Data

• Near Real-Time GASP-West Data (Binary Format)

• Archived GASP-West Data at the NOAA/NESDIS/NCDC (National Climate Data Center)

Imagery Description

• Time (UTC)
• EST = UTC -5, CST = UTC - 6, MST = UTC - 7, PST = UTC - 8
• Latest Image
• The latest GOES image available to the processing system.
• Aerosol Optical Depth (from latest image and most recent surface reflectance retrieval)
• Color scale represents the aerosol optical depth.
• The gray scale in the sunlit portion of the image represents the reflectance of either clouds, sun glint or regions where the retrieval is insensitive to aerosol (e.g., over bright surfaces)
• The thick black line is where the solar zenith angle is 80 degrees.
• The retrieval is not performed at solar zenith angles above 80, so the visible reflectance is provided between 80 and 89 degrees
• Beyond 89 degrees, the IR data (from channel 4) is shown to provide a continuous image.

Method Summary

• Effective January 7, 2009, a new GASP algorithm update was put into operations.
• A clear sky composite reflectance (background) image is created by selecting the second darkest pixel from the previous 28 days for each observation time.
• The surface reflectance is obtained from the composite background image, using look-up tables calculated with the 6S Radiative Transfer model.
• The Aerosol Optical Depth is estimated using look-up tables from the 6S Radiative Transfer model and the calculated surface reflectance.
• Radiative Transfer calculations assume a continental aerosol model and Lambertian surface.
• Clouds are identified using spatial and spectral tests similar to those developed for CLAVR (Clouds from AVHRR). The AOD is shown only for cloud free pixels.

GOES Aerosol Smoke Products (GASP):

• GASP-East AOD and ASDTA Smoke-East AOD
• GASP-West AOD, ASDTA Smoke-West AOD and ASDTA Smoke-Hawaii AOD