J. Crawford ◽  
Jeannette van den Bosch ◽  
Kelly M. Brunt ◽  
Milton G. Hom ◽  
John W. Cooper ◽  
...  
Keyword(s):  
Surface Properties ◽  
Spectral Response ◽  
Ice Sheet ◽  
Greenland Ice Sheet ◽  
Spectral Irradiance ◽  
Spectral Radiance ◽  
Landsat 8 ◽  
Radiometric Calibration ◽  
Bare Rock ◽  
Sheet Surface

Abstract. Methods to radiometrically calibrate a non-imaging airborne visible-to-shortwave infrared (VSWIR) spectrometer to measure the Greenland Ice Sheet surface are presented. Airborne VSWIR measurement performance is then benchmarked for bright Greenland ice and dark bare rock/soil targets using the MODerate resolution atmospheric TRANsmission (MODTRAN) radiative transfer code (version 6.0), and a coincident Landsat 8 Operational Land Imager (OLI) acquisition on 29 July 2015 during an in-flight radiometric calibration experiment. Airborne remote sensing flights were carried out in northwestern Greenland in preparation for the Ice, Cloud and land Elevation Satellite 2 (ICESat-2) laser altimeter mission. Nine science flights were conducted over the Greenland Ice Sheet, sea ice, and open ocean water. The campaign’s primary purpose was to correlate green laser pulse penetration into snow and ice with spectroscopic derived surface properties. An experimental airborne instrument configuration that included a nadir viewing (downward looking at the surface) non-imaging Analytical Spectral Devices Inc. (ASD) spectrometer that measured at-sensor upwelling VSWIR (0.35 to 2.5 µm) spectral radiance (Watts/m−2/sr−1/nm−1) in the two color Slope Imaging Multi-polarization Photon-Counting Lidar’s (SIMPL) ground Instantaneous Field-of-View, and a zenith viewing (upward looking at the sky) ASD spectrometer that measured at-sensor VSWIR spectral irradiance (Watts/m−2/nm−1) was flown. Rigorous radiometric calibration procedures for laboratory, in-flight, and field environments are described in detail to achieve a targeted at-sensor VSWIR measurement requirement of within 5 % to support calibration/validation (cal/val) efforts and geophysical science algorithm development. Our MODTRAN simulations for the 29 July flight line over dark and bright targets indicate that the nadir viewing airborne VSWIR spectrometer achieved an at-sensor spectral radiance measurement accuracy of between 0.6 and 4.7 % for VSWIR wavelengths (0.4 to 2.0 µm) with atmospheric transmittance greater than 80 %. At-sensor MODTRAN simulations for Landsat 8 OLI relative spectral response functions suggest that OLI is measuring 6 to 16% more at-sensor top-of-atmosphere (TOA) spectral radiance from the Greenland Ice Sheet surface than was observed from the nadir viewing airborne VSWIR spectrometer. While more investigation is required to convert airborne at-sensor VSWIR spectral radiance into atmospherically-corrected airborne surface reflectance, it is expected that airborne science flight data products will contribute to spectroscopic determination of Greenland Ice Sheet surface properties to improve understanding of their potential influence on ICESat-2 measurements.

Portable detector-based primary scale of spectral irradiance

2000 ◽  
Vol 105 (D4) ◽  
pp. 4803-4807 ◽  
Author(s):  
Petri Kärhä ◽  
Toomas Kübarsepp ◽  
Farshid Manoocheri ◽  
Pasi Toivanen ◽  
Erkki Ikonen ◽  
...  
Keyword(s):  
Spectral Irradiance ◽  
Primary Scale ◽  
Portable Detector

Spectral irradiance primary scale realization and characterization of deuterium lamps from 200 to 400 nm

2020 ◽  
Vol 59 (27) ◽  
pp. 8494
Author(s):  
Caihong Dai ◽  
Zhifeng Wu ◽  
Yanfei Wang ◽  
Ling Li ◽  
Shufang He ◽  
...  
Keyword(s):  
Spectral Irradiance ◽  
Primary Scale

The Imaging Optical Setup in the Spectral Radiance Facility

2012 ◽  
Vol 571 ◽  
pp. 406-410
Author(s):  
Zhi Feng Wu ◽  
Cai Hong Dai ◽  
Bo Huang ◽  
Jia Lin Yu ◽  
Hui Quan Ouyang
Keyword(s):  
Solid Angle ◽  
Spectral Irradiance ◽  
Spectral Radiance ◽  
Optical Setup ◽  
Imaging Parameters ◽  
Object Distance ◽  
Imaging Optics

The spectral radiance of the lamps are calibrated in the experiment. Different from the spectral irradiance mode, the spectral radiance involves mirror imaging optics and some instructions must be followed strictly. During the experiment, several different imaging parameters in the spectral radiance transfer were investigated, such as the imaging area, the width of the entrance slits, the solid angle, and the object distance of the imaging optics.

Brightness In The Photopic Range: Psychophysical Modelling With Blue-sensitive Retinal Signals

2020 ◽  
pp. 9-24
Author(s):  
Peter Bodrogi ◽  
Xue Guo ◽  
Tran Quoc Khanh
Keyword(s):  
Ganglion Cells ◽  
Light Stimulus ◽  
Spectral Radiance ◽  
Psychophysical Experiment ◽  
Retinal Ganglion ◽  
Reasonable Accuracy ◽  
Brightness Perception ◽  
Content Model ◽  
The Difference ◽  
Cone Signal

The brightness perception of a large (41°) uniform visual field was investigated in a visual psychophysical experiment. Subjects assessed the brightness of 20 light source spectra of different chromaticities at two luminance levels, Lv=267.6 cd/m2 and Lv=24.8 cd/m2. The resulting mean subjective brightness scale values were modelled by a combination of the signals of retinal mechanisms: S-cones, rods, intrinsically photosensitive retinal ganglion cells (ipRGCs) and the difference of the L-cone signal and the M-cone signal. A new quantity, “relative spectral blue content”, was also considered for modelling. This quantity was defined as “the spectral radiance of the light stimulus integrated with the range (380–520) nm, relative to luminance”. The “relative spectral blue content” model could describe the subjective brightness perception of the observers with reasonable accuracy.

Sign in / Sign up

Export Citation Format

Share Document