World Library  

Add to Book Shelf
Flag as Inappropriate
Email this Book

A Spectral Method for Retrieving Cloud Optical Thickness and Effective Radius from Surface-based Transmittance Measurements : Volume 11, Issue 1 (17/01/2011)

By McBride, P. J.

Click here to view

Book Id: WPLBN0003975175
Format Type: PDF Article :
File Size: Pages 52
Reproduction Date: 2015

Title: A Spectral Method for Retrieving Cloud Optical Thickness and Effective Radius from Surface-based Transmittance Measurements : Volume 11, Issue 1 (17/01/2011)  
Author: McBride, P. J.
Volume: Vol. 11, Issue 1
Language: English
Subject: Science, Atmospheric, Chemistry
Collections: Periodicals: Journal and Magazine Collection (Contemporary), Copernicus GmbH
Publication Date:
Publisher: Copernicus Gmbh, Göttingen, Germany
Member Page: Copernicus Publications


APA MLA Chicago

Wolfe, D. E., Pilewskie, P., Mcbride, P. J., Kittelman, A. S., & Schmidt, K. S. (2011). A Spectral Method for Retrieving Cloud Optical Thickness and Effective Radius from Surface-based Transmittance Measurements : Volume 11, Issue 1 (17/01/2011). Retrieved from

Description: Laboratory for Atmospheric and Space Physics, University of Colorado, Campus Box 392, Boulder, CO 80309-0392, USA. We introduce a new multispectral method for the retrieval of optical thickness and effective radius from cloud transmittance, which is less sensitive to effective radius than cloud reflectance. Based on data from the moderate spectral resolution observations of the Solar Spectral Flux Radiometer (SSFR) and Shortwave Spectroradiometer (SWS), we use the spectral shape of transmitted radiance as a means of retrieving effective radius from cloud transmittance. The observations were taken during the International Chemistry Experiment in the Arctic Lower Troposphere and at the Southern Great Plains (SGP) site of the Atmospheric Radiation Measurement (ARM) Climate Research Facility. The spectral shape was quantified by fitting a slope to the normalized transmittance between 1565 nm and 1634 nm. The retrieval was performed by comparing the observed slope at 1565 nm and the transmittance at 515 nm with a pre-calculated library (lookup table). An estimate of the retrieval uncertainty was provided by propagating the uncertainty of the observations through the best-fit algorithm. We compare the new retrieval with an algorithm that uses transmittance at two wavelengths, a method often used with cloud reflectance. The liquid water path (LWP) is derived from the retrieved optical thickness and effective radius, assuming a cloud with effective radius varying linearly with altitude above cloud base, and compared to the retrieved liquid water path from a microwave radiometer. Retrievals from two MODIS overpasses of the SGP were also compared. The data taken from the SGP was under thicker cloud than the case used from ICEALOT, with average optical thickness of 44 and 22, respectively. For the time period with the thicker clouds, the dual-wavelength method and the slope method retrieved nearly indistinguishable results. The dual-wavelength method, however, resulted in slightly higher average relative effective radius uncertainty of 12.9 μm±12.8%, as compared to 12.8 μm±8.9% from the slope method. The thinner cloud case resulted in a significant difference between the dual-wavelength and slope algorithms with average retrieved effective radius and uncertainties of 12.5 μm±8.4% and 17.0 μm±21.0% for the slope and dual-wavelength methods, respectively. The retrieved optical thickness values for this case were nearly identical. The average derived LWP was within 12.5% and 20% of the MWR LWP for the ARM and ICEALOT data. For a homogeneous cloud case, the MODIS retrievals (optical depth, effective radius, and LWP) were within the uncertainty of the SWS retrievals. Inhomogeneous clouds resulted in lesser agreement between the MODIS and SWS retrievals.

A spectral method for retrieving cloud optical thickness and effective radius from surface-based transmittance measurements

Barker, H. W. and Marshak, A.: Inferring optical depth of broken clouds above green vegetation using surface solar radiometric measurements, J. Atmos. Sci., 58, 2989–3006, 2001.; Bergstrom, R. W., Pilewskie, P., Schmid, B., and Russell, P. B.: Estimates of the spectral aerosol single scattering albedo and aerosol radiative effects during SAFARI 2000, J. Geophys. Res., 108, 8474, 2003.; Chiu, J. C., Huang, C., Marshak, A., Slutsker, I., Giles, D. M., Holben, B. N., Knyazikhin, Y., and Wiscombe, W. J.: Cloud optical depth retrievals from the Aerosol Robotic Network (AERONET) cloud mode observations, J. Geophys. Res., 115, D14202, 2010.; Clark, R. N., Swayze, G. A., Wise, R., Livo, E., Hoefen, T., Kokaly, R., and Sutley, S. J.: USGS digital spectral library splib06a: US Geological Survey, Digital Data Series 231, 2007.; Coddington, O., Schmidt, K. S., Pilewskie, P., Gore, W. J., Bergstrom, R. W., Román, M., Redemann, J., Russell, P. B., Liu, J., and Schaaf, C. C.: Aircraft measurements of spectral surface albedo and its consistency with ground-based and space-borne observations, J. Geophys. Res.-Atmos., 113, D17209, 2008.; Ehrlich, A., Bierwirth, E., Wendisch, M., Gayet, J.-F., Mioche, G., Lampert, A., and Heintzenberg, J.: Cloud phase identification of Arctic boundary-layer clouds from airborne spectral reflection measurements: test of three approaches, Atmos. Chem. Phys., 8, 7493–7505, doi:10.5194/acp-8-7493-2008, 2008.; Pilewskie, P. and Twomey, S.: Cloud phase discrimination by reflectance measurements near 1.6 and 2.2 μm, J. Atmos. Sci., 44, 1987.; Forster, P., Ramaswamy, V., Artaxo, P., Berntsen, T., Betts, R., Fahey, D. W., Haywood, J., Lean, J., Lowe, D. C., Myhre, G., Nganga, J., Prinn, R., Raga, G., Schulz, M., and Van Dorland, R.: Changes in Atmospheric Constituents and in Radiative Forcing, in: Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, edited by: Solomon, S., Qin, D., Manning, M., Chen, Z., Marquis, M., Averyt, K. B., Tignor, M., and Miller, H. L., Cambridge University Press, Cambridge, UK and New York, NY, USA, 131–217, 2007.; Hansen, J. E. and Hovenier, J. W.: Interpretation of the polarization of Venus, J. Atmos. Sci., 31, 1137–1160, 1974.; Hansen, J. E. and Pollack, J. B.: Near-infrared light scattering by terrestrial clouds, J. Atmos. Sci., 27, 265–281, 1970.; Harrison, L., Michalsky, J., and Berndt, J.: Automated multifilter rotating shadow-band radiometer: an instrument for optical depth and radiation measurements, Appl. Opt., 33, 5118–5125, 1994.; Holben, B.: AERONET: A federated instrument network and data archive for aerosol characterization, Remote Sens. Environ., 66, 1–16, 1998.; Kikuchi, N., Nakajima, T., Kumagai, H., Kuroiwa, H., Kamei, A., Nakamura, R., and Nakajima, T. Y.: Cloud optical thickness and effective particle radius derived from transmitted solar radiation measurements: comparison with cloud radar observations, J. Geophys. Res., 111, D07


Click To View

Additional Books

  • Lightning NoX Emissions Over the USA Inv... (by )
  • Modeling the Influence of Precursor Vola... (by )
  • The Effects of Global Changes Upon Regio... (by )
  • Spatial and Temporal Variability of Sour... (by )
  • The Genesis of Typhoon Nuri as Observed ... (by )
  • Isotope- and Tracer-based Measurements o... (by )
  • Height Increase of the Melting Level Sta... (by )
  • Global Peroxyacetyl Nitrate (Pan) Retrie... (by )
  • Anthropogenic Influence on Soa and the R... (by )
  • Composition and Temporal Behavior of Amb... (by )
  • Radar Observations of Meteor Trails, and... (by )
  • Organics in Environmental Ices: Sources,... (by )
Scroll Left
Scroll Right


Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.