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Proceedings Paper

Characterization and error analysis of an operational retrieval algorithm for estimating column ozone and aerosol properties from ground-based ultra-violet irradiance measurements
Author(s): Thomas E. Taylor; Tristan L'Ecuyer; James Slusser; Graeme Stephens; Nick Krotkov; John Davis; Christian Goering
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Paper Abstract

Extensive sensitivity and error characteristics of a recently developed optimal estimation retrieval algorithm which simultaneously determines aerosol optical depth (AOD), aerosol single scatter albedo (SSA) and total ozone column (TOC) from ultra-violet irradiances are described. The algorithm inverts measured diffuse and direct irradiances at 7 channels in the UV spectral range obtained from the United States Department of Agriculture's (USDA) UV-B Monitoring and Research Program's (UVMRP) network of 33 ground-based UV-MFRSR instruments to produce aerosol optical properties and TOC at all seven wavelengths. Sensitivity studies of the Tropospheric Ultra-violet/Visible (TUV) radiative transfer model performed for various operating modes (Delta-Eddington versus n-stream Discrete Ordinate) over domains of AOD, SSA, TOC, asymmetry parameter and surface albedo show that the solutions are well constrained. Realistic input error budgets and diagnostic and error outputs from the retrieval are analyzed to demonstrate the atmospheric conditions under which the retrieval provides useful and significant results. After optimizing the algorithm for the USDA site in Panther Junction, Texas the retrieval algorithm was run on a cloud screened set of irradiance measurements for the month of May 2003. Comparisons to independently derived AOD's are favorable with root mean square (RMS) differences of about 3% to 7% at 300nm and less than 1% at 368nm, on May 12 and 22, 2003. This retrieval method will be used to build an aerosol climatology and provide ground-truthing of satellite measurements by running it operationally on the USDA UV network database.

Paper Details

Date Published: 18 August 2005
PDF: 12 pages
Proc. SPIE 5886, Ultraviolet Ground- and Space-based Measurements, Models, and Effects V, 58860Y (18 August 2005); doi: 10.1117/12.628877
Show Author Affiliations
Thomas E. Taylor, Colorado State Univ. (United States)
Tristan L'Ecuyer, Colorado State Univ. (United States)
James Slusser, U. S. Department of Agriculture, Colorado State Univ. (United States)
Graeme Stephens, Colorado State Univ. (United States)
Nick Krotkov, Univ. of Maryland, Baltimore County (United States)
John Davis, U. S. Department of Agriculture, Colorado State Univ. (United States)
Christian Goering, Colorado State Univ. (United States)

Published in SPIE Proceedings Vol. 5886:
Ultraviolet Ground- and Space-based Measurements, Models, and Effects V
Germar Bernhard; James R. Slusser; Jay R. Herman; Wei Gao, Editor(s)

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