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GACP Datasets

Global Aerosol Climatology for the Period August 1981 to December 2009

The GACP aerosol optical thickness and Angstrom exponent dataset was initially created covering the time period August 1981 through June 2005. In 2015 the dataset was updated and extended through December 2009 using NOAA-17 and -18 AVHRR data. Monthly averages of the aerosol optical thickness (AOT) for the full period from August 1981 through December 2009 can be downloaded from All files are in plain ASCII text and compressed using gzip.

The files format is as follows: the first line indicates the respective year and month and is followed by 180 rows of 360 floating point numbers. Each number represents the monthly average of the corresponding quantity in the respective 1°×1° grid box. The top row represents the northmost grid boxes (89°N-90°N). The first column represents the 180°W-179°W grid boxes. Absence of data is indicated by -1.

Journal articles related to the production of this dataset are listed on the GACP publications page.

For more information about the data, please contact Dr. Michael Mishchenko or Dr. Igor Geogdzhayev

Transport Models

Joyce Penner's Summary of the IPCC Model Intercomparison Workshop (PDF)

Ina Tegen's Aerosol Optical Thickness Results from Chemistry/Transport Models.

Related Datasets

Brent Holben's Summary of Aerosol Datasets (PDF)

Andrew Lacis' Database of Aerosol Spectral Refractive Indices

  • Introduction: PDF
  • FORTRAN subroutine for calculating aerosol spectral refractive indices
  • Plots of aerosol spectral refractive indices (PDF)

Trish Quinn's ACE 2 Summary (PDF)

Philip Russell's Process & Closure Study Data Summary: Part 1; Part 2 PDFs

Individual Aerosol Datasets

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