Shortwave Infrared Spectroradiometer for Atmospheric Transmittance Measurements

M. Sicard Remote Sensing Group, Optical Sciences Center, The University of Arizona, Tucson, Arizona

Search for other papers by M. Sicard in
Current site
Google Scholar
PubMed
Close
,
K. J. Thome Remote Sensing Group, Optical Sciences Center, The University of Arizona, Tucson, Arizona

Search for other papers by K. J. Thome in
Current site
Google Scholar
PubMed
Close
,
B. G. Crowther Remote Sensing Group, Optical Sciences Center, The University of Arizona, Tucson, Arizona

Search for other papers by B. G. Crowther in
Current site
Google Scholar
PubMed
Close
, and
M. W. Smith Remote Sensing Group, Optical Sciences Center, The University of Arizona, Tucson, Arizona

Search for other papers by M. W. Smith in
Current site
Google Scholar
PubMed
Close
Restricted access

Abstract

The use of a shortwave infrared (SWIR) spectroradiometer as a solar radiometer is presented. The radiometer collects 1024 channels of data over the spectral range of 1.1–2.5 μm. The system was tested by applying the Langley method to data collected at a high altitude site on two consecutive days. Data processed for the 1.15–1.32-μm and 1.47–1.75-μm spectral intervals show temporal results similar to those obtained with a well- understood, visible, and near-infrared radiometer having 10 channels in the 0.38–1.03-μm spectral range. A modified Langley method was used for spectral regions where strong water vapor absorption invalidates the Langley method. It is estimated that the exoatmospheric intercept of the spectroradiometer was determined to better than 4% in nonabsorption regions between 1.15 and 1.75 μm and to better than 5% for a large portion of the 1.38-μm absorption band. These results, in addition to the agreement between the shortwave, and the visible and near-infrared radiometers, imply that the SWIR system operates well as a solar radiometer. The spectral optical depths from one day were used to determine a power-law aerosol size distribution using data from both the visible and near-infrared, and the shortwave infrared. The exponent derived for this power law differed from that obtained by using only the visible and near-infrared by 6%. Aerosol optical depths in the shortwave infrared derived from the visible and near-infrared results differed from the measured values by 0.005 at an optical depth of 0.016 and wavelength of 1.66 μm.

* Current affiliation: CIMEL Electronique, Paris, France.

Current affiliation: National Center for Atmospheric Research, Boulder, Colorado.

Corresponding author address: Michael Sicard, CIMEL Electronique, 5, Cite de Phalsbourg, 75011 Paris, France.

Email: m-sicard@worldnet.fr

Abstract

The use of a shortwave infrared (SWIR) spectroradiometer as a solar radiometer is presented. The radiometer collects 1024 channels of data over the spectral range of 1.1–2.5 μm. The system was tested by applying the Langley method to data collected at a high altitude site on two consecutive days. Data processed for the 1.15–1.32-μm and 1.47–1.75-μm spectral intervals show temporal results similar to those obtained with a well- understood, visible, and near-infrared radiometer having 10 channels in the 0.38–1.03-μm spectral range. A modified Langley method was used for spectral regions where strong water vapor absorption invalidates the Langley method. It is estimated that the exoatmospheric intercept of the spectroradiometer was determined to better than 4% in nonabsorption regions between 1.15 and 1.75 μm and to better than 5% for a large portion of the 1.38-μm absorption band. These results, in addition to the agreement between the shortwave, and the visible and near-infrared radiometers, imply that the SWIR system operates well as a solar radiometer. The spectral optical depths from one day were used to determine a power-law aerosol size distribution using data from both the visible and near-infrared, and the shortwave infrared. The exponent derived for this power law differed from that obtained by using only the visible and near-infrared by 6%. Aerosol optical depths in the shortwave infrared derived from the visible and near-infrared results differed from the measured values by 0.005 at an optical depth of 0.016 and wavelength of 1.66 μm.

* Current affiliation: CIMEL Electronique, Paris, France.

Current affiliation: National Center for Atmospheric Research, Boulder, Colorado.

Corresponding author address: Michael Sicard, CIMEL Electronique, 5, Cite de Phalsbourg, 75011 Paris, France.

Email: m-sicard@worldnet.fr

Save
  • Berk, A., L. S. Bernstein, and D. C. Robertson, 1989: MODTRAN:A moderate resolution model for LOWTRAN 7. GL-TR-89- 0122, Geophys. Laboratory, Air Force Systems Command, 38 pp. [Available from Geophysics Laboratory, Air Force Systems Command, Hanscom AFB, MA 01731-5000.].

  • Biggar, S. F., D. I. Gellman, and P. N. Slater, 1990: Improved evaluation of optical depth components from Langley plot data. Remote Sens. Environ.,32, 91–101.

    • Crossref
    • Export Citation
  • ——, P. N. Slater, and D. I. Gellman, 1994: Uncertainties in the in- flight calibration of sensors with reference to measured ground sites in the 0.4 to 1.1 μm range. Remote Sens. Environ.,48, 245–252.

  • Bruegge, C. J., J. E. Conel, R. O. Green, J. S. Margolis, R. G. Holm, and G. Toon, 1992: Water vapor column abundance retrievals during FIFE. J. Geophys. Res.,97, 18 759–18 768.

    • Crossref
    • Export Citation
  • Fujisada, H., 1995: Design and performance of ASTER instrument. Proc. SPIE Advanced and Next Generation Satellite Symp., Paris, France, SPIE, 16–25.

    • Crossref
    • Export Citation
  • Gellman, D. I., S. F. Biggar, P. N. Slater, and C. J. Bruegge, 1991: Calibrated intercepts for solar radiometers used in remote sensor calibration. Proc. SPIE Calibration of Passive Remote Observing Optical and Microwave Instrumentation Symp., Orlando, FL, SPIE, 175–181.

    • Crossref
    • Export Citation
  • Kasten, F., and T. Young, 1989: Revised optical airmass tables and approximation formula. Appl. Opt.,28, 4735–4738.

    • Crossref
    • Export Citation
  • Neeck, S. P., C. J. Scolese, and F. Bordi, 1995: EOS-AM1: Project update. Proc. SPIE Advanced and Next Generation Satellite Symp., Paris, France, SPIE, 2–15.

  • Pitts, D. E., W. E. McAllum, M. Heidt, K. Jeske, and J. T. Lee, 1977:Temporal variations in atmospheric water vapor and aerosol optical depth determined by remote sensing. J. Appl. Meteor.,16, 1312–1321.

    • Crossref
    • Export Citation
  • Platnick, S., M. D. King, G. T. Arnold, J. Cooper, L. E. Gumley, and S.-C. Tsay, 1994: Status and calibration of the MODIS airborne simulator for earth remote sensing applications. Proc. SPIE Platform and Systems EUROPTO Symp., Rome, Italy, 91–101.

    • Crossref
    • Export Citation
  • Slater, P. N., S. F. Biggar, R. G. Holm, R. D. Jackson, Y. Mao, M. S. Moran, J. M. Palmer, and B. Yuan, 1987: Reflectance- and radiance-based methods for the in-flight absolute calibration of multispectral sensors. Remote Sens. Environ.,22, 11–37.

    • Crossref
    • Export Citation
  • Smith, M. W., 1992: Design and initial performance evaluation of a portable shortwave infrared spectroradiometer. Proc. SPIE Infrared Technology XVIII Symp., San Diego, CA, SPIE, 118–134.

    • Crossref
    • Export Citation
  • ——, 1994: Calibration and performance evaluation of a portable shortwave infrared (1.05 to 2.45 μm) spectrometer. Opt. Eng.,33, 5811–5819.

  • Thome, K. J., B. M. Herman, and J. A. Reagan, 1992: Determination of precipitable water from solar transmission. J. Appl. Meteor.,31, 157–165.

    • Crossref
    • Export Citation
  • ——, M. W. Smith, J. M. Palmer, and J. A. Reagan, 1994: Three- channel solar radiometer for the determination of atmospheric columnar water vapor. Appl. Opt.,33, 5811–5819.

    • Crossref
    • Export Citation
  • Volz, F. E., 1974: Economical multispectral sun photometer for measurements of aerosol extinction from 0.44 microns to 1.6 microns and precipitable water. Appl. Opt.,13, 1732–1733.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 522 102 5
PDF Downloads 288 66 4